Hydration is important to replace water and salts that we lose during our workouts.
Sweating may seem like an annoyance with exercise, but it has an important role in temperature regulation. Because we sweat away our fluid storage when we run, we need to make sure we are constantly hydrated. But it’s not just about water. Along with water loss, athletes also lose important electrolytes like sodium and potassium with sweat. Many people do not realize that electrolyte losses must be replaced. In particular, sodium (“salt”) loss has become a hot topic for long-distance runners and endurance athletes. Hyponatremia is the scientific term for low sodium in the body, and runners should know when they are at risk.
What are the symptoms of hyponatremia?
Early symptoms of hyponatremia such as dizziness, malaise, nausea, and fatigue are so common as a normal part of running that they are often ignored, overlooked, or dismissed. When severe or prolonged, hyponatremia causes a loss of fluid regulation in body tissues, causing brain swelling that can lead to late symptoms of mental status changes and death.
Are all runners at risk for hyponatremia?
Healthy athletes consuming a consistent, regular diet should be at very low risk if exercising for 1 to 2 hours or less per day. However, certain types of runners are at high risk for developing life-threatening hyponatremia:
- Endurance athletes and slow runners who exercise 4 or more hours in a session or day can be at very high risk, especially when consuming only plain water during such an activity.
- Heavy “sweaters” (2 or more pounds of weight loss per hour) can also be at high risk.
“Salty” sweaters who develop white pasty residue on their skin when sweating may also be at higher risk. - Athletes competing in extremely warm weather conditions, especially when poorly acclimated, can be at higher risk.
What should I do to lower my risk of hyponatremia?
The general strategy for prevention of hyponatremia is to replace sodium losses as they occur. Water intake without electrolyte replacement further dilutes body fluids and can worsen the effects of sodium losses.
- Healthy endurance athletes and runners working out more than 4 hours per session or day should eat a salty snack, like pretzels, with water while hydrating during the exercise session. Alternatively, athletes can consume electrolyte-containing endurance/sport beverages for fluid replacement.
- Healthy endurance athletes should satisfy salt cravings that occur after long exercise sessions.
- Athletes should avoid running in the warmest parts of hot days in extreme environmental conditions.
- Athletes should avoid sudden increases in the duration/ distance of training sessions.