Analgesics and Exercise Performance in Pain-Free Situations: A Systematic Review and Meta-Analysis

Analgesics have been largely consumed as ergogenic in sports settings in pain-free situations. We summarized the collective evidence on their effects on exercise performance and exercise-induced pain through a systematic review and meta-analysis. The risk of bias and certainty of evidence of randomized placebo-controlled crossover studies were assessed using the Cochrane Risk of Bias 2 tool and the Grading of Recommendations Assessment, Development and Evaluation approach. A multilevel random-effects model compared the standardized mean difference among studies. Twenty-three studies investigating the effects of aspirin (n=4), ibuprofen (n=6), celecoxib (n=1), flurbiprofen (n=1), paracetamol (n=16) and tramadol (n=4) on exercise performance in pain-free situations showed a low risk of bias and moderate certainty of evidence. The very small effect of analgesics in grouped data (standardized mean difference=0.14; p=0.003) or data separated by exercise modalities (standardized mean difference=0.18; p=0.04) was unlikely to produce ergogenic benefits. Subgroup analysis evidenced that tramadol enhanced exercise performance in cycling exercises (standardized mean difference=0.38; p=0.03). No beneficial effect was observed in pain (standardized mean difference=-0.22; p=0.61). Analgesics commonly used in pain-free situations are unlikely to enhance exercise performance. Beneficial effects of tramadol on performance require confirmation in real-world contexts and different exercise modes.