Effects of resistance training frequency on physical functioning and quality of life in prostate cancer survivors: a pilot randomized controlled trial

BACKGROUND: Resistance training (RT) improves muscular strength, physical functioning and quality of life in prostate cancer survivors, but the optimal frequency of RT is unknown. We conducted a pilot randomized controlled trial to compare the effects of 3 versus 2 days per week of RT in prostate cancer survivors diagnosed within the past 2 years. METHODS: Prostate cancer survivors (N = 30) were randomized to 12 weeks of supervised RT performed either 3 days per week (n = 16) or 2 days per week (n = 14). The primary outcome was muscular strength assessed by a multiple repetition maximum test at baseline and postintervention. Secondary outcomes were objective physical functioning, quality of life and psychosocial functioning. RESULTS: A trend (P < 0.10) and/or potentially meaningful effects (standardized effect size d >= 0.20) were found favoring 3 days per week over 2 days per week for the primary outcome of lower body strength (mean difference = 27.8 kg; 95% confidence interval = -0.9 to 56.5; P = 0.057; d = 0.72) and for the secondary outcomes of 30-s chair stand (d = 0.29; P = 0.31), sit and reach (d = 0.24; P = 0.33), 6 -min walk (d = 0.21; P = 0.42) and the physical component summary (d = 0.21; P = 0.41). Conversely, a trend and/or potentially meaningful effects were found favoring 2 days per week over 3 days per week for the mental component summary (d = -0.38; P = 0.10), mental health (d = -0.44; P = 0.11), vitality (d = -0.31; P = 0.28), role-emotional (d = -0.23; P = 0.43), anxiety (d = 0.32; P = 0.29), happiness (d = -0.31; P = 0.36) and perceived stress (d = 0.23; P = 0.39). CONCLUSIONS: This pilot randomized dose-comparison trial provides preliminary data to suggest that RT 3 days per week compared with 2 days per week may improve the strength and physical functioning in prostate cancer survivors, but may also blunt improvements in psychosocial functioning. Larger and more targeted phase II and III trials are needed to confirm the potentially complex effects of RT frequency in prostate cancer survivors.