Background  High-intensity military training in high temperature and high humidity environments cause an increase in core body temperature, leading to injury when the temperature continues to rise beyond the body’s ability to dissipate heat, thus resulting in heat stroke. Rapid cooling can slow or even reverse the onset of heat injury.

  Objective  To explore the cooling effect of phase change material temperature control blankets after high intensity training and provide reference for the prevention of exertional heat-related diseases.

  Methods  Eighteen male participants aged 18-20 years were recruited from May to October in 2021 at a training base and randomly divided into 3 groups: natural cooling group, ice bag cooling group and temperature control blanket cooling group, with 6 cases in each group. Participants in each group was given oral thermometric capsules and completed a 7km run within 40min with a weight of 10kg according to the training syllabus. In the natural cooling group, the participants lay on the ground immediately after running and unbuttoned their tops to cool down naturally; in the ice bag cooling group, ice bags were placed on the neck, axilla and groin after running; in the temperature control blanket cooling group, the participants lay on a phase change material temperature control blanket immediately after running to cool down; the core temperature of each participant was collected using a thermometric capsule to compare the time required to reduce the body temperature to 37.5℃; After 1h of running, the participants were rated on a visual analogue scale to assess the comfort level of the cooling methods.

  Results  The basal body temperature of the volunteers in the three groups was within the normal range before the run, and the highest core body temperature reached after the completion of the run was around 39.4℃. The ice bag cooling group and the temperature control blanket cooling group had a significant decrease in body temperature compared with the natural cooling group, and the difference between the temperature control blanket cooling group and the natural cooling group was statistically significant at several time points (P <0.05). When comparing the time required to reduce body temperature to 37.5°C in the three groups, the natural cooling group was (42.0±7.7) min, the ice bag cooling group was (35.5±5.3) min and the temperature control blanket cooling group was (26.1±5.8) min, with statistically significant difference (P <0.05). The difference between the comfort scores of the three groups was also statistically significant (P < 0.05), with the natural cooling group of (4.5 ± 2.3), the ice bag cooling group of (5.4 ± 1.6) and the temperature control blanket cooling group of (7.6 ± 1.2).

  Conclusion  Temperature-controlled blankets can rapidly reduce core body temperature and have application value in preventing exertional heat stress injury.