Michael N Sawka

..7 L for adult women meets the needs of the vast majority of persons. However, strenuous physical exercise and heat stress can greatly increase daily water needs, and the individual variability between athletes can be substantial...

..05), but not HW. These results indicate that BVS(On) reduces physiological strain in all three environments by a similar amount; however, in hot-dry conditions the BVS(Off) increases physiological strain...

..m(-2)) ( p < 0.05). These findings suggest that IC provided a favourable skin to LCG gradient for heat dissipation by conduction and reduced heat strain comparable to CC during exercise-heat stress in chemical protective clothing...

..The impact of prior heat stress on subsequent aerobic exercise-heat performance has not been studied...

..07). In conclusion, hypohydration at 3,048 m 1) degrades aerobic performance in an additive manner with that induced by ALT; and 2) did not appear to increase the prevalence/severity of AMS symptoms...

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..DEET can be safely worn during military, occupational and recreational activities in hot, insect infested environments...

..05). SR was higher (P < 0.05) in P and S versus B, but the magnitude of differences was small. A protective vest increases physiological strain independent of added load, while a spacer garment does not alter this outcome...

..05) or the self-selected pacing strategy employed. These findings indicate that the nutritional adenosine receptor antagonists caffeine and quercetin do not enhance endurance exercise performance during compensable heat stress...

..However, the explanatory power of exercise with marked environmental heat stress on the appearance of S-100beta is questionable. It is possible that the process of heat acclimation might afford additional insight...

..Rater and SReg were not different by conventional t-test (P > 0.05). SReg provides a simple, valid, and standardized way to determine sweating threshold temperature and sweating sensitivity values for thermoregulatory studies...

..Dehydration augments hyperthermia and plasma volume reductions, which combine to accentuate cardiovascular strain and reduce Vo(2max). Importantly, the negative performance consequences of dehydration worsen as T(sk) increases...

..This method of pre-acclimatization can therefore be highly recommended for inducing altitude acclimatization without the 'altitude residency' requirement...

..Neither prediction equation provided accurate estimates of TSL in warm or cool conditions for women runners. These results illustrate the difficulty of accurately estimating and predicting sweat losses in the field...

..changes in SR. These findings provide a quantitative basis for study design and optimization of power/sample size analysis in the evaluation of thermoregulatory sweating...

..Moderate HYP had no effect on cognitive and psychomotor performance in either environment, cold exposure produced equivocal effects, and aerobic exercise improved some aspects of military task performance...

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..This study examined the effects of hypohydration and moderate hyperthermia (core temperature elevation) on anaerobic exercise performance in a temperate environment...

..Improved occupational guidelines for fluid and electrolyte replacement during hot weather occupational activities should be developed to include recommendations for fluid consumption before, during, and after work...

..05). These data demonstrate that 1) HYP impairs endurance exercise performance in temperate but not cold air but 2) cold stress per se does not...

..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)...

..Salivary osmolality (Sosm) is a potentially useful hydration marker but may be confounded by oral artifacts...

..A secondary purpose was to validate use of the tool by dehydrating a group of volunteers...

..This report presents USARIEM's unique and world-class facilities, organizational changes, scientific and support personnel, and major research accomplishments, including the publication of 2,200 scientific papers over the past 25 yr...

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..These data demonstrate that physiological adaptations in humans undergoing HA are accompanied by both increases in baseline levels and changes in regulation of cytoprotective HSPs...

..This study evaluated adding reflective thermal inserts (RTI) to reduce the physiological strain during exercise-heat stress with a radiant load. RTI were used with a U.S. Army desert battle dress uniform, body armor, and helmet...

..05). In conclusion, this study demonstrates the failure to improve jump height when HYP can be explained by offsetting reductions in both VGRI and body mass...

..Well-recognized markers for static (one time) or dynamic (monitoring over time) dehydration assessment have not been rigorously tested for their usefulness in clinical, military, and sports medicine communities...

..Adjustments for NSL and clothing saturation dynamics help explain SHAP errors at 2 and 8 h, respectively. These results provide a basis for future development of accurate algorithms with broader utility...

..The data also suggest that daily BM is a sufficiently stable physiological parameter for potential daily fluid balance monitoring...

..By considering thermal stress early in the development process, health hazards related to temperature extremes can be mitigated while maintaining or improving the effectiveness of the PPE for protection from external hazards...

..Differences in urine flow rate and fluid retention were the result of a greater free water clearance with WI. These data indicate glycerol can be an effective hyperhydrating agent during CAE...

..This study examined the impact of 10 d of exercise-heat acclimation on sweat mineral concentrations...

..BC did not alter time-trial performance, cognitive performance, mood, perceived exertion, or perceived thermal comfort. We conclude that BCAA does not alter exercise or cognitive performance in the heat when subjects are hypohydrated...

..Other factors contributing to post-race collapse might include reduced skeletal muscle pump activity and dehydration and prior heat stress mediated changes in cerebrovascular responses to orthostatic challenges...

..Recommendations are provided to individualise fluid intakes with the goal of preventing excessive dehydration (>2% body mass) as well as weight gain. The minor importance of 'matters of debate' to fluid replacement is also discussed...

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..Serious heat illness has received considerable recent attention due to catastrophic heat waves in the United States and Europe, the deaths of high-profile athletes, and military deployments...

..These observations suggest that hypohydration and prior heat stress are associated with greater reductions in CBFV with greater CVR, which likely contribute to orthostatic intolerance...

..The present study assessed the effects of acute hyperoxia on resting-minute ventilation (VE) during altitude acclimatization to 4300 m...

..These findings indicate that the IRC approach to MCC is a more efficient means of cooling when compared with CC paradigms and can improve MCC capacity by reducing power requirements...

..IAE may therefore be used as an alternative to chronic altitude residence to facilitate improvements in muscular performance in athletes, soldiers, mountaineers, shift workers, and others that are deployed to altitude...

..The molecular evidence from these patients is thus consistent with the hypothesis that EHI can result from cumulative effects of multiple adverse interacting stimuli...

..The effects of exertional fatigue on pituitary-adrenal hormones and thyroid hormone responses to exercise-cold stress are unknown...

..It was hypothesized that the cooling systems would be equally effective, and total body cooling would allow 4 h of physical work in the heat while wearing STEPO...

..S. Army. It is known that prior infection is a risk factor for heat illness and some of the 37 heat stroke deaths cited infections (eg, pneumonia, influenza) in the medical records...

..S. Army fluid replacement guidelines (REV) with the old guidelines (OLD) on daily changes in serum sodium concentration (Na+) and body mass (BM) during Basic Combat Training at Fort Benning, GA during two successive summers...

..SSΔHR increased significantly in response to severe hypertonic hypohydration and moderate isotonic hypohydration, but not moderate hypertonic hypohydration. However, the 20 beats/min cut point afforded only marginal diagnostic accuracy...

..Several equation assumptions may limit its accuracy, but none have been systematically tested...

..This can usually be achieved with fluid intakes of under 1 L x h(-1)...

..The combined challenge of exercise and environment associated with marathon running can substantially challenge the human thermoregulatory system...

..In conclusion, our findings suggest that 3 weeks of IAE provide an effective alternative to chronic altitude residence for increasing resting ventilation and reducing the incidence and severity of AMS...

..PICS could also be used with civilian Levels A and B PPE increasing work time and worker safety...

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..After exercise, the goal is to replace any fluid electrolyte deficit. The speed with which rehydration is needed and the magnitude of fluid electrolyte deficits will determine if an aggressive replacement program is merited...

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