Impact Of Short-Term Creatine Supplementation On Muscular Performance In Breast Cancer Survivors

Breast cancer (BC) has a high prevalence of malignancy among women in the United States. Advances in the detection and treatment of BC have resulted in an increased survival rate. Unfortunately, this means there is an ever-increasing population experiencing declines in physiological wellbeing that accompany cancer treatments, specifically declines in muscle mass and strength. Thus, there is a critical need for the investigation of strategies to mitigate treatment related impairments in BC. Prior research suggests that creatine supplementation has a beneficial effect on muscular performance in healthy, older adults. However, the effects of creatine supplementation have not yet been examined in BC survivors. PURPOSE: To investigate the effects of short-term creatine supplementation on muscular performance in BC survivors. METHODS: Using a double-blind, placebo controlled, randomized design, 19 female BC survivors (mean±SD age = 57.63±10.77 years) were assigned to a creatine (CRE)(n=9) or dextrose placebo (PLA)(n=10) group. The study design consisted of 2 familiarization sessions to minimize practice effects, followed by 2 test sessions. After the first testing session, participants supplemented their regular diet 4 times/day for 7-days with 5g of CRE or PLA. Muscular performance was assessed pre- and post-supplementation using the 10-repetition maximum (RM) chest press and leg extension, sit-to-stand power tests, and maximal voluntary isometric and concentric isokinetic contractions of the knee extensors. For each dependent variable, the interaction between supplement (CRE vs PLA) and time (Pre vs Post), was examined using a group × time ANOVA and effect sizes. RESULTS: No significant effects were observed for body mass (p=0.161; ηp2= 0.112), sit-to-stand power (p=0.471; ηp2=0.031), peak torque at 60°/second (p=0.533; ηp2=0.023), peak torque at 120°/second (p=0.944; ηp2<0.001), isometric peak torque (p=0.905; ηp2<0.001), 10RM chest press (p=0.407; ηp2=0.041) and 10RM leg extension (p=0.932; ηp2<0.001). However, there was a large effect size for time on 10RM chest press (ηp2= 0.531) and leg extension (ηp2=0.422), suggestive of improvements across both groups. CONCLUSION: Our findings suggest that 7 days of creatine supplementation does not influence muscular performance among BC survivors.