Exercise‐associated hyponatremia: A review

Abstract

This paper reviews the extensive literature on hyponatremia, a common and potentially serious complication of ultra‐distance exercise. Fluid overload is the likely aetiology. Fluid intakes are typically high in athletes who develop hyponatremia, although hyponatremia can occur with relatively modest fluid intakes. The development of fluid overload and hyponatremia in the presence of a modest fluid intake raises the possibility that athletes with this condition may have an impaired renal capacity to excrete a fluid load. The bulk of evidence favours fluid retention in the extracellular space (dilutional hyponatremia) rather than fluid remaining unabsorbed in the intestine. Female gender is an important risk factor for the development of hyponatremia. Management and prevention of exercise‐associated hyponatremia are discussed. See Commentary, page 5.

Exercise-Associated Hyponatremia

“…Currently, there is insufficient evidence to support the suggestion that ingestion of sodium prevents or decreases the risk for EAH; neither is there any evidence that consumption of sports drinks (electrolyte-containing hypotonic fluids) can prevent the development of EAH (1,(35)(36)(37)(38)42,100,101). Again, most commercial sports drinks are hypotonic with a sodium content of 10 to 20 mmol/L (230 to 460 mg/L).…”

“…In fact, hyponatremia has been stated to be one of the most common medical complications of long-distance racing and is an important cause of race-related fatalities (1). On the basis of recent studies of the incidence and risk factors of hyponatremia in endurance athletes, along with well-publicized reports of fatalities as a result of hyponatremia, medical directors and marathon organizations have begun to warn participants of the dangers of hyponatremia and excessive fluid intake (2).…”

Human Water and Electrolyte Balance

“…Symptomatic hyponatremia (typically associated with serum sodium concentrations of less than 125-130 mEq/ AG-PPKN-0909 R1 CH33 04-07-06 12:03:36 L) has been observed during marathon and ultramarathon competition, [74][75][76] military training, 77,78 and recreational activities. 79 In athletic events, the condition is more likely to occur in females and slower competitors.…”

“…80 The hyponatremia associated with prolonged exercise develops primarily because individuals drink excessively large quantities of hypotonic fluids (relative to sweating rate) for many hours. 3,76,77 Unreplaced sodium losses contribute to the rate and magnitude of sodium dilution. Additionally, nausea (which increases vasopressin levels) and heat/exercise stress (which reduce renal blood flow and urine output) can negatively affect the ability of the kidney to rapidly correct the fluidelectrolyte imbalance.…”

A Flexible Front-End for Wearable Electrochemical Sensing

“…Besides, electrolytes are salient target compounds in monitoring of athletes. Namely, potassium levels are indicators of muscle cramps or dehydration [6], while calcium concentration evidences bone mineral loss [7]. In addition, lithium is monitored for subjects suffering from mental disorders [8].…”