If you are one of the thousands of people who regularly exercise outdoors, you may find that a hot summer day can have a major effect on your routine. Heat exhaustion, heat stroke and other heat-related illnesses become all too common during the summer months and are especially prevalent among those doing strenuous activities in warm temperatures. Heat-induced illness is preventable; so before you decide to stay inside and forgo your workout altogether, consider a few tips that will make exercising outdoors safer and a bit more tolerable.

• Fluids: Drink at least eight to 10 ounces of water 10 to 20 minutes before you begin your workout. During your workout, take frequent water breaks – drinking approximately three to seven ounces of water or sports drink every 20 minutes. After exercise, you should drink 16 to 24 ounces for every pound of body weight you lose during exercise (an easy way to measure this is to weigh yourself naked before and after your workout and note the difference). You should also avoid caffeine and alcoholic beverages.
• Clothing: Wear lightweight, loose-fitting clothing. Choose breathable fabrics (such as cotton) in light colors. Shorts and tank tops are often good choices because they leave large areas open for sweat evaporation. But be sure to cover all exposed areas with sunscreen. Wear a hat to protect your head from the sun.
• Foods: Avoid consuming hard-to-digest foods such as proteins. Because digestion generates body heat, choose foods such as fruits and vegetables that are quick and easy to digest.
• Time of Day: On hot days, avoid exercising outdoors between 10 a.m. and 7 p.m. This is the time where the sun is the hottest and the temperatures peak.
• Choose Your Route Wisely: Try choosing routes that offer a good amount of shade and have minimal contact with direct sunlight. Also remember that it’s hotter in urban areas than in surrounding areas because asphalt and concrete retain heat.
• Pace Yourself: Start off slow, and then gradually increase intensity after the half way point of your workout.

Special Considerations for Children

The American Academy of Pediatrics (AAP) reports that exercising children do not adapt to temperature extremes as effectively as adults when exposed to heat stress. Here are a few of the main reasons these differences occur:

• Children have a greater surface area-to-body mass ratio, which can cause a greater heat gain on a hot day;
• Kids produce more metabolic heat per mass unit during physical activities such as running or walking;
• Children have a lower seating capacity, which reduces the ability to evaporate body heat.

When the temperature is above 95 F, children tend to have a lower exercise tolerance than adults – increasing their risk for heat-related illnesses such as dehydration, heat exhaustion and heat stroke.

Children are also more susceptible to heat-related illnesses because they often don’t recognize the importance of frequent hydration. Many children don’t feel the need to drink enough to replenish the fluid lost during prolonged exercise.

To help avoid heat-related illness in exercising children, the AAP offers the following suggestions:

• Reduce Intensity: When the air temperature, humidity levels and UV index are above critical levels, the intensity of outdoor activities that last more than 15 minutes should be reduced.
• Build Intensity Gradually: When the child begins a new strenuous activity or exercise program, duration should be limited initially and then gradually increase over a period of 10 to 14 days to accomplish acclimatization to heat.
• Proper Hydration: Frequent drinking should be enforced during the activity (about five ounces every 20 minutes for a child weighing about 90 pounds). Even if the child says they are not thirsty, encourage them to drink. For more information on hydration, click here
• Wear Proper Clothing: Children should be dressed in light-colored, lightweight clothing. For more successful sweat evaporation, only one layer should be worn and sweat-soaked clothing should be replaced with dry clothing as soon as possible.

Sources: Texas A & M University; Pediatrics 106(1), 2000, p. 158; Runner’s World Magazine