Comparison of male and female thermal, cardiac, and muscular responses induced by a prolonged run undertaken in a hot environment

• Published in: Canadian journal of applied physiology Vol. 30; no. 4; p. 404
• Main Authors: Ftaiti, Foued, Kacem, Asma, Latiri, Imed, Ben Mdalla, Samia, Tabka, Zouhair, Zouari, Nouri, Ellouze, Feriel, Grélot, Laurent
• Format: Journal Article
• Language: French
• Published: United States 01.08.2005
• Subjects: Adult; Body Temperature - physiology; Body Weight; Dehydration - etiology; Dehydration - physiopathology; Female; Heart - physiology; Heart Rate; Humans; Humidity; Lactic Acid - blood; Male; Muscle, Skeletal - physiology; Muscle, Skeletal - physiopathology; Oxygen Consumption - physiology; Running - physiology; Sex Characteristics; Time Factors; Tympanic Membrane - physiology
• ISSN: 1066-7814; 1543-2718

The aim of this study was to compare male and female thermal, cardiac, and muscular responses induced by a prolonged run undertaken in a hot environment. Twelve volunteers participated in this study. The first group consisted of 6 men and the second one consisted of 6 women. After determination of their VO(2)max and maximal aerobic velocity (MAV), each athlete completed a 40-min run at 65% MAV in a hot and dry environment (temperature 31-33 degrees C, relative humidity 30%). Immediately before and after the run, each subject performed two different vertical jumps, i.e., a squat jump (SJ) and a counter-movement jump (CMJ) on a force platform. Force, velocity, power, and jump height were measured during each jump. The completion of the run was associated with a significant loss (p < 0.001) of body mass (BM) and significant increases (p < 0.001) in heart rate, tympanic temperature, and lactate concentration ([La]). Muscle power was significantly improved (+9%, p < 0.05) during the SJ only in the women. A significant enhancement of this parameter was also demonstrated during the CMJ in both groups (men: +10%, p < 0.05; women: +8%, p < 0.01). Surprisingly, a comparison of thermal, cardiac, and muscular responses did not reveal any significant differences between the sexes. Moderate dehydration (-2.0 to -2.3% of BM) and a rise in core temperature (above 39.2 degrees C) induced by the 40-min run led to an improvement of muscular strength in both men and women. However, the results of this study did not reveal any significant between-sex differences in thermal, cardiac, and muscular responses after exercising in the heat.