Reproducibility of core temperature threshold for sweating onset in humans

Brengelmann, G. L.; Savage, Margaret V.; Avery, D. H.

doi:10.1152/jappl.1994.77.4.1671

Cited by 19 publications

(16 citation statements)

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“…In contrast to the Post-Exercise increase in cold thermal response thresholds, sequential measurements demonstrated a time-dependent similarity in the Pre-and Post-Control thresholds for vasoconstriction and shivering. These results are comparable to the ®ndings of Brengelmann et al (1994) of a small-magnitude decrease in the sweating threshold (0.1°C) following a second period of heating.…”

Section: Discussionsupporting

confidence: 86%

“…First, Brengelmann et al (1994) made sequential measurements and actually demonstrated a slight timedependent decrease in sweating thresholds over a 2-h period. The similar time-dependent response that we demonstrated for cold responses would result in an underestimation of the rise in cold response thresholds in the present study.…”

Section: Possible Explanations For the Resultsmentioning

confidence: 99%

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The effect of dynamic exercise on resting cold thermoregulatory responses measured during water immersion

Kenny

Denis

Proulx

et al. 1999

European Journal of Applied Physiology

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The purpose of this study was to evaluate the effect of exercise on the subsequent post-exercise thresholds for vasoconstriction and shivering measured during water immersion. On 2 separate days, seven subjects (six males and one female) were immersed in water (37.5 degrees C) that was subsequently cooled at a constant rate of approximately 6.5 degrees C x h(-1) until the thresholds for vasoconstriction and shivering were clearly established. Water temperature was then increased to 37.5 degrees C. Subjects remained immersed for approximately 20 min, after which they exited the water, were towel-dried and sat in room air (22 degrees C) until both esophageal temperature and mean skin temperature (Tsk) returned to near-baseline values. Subjects then either performed 15 min of cycle ergometry (at 65% maximal oxygen consumption) followed by 30 min of recovery (Exercise), or remained seated with no exercise for 45 min (Control). Subjects were then cooled again. The core temperature thresholds for both vasoconstriction and shivering increased significantly by 0.2 degrees C Post-Exercise (P < 0.05). Because the Tsk at the onset of vasoconstriction and shivering was different during Pre- and Post-Exercise Cooling, we compensated mathematically for changes in skin temperatures using the established linear cutaneous contribution of skin to the control of vasoconstriction and shivering (20%). The calculated core temperature threshold (at a designated skin temperature of 32.0 degrees C) for vasoconstriction increased significantly from 37.1 (0.3) degrees C to 37.5 ( 0.3) degrees C post-exercise (P < 0.05). Likewise, the shivering threshold increased from 36.2 (0.3) degrees C to 36.5 (0.3) degrees C post-exercise (P < 0.05). In contrast to the post-exercise increase in cold thermal response thresholds, sequential measurements demonstrated a time-dependent similarity in the Pre- and Post-Control thresholds for vasoconstriction and shivering. These data indicate that exercise has a prolonged effect on the post-exercise thresholds for both cold thermoregulatory responses.

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Section: Discussionsupporting

confidence: 86%

Section: Possible Explanations For the Resultsmentioning

confidence: 99%

The effect of dynamic exercise on resting cold thermoregulatory responses measured during water immersion

Kenny

Denis

Proulx

et al. 1999

European Journal of Applied Physiology

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“…Equally, and as noted above, several of the statistical differences between quasi ‐phases probably have little physiological consequence and are within the biological variability or measurement error, such as the onset threshold for sweating (∼0.1 °C; Brengelmann et al . ) and local sweat rate (0.05–0.2 mg cm −2 min −1 ; Kenefick et al . ; Morriss et al .…”

Section: Discussionmentioning

confidence: 99%

“…Similarly, it is worth noting that the current data are derived from an index of T core known to exhibit a lag-time (compared to oesophageal temperature; Mündel et al 2016) and from limited data points for effector responses. Equally, and as noted above, several of the statistical differences between quasi-phases probably have little physiological consequence and are within the biological variability or measurement error, such as the onset threshold for sweating (ß0.1°C; Brengelmann et al 1994) and local sweat rate (0.05-0.2 mg cm −2 min −1 ; Kenefick et al 2012;Morriss et al 2013), albeit these investigations yield data predominantly from male not female participants. Nevertheless, the above is probably not the case for the between-group (OCP vs. eumenorrhoeic) results, which demonstrate clear differences in the onset threshold for sweating ( Figure 4).…”

Section: Considerationsmentioning

confidence: 93%

On exercise thermoregulation in females: interaction of endogenous and exogenous ovarian hormones

