الملخص

The current study aimed to: Identify the significance of differences between the conditions of moderate heat (24 C± 1) and cold conditions (15 C± 1) on a number of respiratory system variables (respiratory rate (RR), breath volume (TV), pulmonary ventilation (V̇E)) and (heart rate (HR), Completion time (Ct)) at rest and after performing the cardiorespiratory effort test (CPET).Researcher used descriptive approach due to its suitability for nature of the study. As for the research sample, it consisted of (8) randomly selected individuals, whose ages ranged between (22-24 years), who practiced physical activity. The final experiment was conducted in two different thermal conditions, once in the moderate temperature condition (24 C± 1) and humidity (30-40%), and other in cold temperature circumstance (15 C± 1) on the study sample in complete rest,and immediately after completing the physical effort (CPET).The researcher reached the following conclusions:• Condition in cold environment leads to a significant increase in comfort in the variables (TV, V̇E, HR) and at the end of the physical effort in the variable(RR) compared with conditions of temperate environment.• Condition in cold environment did not lead to a significant increase in comfort in the variable (RR) and at the end of the effort in the variables (TV, V̇E, HR) compared with the conditions of the temperate environment.• Condition in cold environment during physical effort did not play a clear negative or positive role in (Ct) in terms of time of end of effort compared to condition in the moderate environment.