A Pre-Exercise Dose of Muscle Sentry® has no Effect on Performing Repeated Leg Press Sets to Failure

This study compared the number of bilateral leg presses done at 150% of body mass while on either Muscle Sentry® (MS) or placebo (PL). Participants (16 women, 14 men, college students 19-26 years) performed 2 sets of leg press to failure using 150% of their body mass with 5 min rest separating the 2 sets. Each exercise was performed twice (1× MS, 1× PL) at the same time of day with 48 h separating each exercise. Both MS and PL were ingested 30 min prior to performing the exercise. Just prior to starting the exercise and at the end of each set, heart rate, and blood pressure were obtained and the rate pressure product was calculated to determine myocardial workload. Two-way repeated measures ANOVA for lift number showed no significant main effects for either MS vs. PL, or for Set1 vs. Set2 (p > 0.05). The interaction was also not statistically different (mean repetitions ± std. dev.: MS1= 28±20, MS2= 26±18, PL1 = 30±24, PL2 = 29±20). Two-way repeated measures ANOVA for rate pressure product showed no significance for either the main effect for MS vs. PL, or supplement × pre-post interaction (p > 0.05). The main effect for pre-lift vs. post lift was significant (p<0.001) with post being higher than pre. Ingestion of Muscle Sentry® 30 min prior to leg pressing 150% of body mass to failure had no effect upon either total work performance or myocardial workload.