Comprehensive Assessment of a Pre-Workout Dietary Supplement with and without Synephrine
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The aim of this study was to examine the effect of acute (Study 1) and chronic (Study 2) ingestion of a pre-workout supplement with (PWS+S) and without p-synephrine (PWS) on safety, metabolism, body composition and performance. In Study 1, 25 healthy, recreationally active participants ingested a dextrose flavored placebo (PLA); PWS containing 2 g arginine alphaketoglutarate, 3 g β-alanine, 270 mg caffeine, 2 g creatine nitrate, 15 mg L-Dopa, 300 mg N-acetyl L-tyrosine; or, the PWS with 20 mg p-synephrine, interspersed with a 7-d washout, in a randomized, crossover, counter-balanced manner. Participants were tested at time 0 (unsupplemented), and then 30-min and 90-min post ingestion. Data were analyzed by repeated measure MANOVA and reported as mean ± SD or mean change and 95% CI. Both treatment groups reported a greater sense of vigor and energy prior to exercise; PWS+S and PWS scored significantly higher on a Stroop Test. We observed significant differences in RER [PLA (0.89 ± 0.09) vs. PWS (0.92 ± 0.06, p < 0.02) and PWS+S (0.85 ± 0.04, p = 0.006) and PWS vs. PWS+S (p < 0.001)]. In Study 2, 80 resistance trained male were randomized and ingested supplements; PLA, PWS, or PWS+S for 8-wk with resistance training. Testing occurred at baseline, wk 4, and wk 8. Data were analyzed by repeated measure MANOVA and reported as mean ± SD or mean change and 95% CI. We found significant increases in 1RM-Bench Press at wk 4 for PWS and PWS+S, but not for PLA (5.45 kg, 95% CI, -0.82, 11.73). By wk 8 each group demonstrated significant 1RM-BP for PWS, PWS+S and PLA. A similar pattern was noted for 1RM-Leg Press at wk 4 for PWS and PWS+S, but not the PLA (36.50, 95% CI, -0.21, 73.2). By wk 8, all groups increased 1RM-LP. Our data suggest that a PWS appears safe for acute ingestion and is efficacious regarding indices of cognitive function and exercise performance. We also found that ingesting a PWS during training appears safe, and the inclusion of p-synephrine is unnecessary to achieve the observed favorable effects to training adaptation.
Jung, Yanghoon P (2016). Comprehensive Assessment of a Pre-Workout Dietary Supplement with and without Synephrine. Doctoral dissertation, Texas A & M University. Available electronically from