Performance Benefits of Pre- and Per-cooling on Self-paced Versus Constant Workload Exercise: A Systematic Review and Meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized crossover trials
PubMed 37803106 · doi:10.1007/s40279-023-01940-y
What was done
A systematic review and meta-analysis (preregistered on OSF) evaluating the effects of pre-cooling and per-cooling on exercise performance in the heat (> 30 °C) across self-paced versus constant workload protocols. Searches across PubMed, Web of Science, and MEDLINE through June 2023 identified 59 randomized crossover studies comprising 86 experiments and 563 male athletes (832 paired measurements; 40 self-paced protocols [n = 370] and 19 constant workload protocols [n = 193]; 67 pre-cooling and 19 per-cooling experiments). Average ambient conditions were 34.0 °C and 50.0% relative humidity. Risk of bias was assessed with the Cochrane tool.
What was found
Cooling attenuated heat-induced performance declines and showed larger effects during constant workload (effect size [ES] = 0.62, 95% CI 0.44–0.81) than self-paced exercise (ES = 0.30, 95% CI 0.18–0.42; p = 0.004). This difference was driven by pre-cooling, which was substantially more effective during constant workload versus self-paced exercise (ES = 0.74, 95% CI 0.50–0.98 vs ES = 0.29, 95% CI 0.17–0.42; p = 0.001). Conversely, per-cooling showed similar effects across both protocols (constant workload ES = 0.45, 95% CI 0.16–0.74 vs self-paced ES = 0.35, 95% CI 0.01–0.70; p = 0.68).
Why it matters
Pre-cooling studies using open-loop time-to-exhaustion protocols substantially overestimate performance benefits compared with ecologically valid self-paced trials, whereas cooling during exercise provides consistent moderate benefits regardless of pacing protocol.
Limits
The review included only male participants, limiting generalizability to female athletes. There was an imbalance between pre-cooling (67 experiments) and per-cooling (19 experiments), and the abstract does not report separate analyses for specific cooling modalities.
Cited by
- supports Deliberate cold exposure between exercise bouts improves endurance athletic performance, including running times and reaction times in athletes.