Stay Cool: Exercising Smart In The Heat

Calling all sunshine lovers! Ready to break a sweat and soak up some rays? Exercising in the great outdoors can be exhilarating, especially when the weather is warm and inviting. It can introduce some amazing benefits, too, such as improved cognitive functions like memory and attention, a better mood, and less stress.¹

While a sunny day might seem perfect for a jog or a game of tennis, it’s crucial to remember that exercising in hot weather can pose unique challenges and potential risks. While exercising in the heat can sometimes enhance performance, it carries significant dangers if not appropriately managed. Understanding the effects of heat on the body during exercise is crucial for maintaining health and optimizing performance, but before you lace up your sneakers and hit the pavement, let’s talk about a few tricks to keep you cool, comfortable, and safe. After all, no one wants to turn their workout into a sunburnt, sweaty struggle!

The Physiology of Heat Stress

When you exercise in the heat, your body works harder to maintain its core temperature. The body cools itself primarily through sweating and the evaporation of sweat from the skin; however, high humidity levels can impede this process, leading to increased body temperature. As your body temperature rises, several physiological responses occur:

• Increased Heart Rate: The cardiovascular system works harder to facilitate cooling the body. The heart pumps more blood to the skin, reducing the amount of blood available to muscles, which can lead to an increased heart rate and decreased performance.²

• Dehydration: High temperatures accelerate fluid loss through sweat. Dehydration can impair various bodily functions, including cognitive performance and physical endurance.³ Even a slight loss of body water can affect athletic performance and increase the risk of heat-related illnesses.⁴
• Electrolyte Imbalance: Sweating also results in the loss of electrolytes such as sodium and potassium, essential for muscle function and nerve signaling. An imbalance can lead to muscle cramps, weakness, and, in severe cases, life-threatening conditions like heat stroke.⁴

Performance Implications

Exercising in the heat can have mixed effects on performance. In some cases, athletes can acclimate to hot conditions over time, improving performance in hot and temperate climates. Heat acclimation involves physiological adaptations such as improved sweat response, increased plasma volume, and more efficient cardiovascular function.⁵

However, without proper acclimation and hydration strategies, performance can decline sharply. Heat stress can lead to the early onset of fatigue, reduced endurance, and decreased strength.⁶ The perception of effort is also heightened in the heat, making exercise feel more strenuous than in cooler conditions.

Risks of Heat-Related Illnesses

Exercising in high temperatures can increase the risk of heat-related illnesses, like Heat Cramps, Heat Exhaustion, and Heat Stroke. Be sure you know the signs of each heat-related illness described below to ensure you’re prepared to handle them.⁷

• Heat Cramps: These are painful, involuntary muscle contractions caused by significant electrolyte losses through sweat. They often affect muscles used during exercise, such as the legs and abdomen.

  

• Heat Exhaustion: Symptoms include heavy sweating, weakness, dizziness, nausea, headache, and fainting. It occurs when the body loses excessive water and salt, leading to dehydration and decreased blood volume.
• Heat Stroke: This medical emergency is characterized by a body temperature above 104°F (40°C), altered mental state, rapid heart rate, and hot, dry skin. If not treated promptly, it can cause permanent damage to the brain and other vital organs.
  
  

Preventive Measures

To safely exercise in the heat, it’s essential to take several precautionary measures:

• Hydration Is Key: Drink plenty of fluids before, during, and after exercise. Water is usually sufficient for short workouts, but sports drinks can help replenish electrolytes to balance essential minerals for prolonged exercise, especially in the heat.⁸ 
• Acclimate Over Time: Gradually increase the intensity and duration of workouts over 1-2 weeks to allow your body to adapt to the heat.⁹
• Schedule Workouts for the Right Time and Place: Exercise during cooler parts of the day, such as early morning or late evening, and avoid the midday heat when temperatures are at their highest. Plan your outdoor workouts in shaded areas to reduce direct sun exposure. For example, parks with tree cover or trails can provide natural cooling.

  

• Know Your Workout Weather Forecast: Pay special attention to the heat index, which combines air temperature, humidity, and dew point to indicate what the temperature of the air feels like outside. Humidity measures the amount of water vapor in the air at a percentage, while dew point measures the specific temperature at which the air becomes saturated. When these two measurements are low (humidity below 60% and dew point below 65°F or 18°C), the air feels more comfortable, and your body can cool itself more efficiently through its natural evaporation process of sweating. The higher these values are (humidity above 70% and dew point 65°F or 18°C or higher), the thicker and hotter the air will feel, and the more challenging it becomes for your body to cool itself down by sweating. Exercising in dry heat can also pose challenges, as sweat evaporates quickly and can lead to unnoticed fluid loss and potential dehydration, risking initial overexposure to the heat due to body cooling. Dry heat conditions typically occur at high temperatures (above 90°F or 32°C), low humidity (below 40%), and low dew points (below 55°F or 13°C). All these measurements can indicate the risk of heat-related issues than temperature alone, so before you go outside, make sure you’ve reviewed your local weather forecast in detail.
• Wear Heat-Friendly Clothing: Wear lightweight, light-colored, loose-fitting clothing made from breathable cotton or moisture-wicking materials. These clothing materials will help facilitate sweat evaporation and heat dissipation. Consider wearing SPF clothing specifically designed to block or absorb UV radiation, reducing the amount that reaches your skin. This helps protect against both UVA and UVB rays. Many SPF clothing items have a UPF (Ultraviolet Protection Factor) rating that indicates how effectively they block UV rays. Look for clothing with a high UPF rating for better UV protection – UPF 30+ is considered good, and UPF 50+ offers excellent protection. Also, consider wearing SPF clothing that provides adequate coverage, including long sleeves, high collars, and wide-brimmed hats.
• Use Sunscreen: Apply a high-SPF sunscreen to protect your skin from harmful UV rays, and reapply as needed, especially if you’re sweating heavily.
• Consider Your Nutrition: Proper nutrition can play a significant role in managing heat. Foods with high water content, like fruits and vegetables, can help keep you hydrated.
• Monitoring: Pay attention to your body’s signals. If you experience dizziness, headache, or excessive fatigue, stop exercising and move to a cooler environment.
• Take Breaks: Incorporate frequent breaks into your workout routine to cool down and hydrate. This helps prevent overheating and reduces the risk of heat-related illnesses.
• Know the Signs of Heat-Related Illness: Know symptoms like muscle cramps, nausea, and confusion. If you or a workout partner experience these signs, stop immediately and move to a cooler area.

Exercising under the sun can be a great way to change your workouts, but remember that exercising in the heat requires careful planning and attention to your body’s signals. You can safely enjoy your fitness routine in hot weather by staying hydrated, dressing appropriately, timing your workouts, and acclimating gradually. Always prioritize your health and adjust your workouts to prevent heat-related illnesses.

This information is not intended to diagnose or treat heat-related illnesses or their symptoms. If you or someone you know is experiencing these or any other symptoms that cause concern, please consult your physician or seek medical care immediately.