Exercise substrate utilization and postexercise macronutrient intake

The purpose of this study was to determine the effects of an acute bout of exercise on postexercise energy and macronutrient intake. Healthy sedentary females (n=7) and males (n=3) expended 428 ± 53 (mean ± SE) keals during 1 hr of stationary cycling at 60% of VO2 max. Substrate oxidation was derived from respiratory exchange ratio measured by indirect calorimetry during the exercise bout. After a 60 minute recovery period, subjects were presented with foods varying in macronutrient content and were allowed to eat ad libitum in a private room. The choices varied in carbohydrate (CHO) content (i.e., high simple sugar, high complex CHO, and low CHO) within high and low fat foods. In order to calculate energy and macronutrient balance, a control (no exercise) trial with indirect calorimetry measurements was also performed. Trials were completed in random order one month apart. Nine of the 10 subjects were in negative energy balance following the lunch test meal (- 354 ± 57 kcals). There was a significant positive relationship between exercise CHO utilization and post-exercise CHO intake (r2 = 0.53; p < 0.01). This relationship was stronger for complex CHO (r2 = 0.41) than for simple sugars (r2 = 0.19). Further, those subjects who had a greater utilization of carbohydrate during exercise were in more positive fat balance after the lunch meal (r2 = 0.34; p = 0.08). These data suggest that: 1 )in a majority of our subjects the energy expended during exercise was not compensated for in a single meal, 2) while exercise carbohydrate utilization and postexercise carbohydrate intake are closely matched, CHO balance is not achieved after a single meal, and 3) high CHO burners (i.e., low fat utilization) exhibit a less negative fat balance when allowed to eat from a variety of foods postexercise.

Duke Scholars

Author Nancy Lee Zucker Psychiatry, Child & Family Mental Health & Community Psychia ...