The effect of passive heating and face cooling on perceived exertion during exercise in the heat

Abstract

Increased body temperature is thought to be an important component of the higher perception of exertion that is a feature of fatigue during exercise in the heat but a causal relationship has yet to be demonstrated. We have investigated the effect of passive heating on the perception of exertion during a standard bout of exercise and also assessed the effect of cooling the head on compensating for the increased body temperature on the feelings of exertion. Ten male subjects performed a 14-min cycling exercise [average power $63% of maximum power output ( _ W max )] at an ambient temperature of 35°C at resting rectal temperature [mean (SD): 37.49 (0.27)°C; control (CON) trial] on one occasion, and after sitting in a sauna to raise rectal temperature [mean (SD): 38.95(0.13)°C; sauna (SAU) trial]. During the exercise, subjects reported their ratings of overall perceived exertion (RPE), perceived exertion of the legs (RPE legs ) and thermal comfort (TC). A blood sample was collected by the end of the exercise for determination of plasma glucose, lactate and prolactin and haematocrit. RPE values were significantly elevated after passive heating [mean (SE): 14.5 (0.7) units in CON and 17.2 (0.5) units in SAU, at the end of exercise; P<0.001] as were the RPE legs (P<0.01), while ratings of TC were similar in CON and SAU trials. Passive heating increased blood glucose (P<0.05) but had no effect on lactate at the end of the exercise. Plasma prolactin was markedly elevated as a result of the sauna exposure [mean (SE): 1598 (152) versus 225 (31) mU l )1 in SAU and CON trials, respectively; P<0.001]. Six of the subjects repeated the two trials but with the face cooled during exercise (trials CON FAN and SAU FAN ) that was achieved by combining face fanning and spraying the face with a mist of cooled water. Face cooling decreased RPE values after sauna to a point that no differences between the two conditions existed. RPE legs scores and heart rate, however, remained higher in SAU FAN compared with CON FAN (P<0.05). We conclude that hyperthermia is a causative element of the increased perception of exertion during submaximal exercise in the heat and that the effect of increased core temperature on the feelings of exertion is modulated by face cooling.

Post-exercise cooling techniques in hot, humid conditions

“…The use of face fanning is one means of improving comfort prior to, or during, exercise in the heat and may benefit exercise performance (Mundel et al 2006). Stimulation of cold sensitive thermo-receptors, which are densely distributed over the face, is thought to directly modulate thermoafferent inputs to the hypothalamus, mediating reductions in the neuroendocrine and fatigue responses to exercise in the heat (Armada-da-Silva et al 2004;Mundel et al 2006). The perceptual benefit of face fanning may be reflected in lowered perceptions of thermal comfort (TC) and perceived exertion, which can result in exercise performance benefits (Armada-da-Silva et al 2004).…”

Perceptual Responses While Wearing an American Football Uniform in the Heat

“…These correlations indicated that all measured perceptions may be integrated and may influence RPE ratings. Finally, although the correlation between final RPE and final T re that was expected based on past studies [7][8][9][10]14 was not present, a positive correlation between R Tre and final RPE was observed.…”

“…Heat stress has physiologic consequences that are associated with a decrease in exercise performance and an increase in the rating of perceived exertion (RPE). [7][8][9][10] Similarly, this has been observed 3,4,[11][12][13][14] with exercise while wearing a football uniform. The RPE also increases in hypohydrated individuals who exercise in the heat.…”

Heat Exposure Control Using Non-refrigerated Water in Brazilian Steel Factory Workers

“…Although the data does not provide evidence of the cooling of the analyzed sites by the proposed intervention, we assumed a decrease in the head skin temperature, considering the effect observed in the improvement of comfort provided by the following literature: McCaffrey et al showed significant reduction of the head skin temperature leading to a better thermal sensation 19) ; Armada-da-Silva et al (2003) and Patterson et al (1998) presented evidence on the modulation of the thermal sensation through cooling interventions on the face, which was also a directly affected area in our method 12,20) . An increased body temperature may be an important component of a higher perception of exertion, which is a feature of fatigue during exercise in hot environments 8) .…”

“…Previous studies regarding hand cooling methods presented technical differences, such as the usage of negative pressure heat extractors 5,6) or hand immersion in water [7][8][9][10][11] . Regarding head cooling 12,13) , the previous studies were performed in controlled conditions such as climatic chambers, or wearing cooling devices amidst performance comparisons 14) . In a study performed by Crawshaw et al in 1975, evidence indicated that the forehead would be one of the most sensitive places in the body to reduce sweat loss through skin cooling 15) .…”