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Oral salt supplementation during ultradistance exercise
Dale B Speedy1, John M D Thompson, Ian Rodgers
1Department of General Practice and Primary Care, University of Auckland, New Zealand. dalespeedy@e3.net.nz
Summary
Sodium supplementation during Ironman triathlons reduced weight loss but did not significantly alter serum sodium or plasma volume. Athletes did not develop hyponatremia, suggesting sodium is not necessary for prevention in this context.
Area of Science:
- Sports Medicine
- Exercise Physiology
- Endurance Sports
Background:
- Hyponatremia is a risk in endurance events.
- Fluid and electrolyte balance is crucial for athletes.
- The role of sodium supplementation in Ironman triathletes requires further investigation.
Purpose of the Study:
- To investigate the effects of sodium supplementation on body weight, serum sodium, and plasma volume in Ironman triathletes.
- To determine if sodium supplementation prevents hyponatremia during an Ironman triathlon.
Main Methods:
- Thirty-eight Ironman triathletes were divided into a salt intake (SI) group and a no salt (NS) group.
- The SI group received salt tablets providing approximately 700 mg/h of sodium.
- Measurements included body weight, serum sodium, hemoglobin, and hematocrit before and after the race.
Main Results:
- The SI group experienced less weight loss compared to the NS group when matched for pre-race sodium levels.
- Sodium supplementation did not significantly impact changes in serum sodium or plasma volume compared to fluid replacement alone.
- No athletes in either group finished the race with serum sodium below 135 mmol/L.
Conclusions:
- Sodium supplementation may help reduce weight loss during an Ironman triathlon.
- It is not essential for preventing hyponatremia in Ironman triathletes who experience weight loss.
- Athletes in this study partially replaced fluid and electrolyte losses, which may explain the absence of hyponatremia.