The effect of caffeine consumption on substrate metabolism and time to exhaustion during exercise and one hour after exercise in athletic female

The purpose of present study was to examine the effect of caffeine consumption on substrate metabolism and time to exhaustion during exercise and one hour after exercise in athletic female. Eleven female athlete students (age 23±1.54 years, body weight 56.09±5.99 kg, and aerobic power 40.21±1.01ml/kg/min) volunteered and were randomly divided into three groups of control,placebo (starch capsule), and caffeine (5 mg/kg), in a crossover design. Exercise protocol included exhausting running on treadmill with 70% of intensity of maximal heart rate. Subjects’ respiratory gases were collected at 30 minutes before exercise in prostrate position, during exercise, and one hour after exercise-as EPOC. The amounts of fat oxidation, carbohydrate and energy expenditure were measured by indirect calorimeter.The data was analyzed using the Kolmogrov – Smirnov, ANOVA with repeated measures and LSD post-hoc tests, at significance level of P≤0.05. The results showed that with caffeine consumption carbohydrate oxidation was significantly increased (p<0.05), but there was no significant effect on fat oxidation (p>0.05). Furthermore, caffeine consumption had no significant effect on substrate metabolism EPOC (p>0.05), while it significantly increased time to exhausion (p>0.05). Therefore, female athletes can increse/improve the time to exhausion by consumption of caffeine supplements (5 mg /kg) 1 hour before exercise.