Intervenciones para la promoción del ejercicio habitual en pacientes con cáncer o que han presentado la enfermedad
Resumen
Antecedentes
Los efectos beneficiosos del ejercicio habitual para los pacientes con cáncer o que han presentado la enfermedad son evidentes. Sin embargo, aún no se sabe bien cómo promover la conducta de ejercitarse en cohortes sedentarias con cáncer. Una gran mayoría de pacientes que viven con o se recuperan de un cáncer no cumplen las recomendaciones de ejercitarse. Por lo tanto, es importante examinar las pruebas de cómo promover y mantener la conducta de ejercitarse.
Objetivos
Evaluar los efectos de las intervenciones para promover la conducta de ejercitarse en pacientes sedentarios con cáncer o que han presentado la enfermedad y abordar la siguiente pregunta: ¿Qué intervenciones son las más eficaces para mejorar la capacidad aeróbica y la fuerza y la resistencia musculoesquelética? ¿Qué efectos adversos se atribuyen a las diferentes intervenciones con ejercicios? ¿Qué intervenciones son las más eficaces para mejorar la conducta de ejercitarse entre los pacientes con diferentes cánceres? ¿Qué intervenciones es más probable que promuevan la conducta de ejercitarse a largo plazo (12 meses o más)? ¿Qué frecuencia de contacto con entrenadores profesionales se asocia con un aumento en la conducta de ejercitarse? ¿Qué base teórica se asocia con mayor frecuencia con un aumento en la conducta de ejercitarse? ¿Qué técnicas de cambio de la conducta se asocian con mayor frecuencia con un aumento en la conducta de ejercitarse?
Métodos de búsqueda
Se hicieron búsquedas en las siguientes bases de datos electrónicas: Registro Cochrane Central de Ensayos Controlados (Cochrane Central Register of Controlled Trials) (CENTRAL, The Cochrane Library, número 8, 2012), MEDLINE, EMBASE, AMED, CINAHL, PsycLIT/PsycINFO, SportDiscus y en PEDro, desde su inicio hasta agosto de 2012. También se buscó en la literatura gris, se les escribió a los principales expertos en el campo, se escribió a instituciones de beneficencia y se buscó en las listas de referencias de otras revisiones sistemáticas recientes.
Criterios de selección
Solamente se incluyeron ensayos controlados aleatorios (ECA) que compararon una intervención con ejercicios con un enfoque de atención habitual en pacientes sedentarios mayores de 18 años con un diagnóstico de cáncer primario homogéneo.
Obtención y análisis de los datos
Dos revisores que trabajaron de forma independiente (LB y KH) examinaron todos los títulos y resúmenes para identificar los estudios que podrían cumplir los criterios de inclusión, o que no fue posible excluir de manera segura sin evaluar el texto completo (p.ej. cuando no hubo resúmenes disponibles). Al menos dos miembros del equipo de revisión que trabajaron de forma independiente (LB y KH) resumieron formalmente todos los artículos elegibles mediante un formulario de obtención de datos. Cuando fue posible y apropiado se realizó un metanálisis de efectos fijos de los resultados de los estudios. Para los resultados continuos (p.ej. capacidad cardiorrespiratoria), se extrajo el valor final, la desviación estándar del resultado de interés y el número de participantes evaluados al seguimiento en cada brazo de tratamiento, para calcular la diferencia de medias estandarizada (DME) entre los brazos de tratamiento. Se utilizó la DME porque los investigadores utilizaron métodos heterogéneos para evaluar los resultados individuales. Si no fue posible ni apropiado realizar un metanálisis, los estudios se resumieron como narrativos.
Resultados principales
En esta revisión se incluyeron 14 ensayos con 648 participantes. Sólo se identificaron como elegibles los estudios que incluyeron el cáncer de mama, de próstata o colorrectal. Solo seis ensayos incorporaron un nivel objetivo de ejercicios que podría cumplir las recomendaciones actuales. Sólo se identificaron tres ensayos que intentaron validar objetivamente la conducta de ejercitarse independiente con acelerómetros o la monitorización de la frecuencia cardíaca. El cumplimiento con las intervenciones con ejercicios, que es crucial para comprender la dosis de tratamiento, a menudo se informa de manera deficiente. Es importante señalar que las medidas fundamentales de la conducta de ejercitarse (es decir frecuencia, intensidad y duración, repeticiones, grupos e intensidad del entrenamiento de resistencia), aunque fáciles de administrar e informar, rara vez se incluyen en los ensayos clínicos publicados.
Ninguno de los ensayos incluidos informó que el cumplimiento del 75% o más (el resultado primario declarado para esta revisión) en el grupo de intervención se ajustó a las recomendaciones actuales de ejercicios aeróbicos en cualquiera de los períodos de seguimiento. Solo dos ensayos informaron seis semanas de la conducta de ejercitar la resistencia, que cumpliría con las recomendaciones de las guías. Sin embargo, tres ensayos informaron el cumplimiento del 75% o más de una meta de ejercicios aeróbicos, que fue menor que la recomendación de las guías actuales de 150 minutos por semana. Los tres incorporaron componentes de ejercicios supervisados e independientes como parte de la intervención, y ninguno estableció restricciones en el grupo control en cuanto a la conducta de ejercitarse. Estos tres ensayos compartieron metas de conjuntos de programas y las siguientes técnicas de cambio de la conducta: generalización de una conducta objetiva; estimulación de la automonitorización de la conducta; y la estimulación de la práctica. A pesar de la incertidumbre alrededor del cumplimiento en muchos de los ensayos incluidos, las intervenciones dieron lugar a mejorías en la tolerancia al ejercicio aeróbico a las ocho a 12 semanas (de siete estudios, DME 0,73; intervalo de confianza [IC] del 95%: 0,51 a 0,95) en los participantes en la intervención en comparación con los controles. A los seis meses, la tolerancia al ejercicio aeróbico también mejoró (de cinco estudios, DME 0,70; IC del 95%: 0,45 a 0,94), pero se debe señalar que cuatro de los cinco ensayos utilizados en este análisis tuvieron un alto riesgo de sesgo, por lo que se justifica tener precaución al interpretar los resultados. El desgaste en el curso de estas intervenciones es habitualmente bajo (mediana 6%).
Conclusiones de los autores
Las intervenciones para promover el ejercicio en supervivientes de cáncer que informan mejores niveles de cumplimiento comparten técnicas comunes de cambio de la conducta. Lo anterior incluye fijar metas del programa, estimular la práctica y la automonitorización y estimular a los participantes a que intenten generalizar las conductas aprendidas en los ambientes de ejercicio supervisado a otros contextos no supervisados. Sin embargo, es probable que sea poco realista esperar que la mayoría de los supervivientes sedentarios alcancen las recomendaciones de las guías actuales de al menos 150 minutos por semana de ejercicio aeróbico. Al igual que todos los programas de ejercicio bien diseñados en cualquier contexto, las prescripciones se deben diseñar adaptadas a las capacidades individuales, y la frecuencia, duración e intensidad o los entrenamientos por grupos, repeticiones, intensidad o resistencia se deben generar sobre esta base.
PICOs
Resumen en términos sencillos
Título: Intervenciones para la promoción del ejercicio habitual en pacientes con cáncer o que han presentado la enfermedad
Pregunta: ¿Cuáles son las maneras más eficaces para mejorar y mantener la conducta de ejercitarse en los supervivientes de cáncer, o sea, los pacientes con cáncer o que han presentado la enfermedad?
Antecedentes: Estar habitualmente activo puede tener un amplio rango de efectos beneficiosos para los pacientes con cáncer o que han presentado la enfermedad. Dichos efectos varían desde mejorar la calidad de vida hasta mejorar la función física. También podría reducir el riesgo de recidiva del cáncer y de morir por cáncer. Se sabe que la mayoría de los pacientes con cáncer o que han presentado la enfermedad no son físicamente activos regularmente. Por lo tanto, es necesario comprender cómo hacer que esos pacientes que no realizan actualmente ejercicios empiecen a ser activos y cómo ayudarles a mantener este cambio en la conducta.
Características de los estudios: Solamente se incluyeron estudios que compararon una intervención de ejercicios con una comparación de atención habitual. Solo fueron elegibles los estudios que incluyeron pacientes sedentarios mayores de 18 años con el mismo diagnóstico de cáncer. Los participantes debían haber sido ubicados en un grupo al azar. Se buscaron pruebas en las bases de datos de investigación hasta agosto de 2012.
Resultados clave: Esta revisión incluyó 14 ensayos con 648 participantes. Las pruebas indican que existe una comprensión deficiente de cómo estimular que los pacientes con cáncer o que han presentado la enfermedad cumplan las recomendaciones actuales de ejercicios. Además, no fue apropiada la forma en la cual los investigadores de los ensayos informan qué incluyó el programa de ejercicio y en qué medida los participantes realmente lo siguieron. Sin embargo, se encontraron algunas pruebas de que fijar metas de ejercicios, estimular el ejercicio en los pacientes, lograr que los pacientes monitorizaran su propia conducta y lograr que los pacientes pensaran en cómo realizar ejercicios fuera de un ambiente supervisado podría ser útil. Además, se encontraron algunas pruebas que indicaron que los participantes en los estudios fueron más capaces de tolerar el esfuerzo de realizar el ejercicio hasta seis meses.
Calidad de la evidencia: Los problemas principales que se encontraron con respecto a la calidad de los estudios en esta revisión incluyeron no saber cómo los investigadores de los estudios realizaron la asignación al azar para los ensayos, y si los investigadores que hicieron las evaluaciones en los ensayos conocían a qué grupo se había asignado al azar el paciente que ellos evaluaban.
