The ideal marathon racing temperature is in the mid-50s, but if the temperature soars into the 70s or 80s on race day as it has in the past, you must drink more. Increase your fluid intake by sipping sports drinks, not just water. The carbs in sports drinks help restock spent energy stores. Most sports drinks will also replace the electrolytes you lose in sweat, helping you avoid hyponatremia (low blood-sodium level caused by excessive water intake).