New perspectives for investigating muscular perfusion response after dietary supplement intake: an exploratory, randomized, double-blind, placebo-controlled crossover trial in healthy young athletes using contrast-enhanced ultrasound (CEUS)

ABSTRACT

Background

Various dietary supplements have been reported to enhance muscular perfusion in athletes practicing resistance training, especially through modulation of nitric oxide signaling.

Objectives

The aim of this study was therefore to investigate selected ‘NO-boosting’ supplements in a real-life setting i) to generate novel hypotheses and perfusion estimates for power calculation in view of a definitive trial and ii) to assess the feasibility of the study design with particular focus on the use of contrast-enhanced ultrasound (CEUS) for perfusion quantification.

Methods

Thirty young male athletes (24 ± 4 years) regularly practicing resistance training were enrolled in this three-arm, placebo(PL)-controlled crossover trial with ingestion of two commercially available supplements: an amino acid combination (AA) (containing 3 g of L-arginine-hydrochloride and 8 g of L-citrulline-malate) and 300 mg of a specific green tea extract (GTE). After intake, CEUS examinations of the dominant biceps brachii muscle were performed under resting conditions and following standardized resistance exercising. Quantitative parameters of biceps perfusion (peak enhancement, PE; wash-in perfusion index, WiPI) and caliber were derived from corresponding CEUS video files. Additionally, subjective muscle pump was determined after exercise.

Results

For PE, WiPI, and biceps caliber, the standard deviation (SD) of the within-subject differences between PL, AA, and GTE was determined, thereby allowing future sample size calculations. No significant differences between PL, AA, and GTE were observed for biceps perfusion, caliber, or muscle pump. When comparing resting with post-exercise measurements, the increase in biceps perfusion significantly correlated with the caliber increase (PE: r = 0.266, p = 0.0113; WiPI: r = 0.269, p = 0.0105). Similarly, the biceps perfusion correlated with muscle pump in the post-exercise conditions (PE: r = 0.354, p = 0.0006; WiPI: r = 0.350, p = 0.0007). A high participant adherence was achieved, and the acquisition of good quality CEUS video files was feasible. No adverse events occurred.

Conclusion

Based on our novel examination protocol, CEUS seems to be feasible following higher-load resistance exercising and may be used as a new method for high-resolution perfusion quantification to investigate the effects of pre-exercise dietary supplementation on muscle perfusion and related muscle size dynamics.

KEYWORDS:

• contrast-enhanced ultrasound
• CEUS
• muscle perfusion
• dietary supplements
• resistance training
• feasibility

Acknowledgments

We would like to thank all the participants and the clinical assistants for their great support in data collection.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethics approval and informed consent

This study was performed in accordance with the ethical standards of the Declaration of Helsinki. Ethics approval was obtained from the local Ethics Committee (S-094/2019). Informed consent was obtained from all subjects prior to study inclusion.

Data availability statement

The data supporting the findings of this trial are provided by the corresponding author upon reasonable request.

Authors’ contributions

AN is the creator of the study concept. FB, JD, SG, ST, and CF contributed to the specific design and analysis plan of the study. Recruitment of participants was conducted by FB, AN, ST, and JD. FB, JD, and CF coordinated the trial and data collection. FB, JD, and CF wrote the paper. FB and SG conducted the statistical analysis. AN, SG, and ST reviewed the manuscript. All the authors listed fulfill the criteria of authorship.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15502783.2022.2097018

Additional information

Funding

The study was supported by the Center for Orthopedics, Trauma Surgery and Spinal Cord Injury, Heidelberg University Hospital.