Authors' conclusions
Background
Description of the condition
Approximately 25 million people worldwide are living with cancer (Kamangar 2006). As such, cancer represents one of the largest global health problems. Breast, prostate and bowel cancer account for most of the survivorship population (around 52%) (Maddams 2009). Recent evidence from Macmillan Cancer Support indicates that cancer survival rates have much improved over the past 30 years (Macmillan Cancer Support 2012). Coleman 2011 reported that relative survival has improved in breast, colorectal, lung and ovarian cancer over the period 1995‐2007. This is good news for people living with the more common cancers who are undergoing, or recovering from, treatment. However, this also means that survivors are living longer with the consequences of cancer treatment, which frequently manifest as fatigue, reduced functional capacity and poorer health‐related quality of life (HRQoL). Further, cancer survivors are significantly more likely to report poor health outcomes compared with those with no history of cancer or a chronic condition (Elliott 2011). Throughout this review, we will define a cancer survivor as someone 'living with or beyond cancer', in line with the Macmillan Cancer Support definition (Macmillan Cancer Support 2011).
Description of the intervention
The goal of any exercise regime is a sustained physiological challenge that, over time, will induce a spectrum of beneficial cardiovascular, respiratory, musculoskeletal, neurological and metabolic adaptations. In the context of living with or beyond disease, it is these adaptations that will likely translate to a range of benefits from improvements in HRQoL and physical function to reducing disease progression, secondary recurrence and mortality (Fong 2012; Ibrahim 2011). Evidence for this in cancer populations ranges from epidemiological observations to cause and effect derived from randomised controlled trials (RCTs). As such, the potential for habitual exercise to act as a useful adjunctive therapy is a growing area of research interest (Rock 2012). The UK Chief Medical Officer recommends that in adults, weekly activity should add up to at least 150 minutes of moderate intensity exercise, performed in bouts of 10 minutes or longer (Department of Health 2011; Rock 2012). For example, this could translate to 30 minutes of exercise that raises heart rate and breathing rate, five times per week. Alternatively, 75 minutes of vigorous intensity activity spread across the week can confer similar benefits. The general consensus is that such guidelines are also appropriate for adult cancer survivors (Rock 2012). However, encouraging people to participate in regular exercise from a background of a sedentary lifestyle is difficult, requiring attention to psychosocial and behavioural influences on exercise, as well as the physiological basis of exercise (Greaves 2011). A still greater challenge is to provide a support structure for physical activity until it becomes a pattern of sustained healthy behaviour. In this review, interventions of interest include any programmes that promote increased exercise behaviour in people living with and beyond cancer, with a particular focus on long‐term change in exercise behaviour.
How the intervention might work
RCTs in people living with and beyond cancer have assessed various interventions aimed at promoting both short‐ and long‐term exercise participation. These include approaches such as supervised exercise (Bourke 2011); home‐based exercise (Courneya 2003); group‐based patient education (Carmack Taylor 2006); information leaflets (Demark‐Wahnefried 2007); cognitive behavioural therapy approaches (May 2008) and motivational interviewing (Bennett 2007). Tailored exercise interventions commonly comprise aerobic exercise training, resistance (strength) training or a combination of both, with or without behaviour change support. These approaches tend to vary in the extent to which they are based on behaviour change theory or employ specific behaviour change techniques.
Why it is important to do this review
A large majority of people living with and beyond cancer are not regularly active (for the purposes of this review, referred to as "sedentary") (Department of Health 2012). Systematic reviews and meta‐analyses of interventions promoting exercise participation in people living with and beyond cancer have reported a range of benefits, including reduced fatigue and improved functional capacity/physical fitness and HRQoL (Cramp 2012; Demark‐Wahnefried 2007; Fong 2012; McNeely 2006; Pekmezi 2011; Mishra 2012a; Mishra 2012b). However, most of the current evidence comes from trials with short‐term interventions and follow‐up, with any benefits likely to be transient if exercise behaviour is not sustained. Understanding which interventions are most efficacious in supporting long‐term exercise behaviour would be very useful (Bourke 2012), not just because of the HRQoL benefits, but emerging observational data suggest that being regularly active can reduce the chances of dying from cancer after diagnosis. Physical activity in observational studies is usually estimated as the self‐reported time spent exercising and is reported as metabolic equivalent task (MET)‐hours per week, using typical MET values for specific activities (Ainsworth 2011). In breast, prostate and bowel cancer, increased post‐diagnosis exercise behaviour has been reported to reduce cancer‐specific mortality risk by 32% to 61%, with around 18 to 27 MET‐hours per week of exercise conferring benefit (Haydon 2006; Holick 2008; Holmes 2005; Kenfield 2011; Meyerhardt 2006; Meyerhardt 2009; Nilsen 2006). Furthermore, providing an understanding of which behaviour change theories and behaviour change techniques are most efficacious in improving exercise behaviour will facilitate optimal design for future exercise interventions.
In the UK, the National Cancer Survivorship Initiative has highlighted physical symptoms as a consequence of treatment as an area of research with the highest priority (Richards 2011). Furthermore, from an international perspective, the recent Lancet Oncology Commission called for novel, more effective and less toxic interventions for delivering affordable cancer care (Sullivan 2011). Promoting habitual exercise participation could satisfy both of these high priority agendas.
We have deliberately chosen the term “habitual” over “regular” to reflect the intention to assess which interventions could improve and sustain exercise behaviour. “Regular exercise” can be applied to both short‐term and long‐term contexts, where as a “habitual” exerciser indicates a sustained and regular pattern of behaviour. Furthermore, “habitual” refers to the process of behavioural “habit forming”, which suggests an automaticity of behaviour, thereby improving maintenance of behaviour change (Gardner 2011; Verplanken and Melkelvik 2009). Systematically reviewing variations in frequency, intensity and duration of exercise achieved, the theoretical basis of the intervention and behaviour change techniques used, adherence to these interventions, attrition, reported adverse events and duration of sustained meaningful exercise behaviour is crucial for informing future trial design (in under‐studied cancer populations) and for facilitating the integration of exercise therapy into existing care pathways (when the evidence demonstrates efficacy for a given intervention). The purpose of this review is to summarise the existing literature on the effects of exercise‐promoting interventions on short‐ and longer‐term exercise behaviour in previously sedentary people living with and beyond cancer.
Objectives
Primary objective
To assess the effects of interventions to promote exercise behaviour in sedentary people living with and beyond cancer
Secondary objectives
To address the following questions:
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Which interventions are most effective in improving aerobic fitness and skeletal muscle strength and endurance?
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What adverse effects are attributed to different exercise interventions?
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Which interventions are most effective in improving exercise behaviour amongst patients with different cancers?
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Which interventions are most likely to promote long‐term (12 months or longer) exercise behaviour?
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What frequency of contact with exercise professionals is associated with increased exercise behaviour?
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What theoretical basis is most often associated with increased exercise behaviour?
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What behaviour change techniques are most often associated with increased exercise behaviour?
Methods
Criteria for considering studies for this review
Types of studies
RCTs that allocated participants or clusters of participants by a random method to an exercise‐promoting intervention compared with usual care or 'waiting list' control. We included only RCTs that aimed to improve exercise behaviour compared with a usual care comparison group. We included studies conducted both during and after primary treatment or during active monitoring. Only interventions that included a component targeted at increasing aerobic exercise and/or resistance exercise behaviour will be included in this review. We did not include studies of heterogeneous cancer cohorts (i.e. participants with different primary cancer sites). We did not include studies in 'at risk' populations (i.e. studies involving individuals who have risk factors for cancer but who have not yet been diagnosed with the disease) that addressed primary prevention research questions.
Types of participants
We included only trials involving adults (18 years of age or older) who had a sedentary lifestyle at baseline (i.e. not undertaking 30 minutes or more of exercise of at least moderate intensity, three days per week, or 90 minutes in total of moderate intensity exercise per week). Participants must have been histologically or clinically diagnosed with cancer regardless of sex, tumour site, tumour type, tumour stage and type of anticancer treatment received. We excluded trials directed specifically at end‐of‐life‐care patients and individuals who were currently hospital inpatients.
Types of interventions
For the purposes of this review, the phrases 'exercise' and 'physical activity' were used interchangeably. Definitions of exercise, related terms and nomenclature that describe the performance of exercise must adhere to principles of science and must satisfy the Système International d'Unités (SI), which was adopted universally in 1960. Hence, we referred to the appropriate, combined definition that applies to all situations: "A potential disruption to homeostasis by muscle activity that is either exclusively or in combination, concentric, eccentric or isometric" (Winter and Fowler 2009). Investigators must have reported frequency, duration and intensity of aerobic exercise behaviour or frequency, intensity, type, sets, repetitions and pattern of resistance of exercise behaviour that was prescribed in the intervention.
We acknowledge that the maximal aerobic capacity (VO2max)/peak is often the most informative metric for setting aerobic exercise intensity; however, given the nature of the population involved (elderly, potentially with multiple co‐morbidities), it is often difficult to conduct maximal testing protocols to prescribe intensity on the basis of these measures because of the requirements for medically qualified staff to be present during assessment. As such, for reasons of pragmatism, we accept that exercise intensity is more frequently reported in the cohorts in terms of age‐predicted maximum heart rate max (HRmax) or on the Borg rating of perceived exertion (RPE) scale (Borg 1982). The interventions in this review were categorised as achieving a mild (less than 60% HRmax/10 RPE or less), moderate (60% to 84% HRmax/11 to 14 RPE) or vigorous (85% HRmax or more/15 RPE or more) exercise intensity.
Types of outcome measures
Primary outcomes
Aerobic exercise behaviour as measured by:
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exercise frequency (number of bouts per week);
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exercise duration (total minutes of exercise achieved);
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exercise intensity (e.g. % HRmax, RPE);
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estimated energy expenditure from free living physical activity (e.g. from accelerometer readings [where available]);
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adherence to the exercise intervention (% of exercise sessions completed/attended);
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total duration of intervention when ≥75% adherence is achieved (in weeks); and
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total duration of sustained exercise behaviour meeting American Cancer Society guidelines for exercise in people living with and beyond cancer (Rock 2012; i.e. aim to exercise at least 150 minutes per week, with at least two days per week of strength training).
