A recent 30 year prospective study showed that lifelong sauna use reduces cardiovascular-related and all-cause mortality; however, the specific cardiovascular adaptations cause this chronic protection are currently unknown. We investigated effects of 8 weeks repeated hot water immersion ('heat therapy') on various biomarkers health in young, sedentary humans. that, relative to a sham group which participated thermoneutral immersion, heat therapy increased flow-mediated dilatation, reduced...

Evidence suggests that core temperatures of approximately 40 degrees C can induce fatigue, although this may be confounded by coincident elevations in skin and maximal cardiovascular strain. In an observational field study to examine temperature threshold for we investigated whether running performance is impaired when rectal (T(re)) >40 remains modest. Seventeen competitive runners (7/10 women/men: 8 km best 1,759 +/- 78/1,531 60 s) completed 8-km track time trials cool (WBGT 13 C; n = 6),...

This study determined the effects of hypohydration on aerobic performance in compensable [evaporative cooling requirement (E(req)) < maximal evaporative (E(max))] conditions 10 degrees C [7 wet bulb globe temperature (WBGT)], 20 (16 WBGT), 30 (22 and 40 (27 WBGT) ambient (T(a)). Our hypothesis was that 4% would impair to a greater extent with increasing heat stress. Thirty-two men [22 +/- 4 yr old, 45 8 ml.kg(-1).min(-1) peak O(2) uptake (Vo(2 peak))] were divided into four matched cohorts...

Environmental heat stress degrades aerobic performance; however, little research has focused on performance when the selected task elicits modest elevations in core body temperature (<38.5 degrees C).To determine effect of environmental stress, with hyperthermia, and pacing strategies.After a 30-min cycling preload at 50% VO2peak, eight euhydrated men performed 15-min time trial cycle ergometer temperate (TEMP; 21 C, RH) hot (HOT; 40 25% environments. Core skin (Tc Tsk, respectively) HR were...

Sweating threshold temperature and sweating sensitivity responses are measured to evaluate thermoregulatory control. However, analytic approaches vary, no standardized methodology has been validated. This study validated a simple method, segmented linear regression (SReg), for determination of sensitivity. Archived data were extracted analysis from studies in which local arm sweat rate (m(sw); ventilated dew-point sensor) esophageal (T(es)) under variety conditions. The relationship...

Nutritional adenosine receptor antagonists can enhance endurance exercise performance in temperate environments, but their efficacy during heat stress is not well understood. This double-blinded, placebo-controlled study compared the effects of an acute dose caffeine or quercetin on compensable (40 degrees C, 20-30% rh). On each three occasions, 10 healthy men performed 30-min cycle ergometry at 50% Vo2peak followed by a 15-min time trial after receiving either placebo (Group P), C; 9...

Polycystic ovary syndrome (PCOS) is associated with high rates of obesity and metabolic dysfunction. Repeated passive heat exposure (termed therapy) a novel lifestyle intervention for improving health in obese women PCOS. The purpose this study was to examine changes function PCOS following therapy. Eighteen age- BMI-matched (age: 27 ± 1 yr, BMI: 41.3 1.1 kg/m-2) were assigned therapy (HT) or time control (CON). HT participants underwent 30 one-hour hot tub sessions over 8-10 wk, while CON...

Polycystic ovary syndrome (PCOS) affects up to 15% of women and is associated with increased risk obesity cardiovascular disease. Repeated passive heat exposure [termed "heat therapy" (HT)] a lifestyle intervention the potential reduce in PCOS. Women (n = 18) PCOS [age 27 ± 4 yr, body mass index (BMI) 41.3 4.7 kg/m2] were matched for age BMI, then assigned HT 9) or time control (CON; n 9). subjects underwent 30 one-hour hot tub sessions over 8-10 wk, whereas CON did not undergo HT. Muscle...

