Effect of caffeine on metabolic and cardiovascular responses to submaximal exercise in lean and obese men

Abstract

Effect of caffeine on metabolic and cardiovascular responses to submaximal exercise in lean and obese men Study aim: To compare the effects of caffeine on metabolic and cardiovascular responses to exercise in lean and obese subjects. Material and methods: In a double blind random design, 6 lean (BMI<20) and 6 obese (BMI>28) sedentary young men performed treadmill running for 30 min at similar exercise intensities (60% VO2max) one hour after caffeine (5 mg/kg body mass) or placebo ingestion. Gas exchange was measured by indirect calorimetry/open-circuit spirometry. Heart rate (HR) was measured throughout the exercise. Blood pressure (BP) measurements were taken at baseline, 1 h after caffeine/placebo ingestion and immediately after exercise. Repeated measures ANOVA was used in data analysis. Results: Caffeine significantly (p<0.05 - 0.01) increased the exercise-induced oxygen uptake, energy expenditure, systolic blood pressure and heart rate in both groups, the respiratory exchange ratio remaining unchanged. The effects of caffeine were in both groups alike. Conclusions: Caffeine activates metabolism without inducing major changes in fat/carbohydrate oxidation. The differences in body fat content seem not to affect the caffeine-induced effects in a submaximal exercise.