Abstract
The primary purpose of this study was to examine the acute effects of one versus two doses of a multi-ingredient pre-workout supplement on energy expenditure during moderate-intensity treadmill running. In addition, our second aim was to investigate the responses of associated metabolic factors (i.e., substrate utilization, measures of gas exchange), perceived exertion, and resting cardiovascular variables with one and two doses of the pre-workout supplement. Twelve females (mean ± SD: age = 25.3 ± 9.4 years; body mass = 61.2 ± 6.8 kg) completed three bouts of 30 min of treadmill running at 90% of their ventilatory threshold on separate days after consuming one dose of the pre-workout supplement (1-dose), two doses (2-dose), and a placebo. There were no differences among conditions for energy expenditure, fat or carbohydrate oxidation, respiratory exchange ratio, oxygen consumption, or heart rate across exercise time. The two-dose group, however, had lower (p = 0.036) ratings of perceived exertion (11.8 ± 1.7) than the one-dose (12.6 ± 1.7) and the placebo (12.3 ± 1.2) at the 20-min time point of exercise as well as greater resting systolic blood pressure (110 ± 10 mmHg) compared to the one-dose (106 ± 10 mmHg) and the placebo (104 ± 10 mmHg) conditions. Both the one-dose and two-dose conditions had greater increases in diastolic blood pressure compared to the placebo. Thus, our findings indicated that the present pre-workout supplement had no performance-enhancing benefits related to energy metabolism but did attenuate feelings of exertion.
Highlights
Pre-workout supplementation is a nutritional strategy that involves consuming a mixture of bioactive compounds and dietary ingredients prior to a bout of exercise for ergogenic purposes.For example, pre-workout supplements often contain beta-alanine, caffeine, citrulline, tyrosine, taurine, creatine, arginine, and carnitine as well as numerous vitamins and minerals [1]
Caffeine is one of the most commonly used thermogenic agents that stimulates the release of catecholamines and renin, thereby increasing heart rate, blood pressure, lipolysis, and plasma free fatty acid concentration [3,8,9]
Our findings showed no changes in fat oxidation, carbohydrate oxidation, or EE among the supplement conditions and placebo at any time point during the 30-min run at 90% ventilatory threshold (VT) (Figure 2a)
Summary
Pre-workout supplementation is a nutritional strategy that involves consuming a mixture of bioactive compounds and dietary ingredients prior to a bout of exercise for ergogenic purposes.For example, pre-workout supplements often contain beta-alanine, caffeine, citrulline, tyrosine, taurine, creatine, arginine, and carnitine as well as numerous vitamins and minerals [1]. The purported effects of pre-workout supplements generally consist of elevated metabolic rate, increased measures of anaerobic and aerobic performance, and improvements in body composition [2,3,4,5,6]. Sports 2020, 8, 52 concerning the influence of these multi-ingredient products on their ergogenic potential and variables related to general health (e.g., resting heart rate and blood pressure). The findings of these investigations [8,10,11,12,14,15] indicated that acute caffeine supplementation within a wide dosing range (3–6 mg·kg−1 of BM) may influence metabolic, cardiovascular, psychological, and performance variables at rest and during exercise
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