Abstract
Creatine monohydrate (CrM) supplementation has been shown to improve body composition and muscle strength when combined with resistance training (RT); however, no study has evaluated the combination of this nutritional strategy with cluster-set resistance training (CS-RT). The purpose of this pilot study was to evaluate the effects of CrM supplementation during a high-protein diet and a CS-RT program on lower-limb fat-free mass (LL-FFM) and muscular strength. Twenty-three resistance-trained men (>2 years of training experience, 26.6 ± 8.1 years, 176.3 ± 6.8 cm, 75.6 ± 8.9 kg) participated in this study. Subjects were randomly allocated to a CS-RT+CrM (n = 8), a CS-RT (n = 8), or a control group (n = 7). The CS-RT+CrM group followed a CrM supplementation protocol with 0.1 g·kg−1·day−1 over eight weeks. Two sessions per week of lower-limb CS-RT were performed. LL-FFM corrected for fat-free adipose tissue (dual-energy X-ray absorptiometry) and muscle strength (back squat 1 repetition maximum (SQ-1RM) and countermovement jump (CMJ)) were measured pre- and post-intervention. Significant improvements were found in whole-body fat mass, fat percentage, LL-fat mass, LL-FFM, and SQ-1RM in the CS-RT+CrM and CS-RT groups; however, larger effect sizes were obtained in the CS-RT+CrM group regarding whole body FFM (0.64 versus 0.16), lower-limb FFM (0.62 versus 0.18), and SQ-1RM (1.23 versus 0.75) when compared to the CS-RT group. CMJ showed a significant improvement in the CS-RT+CrM group with no significant changes in CS-RT or control groups. No significant differences were found between groups. Eight weeks of CrM supplementation plus a high-protein diet during a CS-RT program has a higher clinical meaningfulness on lower-limb body composition and strength-related variables in trained males than CS-RT alone. Further research might study the potential health and therapeutic effects of this nutrition and exercise strategy.
Highlights
Several changes with regard to the synthesis and hydrolysis of adenosine triphosphate (ATP) occur inside muscle cells during all-out short-term physical exercise [1]
We evaluated the effects of Creatine monohydrate (CrM) supplementation on protein diet diet during during eight eight weeks weeks of of aa CS-resistance training (RT)
The countermovement jump (CMJ) test was performed on a jump mat (Smart Jump; Fusion Sport, Coopers Plains, Australia) as we have reported previously [26]
Summary
Several changes with regard to the synthesis and hydrolysis of adenosine triphosphate (ATP) occur inside muscle cells during all-out short-term physical exercise [1]. This relationship between energy production and consumption (myocellular ATP/ADP ratio) is crucial for the onset of muscle fatigue, which is characterized by an acute reduction in force and power in response to contractile activity [2]. In parallel to the decrease of the ATP/ADP ratio, muscle concentrations of inorganic phosphate (Pi) and hydrogen ions (H+ ) significantly rise over the course of high-intensity physical exercise This metabolic stress is currently considered one of the main mechanisms evoking muscle fatigue [3]. It has been proposed that initial phase of force reduction is accompanied by an increase in Pi concentration and dysregulation of Ca2+ handling (i.e., disruptions in the Ca2+ release–reuptake process in the sarcoplasmic reticulum), suggesting a possible precipitation of calcium phosphate in the sarcoplasmic reticulum [6]
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