Fluid, hydration, and sodium balance

By Susan M. Parks M.S., R.D.,C.S.S.D.,L.D., C.P.T. Sports Nutritionist

Is cutting back on sodium appropriate for the healthy athlete?

NO--- Athletes who lose a large volume of sweat during activity should not restrict their sodium intake!

That does not mean to OVER consume sodium on a continuous basis! Even though the general public health message is to decrease habitual high salt intake for hypertension is correct, a short term high intake of sodium causes a short term rise in blood pressure in healthy individuals, but for the healthy athlete sodium may be needed to maintain proper fluid and electrolyte balance during strenuous workouts. It restores plasma volume after strenuous exercise. Both dehydration AND hyponatremia (low sodium plasma) can have serious consequences for the endurance athlete, running or biking. Under-and over-drinking water during activity and ignoring mineral balance besides hydration can be the main cause of most medical problems seen in athletes.


CAN THIS BE AVOIDED? WHAT CAN YOU DO?
Hydration (fluid balance) is a very individual situation. Sweat, sodium and volume shifts and rates are highly variable, depending on individual responses to exercise intensity, duration, and environmental conditions (heat, humidity, heat index, and altitude). Athletes SHOULD learn their OWN fluid requirements.


WEIGH BEFORE AND AFTER a STRENUOUS and/or LONG WORKOUT.
This will provide you with a personal guide to your sweat loss, in order to create a fluid plan for your future workouts or training.


AS A RULE: Drink 3 cups (24 fluid ounces) per pound lost to replace the lost water weight as well as to account for urine production. Dehydration usually causes thirst, but for athletes drinking plain water without ingesting adequate sodium suppresses thirst BEFORE fluid balance can be restored. Therefore, consuming a sport drink with at least 100 mg. OF SODIUM for each 8 ounce serving can help counteract dehydration and avoid hyponatremia. Rebalancing both thirst and mineral needs for a heavy sweater can prevent severe muscle cramping and even death for some individuals.

Please let me know your thoughts and comments by posting questions/comments on this blog.