Effects of Resistance Training and Protein Supplementation in Breast Cancer Survivors
This study aimed to evaluate 12 wk of resistance training (RT; n = 16) and protein supplementation (RT + protein; n = 17) on muscular strength, body composition, and blood biomarkers of muscle (insulin-like growth factor 1 [IGF-1]), fat (adiponectin), and inflammation (human C-reactive protein [CRP]) in breast cancer survivors (BCS).Methods
Thirty-three BCS (59 ± 8 yr) were measured pre- and posttraining for one-repetition maximum (1-RM) muscular strength (chest press and leg extension), body composition (lean mass [LM] and fat mass [FM]) via dual-energy x-ray absorptiometry, and serum concentrations of IGF-1, adiponectin, and CRP. RT consisted of 2 d·wk−1 using 10 exercises for two sets of 10–12 repetitions and a third set to failure at ~65%–85% of 1-RM. RT + protein consumed 20 g of protein twice a day. ANOVA was used for analyses. Significance was set at P ≤ 0.05.Results
Average RT intensity was 65%–81% of 1-RM and was not different between RT and RT + protein. There were no group–time interactions for strength, LM, FM, and biomarkers. Both groups significantly increased upper (+31 ± 18 kg) and lower (+19 ± 12 kg) body strength, LM (+0.9 ± 1.0 kg) and decreased FM (−0.5 ± 1.2 kg), and percent body fat (−1.0% ± 1.2%). Serum levels of IGF-1 significantly increased from baseline to 12 wk in both RT (102 ± 34 to 115 ± 33 ng·mL−1) and RT + protein (110 ± 40 to 119 ± 37 ng·mL−1); adiponectin and CRP did not change.Conclusions
Twelve weeks of RT at 65%–81% of 1-RM, 2 d·wk−1 in BCS, was well tolerated and significantly improved strength, body composition, and IGF-1. Supplemental protein (40 g·d−1) did not induce a change in any variable. However, on the basis of food logs, reductions in total calories and dietary protein intake from whole foods resulted in only a net protein increase of 17 g·d−1 for RT + protein, which may have influenced the results.