Impact of Six Months of Three Different Modalities of Exercise on Stress in Post-Treatment Breast Cancer Survivors

Simple Summary Research continues to show that exercising at recommended levels is associated with lower mortality rates and decreased risk of recurrence in breast cancer survivors (BCS). Moreover, those BCS exercising at levels meeting guidelines have higher self-reported health-related quality of life (HR-QOL) than those that do not. This includes lowered levels of perceived global stress. However, which modalities of exercise are most effective has yet to be determined. Our study investigates changes in stress experienced by breast cancer survivors participating in one of three different exercise modalities conducted over six months, as indicated by self-report and salivary cortisol measures. The revealed improvement in constructs of Health Related-Quality of Life (HR-QOL) suggest that engagement in exercise had a greater impact on outcomes than any particular modality.Abstract Background/Objectives: Extensive evidence suggests that exercise is physically and mentally beneficial for cancer survivors. This study reports on changes in self-reported stress, physiological biomarkers for stress (salivary cortisol), and HR-QOL constructs for fifty breast cancer survivors participating in one of three different exercise programs over 6 months. Methods: Fifty post-treatment breast cancer survivors were randomized to either therapeutic yoga-based exercise (YE), comprehensive exercise (CE) (aerobic, resistance, flexibility), or choosing (C) their own exercise activities. Participants completed the Perceived Stress Scale (PSS), Medical Outcomes Short-Form 36 (R) (SF-36), and the Pittsburgh Sleep Quality Index (PSQI). Five samples of salivary cortisol were collected on two consecutive days. The 10 samples were used to calculate the diurnal rhythm slope. Outcome measures were repeated after six months. Results: All groups improved in HR-QOL measures of PSS; PSQI sleep quality components of latency and daytime functioning; and five of the ten SF-36 scales (Mental Component Scale, Social Functioning subscale, Mental Health subscale, Physical Component Scale, Physical Functioning subscale). Although the CE group observed the most favorable change in cortisol (-0.183), where cortisol slope changes approached significance (p = 0.057), but no significant decrease in cortisol between groups were noted. Conclusions: Our results suggest that it is the engagement of, rather than the specific type of exercise, which is associated with improved HR-QOL. However, longer-term studies with better adherence monitoring and larger sample sizes are needed to better determine clinical impact.