Effects of different sodium concentrations in replacement fluids during prolonged exercise in women
Twerenbold R, Knechtle B, Kakebeeke TH, Eser P, Müller G, von Arx P, et al.
Published in Br J Sports Med, Vol. 37 (4), pp. 300-3; discussion 303
Methodology
Thirteen female endurance athletes ran three 4-hour track sessions drinking 1 L of fluid an hour, in random order: high-sodium fluid (680 mg/L), low-sodium fluid (410 mg/L) or water.
Key Findings
Plasma sodium fell 2.5 mmol/L with high-sodium fluid versus 6.2 mmol/L with water (p < 0.001). Mild hyponatraemia still occurred in 46% with high-sodium fluid, 69% with low-sodium fluid and 92% with water; two developed severe hyponatraemia on water.
Conclusions
When women overdrink, sodium in the drink softens the fall in plasma sodium but does not stop hyponatraemia; the fall tracked weight change.
Limitations
Thirteen women; weather differed between trials; fixed, deliberately high fluid intake.
Supplements Studied
This can be minimised by the use of replacement fluids of high sodium concentration
Related Health Concerns
Study Details
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