1. Wear a visor and sunglasses. The visor will help shade your eyes but still allow heat to escape out your head.

2. Stay away from blacktop. It gets hot!

3. Run indoors if you can.

4. Run by a body of water. It is usually cooler by a lake or river.

Let’s also not forget that the marathon is an extreme case – for fitness runners, say 2-10 milers, dehydration is, as Jon noted, way more of a concern. I’ve seen guys carted off due to poor hydration pretty much every summer I’ve run, and have yet to see a case of too little sodium.

Thanks for your comments.

I would definately agree that a significant number of marathoners experience a decreased sodium level by the end of the race. There’s no question that affects performance. Likewise, heat stroke/exhaustion and dehydration play an equally large (if not greater) role in degrading performance, not to mention dropping blood sugar levels. Certainly, bonking during a marathon is a very common occurrence for marathoners and requires quick medical attention for extreme cases.

For optimum performance, you need to balance your fluid/electrolyte/calorie intake with your fluid/electrolytes excreted and calories burned.

One important point about hyponatremia is that you can count the number of runner deaths due to it on your hands. It has received alot of press in recent years but remains an extremely rare cause of death among runners. Far more athletes are killed by heat stroke, heart failure, and car crashes on the way to the race, than by hyponatremia.

Proper hydration and electrolyte intake are suggested as preventative measures for hyponatremia, as it pertains to athletes. Eleviating the condition when it has progressed to more severe stages, should involve medical personnel. The exact cause of the condition in runners may be far more complex than just drinking too much water, and other physiological factors may contribute to an athlete’s susceptibility, such as BMI.