Thursday, January 15, 2009

Guidelines for Preventing Hyponatremia

I was very irritated at the Bellingham Marathon organizers when I discovered they were serving Ultima Replenisher on race day. Ultra Replenisher is a sports drink containing electrolytes but only 10 calories per 8 ounces, virtually worthless. When I asked a race official about it, the answer I got was "What about hyponatremia?"

Hyponatremia is a potentially life threatening condition characterized by low sodium levels in the blood. How does it occur? Overdrinking to the point that you actually gain weight during a long race. According to one study conducted on 488 Boston Marathon finishers, 63 were classified as hyponatremic. Primary risk factors identified were weight gain, a finishing time > 4 hours, and low or high body weight. Most drank more than 3 liters (a liter is about a quart). Others have identified the possibility that genetics, anti-inflammatories, stress, and nausea are contributing factors. Another important factor is sweat rate- the more you lose the greater the risk.

Symptoms of hyponatremia include feeling bloated, nausea, vomiting, swelling in extremities, headache. Lethargy, confusion can also appear. In advanced stages, seizure, trouble breathing, and unconsiousess may occur.

Back to Bellingham- can you prevent hyponatremia by using an electrolyte drink instead of water. The answer to that question is clearly no. While sports drinks are recommended over water "Hyponatremia is caused by excess fluid from any source, not by lack of salt or calories." (Sports Drinks Won't Prevent Dehydration or Hyponatremia).

Recommendations for preventing hypotatremia include:

1. Don't drink obessively in the days leading up to a marathon.

2. Avoid taking anti-inflammatories such as aspirin or ibuprofen before, during, and immediately after a marathon. Wait until you are fully rehydrated.

3. Weigh yourself before the start and write it on your number- this will help any medical staff should you need attention.

4. Drink when you are thirsty during the race but don't overdo it.

5. In workouts, weigh yourself before and after without drinking to estimate your fluid loss (remember 16 oz = 1 lb). This gives you a guide (assuming the same environmental conditions) on how much you need to be drinking to just maintain losses.

6. Acclimatize by wearing extra layers during your workouts for 7-10 days prior to your race.

7. After your race nibble on salty snacks and be careful not to drink too much.


How much should you drink during a marathon?


(c) Dave Elger 2009

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