Overview
Cancer survivors face ongoing health challenges, with physical activity (PA) firmly established as a safe and beneficial intervention. To address suboptimal PA levels, researchers developed WExercise, a smartphone app grounded in the multi‑process action control (M-PAC) framework. An assessor‑blinded randomized controlled trial (RCT) tested whether WExercise could effectively promote PA, improve exercise capacity, and influence key behavioral determinants among survivors living in Hong Kong.
What is WExercise?
WExercise is a 12‑lesson app designed around reflective, regulatory, and reflexive processes described by M-PAC. Eleven lessons (10 weekly plus 1 introduction) deliver text, videos, infographics, and self-monitoring tools. The app integrates phone data (eg, step counts), includes quizzes to sustain engagement, and provides a diary for logging PA sessions. Each lesson takes roughly 20–30 minutes and is structured to (1) forge intention, (2) translate intention into action through planning and self‑monitoring, and (3) cultivate habits and an exerciser identity. Participants received reminders every few days to complete lessons, supporting ongoing engagement and action control.
Study Design at a Glance
The trial compared WExercise with standard self‑directed PA education across two groups in Hong Kong from November 2022 to May 2024. Eligibility required adults (≥18) at least 12 months post‑treatment for cancer, not meeting PA guidelines, and having access to a smart device. The sample size targeted 98 participants to achieve adequate power, accounting for potential dropouts. Randomization was 1:1 with concealed allocation, and assessors collecting outcomes were blinded to group assignment.
Outcomes Measured
The primary outcome was PA behavior, assessed both objectively with ActiGraph MVPA (minutes per day) and subjectively via the Godin Leisure Time Exercise Questionnaire (GLTEQ). Secondary outcomes included exercise capacity (6‑minute walk test, 6MWT), cancer‑specific QoL (EORTC QLQ‑C30), and eight M‑PAC constructs (reflective, regulatory, and reflexive processes underpinning PA behavior).
Key Findings
Participant flow ended with 81 completers (36 in the intervention and 45 in the control group). About 70% of intervention participants completed at least 75% of the lessons, indicating moderate engagement with the app.
Primary outcomes revealed a nuanced picture. For objective PA, ActiGraph MVPA showed no significant group by time effect (P = 0.74). In contrast, self‑reported MVPA demonstrated a significant between‑group difference over time (P = 0.003): the WExercise group increased more than controls, by 89.0 minutes at post‑intervention (T1) and 49.4 minutes at 12 weeks post‑intervention (T2). Corresponding percentages meeting the 150 minutes/week MVPA guideline were higher in the WExercise group at T1 (27% vs 6.7%) and T2 (25.7% vs 4.7%).
Exercise capacity improved modestly in the intervention arm, with the 6MWT showing a greater gain at T1 (≈25 meters; P = 0.05). QoL, however, did not show significant between‑group changes over time.
Regarding M‑PAC constructs, the between‑group interaction was not statistically significant overall, yet within‑group patterns favored the intervention: affective attitude, behavioral regulation, habit, and PA identity improved in the WExercise group, while control participants mainly improved in behavioral regulation and identity. Per‑protocol analyses (focusing on highly compliant participants) paralleled the intention‑to‑treat findings, reinforcing the overall conclusions.
Interpretation and Implications
The trial provides the first evidence that a theory‑driven smartphone app, based on M‑PAC, can meaningfully increase self‑reported PA and exercise capacity among cancer survivors. The discrepancy between self‑reported and ActiGraph‑measured PA highlights a common challenge in PA research: objective devices may miss some activities (e.g., cycling or upper‑body movements) that participants perceive as MVPA, while social desirability can inflate self‑reports. Nonetheless, the observed gains in the 6MWT and higher engagement with the app suggest real health and behavioral benefits beyond mere numbers.
From a clinical perspective, WExercise could be a scalable adjunct to conventional care for inactive survivors who have no contraindications to unsupervised exercise. The findings also point to future enhancements: adding personalized feedback, motivational incentives, or optional in‑person/remote exercise sessions to strengthen capability, opportunity, and actual behavior. Further work should refine strategies to align objective measurements with perceived activity and explore longer-term maintenance beyond 12 weeks post‑intervention.
Strengths, Limitations, and Next Steps
Strengths include theory‑based design, iterative usability testing, and rigorous RCT methodology. Limitations involve a predominantly educated, female, single‑site sample that may limit generalizability, potential biases from lack of participant blinding, and reliance on self‑selected participants who may already be motivated to change. Replication in diverse populations and integration with tailored support could further enhance effectiveness.
Conclusion
WExercise demonstrates promising potential as a smartphone‑based intervention to promote PA and improve exercise capacity among cancer survivors. While objective PA gains were not observed, the robust improvements in self‑reported activity and functional capacity, coupled with positive shifts in key M‑PAC determinants, support the value of theory‑driven digital health approaches in cancer survivorship care.
