Pain-based Pacing And Cycling Time-trial Performance

Abstract

Caffeine has frequently been shown to improve exercise performance, especially during endurance time-trials. Reductions in muscle pain have been hypothesized as a potential mechanism of caffeine’s ergogenic effects. However, no study to date has demonstrated reduced pain during time-trials. Whether caffeine does not reduce muscle pain at the high exercise intensities achieved during time-trials or whether performance is “paced” based upon sensations of pain is unclear. PURPOSE: To examine the effects of caffeine on time-trial performance when work output is “paced” based upon muscle pain. METHODS: Data were collected on 11 recreationally trained (V†O2 peak 46.6±7.1 ml•kg-1•min-1) male participants (22±5 years; 1.80±0.04 meters, 77.2 ± 3.5 kilograms). Participants performed a V†O2 peak test followed by 3 days of familiarization with the pain-based pacing protocol. Participants then completed two testing sessions consisting of an 8-minute warm-up (5-min at 50 W followed by 3-min at the wattage that elicited a “1” on a 0–10 pain scale during the maximal exercise test) and a 15-min performance trial. The participants controlled the resistance on the cycle ergometer during the 15-min trial in order to maintain a muscle pain rating of “3”. Caffeine (5 mg•kg-1•body weight) or placebo (sugar pill) were ingested in a randomized, double-blind manner one hour prior to exercise. V†O2, distance covered, energy, work rate, and heart rate were measured every three minutes throughout the test. RESULTS: Participants performed more work (150.5±29.9 vs 142.8±32.6 kJ; p=0.031) covered a greater distance (10.1±2.5 vs 9.5±2.2 km; p=0.029) at a higher power output (172±29 vs 159±36 W; p=0.023) compared to placebo following caffeine ingestion. Oxygen consumption (31.8±6.2 vs 30.1±5.7 ml•kg-1•min-1; p=0.081) and heart rate (154.1±20.3 vs 146.9±20.3 beats•min-1; p=0.128) did not differ between the caffeine and placebo conditions. CONCLUSIONS: When exercise intensity was “paced” based upon sensations of moderate levels of muscle pain, caffeine allowed greater work to be performed for a given amount of muscle pain. Suggesting a pain-based pacing strategy may account for the improved performance in the absence of alterations in perceptual factors in previous studies.