Separate and combined blockades of α- and β-adrenergic receptors in forearm sweating induced by adrenergic agents and exercise in the heat in young adults.

The assessment of adrenergic modulation of sweating as assessed via pharmacologic administration of α- and β-adrenergic receptor blockers during exercise has yielded mixed findings. However, the underlying mechanisms for this disparity remains unresolved. We investigated the effects of separate and combined blockade of α- and β-adrenergic receptors on forearm sweating induced by a 30-min moderate-intensity exercise bout (n=17, protocol 1) and the administration of adrenergic agonists epinephrine and norepinephrine (n=16, protocol 2) in the heat.

Effect of voluntary electric fan use on autonomic and perceptual responses to lower leg passive heating in humans.

This study investigated the efficacy of voluntary fan utilization on autonomic thermoeffector responses and thermal perceptions during passive heating by lower leg immersion (42 °C) in a 27 °C ambient temperature, 50% relative humidity. Fourteen young healthy adults (8 females) were recruited for this study where they underwent two trials with (Fan) and without an electric fan (No fan) during 50 min of passive heat stress. The skin temperature on forearm and abdomen was lower in Fan than in No fan (all p < 0.

Nicotine exacerbates exertional heat strain in trained men: a randomized, placebo-controlled, double-blind study.

To determine whether using nicotine exacerbates exertional heat strain through an increased metabolic heat production (H) or decreased skin blood flow (SkBF), 10 nicotine-naïve trained males [37 ± 12 yr; peak oxygen consumption (V̇o): 66 ± 10 mL·min·kg] completed four trials at 20°C and 30°C following overnight transdermal nicotine (7 mg·24 h) and placebo use in a crossover, double-blind design. They cycled for 60 min (55% V̇o) followed by a time trial (∼75% V̇o) during which measures of gastrointestinal (T) and mean weighted skin ([Formula: see text]) temperatures, SkBF, H, and mean arterial pressure (MAP) were made. The difference in ΔT between nicotine and placebo trials was greater during 30°C (0.

GH and IGF-1 in skin interstitial fluid and blood are associated with heat loss responses in exercising young adults.

Purpose: Sweat glands and cutaneous vessels possess growth hormone (GH) and insulin-like growth factor 1 (IGF-1) receptors. Here, we assessed if exercise increases GH and IGF-1 in skin interstitial fluid, and whether baseline and exercise-induced increases in GH and IGF-1 concentrations in skin interstitial fluid/blood are associated with heat loss responses of sweating and cutaneous vasodilation.

Methods: Sixteen young adults (7 women) performed a 50-min moderate-intensity exercise bout (50% VO) during which skin dialysate and blood samples were collected.

The effects of high-intensity exercise training and detraining with and without active recovery on postexercise hypotension in young men.

Whether high-intensity exercise training and detraining combined with skeletal muscle pump (MP) could alter the magnitude of postexercise hypotension has not been investigated. We therefore sought to determine whether the combination of MP (unloaded back-pedaling) with 4 weeks of high-intensity exercise training and detraining could alter the magnitude of postexercise hypotension. Fourteen healthy men underwent 4 weeks of high-intensity exercise training (5 consecutive days per week for 15 min per session at 40% of the difference between the gas exchange threshold and maximal oxygen uptake [i.

Comparing thermoregulatory responses between short and long moderate intensity intermittent exercise protocols with the same duty cycle.

To date, the thermoregulatory response between continuous and intermittent exercises has been investigated whilst limited studies are available to examine the thermoregulatory responses between different modes of intermittent exercises. We sought to determine the effect of two patterns of short duration intermittent exercises (180:180 (3-min) and 30:30 s (30-s) work: rest) on thermoregulatory responses in a temperate environment (25 °C, 50% RH, vapor pressure: 1.6 kPa) with low airflow (0.

Galanin receptors modulate cutaneous vasodilation elicited by whole-body and local heating but not thermal sweating in young adults.

