How Hot Weather Affects Our Bodies During Outdoor Work and Exercise

Discussion: As we move into July and August in the northern hemisphere, temperatures start to climb to their highest peak for the summer. Whether it be southern or northern parts of the United States, humid or dry, daily temperatures are on the rise. For those of you that work and/or exercise outside in the heat, this means that it’s time to be extra cautious. This is due to the nature of high temperatures having a negative effect on the body. Overexerting yourself in the heat can pose as a health risk if you are not careful.

During vigorous outdoor work and exercise, the heart works excessively to pump blood throughout your body and deliver oxygen to your muscles. Your core body temperature also increases with any type of strenuous activity. In order to cool itself down, the heart works hard to pump sufficient blood into the skin for cooling. This cooling mechanism is called perspiration, which evaporates off the surface of the skin. High temperatures can also cause excessive sweating which will lead to dehydration. In the case of high temperatures and high humidity conditions, sweat is less likely to evaporate. This causes insufficient cooling of the skin’s surface. Insufficient cooling can contribute to increasing core body temperature, bringing it closer to a dangerous temperature level. The threshold for this core temperature is 104?. Exactly the temperature that is dangerous to exceed when you are ill with a fever. During outdoor exercise in the heat, once the body approaches this temperature, it can suffer from one of the following health issues:

• Heat cramps:
  • A person may suffer painful muscle contractions and spasms.
• Heat Collapse:
  • Fainting and lightheaded from excessive heat and dehydration.
• Heat Exhaustion:
  • Nausea, vomiting, headache, weakness, fainting and excessive sweating.

Once the body temperature approaches 104?, it is critical that a person immediately cease exercising, take sips of water and cool themselves off. A person’s core temperature should not reach above 104? for they may risk having a heat stroke. This can cause brain damage along with dizziness, confusion, organ failure and possible death.

A study done by Dr. Lawrence Armstrong and Dr. Douglas Casa of the University of Connecticut studied a runner in a controlled high temperature environment. For approximately one hour they examined the runner’s body temperature, sweat loss, heart rate and dehydration percentage while they ran on a treadmill in a 90? room. After an hour of running, the runner’s core body temperature measured 103?, almost to the threshold of 104. Other measurements concluded that the runner produced 54 ounces of sweat, their heart rate increased to 175 bpm (beats per minute) and their body was dehydrated by about 2.6%. It was concluded that if the runner had continued their exercise for longer than an hour in the 90? heat, they would have suffered heat exhaustion and would have been at high risk of a heat stroke.

This also applies to outdoor workers who spend hours in the sun during the day. Unlike exercise, which can be intense and short, workers spend a longer time out in the heat. Outdoor work often involves exerting the body in some way. This can still cause the body to sweat and increase in temperature. It is important to follow necessary precautions when working or exercising outside in the heat. Here are some tips on what you can do to keep yourself safe from heat related health risks while still working outside and getting your exercise in:

• Pay attention to weather forecasts, especially heat indexes. Where it may be forecast to be 90?, heat indexes could reach 95? or higher. This is because heat indexes take both humidity and temperature into consideration. If it’s hot, high humidity can make it seem even hotter by inhibiting sweat from evaporating and cooling the skin.  
• Drink plenty of water to maintain enough fluids in your body to produce sweat sufficiently. The amount of water a person should drink daily is eight cups on average. During a hot day of work and exercise, it is good to consume two to four cups every hour.
• If you are planning your exercise, avoid exercising during afternoon hours. This is a time during the day where temperatures typically reach their peak. Try to plan your workout early in the morning when temperatures are still cool from the night or before sunset, when temperatures from the day are cooling down.
• Make sure to dress in cooler,  loose-fitting, and light-colored clothing. Long, dark sleeves and pants can trap body heat, absorb heat from the sun and prevent sweat from evaporating.  Loose-fitting clothes will allow your body to regulate properly and cool itself down.
• If you are not acclimated to the heat, get your body accustomed to it first. People who are not accustomed to heat are more at risk. Take a few weeks to get your body acclimated. Start off slow and then gradually increase your exercise or work intensity. It takes about two weeks for your body to adjust itself to high temperatures.

High temperatures increase stress on the heart and body during strenuous work and exercise. It is important during this time of year to be cautious when working or exercising outdoors. Especially for those exercisers that love to be outdoors and hate the gym. Pay attention to what your body is telling you. If you find yourself feeling weak and fatigued, stop whatever activity you are doing, drink some water, cool yourself down and take it easy. 

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© 2018 Meteorologist Alex Maynard