What are the risks of hiking or running in a heatwave?
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Loading... - Martina Castro
- 19 Jul 2022
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Knowing what can happen if you exercise in extreme heat is more pertinent than ever. Across the world, we are seeing longer summers and sustained periods of hot weather. Temperature records continue to be toppled across both the American continent and in Europe as the impact of global warming is felt in a very tangible way.
Love them or hate them, heatwaves are now a fact of life. It might be tempting to get out into the bright sunshine and set forth on an invigorating hike, or hit the local trails in your best trail running shoes to make the most of it. Many of the benefits of exercise in the heat are well documented but, in extreme heat, there are significant dangers.
Hiking with a heavy backpack is not recommended during a heat wave (Image credit: Getty)
If your body’s temperature regulation system is put under too much pressure, you could be at risk of dehydration and heat-related illnesses. These illnesses include: heat cramps, which are painful muscle contractions; heat exhaustion, when you may experience nausea, vomiting, headaches or you may even faint; or heatstroke, a life-threatening condition that can develop when heat exhaustion isn’t treated.
In order to function properly, your body needs to maintain a consistent temperature of around 98.5°F (37°C). In extreme conditions or during exercise, the body works harder to sustain this. Add both extreme heat and exertion together and your body is really scrambling and expending energy in order to regulate itself. This is why heading out in your best hiking boots in the blazing midday summer sun can feel much more taxing than during other seasons.
In this feature, we look at the effects of exercise in extreme heat, taking a look at dehydration, heat exhaustion, heatstroke and sun burn.
Effects of exercise in extreme heat: dehydration
Water is the giver of life. All living things rely on it to survive. It's why astronomers get excited when they discover water on another planet. It's why you can go over a week without food but go without water for more than three days you're a goner. Between 55% and 60% of your body is made up of the stuff. Needless to say, when you go running in hot weather, you should carry plenty.
This is because the average person can expect to lose between 0.8 and 1.4 liters in sweat during normal exercise. The hotter it gets, the more your body needs to sweat to cool down. In extreme heat, you lose it faster and it is far easier to become dehydrated than in normal circumstances.
Dehydration is when your body loses more fluids than you take in and, if not treated, can be a serious problem. You are more prone to dehydration if you are diabetic, have been drinking alcohol, have a sickness bug or diarrhoea or have been taking diuretics – substances that make you urinate more than usual. Infants, children and elderly people are also more at risk of dehydration.
Exercising without replenishing fluids is a surefire way to become dehydrated, this is why long-distance runners wear hydration packs. The good news is that treatment is super straightforward – simply drink fluids.
The symptoms of dehydration include:
Feeling thirsty
Dark yellow, strong smelling urine
Dizziness
Fatigue
A dry mouth, lips and eyes
Less frequent urination than usual (less than four times a day)
Prolonged or repeated dehydration can lead to urinary and kidney problems, such as urinary tract infections, kidney stones or even kidney failure. You lose electrolytes when you sweat and if they become imbalanced can lead to muscle cramps, seizures or even loss of consciousness.
One of the more serious and potentially life-threatening complications includes low blood volume shock – also known as hypovolemic shock. This is when low blood volume leads to a drop in blood pressure, thus leading to a less oxygen in your body.
Heat exhaustion and the more serious heatstroke are another two complications that arise with dehydration...
Effects of exercise in extreme heat: heat exhaustion
Heat exhaustion occurs as a result of your body overheating to between 100.4°F (38°C) and 104°F (40°C). Untreated, it can lead to heatstroke. Fortunately, heat exhaustion is not usually an issue if it's treated within the first half an hour.
The onset of heat exhaustion can be gradual, perhaps over many days of exposure to high temperatures without proper replacement of fluids. However, exercise in extreme heat can very quickly lead to heat exhaustion. Signs to look out for are:
Fatigue and weakness
Muscle cramps in arms, legs or stomach
Dizziness and confusion
Excessive sweating
Headaches
Nausea
Loss of appetite
Vomiting
Rapid breathing or pulse
Body temperature above 100.4°F (38°C)
A strong thirst
Fainting
Cold, clammy skin
Dark urine
In the instance of heat exhaustion, the following steps should be followed to cool the person down:
1) Move them out of the heat and into a cool, shaded spot.
2) Get them to lie down and raise their feet slightly.
3) Give them plenty of water or sports hydration drinks.
4) Cool their skin down using water and/or a fan.
You should stay with the person until their symptoms have subsided.
Effects of exercise in extreme heat: heatstroke
Heatstroke is a life-threatening condition that occurs when your body temperature rises above 104°F (40°C). There are two kinds of heatstroke, exertional and non-exertional. Typically, exertional heatstroke it is the result of too much physical exertion in hot, humid conditions. Non-exertional heatstroke occurs due to other factors like underlying health conditions and age.
Symptoms of heatstroke include those associated with heat exhaustion plus a host of others that indicate a more serious problem. The person in question may initially become irritable, acting irrationally. Vision may become impaired or balance and coordination may be hindered.
In extreme cases, seizures may occur and the affected may become non-responsive or lose consciousness altogether. If left untreated, it can lead to organ failure, brain damage, a coma or even death.
Call the emergency services immediately if you suspect someone has heatstroke and put them in the recovery position if they have lost consciousness. Read More...
