Effect of Caffeine on the Metabolic Responses of Lipolysis and Activated Sweat Gland Density in Human During Physical Activity

This study measured caffeine-induced changes in activated sweat gland density (ASGD) and fat oxidation using a randomized crossover design with 10 healthy volunteers given caffeine (Caffe-I, 3 mg/kg ingested 30 min before experiment) and non-caffeine (No-Caff). Subjects were 173.0 +/- 3.2 cm in height, 72.5 +/- 4.3 kg in weight, and 21.0 +/- 2.5 years in age. All experiments were performed in an automated climate chamber (24.0 +/- 0.5 degrees C, relative humidity 50 +/- 3%, air velocity less than 1 m/sec) between 2-5 p.m. The ASGD on the chest, upper arm, upper back, and lower back were measured (after 30 min running at 60% VO2max), and blood samples were taken (at 40 min before, immediately before and after 30 min running). Activated sweat gland density levels were higher in Caffe-I (Chest p < 0.05 and U-Back p < 0.01) and free fatty acids (FFA) were higher in Caffe-I compared to No-Caff immediately before (p < 0.05) and after running (p < 0.01). In summary, caffeine increases ASGD and FFA by stimulating the sympathetic nervous system and increasing of lipolysis.