Synergistic Effect of L-Carnitine and Caffeine Supplements on Physiological Variables Corresponding to Anaerobic Threshold in Elite Male Karate

Optimization of positive effects of exogenous supplements on sports performance is very important. The aim of this study was to investigate the Synergistic effectof L-carnitine and caffeine supplements on physiological variables corresponding to anaerobic threshold (AT) in Kerman karate men.

Fifteen elite karate athletes performed a progressive standard test following placebo (250 mg Lactose), caffeine (5 mg/kg), L-carnitine (3 g), and caffeine and L-carnitine (5 mg/kg, 3 g) consumption in four sessions separated by one-week intervals. Blood sample was collected before supplement consumption and immediately after exercise. Respiratory gases were measured throughout the test. Heart rate and oxygen consumption corresponding to AT were determined, and compared among trials by repeated measures analysis of variance.

End test values of plasma fatty acid (FFA) and its changes during exercise in caffeine and combined trial were significantly higher than those values in the control trial (both p <0.05), but plasma triglyceride levels were not significantly different between trials. The workload and oxygen (O2) corresponding to AT were significantly higher in the caffeine and combined trials compared to the values found in the control trials (all p <0.05). There was no significant difference regarding other variables among trials. Simultaneous consumption of caffeine and L-carnitine improved the values of O2 (11 vs. 17%) and workload (12 vs. 21) corresponding to AT compared to caffeine consumption alone, although there was no significant difference between groups.

Caffeine consumption can improve endurance performance through increasing fatty acid availability and this effect could be exacerbated by simultaneous consumption of L-carnitine.