Resistance exercise behaviour as measured by:
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exercise frequency (number of bouts per week);
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exercise intensity (e.g. % of 1 repetition max or % of body mass);
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type of exercise (e.g. free weights, body weight exercise);
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repetitions;
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sets; and
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pattern (quantification of rest period in relation to sets and repetitions).
Secondary outcomes
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Change in aerobic fitness or exercise tolerance (maximal or submaximal when measured directly or by a standard field test).
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Change in skeletal muscle strength and endurance.
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Adverse effects.
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Trial recruitment rate.
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Intervention attrition rate.
Interventions were judged as successful in achieving exercise goals as identified in the study methods if investigators reported at least 75% adherence over a given follow‐up period. Data on compliance with the intervention were quantified in terms of number of prescribed exercise sessions completed as a proportion of the total set. The intervention must have included at least 6 weeks of follow‐up. Interventions were categorised according to whether they were based on a behaviour change theory (e.g. control theory, social cognitive theory; Bandura 2000; Bandura 2002; Carver 1982). This relates to the National Institute for Health and Clinical Excellence (NICE) guidance for behaviour change, which recommends that clinicians should be explicit about the theoretical constructs on which interventions are based (NICE 2007). Interventions were also categorised using the ‘Coventry, Aberdeen & London－Refined’ (CALO‐RE) taxonomy (Michie 2011). This is a validated taxonomy of behaviour change techniques (BCTs) that can be used to help people change their exercise behaviour. Categorising interventions according to this taxonomy resulted in a better understanding of which techniques are employed by current interventions and how they are related to short‐ and longer‐term exercise behaviour change.
Search methods for identification of studies
Electronic searches
We searched the following electronic databases.
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CENTRAL (Cochrane Central Register of Controlled Trials).
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MEDLINE (Medical Literature Analysis and Retrieval System Online).
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EMBASE (the Excerpta Medica database).
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AMED (Allied and Alternative Medicine Database; covers occupational therapy, physiotherapy and complementary medicine).
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CINAHL (Cumulative Index to Nursing and Allied Health Literature).
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PsycINFO (Database of the American Psychological Association).
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SportDiscus (Sports Evidence Database).
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PEDro (Physiotherapy Evidence Database).
The MEDLINE search strategy is presented in Appendix 2. For databases other than MEDLINE, we adapted the search strategy accordingly: EMBASE (Appendix 3), AMED (Appendix 4), CINAHL (Appendix 5) and PsycINFO (Appendix 6).
The search strategies were developed with the Cochrane Gynaecological Cancer Group Information Manager (Jane Hayes) and included MeSH and text word terms as appropriate.
We attempted to identify all relevant articles on PubMed, using the 'related articles' feature, and performed further searches for newly published articles.
Searching other resources
We searched reference lists of retrieved articles and published reviews on the topic. We contacted the principal investigators of the identified studies, as well as 10 national and international experts in the field, to ask whether they were aware of any other relevant unpublished studies in the area.
We expanded the database search by identifying additional relevant studies for this review, including unpublished studies and references in the grey literature. This was done by searching the OpenGrey database (http://www.opengrey.eu/), which includes technical or research reports, doctoral dissertations, conference papers and other types of grey literature. We also searched the following clinical trials web pages:
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Metaregister (http://www.controlled‐trials.com/rct);
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ClinicalTrials.gov (http://www.clinicaltrials.gov); and
We screened the full text of any relevant papers identified through these searches. We also approached the principal investigators and major co‐operative groups active in this area to ask for relevant data. Furthermore, we wrote to Cancer Research UK (CRUK), Macmillan Cancer Support, the World Cancer Research Fund (WCRF), the Association for International Cancer Research (AICR), the American Association for Cancer Research (AACR), the American Cancer Society (ACS) and the American Society of Clinical Oncology (ASCO) to enquire about relevant unpublished papers.
Data collection and analysis
Selection of studies
We imported results from each database into the reference management software package Endnote, from which we removed duplicates and selected relevant articles for screening. After training on the first 100 references retrieved from two different databases was provided to ensure a consistent approach, two review authors (LB and KH) worked independently to screen all titles and abstracts to identify studies that met the inclusion criteria, or that could not be safely excluded without assessment of the full text (e.g. when no abstract was available). Disagreements were resolved by discussion with another review author (ST or DR). Full texts were retrieved for these articles.
After training was provided to ensure a consistent approach to study assessment and data abstraction, two review authors worked independently to assess the retrieved full texts. We linked together multiple publications and reports on the same study. Studies that appeared to be relevant but are excluded at this stage were listed in the 'Characteristics of excluded studies' table. We resolved disagreements by discussion with other group members. We attempted to contact study corresponding authors if we could not access a full text (e.g. if only an abstract was available), if we required more information to determine whether a study could be included (e.g. to determine baseline exercise behaviour of a cohort) or if we required supplementary information about an already eligible trial (please also see Excluded studies).
Data extraction and management
We extracted the following data.
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Study details: author, year, research question/study aim; country where the research was carried out; recruitment source (e.g. consecutive sampling from outpatient appointments; advertising in the community; convenient sample from support groups); inclusion and exclusion criteria; study design (cluster RCT, non‐cluster RCT, single centre or multi‐centre); length of follow‐up; description of usual care.
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Intervention details: categorisation of intervention (e.g. supervised, independent, educational); setting (e.g. dedicated exercise facility, community, home); exercise prescription components (e.g. aerobic exercise, resistance exercise, stretching); theoretical basis, behaviour change techniques (using CALO‐RE taxonomy), frequency of contact with an exercise professional.
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Participant characteristics: primary cancer diagnosis; any cancer treatment currently undertaken; metastatic disease status; age; sex; socio‐economic status; ethnicity; reported comorbidities.
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Resulting exercise behaviour: method of measuring exercise (e.g. self‐report questionnaire). Numbers of participants randomly assigned and assessed at specified follow‐up points. Frequency, duration, intensity of aerobic exercise achieved; frequency, intensity, type, sets, repetitions and pattern of resistance exercise achieved; total duration of the intervention and total duration of sustained meaningful exercise behaviour as a result of the intervention. Adherence to the intervention; rate of attrition and adverse effects reported.
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Resulting change in other outcomes: changes in aerobic fitness and estimated energy expenditure from free living physical activity.
Two members of the group worked independently (LB and KH) to abstract data from all eligible papers using the data collection form. Data were to be entered into the Cochrane Collaboration's statistical software, Review Manager 2011, by one review author and checked by a second review author.
Assessment of risk of bias in included studies
Risk of bias and methodological quality were assessed in accordance with the Cochrane Collaboration's tool for assessing risk of bias (Higgins 2011). The tool includes the following seven domains:
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sequence generation (method of randomisation);
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allocation concealment (selection bias);
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blinding (masking) of participants and personnel (detections bias);
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blinding (masking) of outcome assessors (detection bias);
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incomplete outcome data;
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selective outcome reporting; and
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other sources of bias.
However, we did not include whether participants were blind to their allocation of intervention or to control groups, as it is often not possible (e.g. in a supervised exercise setting) to blind participants to an intervention while promoting exercise behaviour. Two review authors (LB and KH) applied the risk of bias tool independently, and differences were resolved by discussion with a third review author (ST or DR). We summarised results in both a risk of bias graph and a risk of bias summary. Results of meta‐analyses were interpreted in light of the findings with respect to risk of bias. We contacted study authors to ask for additional information or for further clarification of study methods if any doubt surrounded potential sources of bias. Individual risk of bias items can be seen in Appendix 7.
Measures of treatment effect
For the purposes of this review, all exercise behaviour was synthesised as specified in the primary outcomes. For comparison of measures of change in fitness levels or estimated energy expenditure from free living physical activity, please see the section on "Continuous data", Data synthesis.
Unit of analysis issues
We included no cross‐over trials in this review because of the high risk of contamination. It can be very difficult to “wash out” exercise behaviour. Cancer survivors in particular can be a highly motivated cohort, and significant contamination has been reported even in conventional RCT settings (Courneya 2003; Mock 2005). Indeed, some trials have reported significant maintenance up to three months after cessation of the intervention.(Bourke 2011). Hence this learning effect distorts results. Furthermore, asking individuals to revert to sedentary behaviour could be considered unethical (Das and Horton 2012). Therefore, any cross‐over trials identified were rejected at the title and abstract screening stage.
Dealing with missing data
We assessed missing data and dropout rates for each of the included studies and reported the numbers of participants included in the final analysis as a proportion of all participants included in the study. We assessed the extent to which studies conformed to an intention‐to‐treat analysis.
Assessment of heterogeneity
Consistency of results was assessed visually and through examination of the I2 statistic, a quantity that describes approximately the proportion of variation in point estimates that is due to heterogeneity rather than sampling error. I2 greater than or equal to 50% was considered significant heterogeneity. We addressed this by performing a sensitivity analysis that excludes any heterogeneous trials. We supplemented this with a test of homogeneity to determine the strength of evidence that the heterogeneity is genuine. When significant statistical heterogeneity was detected, differences in characteristics of the studies or other factors were explored as possible sources of explanation. Any differences were summarised in a narrative synthesis.
Assessment of reporting biases
Publication bias
We intended to examine funnel plots corresponding to meta‐analysis of the primary outcomes to assess the potential for small study effects such as publication bias if a sufficient number of studies (i.e. more than 10) was identified. However, this was not the case; therefore this step was not included in the analysis.
Data synthesis
Continuous data
For continuous outcomes (e.g. cardiorespiratory fitness), we extracted the final value, the standard deviation of the outcome of interest and the number of participants assessed at endpoint for each treatment arm at the end of follow‐up, to estimate standardised mean differences between treatment arms.
Dichotomous outcomes
For dichotomous outcomes (e.g. adverse effects, deaths), if it was not possible to use a hazard ratio, we extracted the number of participants in each treatment arm who experienced the outcome of interest and the number of participants assessed at endpoint, to estimate a risk ratio.
