Abstract
BackgroundConsumption of pre-workout dietary supplements by both recreational and competitive athletes has increased dramatically in recent years. The purpose of this study was to determine the acute effects of a caffeine-containing pre-workout dietary supplement on various measures of performance including anaerobic power, upper and lower body power, and upper body strength in recreationally trained males.MethodsThirteen males (mean ± SD age = 24 ± 6 yrs; height = 180.3 ± 5 cm; body mass = 83.4 ± 9 kg) participated in this investigation in which they reported to the laboratory on four separate occasions, each separated by one week. Each subject underwent an initial familiarization session on week one followed by baseline (BA) performance testing on week two. Performance testing included a medicine ball put (MBP) to determine upper body explosive power, vertical jump test (VJ) to determine lower body explosive power, one-rep maximum bench press (1-RM) for determining upper body strength, and a Wingate Anaerobic Power Test (WAnT) to determine measures of anaerobic power. On week three, subjects were randomly assigned to ingest either a pre-workout supplement (SUP) or a placebo (PL) and again complete the performance testing protocol. Subjects were provided with the crossover treatment on the fourth and final week. Performance testing commenced 20-minute following ingestion of both treatments, which was similar to previous investigations.ResultsSignificant differences in anaerobic peak power relative to the WAnT were observed following ingestion of the SUP (782 ± 191 W) in comparison to the PL (722 ± 208 W; p = 0.003; effect size = 0.30) and BA (723 ± 205 W; p = 0.011; effect size = 0.28). Significant differences were also observed for anaerobic mean power following ingestion of the SUP (569 ± 133 W) in comparison to the PL (535 ± 149 W; p = 0.006; effect size = 0.24) and BA (538 ± 148 W; p = 0.020; effect size = 0.22). No significant differences between trials were observed for upper body power, lower body power, or upper body strength.ConclusionsIngestion of the pre-workout dietary supplement led to significant improvements in anaerobic peak and mean power values in comparison to the placebo and baseline treatments. No improvements were observed in upper and lower body power or upper body strength. Taken prior to exercise, a caffeine-containing pre-workout dietary supplement may improve anaerobic power performance.
Highlights
Consumption of pre-workout dietary supplements by both recreational and competitive athletes has increased dramatically in recent years
While beet extract and dimethylglycine HCL are both theorized to improve mitochondrial efficiency, recent research demonstrated no significant differences between supplement and placebo groups when measuring the effect of beet extract [25] and dimethylglycine HCL on anaerobic power [26]
While recent research has reported that pre-exercise tyrosine supplementation improves cognitive function during soccer specific exercise in a warm environment, there is little evidence for tyrosine improving anaerobic power or acting more globally as an ergogenic aid [1, 27]
Summary
Consumption of pre-workout dietary supplements by both recreational and competitive athletes has increased dramatically in recent years. The purpose of this study was to determine the acute effects of a caffeinecontaining pre-workout dietary supplement on various measures of performance including anaerobic power, upper and lower body power, and upper body strength in recreationally trained males. Pre-workout supplementation has continued to rise in popularity among both recreational and athletic populations interested in improving performance. 70 % of young adults consume at least one nutritional supplement, and one of the most popular categories of nutritional supplements consumed is preworkout energy drinks [1, 2]. 30 % of young adults consume these energy-boosting supplements on a regular basis; this rate of consumption places preworkout supplements second in usage only behind that of multivitamins [3]. Further investigation of these ergogenic aids and their potential impact on various measures of performance is of importance to both the scientific and athletic communities
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