Effects of pre‐ or post‐exercise whey protein supplementation on oxidative stress and antioxidant enzymes in older women

Background Oxidative stress is an imbalance between antioxidant system and production of free radicals and has been associated with the age‐related deleterious changes. The defense system can be modulated by exercise and nutrition. Objective The purpose of this investigation was to evaluate the effect of whey protein supplementation pre‐ or post‐resistance training on oxidative stress and antioxidant enzyme activity in pre‐conditioned older women. Methods In a randomized, double‐blind, and placebo‐controlled design, 70 older women (≥60 years) were randomly assigned to one of the following three groups: whey protein‐placebo (WP‐PLA, n = 24), placebo‐whey protein (PLA‐WP, n = 23), and placebo‐placebo (PLA‐PLA, n = 23). Each group received 35 g of whey product or placebo pre‐ and post‐training. The RT program was carried out over 12 weeks (3x/week; 3x 8‐12 repetitions maximal). Oxidative stress and blood markers were assessed before and after intervention period. ANOVA for repeated measures was used for data analysis. Results There was a significant time effect (P