Group-based exercise interventions for increasing physical activity in cancer survivors: a systematic review of face-to-face randomized and non-randomized trials

Purpose: To increase physical activity (PA), interventions based on group dynamics may be superior to interventions that target aggregates of people but do not have formal strategies to enhance cohesion. This review examined the extent to which group dynamics processes have been integrated within exercise and/or PA interventions in cancer survivors, and explored the implementation and effectiveness of these interventions for increasing PA. Methods: A systematic review was conducted of English articles published January 2005–March 13, 2017 using the electronic databases PsycINFO, CINAHL, and PubMed Medline (National Library of Medicine). Studies in adult cancer survivors that had a controlled or uncontrolled experimental design, included face-to-face exercise, had a group-based component, and reported PA pre- and post-intervention were included. Self-reported PA effect sizes were estimated for pre- to post-intervention, separately for studies that implemented ≥ 1 group dynamics strategy versus none. Results: Twenty-three studies were reviewed, 34.8% (n = 8) included ≥ 1 group dynamics strategy (M = 1.6 ± 0.7, range = 1–3). Most interventions were delivered in a healthcare or rehabilitation setting by an exercise professional, and face-to-face exercise dose ranged from 72.0–6000.0 min. PA effect size ranged from 0.3–1.2 for studies that implemented ≥ 1 group dynamics strategy versus 0.4–2.4 for those with none. Studies reviewed lacked detailed examples of group dynamics strategies, and none measured group cohesion. Conclusions: The additional benefit of group dynamics–based interventions for increasing PA in cancer survivors remains unclear. More research is needed to enhance the generalizability of face-to-face exercise interventions, and determine how to maximize the potential of including group dynamics strategies.