Chan, K.-H., Hu, S.-Z., Lu, K.-H., & Shih, C. Y. (2012). Effects of three weeks of carnitine supplementation and high-intensity interval training on endurance performance. Presentation 1367 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

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"It has been suggested that carnitine has anti-oxidative and endurance capacity benefits. High-intensity interval training has been shown to increase endurance capacity and oxidative stress."

This study investigated the effects of three weeks of carnitine supplementation and high-intensity training in combination on aerobic capacity and oxidative stress. Untrained healthy males (N = 10) were recruited and randomly assigned to a carnitine group or placebo group. Ss received carnitine or placebo supplementation (2 g/day) for three weeks. Ss also performed the high-intensity training three times per week. The high-intensity training session protocol consisted of 10 bouts of cycling at 90%VO2max, with each bout lasting two minutes separated by one minute of rest. Incremental running tests and high-intensity interval exercise tests were conducted before and after supplementation. The VO2max and time to fatigue were measured by the incremental running test. Blood samples were drawn before each test, immediately after the test, and one and three hours after the high-intensity interval exercise test to determine the status and concentrations of creatine kinase (CK) and uric acid.

VO2max and time to fatigue significantly increased in the carnitine group. There were no differences in the placebo group. In the carnitine group, the values of blood creatine kinase and uric acid after the high-intensity interval exercise test before supplementation remained elevated at three hours post-test. That elevation disappeared after supplementation.

Implication. Carnitine supplementation and high-intensity interval training in initially untrained males improve aerobic capacity and recovery from high-intensity interval exercise. High-intensity training alone does not stimulate those factors. [Ss were untrained males and it should not be inferred that similar effects would occur with highly-trained individuals or females.]

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