Although it doesn’t seem like it, warm weather will be here before we know it! Several years ago, I explained how to stay safe and train well running in the winter. Today’s topic is safe summer running.
First, the physiology! The human body has an amazing ability to maintain a relatively stable internal temperature. This is accomplished by auto-regulation, balancing heat production with dissipation. Most of the heat in the body is produced by contraction of the muscles. So, during exercise like running, heat generation rises. If the body cannot step up heat elimination and internal temperature rises too high, heat- related illness can occur. Symptoms of these illnesses range from mild heat exhaustion with fatigue and muscle cramps, to severe heat stroke with loss of consciousness and multi-system organ failure. Other factors contributing to heat related illnesses are inadequate conditioning and dehydration. Lack of acclimatization can also contribute. This may affect all of us if we transition rapidly from our long cool spring to heat and humidity this summer without about 2 weeks of moderate temperatures in between.
The body cools itself by several mechanisms. Radiation is loss of heat from the warm skin to the cooler environment. The body can also be cooled by convection – air is blowing over the skin. Evaporation occurs when we sweat and the water in the sweat converts to water vapor. All of these cooling mechanisms are hampered if the weather is very hot and humid.
Here are some simple strategies recommended by the American College of Sports Medicine to prevent heat-related illness while running:
Hydration: You can lose between 6-12 ounces of fluid each hour during a long run on a hot day. Adequate hydration is probably the most important factor preventing heat-related illness. You should drink adequately throughout the day and at least 16-32 ounces of water about 2 hours before a run in the heat. Weigh yourself before you run so you know how much fluid you need to replace after the run. Drink 5-10 ounces of water every 15 – 20 minutes during exercise. If you run for longer than an hour, you may want to switch to a sport drink with 4-8% carbohydrates. Weigh yourself after the run and replace 16 ounces of fluid for every pound lost. If you are a newer runner, be sure to practice drinking on the run before trying it in a race.
Clothing: Don’t over-dress. Wear loose-fitting running clothes made of tech fibers that wick sweat to aid evaporation. Light colors reflect the sun’s rays, dark colors absorb them. Don’t wear cotton. It wicks inefficiently soaking up sweat. Avoid hats. If you must wear one, make sure it’s well ventilated and light in color.
Time & Place: Run early in the day or later in the evening when it is cooler. Stay off the asphalt and run on the trails. Run in the shade or better yet, in the woods.
Be Sensible! The hotter it is the easier you should take it. If it is extremely hot, forget it! Be aware of the symptoms of heat-related illness. If you develop a headache, lightheadedness, weakness or muscles cramps, stop immediately! Get in a cooler environment and drink fluids.
I recommend avoiding NSAIDs like ibuprofen before you run, especially on a hot day. These meds make the renal arteries constrict and if you are not adequately hydrated, your kidneys can suffer. Last but not least, don’t forget the sunscreen!
Dr. Marie-Christine Leisz is a Physical Medicine and Rehabilitation and Sports Medicine Physician at Courage Kenny Running and Endurance Sports Injury Clinic. She collaborates with the Courage Kenny RunSmart Physical Therapy program. Learn more at our websites: http://www.allinahealth.org/ahs/ski.nsf/page/running_endurance http://www.allinahealth.org/ahs/ski.nsf/page/Run_smart