Comparative efficacy of portable active cooling vs. passive cooling for reducing core temperature in exertional heat stroke: a systematic review and meta-analysis.

BACKGROUND

Exertional heat stroke (EHS) and exercise-induced hyperthermia require rapid reduction of core temperature (Tc). Portable active cooling devices are uesed in field settings where cold-water immersion (the gold standard) is not feasible, but their efficacy compared to passive cooling remains unclear.

OBJECTIVE

This review and analysis compared cooling rates between portable active cooling and passive cooling.

METHODS

We performed a systematic review and meta-analysis (PRISMA 2020, PROSPERO: CRD420261292698) of randomized and crossover trials. Eligible studies compared portable active cooling (type A: external refrigerant-based cooling systems; type B: wearable pre-cooling systems) with passive cooling in adults with exercise-induced hyperthermia. The primary outcome was mean Tc cooling rate (°C/min), analyzed using a random-effects model.

RESULTS

11 trials (n = 148 participants) were included. Portable active cooling produced a significantly faster cooling rate than passive cooling (MD = 0.02 °C/min, 95% CI: 0.01 to 0.03, p < 0.00001). Subgroup analysis revealed that type A devices had superior cooling efficacy (MD = 0.04 °C/min, 95% CI: 0.02-0.04), particularly when ambient temperature exceeded 30 °C. In contrast, type B devices showed no significant advantage (MD = 0.00 °C/min).

CONCLUSIONS

For field management of exertional heat stroke or severe exercise-induced hyperthermia, portable active cooling systems that use external refrigerant-based cooling (type A) are more effective than passive cooling. Wearable pre-cooling systems (type B) do not demonstrate superior efficacy. Selection of cooling devices should prioritize cooling mechanism over mere portability.

SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/PROSPERO/view/CRD420261292698, identifier: CRD420261292698.