Appropriate quantification of analytical and biological variation thermoregulatory sweating has important practical utility for research design statistical analysis. We sought to examine contributors variability in local forearm rate (SR) onset (SO) evaluate the potential using bilateral measurements. Two women eight men (26 ± 9 yr; 79 12 kg) completed 5 days heat acclimation walked (1.8 l/min VO(2)) on three occasions 30 min 40°C, 20% RH, while SR SO were measured. Local measures among not...

Ischemia-reperfusion (I/R) injury is a primary cause of poor outcomes following ischemic cardiovascular events. We tested whether acute hot water immersion protects against forearm vascular I/R. Ten (5 male, 5 female) young (23 ± 2 yr), healthy subjects participated in two trials random order 7–21 days apart, involving: 1) 60 min seated rest (control), or 2) 40.5°C (peak rectal temperature: 38.9 0.2°C). I/R was achieved 70 each intervention by inflating an upper arm cuff to 250 mmHg for 20...

Abstract Background: Dehydration is a common medical problem requiring heuristic evaluation. Our aim was to develop quantitative and graphical tool based on serial changes in either plasma osmolality (P osm ), urine specific gravity (U sg or body mass (B m ) aid determining the probability that person has become dehydrated. A secondary purpose validate use of by dehydrating group volunteers. Methods: Basic data were obtained from recent study biological variation hydration status markers....

We investigated the validity of employing a fuzzy piecewise prediction equation (PW) [Gonzalez et al. J Appl Physiol 107: 379-388, 2009] defined by sweat rate (m(sw), g·m(-2)·h(-1)) = 147 + 1.527·(E(req)) - 0.87·(E(max)), which integrates evaporation required (E(req)) and maximum evaporative capacity environment (E(max)). Heat exchange physiological responses were determined throughout trials. Environmental conditions ambient temperature (T(a)) 16-26°C, relative humidity (RH) 51-55%, wind...

Salivary osmolality (Sosm) is a potentially useful hydration marker but may be confounded by oral artifacts. Purpose: This study aimed to determine the efficacy of Sosm for detecting hypohydration and evaluate effect simple mouth rinse. Methods: Eight healthy volunteers (six males two females; age = 22 ± 7 yr, body mass 83.7 14.9 kg, height 176.9 9.2 cm) were measured nude (BM), plasma (Posm), when euhydrated (EUH) again hypohydrated (HYP) exercise-heat exposure with fluid restriction. After...

The impact of prior heat stress on subsequent aerobic exercise-heat performance has not been studied. Purpose: To determine whether degrades exercise in the heat. Methods: Eighteen nonheat acclimated males were trained (four practice trials) an test 22°C and then divided into two (n = 8) groups. One group (EUHPH; V˙O2peak 44 ± 7 mL·kg−1·min−1) was tested after 90 min recovery (in 22°C) from 3 h intermittent light-intensity (<30% V˙O2peak) (50°C) stress, where sweat losses matched with fluid...

The use of caffeine supplements in athletic and military populations has increased recent years. Excessive consumption conjunction with exercise a hot environment may predispose individuals to heat illness. Purpose: To examine balance induced by large dose during environment. Methods: Ten men, not acclimated habitual users, consumed either (CAF; 9 mg/kg) or placebo (PLA) before performing cycle-ergometer for 30 min at 50% VO 2peak 40 °C, 25% relative humidity while body temperature (core...

Exercise alone or in combination with environmental heat stress can elevate blood S-100beta protein concentrations. However, the explanatory power of exercise marked on appearance is questionable. It possible that process acclimation might afford additional insight.Determine response to moderate-intensity strain before and after acclimation.Nine healthy male volunteers completed 10 consecutive days consisting up 100 min treadmill walking (1.56 m x s(-1), 4% grade) (45 degrees C, 20% relative...

Accurate measurement of sweat mineral loss is important for whole body balance estimates and dietary reference intake formulation. Currently, common localized collection methods such as the pouch patch techniques may be limited by skin encapsulation and/or hidromeiosis, which alter concentrations. The design newly developed Megaduct collector avoid these possible limitations. Therefore, purpose this study was to evaluate utility analysis. collectors were affixed ten volunteers on final day a...