Effects of Citrulline Malate Supplementation on Muscle Strength in Resistance-Trained Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Abstract

Although the ergogenic mechanisms of supplementation with citrulline malate are well known, unclear findings regarding variables of muscle strength have been recorded. Such misleading findings in the literature illustrate the need for well-conducted meta-analysis research to elucidate the possible ergogenic impact, which could have major practical consequences for athletes and recreational practitioners seeking to optimize gains in muscle strength. The objective of this systematic review was to summarize the existing literature that evaluated the effects of citrulline malate supplementation on muscle strength outcomes from resistance exercise in resistance-trained individuals. A systematic electronic search in Medline and Scientific Electronic Library Online (SciELO) was completed in August 2020 identifying randomized controlled trials investigating the effect of citrulline malate supplementation on muscle strength in resistance-trained adults. A subsequent meta-analysis was performed. The meta-analysis involved four studies and 138 assessments (69 in citrulline-malate and 69 in placebo groups). We did not observe an overall effect favoring citrulline-malate supplementation (SMD_95% = 0.13 [−0.21; 0.46]). Considering the lower (SMD_95% = 0.06 [−0.47; 0.60]) and upper (SMD_95% = 0.17 [−0.26; 0.60]) limbs, a non-significant overall effect was identified. The mean effects were similar for “limbs” (upper vs lower) [p = 0.763]. Accordingly, our findings suggest that citrulline malate supplementation does not improve muscle strength in healthy and resistance-trained individuals (PROSPERO registration number: CRD42020159338).

Keywords:

• citrulline
• muscle strength
• physical fitness
• resistance training

Acknowledgements

FUNADESP—Fundação Nacional de Desenvolvimento do Ensino Superior Particular.

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Additional information

Notes on contributors

Andreo F. Aguiar

Andreo Aguiar, PhD, is an associate professor of exercise physiology at University of Northern Paraná (UNOPAR), Londrina, Brazil, where he works as supervisor and professor in the graduate courses (master and doctoral) in (1) Rehabilitation Sciences and (2) Physical Exercise in the Health Promotion. He is the coordinator of Laboratory of Research in Muscle System and Physical Exercise (LAPEME) and reviewer of several peer-reviewed scientific journals in the field of nutrition and exercise. He also is a research productivity scholarship and a consultant on research projects from the National Foundation for Development of Private Education (FUNADESP). Andreo’s research is focused on the impact of nutritional ergogenic aids and physical exercise on skeletal muscle performance and recovery.

Juliano Casonatto

Juliano Casonatto, PhD, is an associate professor of Physical Education at University of Northern Paraná (UNOPAR), Londrina, Brazil, where he works as supervisor and professor in the undergraduate and graduate courses (master and doctoral) in the Physical Exercise in the Health Promotion program. He is the coordinator of Research Group in Physiology and Physical Activity (GEPEFAF) and reviewer of several peer-reviewed scientific journals. He is a research productivity scholarship and a consultant on research projects from the National Foundation for Development of Private Education (FUNADESP). Juliano’s research is focused on the physiological responses arising from exercise and nutritional strategies.