THE EFFECT OF L-CARNITINE SUPPLEMENTATION ON EXERCISE-INDUCED MUSCLE DAMAGE: A SYSTEMATIC REVIEW AND META-ANALYSIS OF RANDOMIZED CLINICAL TRIALS

Background and Aim: Background: Accumulating evidence of previous experimental studies demonstrated a positive effect of L-Carnitine supplementation on muscle damage. However, findings from trials vary substantially across studies. Therefore, the aim of this meta-analysis was to examine the effect of L-Carnitine supplementation on exercise-induced muscle damage.Methods: Methods: An electronic search of the literature was performed up to October 2017, using three online databases: Medline (PubMed), Scopus and Google Scholar. Either a fixed-effects model or a random-effects model (Diasorin-Liard) was used in order to estimate the effect’s size; Cochran’s Q test and I2 tests were used to assess heterogeneity among the studies. Funnel plot and Egger’s regression test were used in order to assess the publication bias.Results: Results: Of 604 studies, six eligible RCTs were included in the meta-analysis. Pooled data from six studies showed that L-Carnitine resulted in significant improvements in muscle soreness at the five follow-up time points (0, 24, 48, 72 and 96 hours) in comparison with placebo. Also, pooled data showed that L-Carnitine significantly reduced creatine kinase (CK) and lactate dehydrogenase (LDH) levels at one follow-up period of time (24 h) in comparison with placebo. L-Carnitine supplementation decreased myoglobin’s level immediately after exercise, 15 min, and 30 min into the recovery period. However, no effects have been observed beyond this period of time.Conclusion: Conclusion: The current evidence indicates that L-Carnitine supplementation improved delayed-onset muscle soreness (DOMS) and markers of muscle damage.

Keywords:

Muscle soreness , Supplementation , L-carnitine , muscle damage , meta-analysis