2.2. Experimental Procedure

The preparation process was conducted in a room with an air temperature of 26 °C. ECG recorders (Healink Ltd., Bengbu, China) were mounted at designated sites on the subjects and then coveralls were donned. The entire preparatory process lasted approximately 15 min. When the temperature and humidity of the cabin reached the experimental requirements, the ECG recorder was turned on, and the subjects entered the environmental chamber and sat still for 25 min. They came out of the cabin and entered the preparation room to rest for 5 min. Water was allowed during rest. The subjects entered the cabin and began the first-stage running test with a speed controlled at 5.5 km/h. Running at this speed is equivalent to heavy labor [11]. After running for 25 min, the subjects went to the preparation room and rested for 5 min. Running and resting were repeated 2 more times, and the whole experiment was completed. The procedure of the test is shown in Table 1. The study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Ethics Committee of Guilin University of Electronics and Technology.

Experimental Procedure.