Galanin receptor subtypes GAL, GAL, and GAL are involved in several biological functions. We hypothesized that 1) GAL receptor activation contributes to sweating but limits cutaneous vasodilation induced by whole-body and local heating without a contribution of GAL; and 2) GAL receptor activation attenuates both sweating and cutaneous vasodilation during whole-body heating. Young adults underwent whole-body (n = 12, 6 females) and local (n = 10, 4 females) heating.

Serum, interstitial and sweat ATP in humans exposed to heat stress: Insights into roles of ATP in the heat loss responses.

Hyperthermia increases intravascular adenosine triphosphate (ATP) and is associated with greater hyperthermia-induced cutaneous vasodilation. Hyperthermia may also increase skin interstitial fluid ATP thereby activating cutaneous vascular smooth muscle cells and sweat glands. We evaluated the hypothesis that whole-body heating would increase skin interstitial fluid ATP, and this response would be associated with an increase in cutaneous vasodilation and sweating.

In vivo assessments of microneedle arrays and iontophoresis of pilocarpine in human palmar sweating.

Emotional stress-induced sweating in glabrous skin of the palm and sole, which can be excessive in some individuals (hyperhidrosis), can negatively impact quality of life. Understanding the mechanisms underlying this response can lead to potential treatments. Transdermal iontophoresis is a method to administer ionized sudorific agents to sweat glands within the dermis.

Induction and decay of seasonal acclimatization on whole body heat loss responses during exercise in a hot humid environment with different air velocities.

Whether whole body heat loss and thermoregulatory function (local sweat rate and skin blood flow) are different between summer and autumn and between autumn and winter seasons during exercise with different air flow in humid heat remain unknown. We therefore tested the hypotheses that whole body sweat rate (WBSR), evaporated sweat rate, and thermoregulatory function during cycling exercise in autumn would be higher than in winter but would be lower than in summer under hot-humid environment (32 C, 75% RH). We also tested the hypothesis that the increase of air velocity would enhance evaporated sweat rate and sweating efficiency across winter, summer, and autumn seasons.

Do E and P contribute to the explained variance in core temperature response for trained women during exertional heat stress when metabolic rates are very high?

Purpose: Women remain underrepresented in the exercise thermoregulation literature despite their participation in leisure-time and occupational physical activity in heat-stressful environments continuing to increase. Here, we determined the relative contribution of the primary ovarian hormones (estrogen [E] and progesterone [P]) alongside other morphological (e.g.

TMEM16A blockers T16Ainh-A01 and benzbromarone do not modulate the regulation of sweating and cutaneous vasodilatation in humans in vivo.

New Findings: What is the central question of this study? Do transmembrane member 16A (TMEM16A) blockers modulate the activation of heat loss responses of sweating and cutaneous vasodilatation? What are the main finding and its importance? Relative to the vehicle control site, TMEM16A blockers T16Ainh-A01 and benzbromarone had no effect on sweat rate or cutaneous vascular conductance during whole-body heating inducing a 1.1 ± 0.1°C increase in core temperature above baseline resting levels.

Effects of tetraethylammonium-sensitive K channel blockade on cholinergic and thermal sweating in endurance-trained and untrained men.

New Findings: What is the central question of this study? Does inhibition of K channels modulate the exercise-training-induced augmentation in cholinergic and thermal sweating? What is the main finding and its importance? Iontophoretic administration of tetraethylammonium, a K channel blocker, blunted sweating induced by a low dose (0.001%) of the cholinergic agent pilocarpine, but not heat-induced sweating. However, no differences in the cholinergic sweating were observed between young endurance-trained and untrained men.

Influence of exercise intensity and regional differences in the sudomotor recruitment pattern in exercising prepubertal boys and young men.

