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Results 451 - 500 of 1087
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Gill N - - 2001
In order to compare the effectiveness of a daily to an intermittent acclimation protocol, 14 competitive rowers (mean +/- SD VO2peak = 48 +/- 7 ml x kg x min(-1)) were randomly assigned to either a consecutive (10 consecutive days) or intermittent acclimation group (10 sessions over 3 weeks). For ...
McLellan T M - - 2001
When protective clothing is worn that restricts evaporative heat loss, it is not valid to assume that the higher sweat rates associated with improvements in aerobic fitness will increase heat tolerance. An initial study compared thermoregulatory and cardiovascular responses to both compensable and uncompensable heat stress before and after 8 ...
Liang Y F - - 2001
Excitation and sensitization to heat of nociceptors by bradykinin (BK) were examined using an isolated rat skin-saphenous nerve preparation. A total of 52 C-fibres was tested: 42 were mechano-heat sensitive (CMH) and 40% of them were excited and sensitized to heat by BK superfusion (10-5 M, 5 min) of their ...
Gutierrez E - - 2001
The paper presents the results of heat treatment in three cases of anorexia nervosa (AN), in which marked overactivity and/or strenuous exercising were prominent clinical features. Heat was supplied in three ways: continuous exposure to a warm environment, wearing a thermal waistcoat, and sauna baths in an infrared cabin. The ...
Scheett T P - - 2001
On two occasions, 8 male subjects completed a dehydration protocol, immediately followed by a 180-min rehydration protocol, then a subsequent exercise bout. During each dehydration session, subjects lost 3.1 +/- 0.4% body weight (BW) following discontinuous exercise in the heat (40 degreesC, 33% rh). During the first 30 min of ...
Gölfert F - - 2001
The effect of extremely low frequency electromagnetic fields (EMF) on microvesicles was examined in rat astrocytes by video-enhanced microscopy in combination with a perfusable cell chamber. The EMF effect was compared with the effect of heat shock (HS) and with a combination of them both. The velocity of microvesicles was ...
Frank A - - 2001
We studied the sympatho-vagal balance during acclimation to heat in eight healthy individuals. The subjects, dressed in shorts and tennis shoes, underwent a 10 d procedure of acclimation. Daily exposure lasted 115 min--5 min rest followed by 2 bouts of 50 min exercise (walking on a treadmill at a work ...
Rehrer N J - - 2001
It is well known that fluid and electrolyte balance are critical to optimal exercise performance and, moreover, health maintenance. Most research conducted on extreme sporting endeavour (>3 hours) is based on case studies and studies involving small numbers of individuals. Ultra-endurance sportsmen and women typically do not meet their fluid ...
Shirreffs S M - - 2001
Post-exercise restoration of fluid balance after sweat-induced hypohydration avoids the detrimental effects of a body water deficit on physiological function and subsequent exercise performance. For effective restoration of fluid balance, the consumption of a volume of fluid in excess of the sweat loss and replacement of electrolyte, particularly sodium, losses ...
Febbraio M A - - 2001
Much of the research that has examined the interaction between metabolism and exercise has been conducted in comfortable ambient conditions. It is clear, however, that environmental temperature, particularly extreme heat, is a major practical issue one must consider when examining muscle energy metabolism. When exercise is conducted in very high ...
Cadarette B S - - 2001
This study evaluated physiological heat strain from two developmental toxic agent protective systems compared with the standard Toxicological Agent Protective (TAP) suit during exercise-heat stress. Eight subjects (six men, two women) completed three experimental trials, at 38 degrees C, 30% rh, wearing: 1) Self Contained Toxic Environment Protective Outfit (STEPO) ...
Cheuvront S N - - 2001
The extreme physical endurance demands and varied environmental settings of marathon footraces have provided a unique opportunity to study the limits of human thermoregulation for more than a century. High post-race rectal temperatures (Tre) are commonly and consistently documented in marathon runners, yet a clear divergence of thought surrounds the ...
