Caffeine does not alter RPE or pain perception during intense exercise in active women

Attenuated perceptions of exertion and leg pain are typically reported during exercise with caffeine ingestion, yet these responses are relatively unexplored in women. The primary aim of this study was to assess the effect of caffeine on rating of perceived exertion (RPE) and pain perception during a simulated time trial. Ten active women (age=22.1±1.9yr) completed an 8.2km "all out" time trial on each of 3days separated by at least 48h. Initially, a practice trial was completed, and participants refrained from products containing caffeine and lower-body exercise for 24h prior to subsequent trials. During exercise, heart rate (HR), RPE, and leg pain were recorded. Using a double-blind, randomized crossover design, participants ingested anhydrous caffeine and glucose (each 6mg/kg bw+each 6mg/kg bw glucose) or placebo (each 6mg/kg bw of glucose) 1h pre-exercise. Despite not altering (P>0.05) RPE, HR, or leg pain, caffeine improved (P<0.05) cycling performance (17.7±1.0min versus 18.2±1.1min) and power output (121.6±17.5W versus 114.9±17.9W) versus placebo. Caffeine's ergogenic effects may be independent of changes in RPE or leg pain in active women performing a simulated time trial.