A sports medicine physician offers advice on exercising safely as temperatures soar
BRYAN-COLLEGE STATION, Texas—With average temperatures and heat-related illness and injury on the rise, heat-conscious exercise practices are more important than ever. Taking a few simple precautions can prevent heat-related harm when exercising outdoors, according to Laura Marsh, MD, head team physician for Texas A&M student-athletes and a clinical assistant professor with the Texas A&M University Naresh K. Vashisht College of Medicine and the Texas A&M Health Sports Medicine clinic.
Heat-related illness can be categorized into four different stages, Marsh said, each with its own accompanying sets of risks and treatments:
STAGE 1: Dehydration. Caused by more fluid leaving the body than is going in, dehydration is exacerbated by the heavy sweating that can accompany exercising in high heat and humidity. Symptoms may include a mild headache and thirst.
STAGE 2: Heat stress. Dehydration worsens, leading to lightheadedness and dizziness with potential for a heat rash or minor muscle cramps.
STAGE 3: Heat exhaustion. Extreme loss of water and salt leads to overheating, accompanied by heavy sweating. Additional symptoms usually include cramping, increased heart rate and a headache. Occasionally, heat exhaustion may cause some nausea or vomiting.
STAGE 4: Heat stroke. Without treatment, the body may progress to heat stroke, which is a medical emergency. During heat stroke, all other attempts from the body to regulate have failed, and it is no longer able to cool itself. Sweating has stopped, heart rate is high, and internal temperature exceeds 104 degrees Fahrenheit (40 degrees Celsius). Sometimes, this can lead to neurologic symptoms like slurred speech or seizures.
Cooling methods like an ice bath are critical at the first sign of heat stroke, Marsh said. And anytime heat stroke is suspected, emergency medical personnel should be called.
Take a break and find a shaded, air-conditioned space to cool down at the first signs of dehydration or heat stress, she said. Outdoor activities can resume cautiously, once symptoms subside. But take another break at the first sign of dizziness, nausea, headache or any other symptoms. It’s always better to be safe than sorry, Marsh stressed.
Fortunately, heat-related illness can be easily mitigated through hydration, acclimatization and avoidance, Marsh said.
“The acclimatization is huge,” Marsh said. “Give yourself an opportunity to ramp up to the heat. The weather itself kind of helps us do that, because it’s generally cooler in the spring and then it gradually gets hotter. You also want to use mornings and evenings—not in the heat of the day—to do your outdoor activities. Finally, hydration is key. If you are out exercising and sweating, you need water and you also need some electrolytes.”
Heavy sweating makes replenishing electrolytes even more important, she stressed, because the combination of heavy sweating and drinking only water can create an electrolyte imbalance, as the water further flushes electrolytes from the body. An electrolyte imbalance may cause cramping, a headache and other discomfort.
The type of electrolyte doesn’t matter, she said, but be aware of electrolyte sources with high sodium content if sensitive to salt. Also, try not to drink high-sugar sports drinks excessively. A low-sugar or sugar-free option will do the job and help replenish necessary minerals, Marsh said.
Recommended water intake changes based on activity, heat, humidity and the individual person, Marsh said. According to the Centers for Disease Control and Prevention (CDC), eight ounces of water every hour is the baseline recommendation, but if you begin experiencing cramping, dizziness or other symptoms, you should move to a cool place and hydrate immediately, she continued.
“Avoidance” comes into play when planning physical activity with heat in mind, Marsh said. She recommends trying not to exercise outside during the hottest time of the day—11 a.m. to 4 p.m.—and paying attention to temperature and humidity to determine if you should postpone a workout.
The Wet Bulb Globe Temperature (WGBT) offers the standard for determining when it’s too warm and humid for outdoor physical activity. Many organizations, including Texas’ University Interscholastic League, have adopted it as official policy for guiding student extracurricular organizations. The University of North Carolina WGBT tool is useful for monitoring conditions in specific areas based on the recommendations of several organizations, including the American Academy of Pediatrics and the American military.
Equipment like neck fans, cooling towels and appropriate attire can help, too, Marsh said. She recommended wearing light colors and lightweight clothing when exercising in the heat. For shorter, less strenuous activities, she said cotton is recommended because of its ability to hold sweat and then use that sweat to cool the body. However, in more strenuous conditions—like a sports practice or long run—moisture-wicking material has been shown to significantly lower core body temperature, likely because it’s better at removing some of the extra moisture from persistent sweating.
“It’s really just important to take the precautions,” Marsh said. “Acclimatize, hydrate, know when to take breaks, what surfaces you’ll be on and how much shade you have—and know when to quit and get indoors.”
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