EFFECT OF CAFFEINE INGESTION ON HIGH-INTENSITY INTERMITTENT EXERCISE PERFORMANCE IN ATHLETES

Abstract

2067 To determine whether acute caffeine ingestion improves high-intensity intermittent exercise performance, 17 college-level, competitive athletes (9 males, 8 females, mean age 22 y) performed caffeine (CAF) and placebo (PLC) trials in a double-blind randomized study. Caffeine and placebo (lactose) doses of 6 mg/kg body weight (rounded to nearest 100 mg) were given in 100 mg capsules; a dose consistently shown to produce urine caffeine levels below the maximum permitted by the International Olympic Committee. Habitual caffeine consumption, usual physical activity level, and food intake for 3 days prior to each trial (CAF or PLC) were determined by questionnaire. At each trial, one week apart, subjects performed three 30-second sprints on a treadmill (7.5 mph, 20% incline) separated by 2 minutes of walking, followed by a final sprint to exhaustion. Time to exhaustion (TM-EXH) was recorded and ranged from 20-90 seconds. Subjects reported a rating of perceived exertion (RPE) at the end of each sprint. Blood lactate (LACT) was measured following the 3rd and final (4th) sprints and after 5 minutes of recovery. Respiratory variables were measured during all trials and the respiratory exchange ratio (RER) was determined for each trial. Repeated measures ANOVA showed no significant differences between the CAF and PLC trials for TM-EXH, RPE, LACT or RER. However, there was a trend for all subjects towards an increase in TM-EXH during the CAF trial by an average of 2 sec (4%); 6 of 9 males and 5 of 8 females ran longer during the CAF trial. RPE was lower after all 4 sprints and LACT levels higher after the 3rd and 4th sprints and at recovery during the CAF trial. Habitual caffeine consumption did not appear to influence the results. Although not statistically significant, a 4% improvement in performance could give an elite athlete the extra edge they need to become a champion. Supported by the College of Kinesiology, Dean's Research Fund