Skip to main content

Effects of 8 weeks pre-workout dietary supplement ingestion with and without synephrine on blood chemistry panel


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 effects of 8 weeks pre-workout dietary supplement ingestion with and without synephrine on blood chemistry panel.


In a double-blind, randomized and placebo-controlled manner; 80 apparently healthy and resistance-trained men (21.76 ± 3.59 yr, 15.29 ± 6.19% fat, 25.60 ± 4.03kg/m2) ingested in a randomized and counterbalanced manner a dextrose flavored placebo (P); a pre-workout supplement (PWS) containing 3.0 g beta alanine, 2 g creatine nitrate, 2g arginine AKG, 300mg N-acetyl tyrosine, 270mg caffeine, 15mg Mucuna pruriens; or, the PWS with 20mg synephrine (PWS+S), and then had blood donation at week 0, week 4, and week 8. The participants had resistance training 4 times per week during 8 weeks supplementation. Data were analyzed by repeated measure ANOVA and presented as mean (95% CI) delta change from baseline.


Repeated MANOVA revealed no significant differences among groups in blood urea nitrogen (BUN) (p = 0.62) and creatinine (CRE) (p = 0.27), and the ratio of BUN/CRE (BCr) (p = 0.20). An overall Wilks' Lambda analysis showed significant time effects (p < 0.01) in mean changes in BUN (unit conversion to mg/dl by mmol/l × 2.8011) (2.79mg/dl; 1.58, 4.00) at week 8, CRE (unit conversion to mg/dl by µmol/l × 0.0113) (-0.35mg/dl; -0.49, -0.21) at week 4 and (-0.16mg/dl; -0.28, -0.05), and BCr: (8.17; 4.01, 12.33) at week 4 and (7.02; 3.02, 11.02) at week 8. Greenhouse-Geisser univariate analysis revealed no time × group interaction of BUN (p = 0.54), CRE (p = 0.78), and BCr (p = 0.62). In liver enzymes, there were no significant differences among groups in alkaline phosphatase (ALP) (p = 0.24), alanine amino transferase (ALT) (p = 0.74), and aspartate amino transferase (AST) (p = 0.47). Delta analysis revealed significant difference in ALP: (-11.23 U/L; -13.93, -8.5) at week 4 and (-5.44 U/L; -8.48, -2.4) at week 8. LSD Post hoc analysis revealed no significant mean changes in liver enzymes; however, there was a significant difference (p = 0.04) of ALP between PWS+S (-3.44 U/L; -6.52, -0.36) and PWS (-7.86 U/L; -10.88, -4.84) compared with P (-5.36 U/L; -8.388, -2.34). However, the range of both groups PWS+S: (68.14 ± 17.39 U/L) at week 4 and (74.44 ± 19.64 U/L) at week 8 and PWS: (87.20 ± 24.72 U/L) at week 4 and (78.49 ± 24.96 U/L) at week 8 were within safe clinical range (30-92 U/L). There were no significant time (p = 0.23) and time × group interaction (p = 0.78) of creatine kinase (CK) and lactate dehydrogenase (LDH), no significant time × group interaction (p = 0.78) of total cholesterol, LDL-C, HDL-C and triglyceride, and a significant time effect (p < 0.01) but no time × group effect (p = 0.083) of glucose levels.


Ingesting a dietary PWS or PWS+S for 8 weeks had no adverse effect 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).

Author information

Authors and Affiliations


Corresponding author

Correspondence to YP Jung.

Rights and permissions

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Jung, Y., Dalton, R., Rasmussen, C. et al. Effects of 8 weeks pre-workout dietary supplement ingestion with and without synephrine on blood chemistry panel. J Int Soc Sports Nutr 12 (Suppl 1), P4 (2015).

Download citation

  • Published:

  • DOI: