European Journal of Physical Education and Sport Science ISSN: 2501 - 1235 ISSN-L: 2501 - 1235 Available on-line at: www.oapub.org/edu Copyright © The Author(s). All Rights Reserved 1 Published by Open Access Publishing Group ©2015. 10.5281/zenodo.56170 Volume 2│Issue 1│2016 THE EFFECT OF FOUR WEEKS HIIT TRAINING WITH THE USE OF L-CARNITINE ON FAT PERCENTAGE OF TRAINED OVERWEIGHT WOMEN Maryam Karimi*, Ebrahim Karimi, Sepideh Mizani 1 Department of Sport Physiology, North Khorasan Science and Research Branch, Islamic Azad University, Bojnourd, Iran 2 Department of Sport Management, Mashhad Branch, Islamic Azad University, Mashhad, Iran 3 Department of Sport Physiology, Eslamshahr Branch, Islamic Azad University, Eslamshahr, Iran Abstract: The change in phenotype of adipose tissue as a result of practice is a new theory that has recently been proposed and its cell-molecular mechanism is under investigation. The aim of this study was to investigate the effect of high-intensity interval associated with consumption of L-Carnitine on body composition factors in the selective Orexin hormone. The population was trained overweight women, 25 to 35, and out of which, 40 persons voluntarily participated in the study and were divided randomly into 4 groups of 10 people of L-Carnitine, placebo, HIIT and placebo, HIIT L-carnitine. For the sports background and non-suffering of disease, a questionnaire was used. After explaining on implementing the protocol, measuring body composition and blood samples were conducted. Next, the subjects were participated in an intense training programme (with a maximum power) during 12 sessions. Each of the exercise includes a 10-minute warm-up and then a repeated 10 times for 30 seconds and, then, cool down was performed in 5 to 10 minutes. Forty-eight hours after the last training session, the necessary measurement of body composition and blood samples were conducted and data were analyzed using SPSS software and statistical methods. Four weeks of taking L-carnitine, HIIT training with placebo and with L-Carnitine has a significant effect on the percentage of body fat in overweight trained women. Four weeks of HIIT training with L-Carnitine had a significant effect on the percentage of body fat. Keywords: HIIT, L-carnitine, fat percentage