Meta‐analysis
When possible, and if appropriate, we performed a meta‐analysis of review outcomes. If statistical heterogeneity was noted, a meta‐analysis was performed using a random‐effects model. A fixed‐effect model was to be used if no significant statistical heterogeneity was observed.
When possible, all data extracted were those relevant to an intention‐to‐treat analysis in which participants were analysed in groups to which they were assigned. We noted the time points at which outcomes were collected and reported.
Subgroup analysis and investigation of heterogeneity
If a sufficient number of studies were identified, we performed subgroup analyses for the following.
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Cancer site.
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Type of intervention (i.e. supervised, home‐based, etc).
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Age of individuals (i.e. elderly vs non‐elderly).
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Current treatment (currently undergoing treatment vs not currently undergoing treatment).
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Participants with metastatic disease (metastatic cohort vs non‐metastatic cohort).
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Accordance with behaviour change theory.
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Interventions in obese individuals (mean body mass index (BMI) of intervention group > 30 kg/m2 vs mean BMI of intervention group < 30 kg/m2).
Sensitivity analysis
Methodological flaws were judged using the Cochrane Collaboration's tool for assessing risk of bias to identify studies of high and low quality (Higgins 2011). Sensitivity analyses were performed with the studies of low quality excluded.
Results
Description of studies
Please see Table 1, 'Summary of included studies'. See 'Characteristics of included studies'; 'Characteristics of excluded studies'; 'Characteristics of studies awaiting classification'; and 'Characteristics of ongoing studies'.
| Study | Exercise components | n | Meets Rock et al guidelines? | Adherence summary | At least 75% adherence? | High risk of bias? | Change in AET reported? | Adverse effects |
| Aerobic | 37, 38 (intervention vs control) | 33% reported 150 minutes/wk of moderate intensity aerobic exercise at an average of 76% HR, for six months | 75% of women were doing between 90 and 119 minutes of moderate intensity aerobic activity per week at six months | Yes; for up to 119 minutes per week | No | No | Five of the 37 women randomly assigned to exercise experienced an adverse effect; two were related to the study (plantar fasciitis) | |
| Aerobic | 34, 36, 38 (intervention, sham, control, respectively) | No | 77% of the exercise therapy; attended 70% (at least 17 of 24 sessions) or more of sessions | Unclear | Yes; outcome assessors were not blinded to participants’ group allocation | Yes | Three withdrawals in the intervention group: unclear as to why this occurred. Some withdrawals because of medical complications in placebo and control arms but unclear whether study related | |
| Aerobic | 13 intervention, 8 placebo stretching controls | Unclear | Participants in the intervention group averaged 3.6 days per week of aerobic exercise over an 8‐week period | Unclear | No | Yes | None reported | |
| Aerobic | 14, 13 (intervention vs control) | Unclear | Not reported | Not reported | Yes; method of measuring exercise and adherence not reported | No | None reported | |
| Aerobic | 22,19 (intervention vs control). | No | Average weekly frequency of exercise was 2.4 ± 0.6 sessions, and average duration of exercise within prescribed target HR was 27.8 ± 8.1 minutes per session. Overall adherence was 78.3% ± 20.1% | Yes | Yes; data missing for 45% of the cohort | Yes | Reasons for withdrawal included personal problems (n = 2), problems at home (n = 2), problems related to chemotherapy (n = 3), thrombophlebitis in the lower leg (n = 2), non－exercise‐related injuries (n = 1), and death (n = 1). Unclear to which arm of the trial these date relate | |
| Aerobic | 12, 12 (intervention vs control) | Unclear | Participants attended a mean of 88% of the 36‐session supervised exercise programme | Yes | Yes; 38% lost to follow‐up. Exercise tolerance test was performed but no control group comparison data were reported | Yes | None reported; however, it is unclear why the six controls dropped out | |
| Aerobic | 43, 43 (intervention vs control) | Unclear | At week 12, intervention participants reported a mean of 128.53 minutes/wk of moderate intensity exercise. However, no changes were reported in the accelerometer data in the intervention group (change score = ‐0.33 kcal/h) | Less than 75% of the intervention group was meeting the prescribed goal after week 4 | Yes; significantly more control group participants were receiving hormone treatment. Accelerometer data do not support the self‐reported physical activity behaviour | Yes | Not clear whether chest pain was related to exercise in dropout whose participation was terminated | |
| Aerobic | 20, 26 (intervention vs control) | Three‐day PAR questionnaire indicates that 64.7% of the intervention group and 40.9% of the control group were achieving the guidelines at three months | Correlation between self‐reported moderate intensity exercise and accelerometer data at three‐month follow‐up, when the only significant between‐group change is reported: r = 0.32 | No | Yes; accelerometer data were not reported; also, cited correlation is weak (0.32). Further, substantial contamination was noted in the control group | Yes | One cancer recurrence in the control group at three months | |
| Aerobic and resistance | 9, 9 (intervention vs control) | Six weeks of resistance exercise twice a week | 90% attendance at the supervised sessions. 94% of independent exercise sessions were completed | Yes | No | Yes | One stroke in the intervention group, unrelated to the exercise programme | |
| Aerobic and resistance | 25, 25 (intervention vs control) | Six weeks of resistance exercise twice a week | 95% attendance at supervised exercise sessions. Compliance with self‐directed exercise aspect of the lifestyle intervention was 87% | Yes | Yes; high dropout rate at postintervention six‐month follow‐up assessment | Yes | Two men in the intervention arm were discontinued because of cardiac complications before the 12‐week assessments. Two more reported musculoskeletal complaints before the six‐month assessment. Five men reported various health problems in the control group that prohibited them from attending the six‐month assessment | |
| Aerobic and resistance | 16, 16 (intervention vs control) | Unclear | Most women (88%) allocated to the intervention group participated in 70% or more of scheduled supervised exercise sessions | Unclear | Yes; adherence data on unsupervised aspect of the intervention are not clear | No | None reported | |
| Aerobic and resistance | 7,7 (intervention vs control) | No | Unclear | Unclear | Yes; adherence to exercise not reported | No | None reported | |
| Aerobic and resistance | Flexibility group (n = 13), aerobic group (n = 12), resistance group (n = 17), aerobic and resistance group (n = 13) | 12 weeks of resistance exercise two or three times per week | Mean percentages of adherence were as follows: flexibility = 85%, aerobic = 81%, resistance = 91% and aerobic plus resistance = 86% | Unclear | Yes; a significant number of dropouts belonged to the resistance exercise group (n = 8/13). Only 50% of activity logs were returned | Yes | Adverse effects were reported in two women during the study. In both cases, the women developed tendonitis: one in the shoulder and the other in the foot. Both had a history of tendonitis, and both received standard treatment | |
| Aerobic and resistance | 51 participants in total. Numbers randomly assigned to each arm are unclear | Three months of resistance exercise three times per week | Women assigned to the structured intervention completed an average of 83% of their scheduled hospital‐based exercise sessions (only 4 weeks in duration), and 76.9% completed all 12 sessions. Home‐based component (8 weeks in duration) | Unclear | Yes; numbers randomly assigned to intervention and control groups are unclear, as are numbers completing in each arm | No | Unclear |
AET = aerobic exercise tolerance.
Results of the search
Figure 1 illustrates the process of the literature search and study selection for the review. We identified 4827 unique records from research databases and 732 records through grey literature and "snowballing" techniques, which included reference checking from recent large systematic reviews (Fong 2012; Mishra 2012a; Mishra 2012b). Given that the details of prescribed exercise are rarely reported in manuscript abstracts (e.g. frequency, intensity, duration of exercise prescription), this led to evaluation of a large number of manuscripts at full text stage (n = 402). From these full text articles, 377 manuscripts were excluded, leaving 25 publications included in the review. Reasons for excluding these 377 publications are covered in the Excluded studies section below.
PRISMA flow diagram.
Included studies
After consensus agreement was reached by review authors (LB and KH), 14 trials were included in this review (Bourke 2011a; Bourke 2011b; Cadmus 2009; Daley 2007a; Drouin 2005; Hayes 2009; Kaltsatou 2011; Kim 2006; McKenzie 2003; Musanti 2012; Perna 2010; Pinto 2003; Pinto 2005; Pinto 2011). We also included in our analysis 11 follow‐up papers that performed secondary analyses of data from a primary RCT. We sent 116 emails to request unpublished information for manuscripts that were unclear in reporting relative to our inclusion/exclusion criteria. We were able to include 15 and to exclude 34 published manuscripts on the basis of information received in correspondence from authors.
Only RCTs were included in the review. All included trials used a parallel‐group design with baseline assessment and follow‐up of 12 months maximum. All included trials were conducted using participant level randomisation. The format of reporting precluded data extraction for meta‐analytical combination in two studies (Drouin 2005; Pinto 2003). Sample size ranged from 14 to 108, with a total of 648 participants included in this review (mean age range 51 to 72).
Participants
Most trials were conducted in breast cancer survivors (Cadmus 2009; Daley 2007a; Drouin 2005; Hayes 2009; Kaltsatou 2011; Kim 2006; McKenzie 2003; Musanti 2012; Perna 2010; Pinto 2005; Pinto 2003); only two trials involved colorectal cancer (Bourke 2011a; Pinto 2011), and one prostate cancer (Bourke 2011b). Of these trials, eight included participants who were currently undergoing active treatment inclusive of hormone‐based therapy (Bourke 2011b; Cadmus 2009; Daley 2007a; Drouin 2005; Kim 2006; Musanti 2012; Perna 2010; Pinto 2005). We found only one study that reported data from participants with metastatic disease (Bourke 2011b) and two that were conducted in obese cohorts (i.e. mean BMI > 30 kg/m2; Cadmus 2009; Drouin 2005). An overwhelming proportion of participants were white, and only one study reported data from an ethnically diverse sample (Perna 2010). Comorbidities at baseline were largely unclear or unreported; only Daley 2007a and Hayes 2009 reported on proportions with lymphedema, and Perna 2010 reported on proportions with clinically relevant depression scores.
