Effect of Combined Grape Seed Extract and L-Citrulline Supplementation on Hemodynamic Responses to Exercise in Young Males

Abstract

Grape seed extract (GSE) or L-citrulline supplement has been known to increase nitric oxide (NO) bioavailability and enhance endothelial-mediated vasodilation. Accordingly, to examine the additive benefits of combination of the two supplementations on hemodynamic responses to dynamic exercise, young, healthy males were recruited for this study. Effects of 7 days of 1) GSE + L-citrulline, 2) GSE, 3) L-citrulline, and 4) placebo supplementation on systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MAP), cardiac output, total vascular conductance (TVC), and oxygen (O₂) consumption were examined at rest and during cycling exercise. Compared with placebo, GSE, L-citrulline, and combined supplementations did not reduce SBP, DBP, and MAP, while cardiac output (placebo; 23.6 ± 1.3 L/min, GSE; 25.7 ± 1.1 L/min; L-citrulline, 25.2 ± 1.2 L/min; GSE + L-citrulline; 25.3 ± 0.9 L/min) and TVC (placebo; 234.7 ± 11.3 ml/min/mmHg, GSE; 258.3 ± 10.6 ml/min/mmHg; L-citrulline, 255.2 ± 10.6 ml/min/mmHg; GSE + L-citrulline; 260.4 ± 8.9 ml/min/mmHg) were increased at only the 80% workload (p < 0.05). Compared with placebo and L-citrulline, GSE and combined supplementations had a reduction in VO₂ across workloads (p < 0.05). However, there was no additive benefits on these variables. We conclude that supplementation with GSE, L-citrulline, and combined supplementations increased cardiac output due partially to decreased vascular resistance. Our findings suggest that GSE may act as an ergogenic aid that can improve O₂ delivery to exercising muscles.

Keywords:

• Grape seed extract
• L-citrulline
• cardiac output
• total vascular conductance
• nitric oxide

Acknowledgements

We sincerely thank the subjects for volunteering to participate in the study.

Disclosure statement

Each author has declared that they do not have a conflict of interest.

Funding

The author(s) reported there is no funding associated with the work featured in this article.

Additional information

Notes on contributors

Brian Shariffi

Brian Shariffi, Cardiovascular Physiology, California Baptist University, Riverside, CA, USA.

Katherine Dillon

Katherine Dillon, Cardiovascular Physiology, California Baptist University, Riverside, CA, USA.

Trevor Gillum

Trevor Gillum, Environmental Physiology, California Baptist University, Riverside, CA, USA.

William Boyer

William Boyer, Physical Activity Epidemiology, California Baptist University, Riverside, CA, USA.

Sean Sullivan

Sean Sullivan, Sports Management, California Baptist University, Riverside, CA, USA.

Esther Lee

Esther Lee, big data analysis, Division of Natural and Mathematical Sciences, California Baptist University, Riverside, CA, USA.

Jong-Kyung Kim

Jong-Kyung Kim, Cardiovascular Physiology, California Baptist University, Riverside, CA, USA.