Effects of Citrulline alone or combined with exercise on muscle mass, muscle strength, and physical performance among older adults: a systematic review.

To Establish the potential of Citrulline supplementation (CIT) combined or not with exercise on muscle function and physical performance via a systematic review of randomized controlled trials (RCTs) in human aged 50 years and older. Based on Preferred Reporting Items for Systematic Reviews and Meta-analysis guideline, 103 references have been identified. Among this number, only six RCTs (250 participants) matched the inclusion criteria and were included in the present systematic review. Among the included studies, five of six reported beneficial effects of CIT on muscle mass. Then, four of six studies reported CIT effects on muscle strength but also that CIT when combined to exercise results in further improvements in upper muscle strength. Finally, three of six studies reported beneficial CIT effect on physical performance and suggested that CIT with exercise displayed greater improvements in walking speed than exercise alone. CIT supplementation seems to be able to improve muscular and physical factors in frail elderly people (malnourished, hypertensive, obese, dynapenic-obese) compared to placebo. More importantly, CIT combined to exercise is more efficient than exercise or CIT alone. However, because of the small number (six) and heterogeneity (dose, duration, population) of the studies realized in older adults, further studies are needed to confirm its promising potential.