Reza Ghiasvand^{1, 2}, Zinat Sharifhosein^{1, 3,}, Ahmad Esmailzadeh^{1, 2}, Awat Feizi⁴, GHolamreza Askari^{1, 2}, Mohammad Marandi⁵, Zahra Maghsoudi⁶

Athletes usually search for strategies to optimize their performance. Manipulation of carbohydrate (CHO) resources glycemic load in order to optimizing athletic performance provides new research areas in nutritional sport. Purpose of this study is to examine the effects of two isocaloric meals with different glycemic load (GL) on exercise performance and serum free fatty acids. Thirty six non-professional athletic women with ages between 19 and 24 were assigned in a double blinded randomized clinical trial with two period cross-over design. Participants in each group received a high or low GL meal as a breakfast, and 7-day wash out period is determined. serum free fatty acid (FFA) measurements were performed before and after each phase of intervention.3 hour After ingestion of a meal, participants run to exhaustion, in a 20 meters shuttle run pacer. Time to exhaustion (TTE) was recorded as a measure of exercise performance. In an attempt to ensure that subjects run to exhaustion, rating of perceived exertion (RPE) was measured, using a Borg scale, too. The ingestion of a low GL or high GL pre-exercise meal did not lead to different TEE and RPE at 3 hours before exercise in female athletic students. Mean changes of serum FFA were higher in low GL than high GL meal. Consumption of a low GL meal compared with a high GL meal at 3-hr before a shuttle run pacer, was not associated with significant changes in TEE and RPE levels but low GL meal led to more increase serum FFA than high GL.

glycemic load, glycemic index, pre-exercise meal, exercise performance, metabolism