Serum IL-6 Is Increased During Performance Cycling After Energy Drink Consumption

Abstract

Energy Drinks have become a popular preexercise supplement due to the combination of caffeine and carbohydrate. Other ingredients such as glucuronolactone and taurine may play a role in performance enhancement. PURPOSE: The purpose of this study was to investigate the influence of a common energy drink on cycling performance, substrate oxidation and immune-related variables. METHODS: This study was a blinded, randomized, cross-over design. Eleven trained male cyclists (mean age 33.4 ± 8.9 yr, body mass 81 ± 7.6 kg, maximal VO2 51.72 ± 3.4 ml*kg-1*min-1) consumed either 500 ml of Red Bull Energy Drink (ED1- 2.0g taurine, 1.2 g glucoronolactone, 160 mg caffeine, 54 g carbohydrate (CHO), 40 mg niacin, 10 mg pantothenic acid, 10 mg vitamin B6, and 10 μg vitamin B12), Coke-a-Cola Classic matched for caffeine and CHO (ED2), or flavored placebo (ED3- crystal light and Perrier) 55 min prior to racing. Performance was measured as time to complete a 25-mile simulated road race. Blood was collected pre-drink (PrD), 30 minutes after drink (pre-exercise, PrEx), during exercise at mile 5 (M5), mile 15 (M15), and immediately (PoEx) & 30 min post-exercise (30min). RESULTS: Performance time was not different among trials (ED1 4117 ± 161 s, ED2 4132 ± 230 s, ED3 4173 ± 225 s). PrEx IL-6 was not different among PD1, 2 or 3 (0.61±0.09, 0.78±0.1, 0.56±0.07, pg*mL-1). PoEx IL-6 was greatest after ED1 while ED2 IL-6 response was greater than ED3 (10.2±1.6, 6.7±0.6, 4.8±0.7 pg*ml-1, p<0.001). IL-6 declined after ED1 & ED2 by 30min, but remained significantly greater than baseline after all trials (5.3±1, 4.1±0.5, 3.6±0.7, 30min ED1, 2 and 3, p<0.001). Cycling increased leukocyte number in all conditions with ED1 leukocyte number greater than that of ED3 at M15 (9.8±0.6, 8.5±0.3 ×10∧6 cells/mL). Mean fat oxidation was greater in ED3 compared to ED2 (0.43±0.06, 0.28±0.04 g*min-1, p=0.033) but did not differ between ED1 (0.32±0.06) and ED3. CHO oxidation did not differ among trials. Lactate was greater for ED1 & ED2 at PrEx, M5, M15 and PoEx (p=0.003). CONCLUSION: Coingestion of caffeine and CHO prior to endurance cycling significantly increased the IL-6 response to exercise, and the additional ingredients of ED1 appear to have further augmented this response. ED1 also appears to have influenced leukocyte number and fat oxidation during performance cycling.