Discussion
thirst, stroke, hyponatremia, hypohydration, sweat loss, mass loss
STROKE, HYPONATREMIA, EVENT, FLUID LOSS, HEAT
The current finding of maintaining plasma sodium concentration and plasma volume when fluid loss was replaced with a beverage having a sodium concentration of 60 mmol LSodium has direct and indirect effects to regulate plasma volume which can affect exercise performance and strain, particularly due to effects on stroke volume and cardiac output (Luetkemeier and Thomas In line with our plasma volume results, body mass loss also tended to be less with High NaWith shorter exercise endeavors than in the present study, lower intensity and/ or cooler temperatures, sweat rate, sweat sodium concentration and total sweat loss would be less (Baker The lack of difference in heart rate and core temperature between conditions in the present study correlates with the similar RPE observed, however, unexpectedly, perceived warmth was greater with Low NaAdvocating “drinking to thirst”, while thirst is not always associated with a given level of hydration (Armstrong et al. Although not replacing sweat losses and allowing hypohydration to ensue is one way to ensure that plasma sodium concentration is not reduced, this may be at the expense of total body and extracellular water, and plasma volume. For the recreational athlete this may be acceptable, when maintaining a given intensity or performance is not critical. This may even be preferable to risking hyponatremia in the large group of non-competitive endurance event participants that are most at risk. For competitive endurance athletes, particularly in the heat, sweat rates can exceed 2 L h