No significant effect of caffeine on five kilometer running performance after muscle damage.

Abstract

Caffeine has documented hypoalgesic effects during exercise. However, there is a lack of research focusing on caffeine's potential analgesic effects to ameliorate delayed onset muscle soreness. A placebo controlled randomized cross-over trial was carried out to determine if 5mg/kg of body weight (mg/kgBW) of caffeine attenuates muscle pain and improves 5k running performance following delayed onset muscle soreness. Prior to participating, eleven runners (9 male; 2 female; age, 24.5±6.3years; height, 173.6±7.8cm; body mass, 66.3±7.5kg; BMI, 23.18kg/m2±1.6; VO2max 61.0±6.1ml/kg/min-1), were asked to discontinue supplement use for 72 hours and abstain from caffeine consumption for 48 hours. Participants performed a 30-minute downhill run on a treadmill set at -10% grade at 70% VO2max to induce delayed onset of muscle soreness. Participants then returned 48 hours after to complete a 5k time trial run where they consumed either 5mg/kgBW of caffeine or a placebo. Rate of perceived exertion and heart rate were taken every two minutes during the trial. There was no detectable statistical difference between 5k performance between caffeine (1074.9±119.7 sec) or placebo (1053.8±86.8 sec) (p=.41). Algometer readings were similar between both treatments for muscle soreness in the rectus femoris (p=.791) and the vastus medialis oblique (p=.371). Muscle soreness ratings were found to be greater in the caffeine condition compared to the placebo condition (p=.030). There was no effect of treatment on rating of perceived exertion between conditions (p=.574). The present study suggests that caffeine is not effective at reducing muscle soreness, rating of perceived exertion, or improving running performance in a time trial in the presence of muscle soreness.