Effects of a pre-workout supplement on hyperemia following leg extension resistance exercise to failure with different resistance loads

Abstract

Background: We sought to determine if a pre-workout supplement (PWS), containing multiple ingredients thought to enhance blood flow, increases hyperemia associated with resistance training compared to placebo (PBO). Given the potential interaction with training loads/time-under-tension, we evaluated the hyperemic response at two different loads to failure. Methods: Thirty males participated in this double-blinded study. At visit 1, participants were randomly assigned to consume PWS (Reckless™) or PBO (maltodextrin and glycine) and performed four sets of leg extensions to failure at 30% or 80% of their 1-RM 45-min thereafter. 1-wk. later (visit 2), participants consumed the same supplement as before, but exercised at the alternate load. Heart rate (HR), blood pressure (BP), femoral artery blood flow, and plasma nitrate/nitrite (NOx) were assessed at baseline (BL), 45-min post-PWS/PBO consumption (PRE), and 5-min following the last set of leg extensions (POST). Vastus lateralis near infrared spectroscopy (NIRS) was employed during leg extension exercise. Repeated measures ANOVAs were performed with time, supplement, and load as independent variables and Bonferroni correction applied for multiple post-hoc comparisons. Data are reported as mean ± SD. Results: With the 30% training load compared to 80%, significantly more repetitions were performed (p < 0.05), but there was no difference in total volume load (p > 0.05). NIRS derived minimum oxygenated hemoglobin (O 2 Hb) was lower in the 80% load condition compared to 30% for all rest intervals between sets of exercise (p < 0.0167). HR and BP did not vary as a function of supplement or load. Femoral artery blood flow at POST was higher independent of exercise load and treatment. However, a time*supplement*load interaction was observed revealing greater femoral artery blood flow with PWS compared to PBO at POST in the 80% (+56.8%; p = 0.006) but not 30% load condition (+12.7%; p = 0.476). Plasma NOx was~3-fold higher with PWS compared to PBO at PRE and POST (p < 0.001).

Higher doses of a green tea-based supplement increase post-exercise blood flow following an acute resistance exercise bout in recreationally resistance-trained college-aged men

“…In fact, the nutritional supplement arginine, which is known to stimulate vasodilation, has been shown not to affect muscle mass changes in men that resistance trained [29]. Notwithstanding, arginine and other supplements that increase per-exercise blood flow (e.g., Lcitrulline and beet root juice and extracts) have been found to prolong work and/or power output during maximal resistance exercise repetition attempts, sprinting efforts, and submaximal aerobic exercise events [10,12,13,[29][30][31][32][33]. Therefore, future research should be performed to determine if the GBS-induced increase in peri-exercise blood flow is associated with any of these potential ergogenic effects.…”

“…We adopted a study design similar to one that our laboratory has used in the past to examine the blood flowenhancing efficacy of an L-citrulline-containing nutritional supplement [10]. The main difference between studies is that we previously employed a leg extensor exercise bout and examined femoral artery blood flow patterns, whereas herein participants performed arm curl exercises and we examined brachial artery blood flow patterns.…”

“…Nutritional supplements or dietary ingredients which promote vasodilation may be beneficial for increasing blood flow to working muscle during and following exercise (reviewed in [1,2]). Common dietary supplements that have been examined in this regard have included high nitratecontaining beet root juice [3][4][5][6][7][8], L-arginine [9], L-citrulline [10][11][12], betalains [13], and various plant extracts (e.g., red spinach) [14]. Most of these supplements have been posited to act through increasing endothelium-dependent nitric oxide (NOx) production which, in turn, stimulates smaller artery and arteriole vasodilation.…”

Multi-ingredient pre-workout supplements, safety implications, and performance outcomes: a brief review

“…Similarly, Kraemer et al [ 49 ] found that 7 days of MIPS supplementation significantly improved Smith machine squat repetitions to fatigue during 6 sets at 80% 1RM ( d = 0.41–1.08, p < 0.05, moderate - strong). However, Martin and colleagues [ 50 ] found no effect of short-term MIPS supplementation on total repetitions or volume load completed during four sets of bilateral leg extensions to fatigue at both 30% and 80% 1RM. Again, given the minimal volume of research in this area, no solid conclusions can be made at this point in time.…”

“…Another study demonstrated elevated DBP but not SBP after MIPS ingestion ( d = 15.9, p = 0.011, strong) [ 4 ]. Several investigations have noted higher post-exercise HR in caffeine-based MIPS users [ 37 , 50 ]. Based upon the well-documented physiological effect of the caffeine contained in these supplements, these responses are not unexpected, and no response was outside an acceptable normal range.…”