Abstract
We aimed to determine whether creatine supplementation influences lower-limb muscle endurance following an acute bout of aerobic exercise (AE) in young healthy men. Using a randomized, double-blind, placebo-controlled crossover design, 11 men (26.5 ± 6.2 years, body mass index 26.6 ± 2.1 kg/m2),with 12 months of experience in strength training (three times/week) and AE (two times/week) were randomized to receive creatine (20 g/day plus 20 g/day maltodextrin) and placebo (40 g/day maltodextrin) for 7 days, separated by a washout period of 14 days, before performing an acute bout of AE (30 min on treadmill at 80% baseline maximum velocity) which was followed by four sets of bilateral leg extension endurance exercise using a 10-repetition maximum protocol (10 RM)). There was a significant decrease in the number of repetitions performed in the third (Placebo: −20% vs. Creatine: −22%) and fourth set (Placebo: −22% vs. Creatine: −28%) compared with the first set (p < 0.05), with no differences between creatine and placebo. Additionally, no differences were observed between creatine and placebo for the total number of repetitions performed across all four sets (Placebo: 33.9 ± 7.0 vs. Creatine: 34.0 ± 6.9 repetitions, p = 0.97), nor for total work volume (Placebo: 3030.5 ± 1068.2 vs. Creatine: 3039.8 ± 1087.7 kg, p = 0.98). Short-term creatine supplementation has no effect on lower-limb muscle endurance following an acute bout of aerobic exercise in trained young men.
Highlights
Concurrent exercise (CE) involves the combination of aerobic exercise (AE) and resistance training in the same training session [1]
The purpose of this study was to determine whether creatine supplementation maintains muscle performance following an acute bout of AE in trained young males using a randomized, cross-over design
There are two hypotheses for the reduction in muscle endurance following AE, (i) acute; peripheral fatigue triggered by muscle damage and glycogen depletion during AE training reduces the ability of skeletal muscle to produce tension during resistance training [2,3], and (ii) chronic; skeletal muscle attempts to adapt to both forms of training, morpho-functional adaptations, such as fiber type and size after endurance exercise and weight training are partially opposed resulting in an interference effect
Summary
Concurrent exercise (CE) involves the combination of aerobic exercise (AE) and resistance training in the same training session [1]. Previous studies have shown that performing AE before resistance training results in acute decreases in muscle performance [2,4,7,8,9,10], possibly due to an increase in peripheral fatigue, AMP-activated protein kinase (AMPK) and Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) signaling and decrease in satellite cell activity [1]. Painelli et al [4] showed that creatine supplementation (20 g/day for 7 days + 5 g/day thereafter) maintained lower-body muscle endurance (number of repetitions performed) following acute bouts of intermittent and continuous AE in strength-trained males compared with a decrease in males who received placebo. This study was limited by the parallel group design
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