Interventions
Eight trials prescribed exclusively aerobic exercise (Cadmus 2009; Daley 2007a; Drouin 2005; Kaltsatou 2011; Kim 2006; Pinto 2003; Pinto 2005; Pinto 2011); the remaining RCTs used a mix of aerobic and resistance training (no exclusively resistance training studies met our inclusion criteria). Seven trials used a combination of supervised and home‐based exercise (Bourke 2011a; Bourke 2011b; Cadmus 2009; Hayes 2009; Kim 2006; Perna 2010; Pinto 2003), four trials opted to use an exclusively home‐based design (Drouin 2005; Musanti 2012; Pinto 2005; Pinto 2011), and only three were exclusively supervised trials (Daley 2007a; Kaltsatou 2011; McKenzie 2003). Contact with exercise professionals or study researchers ranged from 20 times over 12 weeks (Hayes 2009) to weekly phone calls after an initial one‐to‐one exercise consultation (Pinto 2005; Pinto 2011). Of note, seven trials (Drouin 2005; Kaltsatou 2011; Kim 2006; McKenzie 2003; Pinto 2003; Pinto 2005; Pinto 2011) placed restrictions on the control group regarding exercise behaviour during the course of the trial, usually taking the form of direct instruction to refrain from changing exercise behaviour. Just six trials incorporated prescriptions that would meet the Rock 2012 recommendations for aerobic exercise (i.e.150 minutes per week; Cadmus 2009; Pinto 2011) or resistance exercise (i.e. resistance training strength training exercises at least two days per week; Bourke 2011a; Bourke 2011b; Musanti 2012; Perna 2010). Only three trials were identified that attempted to objectively validate independent exercise behaviour with accelerometers or heart rate monitoring (Cadmus 2009; Pinto 2005; Pinto 2011).
Full details of intervention (behaviour change technique (BCT)) coding according to the CALO‐RE taxonomy can be seen in Table 2. Of the 14 interventions provided, only five were explicitly based on a theoretical model (Daley 2007a; Musanti 2012; Perna 2010; Pinto 2005; Pinto 2011); the trans‐theoretical model was most common. All interventions had a target exercise level set by the programme. Only sjx trials set exercise goals in conjunction with participants (BCT # 5). In addition, all prompted practise of the behaviour (BCT #26), and all but four (Bourke 2011a; Hayes 2009; McKenzie 2003; Pinto 2005) reported providing instruction on how to perform the behaviour (BCT #21), although it may be anticipated that this did occur but just was not reported. Other common BCTs included setting of graded tasks (i.e. increased exercise duration or intensity over time) and self‐monitoring of behaviour (exercise) and outcomes of behaviour (e.g. heart rate), although it is not clear for all interventions whether this was done primarily for data collection or as a mechanism of behaviour change. It is important to note that when monitoring did occur (BCT #16), feedback on performance (BCT #19) was provided in only 4/10 (Cadmus 2009; Perna 2010; Pinto 2005; Pinto 2011). Similarly, in only two of six interventions (Daley 2007a; Perna 2010) for which participants had some input into setting of goals were these reviewed (BCT #10). Of note, few interventions (Cadmus 2009; Daley 2007a; Kim 2006; Perna 2010) reported providing information on the consequences of behaviour (BCT #1), although less than half reported problem solving with barriers identified (BCT #8) and solutions facilitated (Bourke 2011b; Cadmus 2009; Daley 2007a; Perna 2010; Pinto 2005; Pinto 2011). Only three trials used techniques to increase social support (BCT #29; Cadmus 2009; Daley 2007a; Perna 2010).
| Behaviour change technique | YALE | |||||||||||||
| Theory | TTM | EXSEM | TTM | TTM | TTM SCT | |||||||||
| 1. Provide Info on consequences of behaviour in general | X | X | X | X | ||||||||||
| 2. Provide Info on consequences of behaviour to the individual | ||||||||||||||
| 3. Provide Info about others' approval | ||||||||||||||
| 4. Provide normative info about others' behaviour | ||||||||||||||
| Programme set goal | X | X | X | X | X | X | X | X | X | X | X | X | X | X |
| 5. Goal setting (behaviour) | X | X | X | X | X | X | ||||||||
| 6. Goal setting (outcome) | ||||||||||||||
| 7. Action planning | ||||||||||||||
| 8. Barrier identification/Problem solving | X | X | X | X | X | X | ||||||||
| 9. Setting of graded tasks | X | X | X | X | X | X | X | X | X | |||||
| 10. Prompt review of behavioural goals | X | X | ||||||||||||
| 11. Prompt review of outcome goals | ||||||||||||||
| 12. Prompt rewards contingent on effort or progress towards goal | X | X | X | |||||||||||
| 13. Provide rewards contingent on successful behaviour | X | |||||||||||||
| 14. Shaping | ||||||||||||||
| 15. Prompt generalisation of a target behaviour | X | X | X | X | X | |||||||||
| 16. Prompt self‐monitoring of behaviour | X | X | X | X | X | X | X | X | X | X | ||||
| 17. Prompt self‐monitoring of behavioural outcome | X | X | X | X | X | X | ||||||||
| 18. Prompt focus on past success | X | |||||||||||||
| 19. Feedback on performance provided | X | X | X | X | ||||||||||
| 20. Information provided on where and when to perform behaviour | X | X | ||||||||||||
| 21. Instruction provided on how to perform the behaviour | X | X | X | X | X | X | X | X | X | X | ||||
| 22. Modelling/Demonstration of behaviour | X | X | X | |||||||||||
| 23. Teaching to use prompts/cues | X | X | X | |||||||||||
| 24. Environmental restructuring | X | X | ||||||||||||
| 25. Agreement on behavioural contract | X | |||||||||||||
| 26. Prompt practise | X | X | X | X | X | X | X | X | X | X | X | X | X | X |
| 27. Use of follow‐up prompts | X | X | ||||||||||||
| 28. Facilitating social comparison | ||||||||||||||
| 29. Planning social support/social change | X | X | X | |||||||||||
| 30. Prompt identification as role model/position advocate | ||||||||||||||
| 31. Prompt anticipated regret | ||||||||||||||
| 32. Fear arousal | ||||||||||||||
| 33. Prompt self‐talk | ||||||||||||||
| 34. Prompt use of imagery | ||||||||||||||
| 35. Relapse prevention/coping planning | X | X | ||||||||||||
| 36. Stress management/emotional control training | X | |||||||||||||
| 37. Motivational interviewing | ||||||||||||||
| 38. Time management | ||||||||||||||
| 39. General communication skills training | ||||||||||||||
| 40. Stimulation of anticipation of future rewards |
EXSEM = exercise self‐esteem model; SCT = social cognitive theory; TTM = transtheroretical model.
Excluded studies
Reasons for excluding published studies included the following.
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Non‐RCTs (e.g. review manuscripts, comment/editorial articles).
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Mixed cancer cohorts or cohorts that included non‐cancer populations.
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Trials that failed to describe essential metrics of exercise prescription used in the intervention (e.g. frequency, intensity, duration).
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Trials involving active participants at baseline.
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Trials involving hospital inpatients.
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Interventions that provided follow‐up of less than 6 weeks.
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Trials involving participants younger than 18 years of age.
Because of the volume of studies identified by the search, only the first occurrence of an exclusion criterion was noted in the publication, although frequently, trials exhibited several of the criteria listed above. Therefore, it was neither valid nor informative to present the number of papers excluded under each of the reasons listed above. The extent of exclusion at the full text screening stage (377 publications excluded from 402) provided the first indication of problems associated with quality of reporting in this research area. We sent emails to 116 corresponding authors to request additional information (regarding included studies, excluded studies and studies that we could not access) to determine eligibility and to supplement published data for this review.
Only a subset of excluded studies could be included in the 'Characteristics of excluded studies' section. This is a result of the huge volume of trials that had to be full text screened (N = 402) and the high proportion (around 90%) that were excluded. In accordance with editorial advice, we divided this large number (N = 365) into initially unclear trials that required further investigation (N = 76) and those that clearly were not eligible after full text had been retrieved (N = 289). This approach is analogous to the approach adopted in recent reviews (Galway 2012) and is detailed in the existing PRISMA diagram (Figure 1).
Risk of bias in included studies
Only three trials were judged not to include a high risk of bias (Bourke 2011a; Cadmus 2009; Drouin 2005). Full results of the methodological quality assessment for allocation bias, blinding, incomplete data outcome and selective reporting (along with justifications) are covered in the risk of bias tables for each study and are illustrated in Figure 2 and Figure 3. Seven trials stated that an intention‐to‐treat analysis was used (Bourke 2011a; Bourke 2011b; Cadmus 2009; Daley 2007a; Perna 2010; Pinto 2005; Pinto 2011).
Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.
Allocation
Most trials (8 out of 14) were not clear in their description of concealment in randomisation allocation. However, no trial was judged to have a high risk of bias in this respect.
Blinding
Only four trials explicitly stated whether they had undertaken blinding of study assessors (Bourke 2011a; Bourke 2011b; Daley 2007a; Hayes 2009). The remaining trials did not include enough information for the review authors to make a definitive judgement on this criterion.
Incomplete outcome data
Four trials were judged to have been subject to incomplete data outcome bias. Bourke 2011b reported a 44% attrition at six months of follow‐up; Kim 2006 reported data from only 41 of 74 participants randomly assigned; Musanti 2012 reported that 13 women (24%) did not complete their assigned 12‐week programme; and Pinto 2003 did not report control group data for the exercise tolerance test. However, most studies (8 out of 14) were explicit in their reporting of outcomes.
