Clinical Effects of L-Carnitine Supplementation on Physical Performance in Healthy Subjects, the Key to Success in Rehabilitation: A Systematic Review and Meta-Analysis from the Rehabilitation Point of View
What this study found
L-carnitine supplementation significantly increased serum total and free carnitine levels and VO2 at rest. However, no significant effect on plasma lactate levels at rest or after exercise was observed. The effective dosage for improvements was 2 g/dL for specific durations.
- Study & population
- Included randomized controlled trials, retrospective and prospective studies of healthy adults and athletes who supplemented with L-carnitine.
- Intervention
- The meta-analysis focused on the effects of L-carnitine supplementation on physical performance and metabolic parameters in healthy adults, including elderly individuals and athletes.
- Key limitation
- Heterogeneity in sample characteristics and limited data on optimal dosing for metabolic changes and physical performance outcomes.
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Open PDFOriginal abstract
L-carnitine supplementation improves body strength, sports endurance and exercise capacity, as well as delaying the onset of fatigue. The aim of this study was to identify the correct dosage of supplementation to obtain improvements in physical performance and evaluate the changes related to L-carnitine supplementation in specific metabolic parameters, such as serum lactate, VO2, serum total and free carnitine at rest and after physical activities, in healthy subjects. The search was conducted on PubMed, EMBASE, Cochrane Library, Scopus and Web of Science and identified 6404 articles with the keywords: “carnitine” AND “exercises” OR “rehabilitation” OR “physical functional performance” OR “physical activity” OR “sports” OR “health” OR “healthy”. A total of 30 publications met the inclusion criteria and were included in the systematic review. The meta-analysis did not show any significant differences in serum lactate values at rest and after exercise in healthy subjects who took L-carnitine supplementation (p > 0.05). On the contrary, L-carnitine administration significantly changed maximal oxygen consumption (VO2) at rest (p < 0.005), serum free and total carnitine at rest and after exercise (p < 0.001). The dosage of supplementation that obtained a significant change in serum total carnitine was 2 g/dL for 4 weeks at rest, 1 g/dL for 3 weeks after exercise, and in serum free carnitine was 2 g/dL for 3 weeks and 2 g/dL for 4 weeks at rest. Based on our study, serum total and free carnitine at rest and after exercise, and VO2 at rest could be used to clinically follow individuals during physical activity and rehabilitation programs. Moreover, the supplementation should have a correct dosage to have maximum effect. Other robust trials are needed to find the best dosage to obtain positive results in metabolic parameters and in physical performance.