Holthusen H - - 2000
Hyperalgesia on intradermal capsaicin application can be attenuated by systemic application of local anesthetics. We tested whether low doses of local anesthetics applied pre- or post-traumatically can reduce heat trauma-induced primary and secondary hyperalgesia in humans. Six healthy volunteers consented to the randomized, double-blind, and cross-over designed study. In each ...
Moehrle M - - 2000
BACKGROUND/AIMS: Solar ultraviolet (UV) radiation is the most important environmental risk factor for melanoma and non-melanoma skin cancer. It is known that tap water and saltwater baths have a photosensitizing capacity in subsequent UV irradiation of the skin. The aim of the present study was to determine the influence of ...
Latzka W A - - 2000
Hyperhydration or increasing body water content above normal (euhydration) level was thought to have some benefit during exercise heat-stress; however, attempts to overdrink have been minimized by a rapid diuretic response. The perception that hyperhydration might be beneficial for exercise performance and for thermoregulation arose from the adverse consequences of ...
McLellan T M - - 2000
This study used partitional calorimetry to determine the influence of fluid replacement on heat storage during uncompensable heat stress. Eight males performed either light (L; level treadmill walking at 0.97 m x s(-1) (3.5 km x h(-1)) or heavy (H; 1.33 m x s(-1) (4.8 km x h(-1)) at a ...
Crafts-Brandner S J - - 2000
Experiments were conducted to determine the relative contributions of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) activation state vis-a-vis Rubisco activase and metabolite levels to the inhibition of cotton (Gossypium hirsutum L.) photosynthesis by heat stress. Exposure of leaf tissue in the light to temperatures of 40 or 45 degrees C decreased ...
Casa D J - - 2000
The purpose of this study was to determine if intravenous fluid rehydration, versus oral rehydration, during a brief period (20 min) differentially affects plasma ACTH, cortisol, and norepinephrine concentrations during subsequent exhaustive exercise in the heat. Following dehydration (DHY) to Eth 4% of body weight, 8 nonacclimated highly trained males ...
McCutcheon L J - - 2000
Sweating responses were examined in five horses during a standardized exercise test (SET) in hot conditions (32-34 degrees C, 45-55% relative humidity) during 8 wk of exercise training (5 days/wk) in moderate conditions (19-21 degrees C, 45-55% relative humidity). SETs consisting of 7 km at 50% maximal O(2) consumption, determined ...
Geor R J - - 2000
The effect of humid heat acclimation on thermoregulatory responses to humid and dry exercise-heat stress was studied in six exercise-trained Thoroughbred horses. Horses were heat acclimated by performing moderate-intensity exercise for 21 days in heat and humidity (HH) [34.2-35.7 degrees C; 84-86% relative humidity (RH); wet bulb globe temperature (WBGT) ...
Purvis A J - - 2000
In soccer, goalkeepers routinely wear gloves that may restrict heat loss from the hands and cause thermal discomfort. In order to alleviate this problem phase control materials (PCMs) have been incorporated into gloves to reduce heat load inside the glove, thereby maintaining a comfortable temperature. The aim of this study ...
Zuo L - - 2000
Skeletal muscles are exposed to increased temperatures during intense exercise, particularly in high environmental temperatures. We hypothesized that heat may directly stimulate the reactive oxygen species (ROS) formation in diaphragm (one kind of skeletal muscle) and thus potentially play a role in contractile and metabolic activity. Laser scan confocal microscopy ...
Febbraio M A - - 2000
It has been suggested that exercise performance in the heat is limited by the degree of hyperthermia, which, in some circumstances, compromises cardiovascular function and/or the central nervous system. However, this review presents evidence that a temperature-induced dysfunction to skeletal muscle contraction may contribute to a reduction in performance during ...
Flinn S D - - 2000
A 20-year-old military recruit suffered a generalized tonic-clonic seizure following 9 hours of moderate activity in a hot, humid environment. He had drunk at least 5.8 L of plain water before the seizure, and laboratory studies revealed that his serum sodium concentration was 113 mmol/L. Overconsumption of fluids during exercise ...
