If you are new to running in hot, humid areas like Houston, please read this:
Warm Weather Running Tips
Dr. George Chiampas, Bank of America Chicago Marathon Medical Director
While training through the heart of summer in preparation for a fall marathon, you are inevitably going to encounter hot and uncomfortable running conditions along the way. Each runner responds differently in hot weather conditions, so it’s imperative to begin taking the necessary steps to avoid heat related illness. While running, the body’s internal temperature rises and sends blood to the skin for cooling. As the body tries to cool itself there is an increased need for oxygen, and thereby blood flow to the working muscles, is in high demand. Any imbalance in this process may lead to heat related illness. Keep in mind that if there is high humidity, the cooling measures of the skin may be blunted, leading to higher internal temperatures.
Participating in endurance events in hot and humid conditions can also exacerbate dehydration. Dehydration is the process of losing fluids from the body; in this case, through sweat. As you sweat, you lose water and salt. Each runner sweats and loses salt at a different rate; thus, it is vital to replace fluids and monitor sodium intake in order to avoid any issues.
Consider the following tips for running in the heat:
• Acclimate. Attempt to train in similar temperatures for two weeks prior to the endurance event in which you are participating.
• Weigh yourself before and after you run. Ideally, you should not lose more than 2% of your body weight after long runs. If you are gaining weight, you are over-hydrating and you may subsequently drop critical salt levels in your body. (A condition known as “Hyponatremia” can occur when there is a lower than normal concentration of sodium in the blood. Sodium is a critical electrolyte that aids nerve and muscle function, and helps to maintain blood pressure.)
• Combine water and sports drinks to stay hydrated and maintain sodium levels; you can also utilize salt tablets and salty foods (e.g. pretzels) to supplement salt intake.
• Acclimate to the sports drink (and specific flavor) that will be provided on race day by practicing with it during your training runs. (Note that the Bank of America Chicago Marathon offers lemon-lime Gatorade Endurance Formula on the course.)
• Do not run if you are experiencing any fevers, infections or using medications that increase your body temperature.
• Wear sunglasses and waterproof sunscreen.
• Wear light-colored, micro-fiber clothing (i.e. “technical” running clothing).
• Run early in the morning or later in the evening when temperatures are lowest.
• Listen to your body. If at any time your body gives you signals to slow down or to stop, abide by them.
• Be aware of your heart rate, body temperature and hydration levels. If you experience lightheadedness, confusion, nausea, vomiting, weakness and/or headache, stop running immediately.