Neufer PD, Young AJ, Sawka MN, 1989, Gastric emptying during exercise: effects of heat stress and hypohydration
.Eur J ApplPhysiolOccup Physiol.; 58(4):433-9.
Cheuvront et al., "Effect of hypohydration
and altitude exposure on aerobic exercise performance and acute mountain sickness," Journal of Applied Physiology, vol.
where % mass loss is the percentage of body weight lost due to hypohydration
at the start of exercise.
Effect of hypohydration
on core temperature during exercise in temperate and hot environments.
The effects of hypohydration
and fatigue on neuromuscular activation performance.
Soldiers relocating from cooler climates are known to be at greater risk for developing heat illnesses, (9) thus hypohydration
may also be an exacerbating concern for those in that category.
The combined recommendation from the IOC, ACSM and International Society for Sports Nutrition (ISSN) is to calculate individual fluid needs in order to prevent hyper- and hypohydration
.  The ISSN recommends drinking 500-2 000 mL fluid during every hour of exercise (150-200 mL every 15-20 minutes).
Because previous, uncorrected dehydration can have a negative impact on performance as well , it is also important to assess acute hydration status before a training session or competition and to correct any existing hypohydration
TOKIZAWA, K., YASUHARA, S., NAKAMURA, M., UCHIDA, Y., CRAWSHAW, L.I., NAGASHIMA, K., 2010, Mild hypohydration
induced by exercise in the heat attenuates autonomic thermoregulatory responses to the heat, but not thermal pleasantness in humans.
Meta-analysis of the effects of hypohydration
showed that it starts to affect endurance performance when loss of body mass is 3% or more, but there was no mention of ambient temperatures in the studies ; hypohydration
also impaired some kinds of shorter performance, but a threshold was less clear .
Without further education, and use of other measures such as [U.sub.col], these are the athletes at a high risk of the adverse effects of hypohydration
. High (r = 0.80) to moderate (r = 0.68) correlations of urine [U.sub.col] and [U.sub.sg] have been shown previously (18,19).
Other factors that increase the risk of heat-related illness in infants and children are hypohydration
(inadequate hydration during physical activity), obesity, fewer sweat glands that decrease the ability to dissipate heat, and disease processes such as cystic fibrosis and hyperthyroidism (Gutierrez, 1995).