Noakes T D - - 2000
The strength of modern medicine is its relentless quest for an elusive perfection. That quest requires that we examine our errors even more closely than our successes. It is for this reason that the case report of Flinn and Sherer ("Seizure After Exercise in the Heat: Recognizing Life-Threatening Hyponatremia," page ...
Montain S J - - 2000
This study examined whether muscle injury and the accompanying inflammatory responses alter thermoregulation during subsequent exercise-heat stress. Sixteen subjects performed 50 min of treadmill exercise (45-50% maximal O(2) consumption) in a hot room (40 degrees C, 20% relative humidity) before and at select times after eccentric upper body (UBE) and/or ...
Hasegawa H - - 2000
To examine the role of monoamines and amino acids in thermoregulation, we measured their concentrations in the preoptic area and anterior hypothalamus (PO/AH) in exercising rats, using an in vivo microdialysis technique. Body temperature (Tb) was monitored using a telemetry system. Tb increase by about 1.0 degrees C in the ...
Buono MJ - - 2000
The purpose of this study was to examine the sweat gland recruitment pattern, on multiple trunk and limb sites, during exercise. Nineteen male volunteers performed 30 min of exercise on a cycle ergometer at approx. 25, 50 and 75% of their maximal oxygen uptake. The number of active sweat glands ...
Stern U M - - 2000
Sweating (perspiratio sensibilis) serves predominantly for thermoregulation and is triggered, among other stimuli, by physical stress. Although consensus on sex-dependent differences in sweating has not been reached so far and recent studies revealing abnormal diminution of the sweating capacity in atopic subjects are mainly based on heat exposure experiments, the ...
Sawka M N - - 2000
During exercise in the heat, sweat output often exceeds water intake, resulting in a body water deficit (hypohydration) and electrolyte losses. Because daily water losses can be substantial, persons need to emphasize drinking during exercise as well as at meals. For persons consuming a normal diet, electrolyte supplementation is not ...
- - 2000
For morphologic and physiologic reasons, exercising children do not adapt as effectively as adults when exposed to a high climatic heat stress. This may affect their performance and well-being, as well as increase the risk for heat-related illness. This policy statement summarizes approaches for the prevention of the detrimental effects ...
Buono M J - - 2000
The purpose of this study was to compare directly the physiological consequences of 5% hypohydration or euhydration during exercise in both temperate (23 degrees C) and hot (33 degrees C) environments. The subjects were eight male volunteers. Each performed four 1-h exercise bouts at 60% maximum oxygen uptake, one in ...
Gisolfi Carl V. - - 2000
The gut usually meets the fluid, electrolyte, and nutrient requirements of mild to heavy exercise. Gastric emptying and intestinal absorption rates of beverages ingested during exercise equal sweat rates. However, strenuous or prolonged exercise under dehydrated conditions can produce gastrointestinal distress and tissue damage.
Cheung S S - - 2000
In many athletic and occupational settings, the wearing of protective clothing in warm or hot environments creates conditions of uncompensable heat stress where the body is unable to maintain a thermal steady state. Therefore, special precautions must be taken to minimise the threat of thermal injury. Assuming that manipulations known ...
González-Alonso J - - 2000
1. We hypothesised that heat production of human skeletal muscle at a given high power output would gradually increase as heat liberation per mole of ATP produced rises when energy is derived from oxidation compared to phosphocreatine (PCr) breakdown and glycogenolysis. 2. Five young volunteers performed 180 s of intense ...
Koulmann N - - 2000
Physiological measurements including body mass, plasma osmolality, natremia, plasma volume measured by Evans Blue dilution, and total body water (TBW) and extracellular water (ECW) volumes estimated by bioelectrical impedance analysis (BIA) were recorded in eight healthy young Caucasian subjects before and after acute variations of their body hydration state on ...
Downey D - - 2000
A model of the human body that integrates the variables involved in temperature regulation and blood gas transport within the cardiovascular and respiratory systems is presented here. It expands upon previous work to describe the competition between skin and muscles when both require increased blood flows during exercise and/or heat ...
