Seyyed Javad Ziaolhagh* and Seyedhadi Naghibi
The purpose of this study was to determine the effect of pre-exercise carbohydrate meals with high glycemic index (HGI) or low glycemic index (LGI) on circulating leucocytes and plasma cortisol concentrations following subsequent endurance exercise. 12 male subjects (age 24.8 ± 0.35 yrs, body mass 76.1 ± 3.5 kg, height 1.77 ± 0.02 m, body fat percentage 11.1 ± 3.23, VO2max 51.18 ± 0.65 mL·kg-1·min-1; mean ± S.E.M.) performed two 90-min runs on a treadmill at 70% VO2max two hours after ingesting a HGI or LGI meal. Each isocaloric test meal contained 1 g·kg-1 body mass of carbohydrate and the glycemic index values were 94 and 40, respectively. Trials were separated by at least 7 days in counterbalanced order. Results were analyzed using a two-factor (trial × time) repeated measures ANOVA with post hoc (Bonferoni) comparison as appropriate.Reduced circulating lymphocytes concentrations were observed immediately after exercise compared to pre exercise levels in both HGI and LGI. However, no differences were found in all the lymphocytes counts between the HGI and LGI trials (p=0.443). Indeed, Results indicated a slight increase in the number of neutrophils in each of the groups, but this increase was not statistically significant in both groups (p=0.376). Although During the LGI trial, there was a progressive increase in monocyte concentrations immediately after exercise (p=0.013), Results indicated insignificant differences between HGI and LGI groups (p=0.583).Serum cortisol concentrations increased after the onset of exercise in both HGI and LGI (p=0.11), but no differences were found among the trials throughout the exercise period (p=0.594).This paper indicated that ingestion of 1 g·kg-1 body mass of carbohydrate with high or low glycemic index 2 hours before endurance exercise had limited effects on circulating leucocytes and cortisol concentration.
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