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 (O₂Hb) 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).

Conclusions: Compared to PBO, the PWS consumed herein augmented hyperemia following multiple sets to failure at 80% of 1-RM, but not 30%. This specificity may be a product of interaction with local perturbations (e.g., reduced tissue oxygenation levels [minimum O₂Hb] in the 80% load condition) and/or muscle fiber recruitment.

Keywords: Blood flow; Nitric oxide, Volume load; Oxygenation; Reactive hyperemia; Resistance exercise; Sports supplements.

Fig. 1

Near infrared spectroscopy variable responses during leg extensor exercise. ANOVA revealed no main effect of treatment or interaction with independent variables. Thus, a) minimum oxygenated hemoglobin (Min O₂Hb), b) maximum deoxygenated hemoglobin (Max HHb), c) minimum O₂Hb and HHb difference (Min HbDiff), and d) maximum total hemoglobin (Max tHb) are presented as mean values ± standard deviation for low (30% of 1RM) and high (80% of 1RM) load conditions for each set of leg extensor exercise. Relevant ANOVA p-values regarding set and load variables are presented within each panel. When a significant set*load interaction was found, post-hoc analysis with Bonferroni correction was employed for between intensity differences within each set. *, significantly different from 30% load condition (p < 0.0125)

Fig. 2

Near infrared spectroscopy (NIRS) variable responses between sets of leg extensor exercise. Maximum (Max) a) oxygenated hemoglobin (O₂Hb), b) deoxygenated hemoglobin (HHb), c) total hemoglobin (tHb), d) O₂Hb and HHb difference (HbDiff) and minimum (Min) e) O₂Hb, f) HHb, g) tHb and h) HbDiff) are presented as mean values ± standard deviation for low (30% of 1RM) and high (80% of 1RM) load conditions for each set of leg extensor exercise. Relevant ANOVA p-values regarding set and load variables are presented within each panel. When a significant set*load interaction was found, post-hoc analysis with Bonferroni correction was employed for between load condition differences within each set. *, significantly different from 30% load condition (p < 0.0167)

Fig. 3

Minimum deoxygenated hemoglobin (Min HHb) across all leg extension exercise rest intervals and loads by treatment. ANOVA revealed a significant main effect of treatment (p < 0.05). Data are presented as individual values with solid bars indicating mean values ± standard deviation. *, significantly different from PBO (p < 0.05)

Fig. 4

Heart rate (HR) and blood pressure (BP) values (mean ± standard devation) at baseline (BL), 45-min post ingestion of pre-workout supplement (PWS) (i.e., pre-leg extensor exercise; PRE), and 5-min post-leg extensor exercise (POST) for each load condition (i.e., 30 and 80% of 1RM) and treatment (i.e., placebo [PBO] and PWS). a) HR, b) systolic BP (SBP), c) diastolic BP (DBP), and d) mean arterial pressure (MAP). ANOVA revealed no main effects of load or its interaction with other independent variables (p > 0.05). Relevant ANOVA p-values regarding time (i.e., time point) and treatment variables are presented within each panel

Fig. 5

Femoral artery diameter (panel a) and femoral artery blood flow (panel b) values (mean ± standard deviation) at baseline (BL), 45-min post ingestion of pre-workout supplement (PWS) (i.e., pre-leg extensor exercise; PRE), and 5-min post-leg extensor exercise (POST) for each load condition (i.e., 30 and 80% of 1RM) and treatment (i.e., placebo [PBO] and PWS). ANOVA revealed a 3-way interaction of time, load and treatment (p < 0.05) and post-hoc analysis with Bonferroni correction was employed to evaluate between treatment differences at each time point for each leg extensor exercise load condition. *, significantly different from PBO at the same time point within the 80% load condition (p < 0.008)

Fig. 6

Plasma nitrate and nitrite (NOx) values (mean ± standard deviation) at baseline (BL), 45-min post ingestion of pre-workout supplement (PWS) (i.e., pre-leg extensor exercise; PRE), and 5-min post-leg extensor exercise (POST) across leg-extensor exercise load conditions (i.e., 30 and 80% of 1RM) for each treatment (i.e., placebo [PBO] and PWS). ANOVA revealed a significant time*treatment interaction (p < 0.05) and post-hoc comparisons were performed using Bonferroni correction for multiple comparisons. *, significantly different from PBO at the same time point (p < 0.0167)