Sunny days and warm weather are here to enjoy but we also need to be cautious exerting in the heat. If you want to exercise in the hot days of summer, your body must be able to handle the elevated temperature and you should know the warning signs of dehydration and heat exhaustion.
Acclimating to the Heat
The human body has an amazing ability to react and adapt to different situations and varying climates. As temperatures rise your body can adjust as long as you give it time to acclimate. Acclimatization is the ability to adapt physiologically with repeated exposure to a different environment, such as higher temperatures. As your body adapts to higher temperatures, you will sweat earlier and more efficiently, and your body will also regulate your heart rate and increase blood flow to your skin to aid in the release of heat. These adaptations enable you to do the same work with a lower core temperature. Aerobic conditioning and fitness determine how fast you can acclimate to exercising at an elevated temperature. These physiological changes usually take about 10 -14 days. The more in shape you are, the faster your body will adapt!
The most important thing when exercising in higher temperatures is to stay hydrated. Signs of dehydration include thirst, fatigue, headache, dry mouth, weakness, muscle aches, dizziness, nausea, and dry skin.
Dehydration can easily be prevented by drinking plenty of water before and during activity. You can also stop the activity and rest in the shade or cool indoor space. You should also avoid the extreme day temperatures by doing the outdoor activity earlier and later in the day.
How to Exercise Safely in the Heat
(* Check with your physician if you have any other medical conditions)
If you are intending to exercise outside in the heat, make sure to take the proper steps and precautions to protect your health and safety!
- Avoid Exercising Mid-day – Exercise during cooler times of the day, before 7 am and after 6 pm, and avoid mid-day(10-4) when it’s the hottest.
- Begin Slowly – Begin with about 15-20 minutes of exercise and slowly increase your time over 14 days.
- Wear lightweight breathable clothing – Wear the least amount of clothing possible that is lightweight and breathable, so moisture is lifted rather than socked into the material.
- Stay hydrated – Stay hydrated before and after exercising
- Limit time with high heat index – Limit your time outside to 1 hr when the heat index is over 100 degrees F or in the Danger zone, as mentioned on the local news.
Exertional Heat Illnesses:
Not only is dehydration an issue with exposure to elevated temperatures, but exertional heat-related illnesses can also come into play. In hot weather, your body cools itself mainly by sweating. The evaporation of your sweat regulates your body temperature. However, when you exercise strenuously or otherwise overexert in hot, humid weather, your body is less able to cool itself efficiently. As a result, your body may develop heat cramps or even heat stroke.
There are 5 different exertional heat illnesses:
(1) exercise-associated muscle cramps
(2) heat syncope
(3) heat exhaustion
(4) exertional heat injury
(5) exertional heatstroke.
Exercise associated muscle cramps (EAMC) or heat cramps.
Heat cramps occur in muscles of your extremities either during or following exercise. Muscle cramps can also occur without an elevated body temperature in both warm and cool environments. Heat cramps are usually painful, involuntary contractions in the affected muscle. They can feel like a twinge, tremor, contracture, or stiffness. They can come on suddenly and may progressively worsen over time. The muscle cramping may become so severe causing the person to be unable to move the body part (e.g., lower leg/calf). The exact cause of these cramps has not been confirmed, but there are contributing factors that have been identified including:
- Electrolyte imbalances
- Altered neuromuscular control
These factors may act alone or in combination with one another, therefore it is important to stay well-hydrated, maintain electrolyte balance, maintain a proper, well-balanced diet, and focusing on attaining adequate rest to let your body properly recover.
Heat syncope (orthostatic dizziness) is when an individual faints or passes out because they do not have enough blood supply to the brain as a result of overheating or exercising in temperatures that the body is not accustomed to. It is caused by blood vessels in your extremities dilating and thus reducing blood to the brain and dehydration. Individuals experiencing heat syncope may faint while in elevated temperature after long periods of exercise, standing, or sudden changes in posture such as getting up from sitting. Dehydration, venous pooling of blood, reduced cardiac filling, and/or low blood pressure are all factors that can contribute to incidents of heat syncope.
Heat syncope most commonly affects individuals who are unfit or unacclimatized to the heat. Usually, it occurs during the first 5 days of exposure to heat to which a person is unaccustomed. For this reason, it is important to slowly increase your exposure to the heat, limit the time of your exposure to the heat, and wear light, cool clothing.
Heat exhaustion is a result of the body overheating and may include heavy sweating and a rapid pulse. Symptoms may also include cool, moist skin with goosebumps when in heat, dizziness, fatigue, nausea, headaches, muscle cramps, and low blood pressure upon standing. Similar to heat syncope, individuals experiencing heat exhaustion are most commonly unacclimatized to the heat and/or may also be dehydrated. *If you are experiencing heat exhaustion, it is important to stop activity and rest, move to a cooler place, and drink water.
Exertional Heat Stroke
Exertional heatstroke is a life-threatening medical emergency. It is the result of your body’s core temperature being too high (rectal temperature over 105 degrees). If left untreated the elevated core temperature will lead to organ damage. Symptoms can include any of the following: erratic pulse, lack of coordination, collapse, low blood pressure, vomiting, headache, loss of consciousness and/or seizures, shock, irritability, confusion, disorientation, sweaty skin.
An exertional heatstroke occurs because of an overwhelming of the thermoregulatory system from a combination of metabolic heat production and environmental heat. It is also brought on by physical exertion. Classic heat stroke, also known as non-exertional heatstroke, occurs from simply being in a hot environment for a prolonged period of time which leads to a rise in core body temperature. Early recognition and treatment are vital to preventing death from exertional heatstroke. Treatment involves lowering the core body temperature to less than 102°F immediately (within 30 minutes or less following initial collapse).