Selective reporting
Most studies reported all listed outcomes; however, three trials were judged to omit outcomes from their results reporting. Musanti 2012 did not report waist and upper, mid and lower arm circumference outcomes; Pinto 2003 reported none of the physiological assessments in the control group at 12 weeks of follow‐up; Pinto 2011 did not report data derived from the use of accelerometers.
Other potential sources of bias
Other sources of bias found in the included trials that are worth highlighting include adherence data missing or not clear (Hayes 2009; Kaltsatou 2011; McKenzie 2003; Musanti 2012); high attrition at follow‐up (Bourke 2011b; Pinto 2003); low recruitment rate (Bourke 2011a); significant differences in participants excluded from trial analysis/dropouts (Kim 2006; Musanti 2012; Pinto 2003); numbers randomly assigned to trial arms with trial completion rate unclear (Perna 2010); significant differences in cohorts at baseline (Musanti 2012; Pinto 2003; Pinto 2005); and inconsistencies between objective and subjective measures of exercise behaviour (Pinto 2005; Pinto 2011). Insufficient information was reported to permit a judgement about any single element of bias because of lack of data in Cadmus 2009; Drouin 2005; Hayes 2009; Kaltsatou 2011; Kim 2006; McKenzie 2003; Pinto 2003; Pinto 2005; and Pinto 2011.
Effects of interventions
Primary outcomes
Please see Table 1, 'Summary of included studies'. As it is not meaningful to interpret individually the component metrics of aerobic (frequency, intensity and duration) or resistance exercise (frequency, intensity, type of exercise, sets and repetitions) behaviour, these primary outcomes are presented in the narrative synthesis below of interventions achieving 75% or greater adherence.
None of the trials included in this review reported that 75% or more of the intervention group met the Rock 2012 aerobic exercise guidelines at any given follow‐up. Only three trials reported adherence of 75% or greater to their specified aerobic exercise prescription (Bourke 2011a; Bourke 2011b; Cadmus 2009). It is notable that all three incorporated both a supervised and an independent exercise component as part of their intervention, and none placed restrictions on the control group in terms of exercise behaviour. Cadmus 2009 was likely the most successful study regarding the promotion of aerobic exercise behaviour, with 75% of the intervention group reporting between 90 and 119 minutes per week of moderate intensity exercise, at an average heart rate of 76% of predicted maximum, for six months. However, of these three trials, only Bourke 2011a and Bourke 2011b met the Rock 2012 exercise guidelines. Specifically, two to four sets of resistance exercise at 60% of one repetition max (RM) for eight to 12 repetitions were carried out twice per week for just six weeks. These three trials all shared the following BCTs.
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Programming a set goal.
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Prompting generalisation of a target behaviour.
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Prompting self‐monitoring of behaviour.
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Prompting practise.
Aside from generalisation of a target behaviour, these three interventions did not differ from other interventions in terms of BCTs reported. Nor did trials explicitly state a theoretical basis. Other studies such as Daley 2007a and Perna 2010 were much more comprehensive in their reporting of BCTs and were based on recognised behaviour change theory. Several trials might have achieved adherence of 75% or greater, but because of unclear reporting, it was not possible to make a judgement on whether this criterion had been fulfilled. Reasons for judgement of unclear or unsuccessful adherence are detailed below.
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Daley 2007a: judgement unclear; adherence reported as a proportion of participants attending a proportion of set exercise sessions (i.e. 77% of the intervention group attending 70% of sessions).
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Drouin 2005: judgement unclear; adherence reported as mean number of days per week when exercise was undertaken, relative to a range within the prescription (i.e. 3.6 days per week, when the prescription was for three to five days per week).
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Kaltsatou 2011: judgement unclear; no adherence data reported.
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Kim 2006: judgement unclear; high adherence was reported (78%) but in tandem with substantial attrition (i.e. data missing for 45% of the cohort).
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Pinto 2003: judgement unclear; high adherence was reported (88%) but in tandem with substantial attrition (i.e. 25% of the intervention group dropped out over the intervention period).
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Pinto 2005: judgement unsuccessful; 75% adherence threshold was not met after week 4.
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Pinto 2011: judgement unsuccessful; three‐day PAR questionnaire indicates that 64.7% of the intervention group and 40.9% of controls were adhering to the exercise guidelines at three months.
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Hayes 2009: judgement unclear; adherence reported as a proportion of participants attending a proportion of set exercise sessions (i.e. 88% allocated to the intervention group participated in 70% or more of scheduled supervised exercise sessions). Further, adherence from the unsupervised aspect is not reported.
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McKenzie 2003: judgement unclear; no adherence data reported.
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Musanti 2012: judgement unclear; high adherence reported but only 50% of activity logs returned.
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Perna 2010: judgment unclear; women assigned to the structured intervention completed an average of 83% of their scheduled hospital‐based exercise sessions (4 weeks in total). Home‐based adherence is not clear.
Ideally, a meta‐analysis of objectively verified (e.g. using accelerometers or heart rate monitoring) minutes per week of moderate intensity aerobic exercise achieved in an intervention group, compared with controls, for whom the exercise prescription adherence is at least 75%, would be most informative. Among trials with at least 75% adherence, only Cadmus 2009 reported behaviour in these terms. However, this trial demonstrated adherence rates of 75% or more only for 90 to 119 minutes per week of moderate intensity exercise. The overall mean (standard deviation (SD)) reported for minutes of moderate intensity physical activity at six months of follow‐up was 161.7 (114.7) minutes, as reported by the 7‐Day Physical Activity Log, with adherence reported as 61%. The other two trials (Bourke 2011a; Bourke 2011b) reported overall exercise behaviour using Godin Leisure Index questionnaire (Godin 1986) scores (without full objective validation). Further, at the same follow‐up point of six months, Bourke 2011b reported 44% attrition and hence was judged as having a high risk of bias. Bourke 2011a reported outcomes at just 12 weeks of follow‐up. Hence, a meta‐analysis of moderate intensity exercise behaviour at any given follow‐up was judged to be not informative. Insuficent data were available for a synthesis of evidence to be conducted around free living energy expenditure. Planned subgroup analysis was not deemed informative because of the lack of identified studies.
Secondary outcomes
A meta‐analysis of change in aerobic exercise tolerance was carried out on seven trials that reported these outcomes and also reported means for final value scores. Standardised mean differences (SMDs) were used to produce effect estimates as variation in how trials assessed this outcome was evident. Standard deviations (SDs) were calculated from 95% confidence intervals (CIs) using the formula in the Cochrane Handbook for Systematic Reviews of Interventions (i.e. SD = √N * (upper limit‐lower limit)/(t distribution *2), and from standard errors (SEs) using SD = SE*√N, when they were not reported. Length of follow‐up ranged from eight (Kim 2006; Daley 2007a) to 12 weeks (Bourke 2011a; Bourke 2011b; Musanti 2012; Pinto 2005; Pinto 2011; see Analysis 1.1). Aerobic exercise tolerance was significantly better in intervention versus control groups in 330 participants: SMD 0.73, 95% CI 0.51 to 0.95). We then removed trials with a high risk of bias relative to this outcome and repeated the analysis with the three remaining trials (Bourke 2011a; Bourke 2011b; Pinto 2005; see Analysis 1.2); aerobic exercise tolerance was significantly better in intervention versus control groups in 154 participants: SMD 0.84, 95% CI 0.51 to 1.17). We were unable to analyse subgroups outlined in the protocol (i.e. by cancer site, type of intervention, etc) because of a lack of included studies reporting changes in aerobic exercise tolerance or fitness. Five trials included data from a follow‐up of six months (Bourke 2011b; Daley 2007a; Kaltsatou 2011; Pinto 2005; Pinto 2011) showing that aerobic exercise tolerance was significantly better at six months in intervention versus control groups in 271 participants: SMD 0.70, 95% CI 0.45 to 0.94; see Analysis 1.3). However, it should be highlighted that four of these trials have a high risk of bias, which could affect this outcome at six months, specifically, a high risk of reporting bias at six months in the Bourke 2011b trial; no adherence data in the Kaltsatou 2011 trial; substantial contamination among controls in the Pinto 2011 trial; and non‐blinded assessors in the Daley 2007a trial. Note that in all meta‐analyses, data from Pinto 2005 have been multiplied by ‐1 to control for direction of effect (i.e. lower values in a timed test indicate a better outcome). Data were extracted from the combined aerobic and resistance training arm of Musanti 2012.
Brief narrative descriptions of studies not suitable for meta‐analyses include the following: Drouin 2005 VO2 peak data are reported as medians and interquartile ranges; for Pinto 2003, no control group data are presented for the exercise tests.
Three trials that used resistance exercise as a component of the intervention reported changes in lower (Bourke 2011a; Bourke 2011b) and upper limb (Musanti 2012) strength. All three trials had reported strength changes at 12 weeks of follow‐up, and we were able to extract means and SDs. Limb strength was significantly better in intervention versus control groups for 91 participants: SMD 0.51, 95% CI 0.19 to 0.93; see Analysis 2.1). After one trial was removed for high risk of bias (Musanti 2012), the moderate effect size was still apparent in 68 participants, but it was no longer significant: SMD 0.47, 95% CI ‐0.01 to 0.96; see Analysis 2.2).
Just six trials produced CONSORT diagrams (Bourke 2011a; Bourke 2011b; Cadmus 2009; Daley 2007a; Pinto 2005; Pinto 2011). Intervention attrition rates from the included trials ranged from 25% (Pinto 2003) to 0% (Drouin 2005) (median 6%), with five trials not clearly reporting attrition in the intervention arm (Kaltsatou 2011; Kim 2006; McKenzie 2003; Musanti 2012; Perna 2010). Eight trials reported adverse effects (Bourke 2011a; Bourke 2011b; Cadmus 2009; Daley 2007a; Kim 2006; Musanti 2012; Pinto 2005; Pinto 2011); these ranged from minor (e.g. musculoskeletal problems; Musanti 2012) to major events (e.g. death; Kim 2006). However, only one study (Cadmus 2009) was explicit as to which of these adverse effects were caused by inclusion of the participant in the intervention group (two instances of plantar fasciitis). The trial recruitment rate ranged from 10% (Bourke 2011a) to 89% (Perna 2010). Eight trials reported a priori sample size estimates (Cadmus 2009; Daley 2007a; Hayes 2009; Kaltsatou 2011; Musanti 2012; Pinto 2003; Pinto 2011; Perna 2010), and only three (Cadmus 2009; Hayes 2009; Perna 2010) met their recruitment target.
