HYPONATREMIA IN DISTANCE RUNNERS: FLUID AND SODIUM BALANCE DURING EXERCISE

Since its first description in 1985, two opposing theories have evolved to explain the etiology of symptomatic hyponatremia of exercise. The first holds that the condition occurs only in athletes who lose both water and sodium during exercise, and fail to fully replace their sodium losses. The second theory holds that the symptomatic form of [...]

ENDOCRINE AND RENAL RESPONSE TO WATER LOADING AND WATER RESTRICTION IN NORMAL MAN

1. Nine normal subjects (eight male, one female) on a fixed daily intake of 150 mmol of sodium and 80 mmol of potassium, were randomized to receive either 3 days of 1.0 litre total water intake/24 h (food + fluid) or 4 days of 6.8 litres total water intake/24 h, and were then crossed over [...]

EFFECTS OF FLUID, ELECTROLYTE AND SUBSTRATE INGESTION ON ENDURANCE CAPACITY

The availability of carbohydrate (CHO) as a substrate for the exercising muscles is known to be a limiting factor in the performance of prolonged cycle exercise, and provision of exogenous CHO in the form of glucose can increase endurance capacity. The present study examined the effects of ingestion of fluids and of CHO in different [...]

EFFECT OF SALT INTAKE ON RENAL EXCRETION OF WATER IN HUMANS

Two studies were performed to determine the quantitative relationship between salt intake and urinary volume (U(v)) in humans. In study 1, 104 untreated hypertensives were studied on the fifth day of a high- and a low-salt diet. The 24-hour U(v) was 2.2 L (urinary sodium [U(Na)] 277 mmol) on the high-salt diet and decreased to [...]

DIFFERENCE IN REHYDRATION PROCESS DUE TO SALT CONCENTRATION OF DRINKING WATER IN RATS

Albino rats were thermally dehydrated (approximately 8% of body wt), divided into five groups, and given tap water or 0.2, 0.45, 0.9, or 2.0% NaCl solution ad libitum for 16 h. Rats given 0.9 or 0.45% NaCl solution regained fluid loss completely in 3-3.5 h, whereas those given 0.2% solution became fully rehydrated at 10 [...]

FLUID REPLACEMENT DURING PROLONGED EXERCISE: EFFECTS OF WATER, SALINE, OR NO FLUID.

This study assessed the need to replace sodium in endurance exercise less than or equal to 6 h in duration by comparing responses to fluid replacement with water, saline (25 mmol.l-1), or no fluid. Eight subjects (five male, three female) participated in three 6-h exercise trials on an electrically braked cycle ergometer at 55% VO2max, [...]

WATER AND SALT TURNOVER.

Intake and output of water were studied in six male subjects from six European countries during 28 days of isolation and confinement in order to assess whether the observed reactions can be compared with those observed during space travel. On the average, the subjects drank 17.5 ml/kg/day fluids. An additional 25 ml/kg/day was recruited from [...]