Safety and efficacy of a pre-wrkout dietary supplement with and without synephrine

A number of nutritional strategies have been developed to optimize nutrient delivery prior to exercise. As a result, a number of pre-workout supplements have been developed to increase energy availability, promote vasodilation, and/or positively affect exercise capacity. The purpose of this study was to examine the safety and efficacy of a pre-workout dietary supplement with and without synephrine.

In a double-blind, crossover, randomized and placebo-controlled manner; 25 apparently healthy and recreationally active men and women (21.76 ± 3.00 yr, 15.24 ± 5.26% fat, 25.09 ± 3.03kg/m²) had the first blood donation after 10-12 hours fasting, and then after 2 hours of a pre-workout supplement ingestion, participants had the second blood donation. Participants ingested in a randomized and counterbalanced manner a dextrose flavored placebo (P); a pre-workout supplement (PWS) containing 3g beta alanine, 2g creatine nitrate, 2g arginine AKG, 300mg N-acetyl tyrosine, 270mg caffeine, 15mg Mucuna pruriens; or, the PWS with 20mg synephrine (PWS+S). Participants repeated the experiment after a one week washout period with the alternate supplements in a randomized and counterbalanced manner. Data were analyzed by repeated measure ANOVA and presented as means (95% CI) delta change from baseline.

Delta analysis revealed significant differences among groups in mean change in blood urea nitrogen (BUN) (unit conversion to mg/dl by mmol/l × 2.8011): P (-1.51mg/dl; -2.26, -0.78), PWS (-2.26mg/dl; -2.99, -1.54), and PWS+S (-0.56mg/dl; -1.28, 0.14), creatinine (CRE) (unit conversion to mg/dl by µmol/L × 0.0113): P (0.05mg/dl; 0.01, 0.10), PWS (0.14mg/dl; 0.09, 0.19), and PWS+S (0.14mg/dl; 0.09, 0.18). An overall Wilks' Lambda time (p < 0.01) and time × group (p < 0.01) interactions for BUN, CRE and the ratio of BUN/CRE (BCr), and Greenhouse-Geisser univariate analysis for BUN, CRE and BCr (p < 0.01) were found. Wilks' Lambda analysis revealed a significant time effect (p < 0.05) of alkaline phosphatase (ALP), aspartate amino transferase (ALT), and alanine amino transferase (AST), and of creatine kinase (CK) and lactate dehydrogenase (LDH), with no time × group interactions (p > 0.05). MANOVA Greenhouse-Geisser univariate analysis revealed significant changes over time for ALP, ALT and AST (p < 0.01), and CK and LDH (p < 0.01). Delta analysis revealed significant differences among groups in mean change in total cholesterol (CHOL): P (0.31mmol/L; 0.12, 0.50), PWS (-0.16mmol/L; -0.35, 0.02), and PWS+S (0.31mmol/L; 0.12, 0.50). An overall Wilks' Lambda time (p < 0.01) and time × group (p < 0.01) interactions for CHO, HDL-C, LDL-C and triglyceride (TAG), and Greenhouse'Geisser univariate analysis for CHO, HDL-C, and LDL-C (p < 0.01) were found. Delta analysis revealed significant differences among groups in mean change in glucose: P (0.60mmol/L; 0.21, 0.99), PWS (0.77mmol/L; 0.39, 1.15), and PWS+S (1.29mmol/L; 0.90, 1.68). A significant time × group interactions (p < 0.03) of glucose was found.

Ingesting a dietary PWS or PWS+S had minor affects within 3 hours, similar to P, on kidney function, liver enzymes, blood lipid levels, muscle enzymes, and blood sugar levels. These findings are in agreement with other studies testing similar ingredients.

Supported by Nutrabolt International, Inc. (Bryan, TX).

Affiliations

1. Exercise & Sport Nutrition Lab, Texas A&M University, College Station, TX, USA

   • R Dalton
   • , YP Jung
   • , C Rasmussen
   • , CP Earnest
   •  & RB Kreider

2. Institute for Obesity Research & Program Evaluation, Texas A&M University, College Station, TX, USA

   • P Murano

3. Nutrabolt International Inc., Bryan, TX, USA

   • CP Earnest

Corresponding author

Correspondence to YP Jung.

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