BACKGROUND: Ice cooling vests can cause tissue damage and have no flexibility. Therefore, these two undesirable properties of ice cooling vest were optimized, and the present study was aimed to compare the impact of the optimized ice cooling vest and a commercial paraffin cooling vest on physiological and perceptual strain under controlled conditions. METHODS: For optimizing, hydrogel was used to increase the flexibility and a layer of the ethylene vinyl acetate foam was placed into the inside layer of packs to prevent tissue damage. Then, 15 men with an optimized ice cooling vest, with a commercial paraffin cooling vest, and without a cooling vest performed tests including exercise on a treadmill (speed of 2.8 km/hr and slope of %0) under hot (40℃) and dry (40 %) condition for 60 min. The physiological strain index and skin temperature were measured every 5 and 15 minutes, respectively. The heat strain score index and perceptual strain index were also assessed every 15 minutes. RESULTS: The mean values of the physiological and perceptual indices differed significantly between exercise with and without cooling vests (P < 0.05). However, the difference of the mean values of the indices except the value of the skin temperature during the exercises with the commercial paraffin cooling vest and the optimized ice cooling vest was not significant (P > 0.05). CONCLUSIONS: The optimized ice cooling vest was as effective as the commercial paraffin cooling vest to control the thermal strain. However, ice has a greater latent heat and less production cost.
Exercise ; Hot Temperature ; Humans ; Hydrogel ; Ice ; Male ; Paraffin ; Pliability ; Skin Temperature

BACKGROUND: Need to a simple, available, accurate, comprehensive, and valid indicator is felt to assess thermal effects. Therefore, the present study was aimed to develop and validate the environmental heat strain risk assessment (EHSRA) index using structural equation modeling (SEM) based on empirical relations. METHODS: This cross-sectional study was performed on 201 male workers in environments with various climatic conditions. The heart rate and tympanic temperature of the individuals were monitored at times of 30, 60, and 90 min after beginning the work. At these times, values of dry temperature, wet temperature, globe temperature, and air velocity were also measured and metabolism rate and clothing thermal insulation value were estimated. At the end, a theoretical model was depicted in AMOS software and obtained coefficients were applied to develop a novel index. The scores of this indicator were categorized into four risk levels via ROC curves and validate using linear regression analysis. RESULTS: Indirect effect coefficients of the globe temperature, dry temperature, wet temperature, air velocity, metabolism, and clothing thermal insulation variables on the tympanic temperature were computed by 0.77, 0.75, 0.69, 0.24, 0.49, and 0.39, respectively. These coefficients were applied to develop the index. Optimal cut-off points of boundaries between risk levels included 12.02, 15.88, and 17.56. The results showed that the EHSRA index justified 75% of the variations of the tympanic temperature (R CONCLUSIONS The novel index possesses appropriate validity. It was suggested that this indicator is applied and validated in various environments in the next studies.
Adult ; Environmental Health/methods* ; Heat-Shock Response ; Hot Temperature/adverse effects* ; Humans ; Iran ; Latent Class Analysis ; Male ; Middle Aged ; Risk Assessment/methods* ; Young Adult