Kay D - - 2000
The development of fatigue during exercise and the subsequent onset of exhaustion occur earlier in the heat than in cooler environments. The underlying mechanisms responsible for the premature development of fatigue in the heat have yet to be clearly identified. However, the proposed mechanisms include metabolic, cardiovascular and central nervous ...
Sassa T - - 2000
3-Carboxy-4-methyl-5-propyl-2-furanpropionic acid (CMPF), a candidate for uremic toxin, was measured in human hair for examining a possible utility as indicator of renal dysfunction. The serum concentration of CMPF was much higher (32.3 +/- 2.7 microg/ml, n = 17; mean +/- SEM) in uremic patients aged 40-55 years receiving hemodialysis treatment ...
Shirreffs S M - - 2000
Restoration of fluid balance after exercise-induced hypohydration avoids the detrimental effects of a body water deficit on subsequent exercise performance and physiological function. Key issues in restoring fluid balance are consumption of a volume of fluid greater than that lost in sweat and replacement of electrolyte losses, particularly sodium.
Ando H - - 2000
OBJECTIVES: To clarify the mechanism of a human reaction to vibration stress by palmar sweating in relation to the autonomic nerve tone. METHODS: The autonomic nerve tone was divided into four types by using digital photoelectroplethysmography (PTG) with auditory stimuli: normal (N), hyperreactive (I and D), and hyporeactive (P) types. ...
Marszalek A - - 2000
In a hot environment, especially during exercise, the main role of thermoregulative mechanisms is to dissipate excessive heat from the body. The most effective way of heat dissipation is sweat production and its evaporation off skin surface. Intense sweating results in a considerable loss of water and electrolytes. There are ...
Epstein Y - - 2000
In most cases, exertional heat stroke (EHS) can be prevented in the military setting. The actions taken by the Israel Defense Forces (IDF) and their outcome prove this well. Unfortunately, despite the available information, there are still incidents of failure of command in conducting physical exercise, leading to EHS. In ...
Moran D S - - 2000
A physiological strain index (PSI) based on rectal temperature (Tre) and heart rate was recently suggested to evaluate exercise/heat stress. This review summarizes the development of PSI which was evaluated from seven different databases during the last three years. PSI was developed from data obtained from man performing exercise in ...
Naghii M R - - 2000
Intake of food and drink during exercise can be effective in enhancing performance, in so far as it prevents or ameliorates exercise-induced changes to body homeostasis. Loss of body fluids containing water and electrolytes during exercise is mostly by sweating. Sweat rates during a sporting event or activity will vary ...
McCutcheon L J - - 1999
This study examined sweating responses in six exercise-trained horses during 21 consecutive days (4 h/day) of exposure to, and daily exercise in, hot humid conditions (32-34 degrees C, 80-85% relative humidity). On days 0, 3, 7, 14, and 21, horses completed a standardized exercise test on a treadmill (6 degrees ...
González-Alonso J - - 1999
1. The present study examined whether reductions in muscle blood flow with exercise-induced dehydration would reduce substrate delivery and metabolite and heat removal to and from active skeletal muscles during prolonged exercise in the heat. A second aim was to examine the effects of dehydration on fuel utilisation across the ...
Coyle E F - - 1999
Performance in endurance events is typically evaluated by the power or velocity that can be maintained for durations of 30 min. to four hours. The two main by-products of intense and prolonged oxidative metabolism that can limit performance are the accumulation of hydrogen ion (i.e. lactic acidosis) and heat (i.e. ...
Kasa I W - - 1999
OBJECTIVE: To compare the sweating responses of three breeds of goats to exercise at 30 degrees C. DESIGN: Factorial experiment with two goats of each of three breeds exercised for 60 min at 3 km/h and 30 degrees C on 6 days. PROCEDURE: Two mature females of the Anglo-Nubian, Saanen ...
Kingston J K - - 1999
OBJECTIVE: To quantify total fluid loss in sweat of Thoroughbreds during >3 hours of low-intensity exercise in controlled conditions and to calculate and compare estimated ion losses in sweat, according to 3 methods. ANIMALS: 6 exercise-trained Thoroughbreds. PROCEDURE: Fluid and ion losses in sweat were measured in 6 horses exercising ...
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