Creatine supplementation combined with resistance training in older men: body composition, muscular performance, and reported side effects

Abstract

Purpose: To study the effect of creatine (Cr) supplementation combined with resistance training on muscular performance and body composition in older men. Methods: Thirty men were randomized to receive creatine supplementation (CRE, n = 16, age= 70.4 ± 1.6 y) or placebo (PLA, n = 14, age= 71.1 ± 1.8 y) using a double blind procedure for the entire length of study. Cr supplementation consisted of 0.3 g Cr·kg-1 body weight for the first 5 days (loading phase) and 0.07 g Cr·kg-1 body weight thereafter. Both groups participated in resistance training (36 sessions, 3 times per week, 3 sets of 10 repetitions, 12 exercises). Body composition measures were assessed at baseline (BL) and post-test (PT) periods, whereas performance measures were assessed at baseline (BL), mid-test (MT), and post-test (PT) periods. Lean tissue mass (LTM) and fat mass measures were assessed using DXA. Muscular strength was assessed by 1-repetition maximum (1-RM) for leg press (LP), knee extension (KE), and bench press (BP). Muscular endurance was assessed by the maximum number of repetitions over 3 sets (separated by 1-min rest intervals) at an intensity corresponding to 70% baseline 1-RM for BP and 80% baseline 1-RM for the KE and LP. Average power (AP) was assessed using a Biodex isokinetic knee extension-flexion exercise (3 sets of 10 repetitions at 60°·s separated by 1-min rest). Lean tissue (LTM) and fat mass were assessed. Side effects and treatment identification were assessed upon completion of the study. Results: Compared to PLA, the CRE group had significantly greater (p ≤ 0.05) increases in LTM (CRE, +3.3 kg; PLA, +1.3 kg), LP 1-RM (CRE, +50.1 kg; PLA +31.3 kg), KE 1-RM (CRE, +14.9 kg; PLA, +10.7 kg), LP endurance (CRE, +47 reps; PLA, +32 reps), KE endurance (CRE, +21 reps; PLA + 14 reps), and AP (CRE, +26.7 W; PLA, + 18 W). CRE group retrospectively reported experiencing loose stools, muscle cramping and decreased muscle soreness above that reported by PLA group. Changes in fat mass, fat percentage, BP 1-RM, and BP endurance were similar between groups. Conclusion: Creatine supplementation, when combined with resistance training, increases lean tissue mass and improves leg strength, endurance, and average power in men 60-84 years of age (mean age of 70 years). Possible side effects of the creatine supplementation include loose stools, muscle cramping, and decreased muscle soreness.