Muscle glycogen restoration in females and males following moderate intensity cycling exercise in differing ambient temperatures

• Published in: Journal of exercise physiology online 2013-08, Vol.16 (4), p.1-18
• Main Authors: Carper, Michael J, Richmond, Scott R, Whitman, Samantha A, Acree, Luke S, Godard, Michael P
• Format: Article
• Language: English
• Subjects: Cycling; Exercise; Glucose metabolism; Glycogen; Physiological aspects; Physiological research
• ISSN: 1097-9751; 1097-9751

The purpose of this study was to determine differences in muscle glycogen restoration between males and females following 90 min of cycle ergometry at varying ambient temperatures. A total of 8 females (n=4) and males (n=4) performed a 90 min cycle ergometry trial (70% V[O.sub.2] max) followed by 8, 1-min sprints (125% V[O.sub.2] max) at 5°C, 25°C, and 35°C ambient temperature. The subjects were placed in a 20°C environment and received a carbohydrate supplement (1 g CHO x kg body [mass.sup.-1]) at immediate- and 60 min post-exercise. Muscle biopsies were obtained before and at immediate- and 180 min post-exercise for the determination of muscle glycogen. Blood samples were obtained before exercise, every 0.5 hr during exercise, and every 0.5 h for 180 min following exercise for determination of serum glucose, insulin, and free fatty acids. There was a significant difference in muscle glycogen resynthesis between groups following cycling exercise at 5°C, 25°C, and 35°C. Males significantly increased muscle glycogen to near or above baseline levels. There was no significant difference between groups for muscle glycogen immediately post-exercise. The primary finding from this study indicates that males restore significantly more muscle glycogen than females in the 180 min immediately following moderate intensity cycling exercise at 5°C, 25°C, and 35°C. Key Words: Carbohydrate, V[O.sub.2] max, Metabolism