Effect of fasting after exercise on blood lactate clearance in untrained male volunteers

Objectives: To determine the effect of fasting immediately after exercise on blood lactate clearance. Methods: This study was conducted at College of Medicine, Dammam University, KSA. Untrained male volunteers (n=26) between 18-23 years of age were divided into two equal groups; fasting and non-fasting. After an overnight fasting both groups were made to exercise on a bicycle ergometer starting with 100 watt resistance with 25 watt increment after every, 2 minutes until voluntary exhaustion. The fasting group was then asked to continue fasting 30 minutes after exercise, while the non-fasting group was given 600ml of carbohydrate-rich (about 16g per 100 ml) drink immediately after exercise. We measured the blood lactate level before, immediately after, and 30 minutes after exercise in both the groups. Results: A significant (p<0.001) increase in mean blood lactate level was observed in both the groups immediately after exercise as compared to the baseline means. Similarly there was a significant (p<0.001) drop of lactate level in both the groups 30 minutes after exercise as compared with the blood lactate level immediately after exercise. There was a significant (p<0.001) difference between the number of subjects with a blood lactate drop of more than 50% between the two groups (84.61% of subjects in the fasting group, versus 46.15% in the non-fasting group). Conclusion: Fasting after exercise accelerates lactate clearance from blood, probably by utilizing gluconeogenesis pathway.