Lei

Cotter

Schlader

et al. 2018

The Journal of Physiology

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Key points One in two female athletes chronically take a combined, monophasic oral contraceptive pill (OCP). Previous thermoregulatory investigations proposed that an endogenous rhythm of the menstrual cycle still occurs with OCP usage. Forthcoming large international sporting events will expose female athletes to hot environments differing in their thermal profile, yet few data exist on how trained women will respond from both a thermoregulatory and performance stand‐point. In the present study, we have demonstrated that a small endogenous rhythm of the menstrual cycle still affects Tcore and also that chronic OCP use attenuates the sweating response, whereas behavioural thermoregulation is maintained. Furthermore, humid heat affects both performance and thermoregulatory responses to a greater extent than OCP usage and the menstrual cycle does. Abstract We studied thermoregulatory responses of ten well‐trained (V̇O2 max , 57 ± 7 mL min−1 kg−1) women taking a combined, monophasic oral contraceptive pill (OCP) (≥12 months) during exercise in dry and humid heat, across their active OCP cycle. They completed four trials, each of resting and cycling at fixed intensities (125 and 150 W), aiming to assess autonomic regulation, and then a self‐paced intensity (30‐min work trial) to assess behavioural regulation. Trials were conducted in quasi‐follicular (qF) and quasi‐luteal (qL) phases in dry (DRY) and humid (HUM) heat matched for wet bulb globe temperature (WBGT) (27°C). During rest and exercise at 125 W, rectal temperature was 0.15°C higher in qL than qF (P = 0.05) independent of environment (P = 0.17). The onset threshold and thermosensitivity of local sweat rate and forearm blood flow relative to mean body temperature was unaffected by the OCP cycle (both P > 0.30). Exercise performance did not differ between quasi‐phases (qF: 268 ± 31 kJ, qL: 263 ± 26 kJ, P = 0.31) but was 5 ± 7% higher during DRY than during HUM (273 ± 29 kJ, 258 ± 28 kJ; P = 0.03). Compared to matched eumenorrhoeic athletes, chronic OCP use impaired the sweating onset threshold and thermosensitivity (both P < 0.01). In well‐trained, OCP‐using women exercising in the heat: (i) a performance‐thermoregulatory trade‐off occurred that required behavioural adjustment; (ii) humidity impaired performance as a result of reduced evaporative power despite matched WBGT; and (iii) the sudomotor but not behavioural thermoregulatory responses were impaired compared to matched eumenorrhoeic athletes.

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“…Brengelmann et al (1994) made sequential measurements and actually demonstrated a time-dependent decrease in the sweating threshold by 0.09 to 0.17°C. Finally, we measured the forehead skin temperature adjacent to the sweat capsule, since it is known that local skin temperature can aect the central control of sweating (Nadel et al 1971a).…”

Section: Discussionmentioning

confidence: 99%

Intense exercise increases the post-exercise threshold for sweating

Kenny

Chen

Johnston

et al. 1997

European Journal of Applied Physiology

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We demonstrated previously that esophageal temperature (T(es)) remains elevated by approximately 0.5 degrees C for at least 65 min after intense exercise. Following exercise, average skin temperature (T(avg)) and skin blood flow returned rapidly to pre-exercise values even though T(es) remained elevated, indicating that the T(es) threshold for vasodilation is elevated during this period. The present study evaluates the hypothesis that the threshold for sweating is also increased following intense exercise. Four males and three females were immersed in water (water temperature, T(w) = 42 degrees C) until onset of sweating (Immersion 1), followed by recovery in air (air temperature, T(a) = 24 degrees C). At a T(a) of 24 degrees C, 15 min of cycle ergometry (70% VO2max) (Exercise) was then followed by 30 min of recovery. Subjects were then immersed again (T(w) = 42 degrees C) until onset of sweating (Immersion 2). Baseline T(es) and T(skavg) were 37.0 (0.1) degrees C and 32.3 (0.3) degrees C, respectively. Because the T(skavg) at the onset of sweating was different during Exercise [30.9 (0.3) degrees C] than during Immersion 1 and Immersion 2 [36.8 (0.2) degrees C and 36.4 (0.2) degrees C, respectively] a corrected core temperature, T((es) (calculated)), was calculated at a single designated skin temperature, T((sk)(designated)), as follows: T((es)(calculated)) = T(es) + [beta/(1-beta)][T(skavg)-T((sk)(designated))]. The T((sk)(designated)) was set at 36.5 degrees C (mean of Immersion 1 and Immersion 2 conditions) and beta represents the fractional contribution of T(skavg) to the sweating response (beta for sweating = 0.1). While T((es)(calculated)) at the onset of sweating was significantly lower during exercise [36.7 (0.2) degrees C] than during Immersion 1 [37.1 (0.1) degrees C], the threshold of sweating during Immersion 2 [37.3 (0.1) degrees C] was greater than during both Exercise and Immersion 1 (P < 0.05). We conclude that intense exercise decreases the sweating threshold during exercise itself, but elicits a subsequent short-term increase in the resting sweating threshold.

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Reproducibility of core temperature threshold for sweating onset in humans

Cited by 19 publications

References 0 publications

The effect of dynamic exercise on resting cold thermoregulatory responses measured during water immersion

The effect of dynamic exercise on resting cold thermoregulatory responses measured during water immersion

On exercise thermoregulation in females: interaction of endogenous and exogenous ovarian hormones

Intense exercise increases the post-exercise threshold for sweating

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