Discussion
Summary of main results
Review findings indicate that currently, convincing evidence are lacking to suggest that existing exercise interventions are useful for achieving the Rock 2012 guidelines of 150 minutes per week of aerobic exercise and twice per week of resistance exercise in sedentary cancer cohorts. Adherence to exercise interventions, which is crucial for understanding treatment dose, is frequently poorly reported. It is important to note that the fundamental metrics of exercise behaviour (i.e. frequency, intensity and duration, or repetitions, sets and intensity of resistance training), although easy to devise and report, are seldom included in published clinical trials. Attempts to reproduce any exercise prescription without detailing these metrics are fraught with problems; most likely, this is not possible. The supportive evidence that we have synthesised as a narrative suggests that interventions that combine supervision of exercise training in tandem with a requirement for independent exercise are likely to promote better adherence. Behaviour change techniques (BCTs) that include programming set goals, prompting self‐monitoring and practicing and generalising behaviour are a common feature of interventions that have reported better adherence.
Despite the uncertainty surrounding adherence in many of the included trials, interventions caused improvement in aerobic exercise tolerance at 8 to 12 weeks: SMD 0.73, 95% CI 0.51 to 0.95) in intervention participants compared with controls. At six months, aerobic exercise tolerance was also improved: SMD 0.70, 95% CI 0.45 to 0.94), but it should be noted that four of the five trials used in this analysis had a high risk of bias, hence caution is warranted in interpretation of findings. Such improvements could be interpreted as reassuring that some of the lack of clarity around adherence extends only to reporting issues rather than reflecting real problems with fidelity. Alternatively, this result could have arisen from the rapid, relatively large early gains in function expected in sedentary participants as the result of exercise training, which could mask smaller changes among non‐adherers. Further, aerobic exercise tolerance should not be considered as definitive evidence of changes in aerobic fitness (with the accompanying spectrum of underlying physiological adaptations). It could simply reflect the fact that individuals have become accustomed to the feeling of exertion from exercise testing and better tolerance towards perceptions of fatigue. Just one of the included trials (Drouin 2005) reported using established cardiopulmonary exercise testing protocols to measure changes in fitness (e.g. VO2 peak derived from Douglas bag or online gas analysis systems). However, this study did not report data that we could use in our meta‐analysis (i.e. only medians and ranges were reported). It is interesting to note that reported attrition over the intervention period for trials included in this review was typically low (median 6%), although it is difficult to interpret adverse effect reports and to identify adverse effects that are attributable to participation in these interventions.
Overall completeness and applicability of evidence
This systematic review included 14 trials, all of which were RCTs. These trials randomly assigned 648 participants to exercise or comparison groups. A large majority of these trials included women with breast cancer. One trial involved men with advanced prostate cancer, and two trials involved colorectal cancer survivors. Although these three primary cancers account for most of the population living with and beyond cancer, other common cancers such as lymphoma and lung cancer do not appear at all in this review. Less common cancers also are not represented in the evidence base. Furthermore, an overwhelming majority of participants were white, and only one trial included an ethnically diverse population. As such, other ethnicities are substantially underrepresented. Although we set a limit in this review of 90 minutes per week of moderate intensity exercise at baseline as the criterion for categorising participants as "sedentary", we did not specify any threshold for vigorous exercisers. It is possible that we could have included individuals who were performing as much as 90 minutes per week of vigorous intensity exercise. Such individuals would be erroneously designated as "sedentary". However, given the population under study, it is likely that such contamination would be minimal. We set a threshold of 75% adherence for any trial to be judged "successful" in this review. This decision was based on previous reports from a review of adherence to exercise schemes in older adults (Martin 2001). This threshold of course is open to debate in the context of cancer specifically, but it was believed that this level represents a minimum for achieving balance between a meaningful dose of the stated exercise prescription and what is realistic for most people living with and beyond cancer. Thirteen of the 14 included trials were conducted in Northern America or Western Europe, and one trial was completed in Australia. All are considered high income nations according to the World Health Organization (WHO) taxonomy. No evidence was derived from developing countries, and it is uncertain whether the resources and/or infrastructure required for some of the interventions included in this review would be applicable in these parts of the world.
Although no single tool for measuring physical activity is infallible (Warren 2010), when possible it is desirable to have self‐reported exercise behaviour supported by objective measurements such as accelerometers or heart rate data. An overwhelming majority of trials evaluated non‐supervised exercise behaviour by using self‐report logs or seven‐day physical activity questionnaires. Whilst these tools are relatively non‐complex and affordable for implementation in trial design, they are prone to multifarious bias, including difficulties in ascertaining the frequency, duration and intensity of physical activity; social desirability bias; the cognitive demands of recall and overestimation of behaviour, particularly when such data are used to extrapolate MET/hours of exercise per week performed, or kcal/wk of energy expenditure. It is admirable that two trials attempted to validate self‐reported independent exercise behaviour by using accelerometers (Pinto 2005; Pinto 2011); however, data either were not supportive of exercise behaviour recorded by participants or were not reported in their entirety.
Analysis by behaviour change theory and outcome (e.g. aerobic exercise tolerance) was not possible given that few trials stated a theoretical basis for their intervention. It is worthy of note, however, that interventions frequently consisted of little more than telling people how to exercise and providing opportunities for this to occur, with little consideration of the psychological aspects of changing behaviour. It is also acknowledged that although coding of BCTs was done primarily on the basis of study reports, it is possible that some BCTs may have been implemented but not reported. To overcome this possibility and enhance understanding of the techniques important for changing behaviour in cancer patients, adoption of the CALO‐RE taxonomy or the broader BCT v1 taxonomy is recommended.
We acknowledge that in this review, we have undertaken a synthesis of RCTs that represent a combination of exercise efficacy and behaviour change trials (Courneya 2010), and we recognise the distinction. However, it should be noted by the reader that all three trials that we judged as successful (i.e. reported 75% or greater adherence over the intervention period) incorporated intervention elements that were designed to promote independent exercise behaviour and did not place any restrictions on the control group in terms of the exercise they were permitted to undertake during the trial. Finally, we stated in the justification for this review that a better understanding of the types of interventions that could promote long‐term, habitual physical activity (i.e. 12 months or longer) in people living with and beyond cancer was a valuable addition to our knowledge. Unfortunately, because of limitations in the evidence that we identified, we have not been able to address this issue. As such, this is an area of uncertainty that represents an important research gap.
Quality of the evidence
Most of the uncertainty in judging trial bias came from lack of clarity around randomisation procedures and blinding of study outcome assessors. Most of the trials in this review were judged to include at least one element of high risk of non‐standard bias, as described in the 'Other sources of bias' outcome. Of note, we chose to refrain from judging trials according to the performance bias criterion because we considered it not possible to realistically blind intervention participants to "sham" conditions. Public health guidelines (e.g. the UK CMO report) for aerobic and resistance exercise (which are identical to the Rock et al recommendations) are freely available to the public, and given their ease of access via the Internet, the validity of a "sham" condition is dubious. The 'Summary of findings' and 'Risk of bias' tables and Figure 2 and Figure 3 provide a summary of the quality of evidence.
Potential biases in the review process
We were not able to translate all non‐English language studies identified through our database, grey literature and snowballing searches. However, a huge effort was made to identify all relevant RCTs in this field. To the review authors' knowledge, we have identified and evaluated more RCTs involving exercise interventions in people living with or beyond cancer than any other systematic review in this field. More than 400 papers were screened at full text stage for eligibility, and we sent 116 emails to request data to inform the screening and data extraction process, so that the conclusions of the review would be as accurate and informative as possible. We were able to perform single extraction only to generate the CALO‐RE taxonomy data (undertaken by LS).
Agreements and disagreements with other studies or reviews
To the review authors' knowledge, this is the first comprehensive review to evaluate RCTs with respect to their success in promoting exercise behaviour in sedentary cancer cohorts. A recent systematic review of predictors of adherence to exercise in people living with and beyond cancer (Husebø 2013) found that the trans‐theoretical model of behaviour change and the theory of planned behaviour were significantly associated with better exercise adherence. The current review does not explicitly support such conclusions. It should be noted that key differences are evident in each review methodology, with the present review including only RCTs and people who were sedentary at baseline. Other recent high‐profile systematic reviews (e.g. Fong 2012) have focused on potential health‐related outcomes of exercise intervention for people living with and beyond cancer. In this respect, Fong 2012 similarly reported improvements in aerobic exercise tolerance and muscle strength. One substantial difference in the methodology of the present review when compared with other Cochrane reviews in this area (e.g. Mishra 2012a; Mishra 2012b) is that we included only studies in which the essential metrics of exercise behaviour are reported.
Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.
Comparison 1 Aerobic exercise tolerance, Outcome 1 Aerobic exercise tolerance (all cancers: 8 to 12 weeks of follow‐up).
Comparison 1 Aerobic exercise tolerance, Outcome 2 Aerobic exercise tolerance (all cancers: 8 to 12 weeks of follow‐up sensitivity analysis).
Comparison 1 Aerobic exercise tolerance, Outcome 3 Aerobic exercise tolerance (all cancers: 6 months).
Comparison 2 Strength tests (all cancers), Outcome 1 Strength tests.
