Safety of a dose-escalated pre-workout supplement in recreationally active females

Abstract

BackgroundPre-workout supplements (PWS) have increased in popularity among athletic populations for their purported ergogenic benefits. Most PWS contain a “proprietary blend” of several ingredients, such as caffeine, beta-alanine, and nitrate in undisclosed dosages. Currently, little research exists on the safety and potential side effects of chronic consumption of PWS, and even less so involving female populations. Therefore, the purpose of the present study was to examine the safety of consuming a dose-escalated PWS over a 28-day period among active adult females.Methods34 recreationally active, adult females (27.1 ± 5.4 years, 165.2 ± 5.7 cm, 68.2 ± 16.0 kg) participated in this study. Participants were randomly assigned to consume either 1 (G1) or 2 (G2) servings of a PWS daily or remain unsupplemented (CRL) for a period of 28 days. All were instructed to maintain their habitual dietary and exercise routines for the duration of the study. Fasting blood samples, as well as resting blood pressure and heart rate, were taken prior to and following the supplementation period. Samples were analyzed for hematological and clinical chemistry panels, including lipids.ResultsSignificant (p < 0.05) group by time interactions were present for absolute monocytes (CRL −0.10 ± 0.10; G1 + 0.03 ± 0.13; G2 + 0.01 ± 0.12×10E3/uL), MCH (CRL −0.13 ± 0.46; G1 + 0.36 ± 0.52; G2 -0.19 ± 0.39 pg), creatinine (CRL 0.00 ± 0.05; G1 -0.06 ± 0.13; G2 -0.14 ± 0.08 mg/dL), eGFR (CRL −0.69 ± 5.97; G1 + 6.10 ± 15.89; G2 + 14.63 ± 7.11 mL/min/1.73), and total cholesterol (CRL −2.44 ± 13.63; G1 + 14.40 ± 27.32; G2 -10.38 ± 15.39 mg/dL). Each of these variables remained within the accepted physiological range. No other variables had significant interactions.ConclusionThe present study confirms the hypothesis that a PWS containing caffeine, beta-alanine, and nitrate will not cause abnormal changes in hematological markers or resting vital signs among adult females. Although there were statistically significant (p < 0.05) group by time interactions for absolute monocytes, MCH, creatinine, eGFR, and total cholesterol, all of the results remained well within accepted physiological ranges and were not clinically significant. In sum, it appears as though daily supplementation with up to 2 servings of the PWS under investigation, over an interval of 28 days, did not adversely affect markers of clinical safety among active adult females.Electronic supplementary materialThe online version of this article (doi:10.1186/s12970-015-0074-y) contains supplementary material, which is available to authorized users.

Short-Term Effects of a Ready-to-Drink Pre-Workout Beverage on Exercise Performance and Recovery

“…Consequently, the acute and short-term use of this RTD appears to be safe within the dosages and manner it was assessed in the current study. These findings are consistent with our prior studies with supplementation periods as long as 8 weeks [ 28 , 29 , 30 , 52 ], as well as other similar studies [ 58 , 59 ].…”

The acute effects of a multi-ingredient pre-workout supplement on resting energy expenditure and exercise performance in recreationally active females

“…More recent studies have focused on the effects of combining caffeine with a variety of ingredients, including beta-alanine, creatine, and various herbal extracts, for their potential synergistic benefits. Together, these ingredients offer specific physiological advantages, which often include enhanced energy availability, metabolism and improved buffering capacity of skeletal muscle [ 4 , 5 , 9 ].…”

“…Previous studies have reported improvements in acute muscular performance in individuals during upper and lower body exercises following ingestion of MIPS [ 2 , 5 , 9 , 10 ]. For example, Beck et al [ 9 ] observed a significant increase in upper body maximal strength in male subjects following acute ingestion of a caffeine-containing supplement.…”

“…It is possible that if exercise is more enjoyable and less exhausting, individuals may participate longer, with greater intensity and more frequency; thereby potentially augmenting training adaptations over time. Several reports of benefits ranging from improvements in feelings of focus and energy to reductions in ratings of fatigue following consumptions of a MIPS during bouts of high-intensity exercise have been previously reported [ 2 , 5 , 14 ]. Specifically, Walsh et al [ 15 ] reported improved ratings of focus, energy, and decreased feelings of fatigue, which also significantly improved time to exhaustion following consumption of a pre-workout supplement.…”

Twelve weeks supplementation with an extended-release caffeine and ATP-enhancing supplement may improve body composition without affecting hematology in resistance-trained men

“…This is also in agreement with Coolen and colleagues [ 13 ] who observed no changes in blood markers following 4 weeks direct supplementation with 5 g/day of ATP. Furthermore, multi-ingredient products containing caffeine have previously been reported to be safe for human consumption as determined by changes in hematology and hemodynamics, but these studies were of relatively short duration (2–4 weeks) compared to the present study [ 16 , 42 ].…”