Resistance exercise-induced apoptosis response to short-term creatine supplementation in middle-aged men Running title: creatine supplementation and apoptosis

Background: Creatine (Cr) as an ergogenic aid for improving health and sports performance is recently researched in attenuating stress-induced apoptosis. No studies to date address the effect of Cr supplementation on systemic apoptosis to acute resistance exercise. Objective: The purpose of this study was to determine the short-term (one week) effects of oral Cr supplementation on apoptosis markers at strenuous acute exercise in middle-aged men. Methods: In a placebo-controlled, double-blind, randomized, parallel study, twenty men (45.59 ± 5.43 years; 77.45 ± 6.65 kg; 173.05 ± 3.48 cm) were randomly assigned to supplement with 20 g per day of Cr monohydrate (n=10) or placebo (maltodextrin, n=10) for a week. On 8th day, subjects performed an acute resistance exercise with 80% 1RM. Blood samples were taken on day prior to supplementation loading and immediately after acute exercise for the measurement of the serum caspase-3, -9 and -12 concentrations. Results: After acute exercise, caspase-3 (41.26%, p<0.001), -9 (38.01%, p=0.003) and -12 (57.02%, p=0.030) levels significantly increased in the placebo group compared to pre supplementation. In contrast, serum level caspases slightly but not significantly increased in the Cr group (p>0.05). Conclusions: Our results indicated that short-term Cr supplementation prevented exercise-induced apoptosis in middle-aged men, which was confirmed by attenuated caspase-3, -9 and -12 in the Cr group. Thus, 7 days Cr supplementation may be a useful strategy for preventing apoptosis by intensive acute exercise.

Resistance exercise-induced apoptosis response to short-term creatine supplementation in middle-aged men Running title: creatine supplementation and apoptosis Keywords:

Creatine loading , caspases , one bout exercise , programmed cell death