Comparison 2 Strength tests (all cancers), Outcome 2 Strength tests (all cancers: sensitivity analysis).
| Study | Exercise components | n | Meets Rock et al guidelines? | Adherence summary | At least 75% adherence? | High risk of bias? | Change in AET reported? | Adverse effects |
| Aerobic | 37, 38 (intervention vs control) | 33% reported 150 minutes/wk of moderate intensity aerobic exercise at an average of 76% HR, for six months | 75% of women were doing between 90 and 119 minutes of moderate intensity aerobic activity per week at six months | Yes; for up to 119 minutes per week | No | No | Five of the 37 women randomly assigned to exercise experienced an adverse effect; two were related to the study (plantar fasciitis) | |
| Aerobic | 34, 36, 38 (intervention, sham, control, respectively) | No | 77% of the exercise therapy; attended 70% (at least 17 of 24 sessions) or more of sessions | Unclear | Yes; outcome assessors were not blinded to participants’ group allocation | Yes | Three withdrawals in the intervention group: unclear as to why this occurred. Some withdrawals because of medical complications in placebo and control arms but unclear whether study related | |
| Aerobic | 13 intervention, 8 placebo stretching controls | Unclear | Participants in the intervention group averaged 3.6 days per week of aerobic exercise over an 8‐week period | Unclear | No | Yes | None reported | |
| Aerobic | 14, 13 (intervention vs control) | Unclear | Not reported | Not reported | Yes; method of measuring exercise and adherence not reported | No | None reported | |
| Aerobic | 22,19 (intervention vs control). | No | Average weekly frequency of exercise was 2.4 ± 0.6 sessions, and average duration of exercise within prescribed target HR was 27.8 ± 8.1 minutes per session. Overall adherence was 78.3% ± 20.1% | Yes | Yes; data missing for 45% of the cohort | Yes | Reasons for withdrawal included personal problems (n = 2), problems at home (n = 2), problems related to chemotherapy (n = 3), thrombophlebitis in the lower leg (n = 2), non－exercise‐related injuries (n = 1), and death (n = 1). Unclear to which arm of the trial these date relate | |
| Aerobic | 12, 12 (intervention vs control) | Unclear | Participants attended a mean of 88% of the 36‐session supervised exercise programme | Yes | Yes; 38% lost to follow‐up. Exercise tolerance test was performed but no control group comparison data were reported | Yes | None reported; however, it is unclear why the six controls dropped out | |
| Aerobic | 43, 43 (intervention vs control) | Unclear | At week 12, intervention participants reported a mean of 128.53 minutes/wk of moderate intensity exercise. However, no changes were reported in the accelerometer data in the intervention group (change score = ‐0.33 kcal/h) | Less than 75% of the intervention group was meeting the prescribed goal after week 4 | Yes; significantly more control group participants were receiving hormone treatment. Accelerometer data do not support the self‐reported physical activity behaviour | Yes | Not clear whether chest pain was related to exercise in dropout whose participation was terminated | |
| Aerobic | 20, 26 (intervention vs control) | Three‐day PAR questionnaire indicates that 64.7% of the intervention group and 40.9% of the control group were achieving the guidelines at three months | Correlation between self‐reported moderate intensity exercise and accelerometer data at three‐month follow‐up, when the only significant between‐group change is reported: r = 0.32 | No | Yes; accelerometer data were not reported; also, cited correlation is weak (0.32). Further, substantial contamination was noted in the control group | Yes | One cancer recurrence in the control group at three months | |
| Aerobic and resistance | 9, 9 (intervention vs control) | Six weeks of resistance exercise twice a week | 90% attendance at the supervised sessions. 94% of independent exercise sessions were completed | Yes | No | Yes | One stroke in the intervention group, unrelated to the exercise programme | |
| Aerobic and resistance | 25, 25 (intervention vs control) | Six weeks of resistance exercise twice a week | 95% attendance at supervised exercise sessions. Compliance with self‐directed exercise aspect of the lifestyle intervention was 87% | Yes | Yes; high dropout rate at postintervention six‐month follow‐up assessment | Yes | Two men in the intervention arm were discontinued because of cardiac complications before the 12‐week assessments. Two more reported musculoskeletal complaints before the six‐month assessment. Five men reported various health problems in the control group that prohibited them from attending the six‐month assessment | |
| Aerobic and resistance | 16, 16 (intervention vs control) | Unclear | Most women (88%) allocated to the intervention group participated in 70% or more of scheduled supervised exercise sessions | Unclear | Yes; adherence data on unsupervised aspect of the intervention are not clear | No | None reported | |
| Aerobic and resistance | 7,7 (intervention vs control) | No | Unclear | Unclear | Yes; adherence to exercise not reported | No | None reported | |
| Aerobic and resistance | Flexibility group (n = 13), aerobic group (n = 12), resistance group (n = 17), aerobic and resistance group (n = 13) | 12 weeks of resistance exercise two or three times per week | Mean percentages of adherence were as follows: flexibility = 85%, aerobic = 81%, resistance = 91% and aerobic plus resistance = 86% | Unclear | Yes; a significant number of dropouts belonged to the resistance exercise group (n = 8/13). Only 50% of activity logs were returned | Yes | Adverse effects were reported in two women during the study. In both cases, the women developed tendonitis: one in the shoulder and the other in the foot. Both had a history of tendonitis, and both received standard treatment | |
| Aerobic and resistance | 51 participants in total. Numbers randomly assigned to each arm are unclear | Three months of resistance exercise three times per week | Women assigned to the structured intervention completed an average of 83% of their scheduled hospital‐based exercise sessions (only 4 weeks in duration), and 76.9% completed all 12 sessions. Home‐based component (8 weeks in duration) | Unclear | Yes; numbers randomly assigned to intervention and control groups are unclear, as are numbers completing in each arm | No | Unclear | |
| AET = aerobic exercise tolerance. | ||||||||
| Behaviour change technique | YALE | |||||||||||||
| Theory | TTM | EXSEM | TTM | TTM | TTM SCT | |||||||||
| 1. Provide Info on consequences of behaviour in general | X | X | X | X | ||||||||||
| 2. Provide Info on consequences of behaviour to the individual | ||||||||||||||
| 3. Provide Info about others' approval | ||||||||||||||
| 4. Provide normative info about others' behaviour | ||||||||||||||
| Programme set goal | X | X | X | X | X | X | X | X | X | X | X | X | X | X |
| 5. Goal setting (behaviour) | X | X | X | X | X | X | ||||||||
| 6. Goal setting (outcome) | ||||||||||||||
| 7. Action planning | ||||||||||||||
| 8. Barrier identification/Problem solving | X | X | X | X | X | X | ||||||||
| 9. Setting of graded tasks | X | X | X | X | X | X | X | X | X | |||||
| 10. Prompt review of behavioural goals | X | X | ||||||||||||
| 11. Prompt review of outcome goals | ||||||||||||||
| 12. Prompt rewards contingent on effort or progress towards goal | X | X | X | |||||||||||
| 13. Provide rewards contingent on successful behaviour | X | |||||||||||||
| 14. Shaping | ||||||||||||||
| 15. Prompt generalisation of a target behaviour | X | X | X | X | X | |||||||||
| 16. Prompt self‐monitoring of behaviour | X | X | X | X | X | X | X | X | X | X | ||||
| 17. Prompt self‐monitoring of behavioural outcome | X | X | X | X | X | X | ||||||||
| 18. Prompt focus on past success | X | |||||||||||||
| 19. Feedback on performance provided | X | X | X | X | ||||||||||
| 20. Information provided on where and when to perform behaviour | X | X | ||||||||||||
| 21. Instruction provided on how to perform the behaviour | X | X | X | X | X | X | X | X | X | X | ||||
| 22. Modelling/Demonstration of behaviour | X | X | X | |||||||||||
| 23. Teaching to use prompts/cues | X | X | X | |||||||||||
| 24. Environmental restructuring | X | X | ||||||||||||
| 25. Agreement on behavioural contract | X | |||||||||||||
| 26. Prompt practise | X | X | X | X | X | X | X | X | X | X | X | X | X | X |
| 27. Use of follow‐up prompts | X | X | ||||||||||||
| 28. Facilitating social comparison | ||||||||||||||
| 29. Planning social support/social change | X | X | X | |||||||||||
| 30. Prompt identification as role model/position advocate | ||||||||||||||
| 31. Prompt anticipated regret | ||||||||||||||
| 32. Fear arousal | ||||||||||||||
| 33. Prompt self‐talk | ||||||||||||||
| 34. Prompt use of imagery | ||||||||||||||
| 35. Relapse prevention/coping planning | X | X | ||||||||||||
| 36. Stress management/emotional control training | X | |||||||||||||
| 37. Motivational interviewing | ||||||||||||||
| 38. Time management | ||||||||||||||
| 39. General communication skills training | ||||||||||||||
| 40. Stimulation of anticipation of future rewards | ||||||||||||||
| EXSEM = exercise self‐esteem model; SCT = social cognitive theory; TTM = transtheroretical model. | ||||||||||||||
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Aerobic exercise tolerance (all cancers: 8 to 12 weeks of follow‐up) Show forest plot | 7 | 330 | Std. Mean Difference (IV, Fixed, 95% CI) | 0.73 [0.51, 0.95] |
| 2 Aerobic exercise tolerance (all cancers: 8 to 12 weeks of follow‐up sensitivity analysis) Show forest plot | 3 | 154 | Std. Mean Difference (IV, Fixed, 95% CI) | 0.84 [0.51, 1.17] |
| 3 Aerobic exercise tolerance (all cancers: 6 months) Show forest plot | 5 | 271 | Std. Mean Difference (IV, Fixed, 95% CI) | 0.70 [0.45, 0.94] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Strength tests Show forest plot | 3 | 91 | Std. Mean Difference (IV, Fixed, 95% CI) | 0.51 [0.09, 0.93] |
| 2 Strength tests (all cancers: sensitivity analysis) Show forest plot | 2 | 68 | Std. Mean Difference (IV, Fixed, 95% CI) | 0.47 [‐0.01, 0.96] |
