Title : Effects of caffeinated beverages on physiological parameters of young adults during exercise
Abstract:
Aims: Caffeine (caff) is used in sports to its ergogenic effects, but the results of different studies are very diverse. The aim was to examine the combined physiological effects of various caffeine-containing drinks in a young healthy adult population. To measure the acute effects of caffeine-containing beverages on physical performance and blood lactate levels, changes in Heart Rate (HR) and Heart Rate Variability (HRV) as well as in maximal oxygen uptake (VO2max).
Methods: In the study the performance of healthy young adults (n=24) aged 18-35 years, (average=24.04±0.9 years), was examined. After determining physiological and anthropometric parameters, measurements were conducted once a week for 5 weeks. Before and after the consumption of caffeinated beverages (20-30 minutes) - Coffee (Co), Energy Drink (ED), Energy Drink with Alcohol (EDwA), Duble Energy Drink (DED), aerobic endurance was assessed with a 20m shuttle run test, and Blood Lactate (BL) concentration was measured before and after it. During the running test, HR was continuously monitored using the Polar Team System®.
Results: Co (p=0.020) and ED (0.037) significantly increased VO2max during the 20m shuttle run test. Aerobic endurance of females was significantly increased by Co (p=0.026) and of males by DED (p=0.026) of males. In the total sample and in women, ED, EDwA and DED significantly increased resting BL levels. During the load, EDwA significantly reduced HRpeak, R-Rav, R-Rmin values of the entire sample and in men and R-Rmax values among males. A significant difference was found between sexes in case of R-Rav (p=0.016) and R-Rmax (p<0.001) after EDwA. HRV parameters were significantly higher in males than in females (VLF p=0.027; HF p=0.002; HF% p=0.007) after consuming EDwA. Among individuals with above-average VO2max had a significant reduction of VLF% (Co p=0.017; DED p=0.045) and increased HF% (Co p=0.017; DED p=0.012) was found. During the running test females felt unpleasant symptoms and became unwell due to DED (100%; p=0.046) in a significantly higher proportion, 100% (p=0.046) than men (62.5%). The rate of bad feelings was higher if the products consumed contained more caff, taurine and/or alcohol.
Conclusions: In the studied sample different caffeinated beverages had different ergogenic effects during and after exercise. Physical exercises and beverages containing caff, taurine, and alcohol highly influenced the sympathetic and parasympathetic nervous system. A strong gender difference was found in beverages containing more caff or alcohol, female body reacted worse to the increased concentrations.
Keywords: Caffeine, Energy Drink, Physical Performance, Gender, Heart Rate