We investigated the influence of exercise intensities and regional differences in the sudomotor recruitment pattern in boys. Six prepubertal boys (age 11 ± 1 yr) cycled at light, moderate, and high exercise intensity (35%, 50%, and 65% VOmax) for 30 min in a temperate condition (28 °C, 40% relative humidity). Local sweat rate (ventilated capsule) and number of activated sweat glands (starch-iodine technique) at five body sites were assessed and sweat gland output was calculated.

Measurement error of self-paced exercise performance in athletic women is not affected by ovulatory status or ambient environment.

Measurement error(s) of exercise tests for women are severely lacking in the literature. The purpose of this investigation was to ) determine whether ovulatory status or ambient environment were moderating variables when completing a 30-min self-paced work trial and ) provide test-retest norms specific to athletic women. A retrospective analysis of three heat stress studies was completed using 33 female participants (31 ± 9 yr, 54 ± 10 mL·min·kg) that yielded 130 separate trials.

Na-K-ATPase plays a major role in mediating cutaneous thermal hyperemia achieved by local skin heating to 39°C.

Na-K-ATPase is integrally involved in mediating cutaneous vasodilation during an exercise-heat stress, which includes an interactive role with nitric oxide synthase (NOS). Here, we assessed if Na-K-ATPase also contributes to cutaneous thermal hyperemia induced by local skin heating, which is commonly used to assess cutaneous endothelium-dependent vasodilation. Furthermore, we assessed the extent to which NOS contributes to this response.

Dissociation between exercise intensity thresholds: mechanistic insights from supine exercise.

This study tested the hypothesis that the respiratory compensation point (RCP) and breakpoint in deoxygenated [heme] [deoxy[heme], assessed via near-infrared spectroscopy (NIRS)] during ramp incremental exercise would occur at the same metabolic rate in the upright (U) and supine (S) body positions. Eleven healthy men completed ramp incremental exercise tests in U and S. Gas exchange was measured breath-by-breath and time-resolved-NIRS was used to measure deoxy[heme] in the vastus lateralis (VL) and rectus femoris (RF).

Eccrine sweat glands' maximum ion reabsorption rates during passive heating in older adults (50-84 years).

Purpose: We examined whether eccrine sweat glands ion reabsorption rate declined with age in 35 adults aged 50-84 years. Aerobic fitness (VO) and salivary aldosterone were measured to see if they modulated ion reabsorption rates.

Methods: During a passive heating protocol (lower leg 42 °C water submersion) the maximum ion reabsorption rates from the chest, forearm and thigh were measured, alongside other thermophysiological responses.

Effects of low-intensity exercise on local skin and whole-body thermal sensation in hypothermic young males.

Thermal sensation, a key component of behavioral thermoregulation, is modulated by the changes in both skin and core temperatures. Although cutaneous thermal sensation to local cold is blunted during exercise as compared to rest in normothermic humans, it remains to be determined whether this holds true during core cooling. Furthermore, when local skin thermal sensation is diminished during exercise, it remains unclear whether whole-body thermal sensation is also attenuated.

The effect of seasonal acclimatization on whole body heat loss response during exercise in a hot humid environment with different air velocity.

Seasonal acclimatization from winter to summer is known to enhance thermoeffector responses in hot-dry environments during exercise whereas its impact on sweat evaporation and core temperature (T) responses in hot-humid environments remains unknown. We, therefore, sought to determine whether seasonal acclimatization is able to modulate whole body sweat rate (WBSR), evaporated sweat rate, sweating efficiency, and thermoregulatory function during cycling exercise in a hot-humid environment (32°C, 75% RH). We also determined whether the increase in air velocity could enhance evaporated sweat rate and sweating efficiency before and after seasonal acclimatization.

Menstrual phase and ambient temperature do not influence iron regulation in the acute exercise period.

The current study investigated whether ambient heat augments the inflammatory and postexercise hepcidin response in women and if menstrual phase and/or self-pacing modulate these physiological effects. Eight trained females (age: 37 ± 7 yr; V̇o: 46 ± 7 mL·kg·min; peak power output: 4.5 ± 0.