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 ± 1.9 yr) completed an 8.2 km “all out” time trial on each of 3 days separated by at least 48 h. Initially, a practice trial was completed, and participants refrained from products containing caffeine and lower-body exercise for 24 h 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 6 mg/kg bw + each 6 mg/kg bw glucose) or placebo (each 6 mg/kg bw of glucose) 1 h pre-exercise. Despite not altering (P > 0.05) RPE, HR, or leg pain, caffeine improved (P < 0.05) cycling performance (17.7 ± 1.0 min versus 18.2 ± 1.1 min) and power output (121.6 ± 17.5 W versus 114.9 ± 17.9 W) versus placebo. Caffeine’s ergogenic effects may be independent of changes in RPE or leg pain in active women performing a simulated time trial.

• Caffeine reduces leg pain and perceived exertion during moderate exercise. • Few studies have examined these responses in untrained persons, especially women. • Caffeine did not alter leg pain or RPE during a simulated time trial versus placebo. • Cycling performance and mean power were improved with caffeine ingestion. • In untrained persons, caffeine’s effects may be unrelated to perceptions of leg pain and exertion.