Written by Dr, Kim Brown, PT, DPT and owner of ONE PT
Hot! Hot! Hot!
Do you know when to stop?
Summer is here and temperatures are rising! Are you one to exercise outdoors? Do you check the temperature before going outside? How about humidity and dew point? As the heat increases so does your body temperature and the danger of heat exhaustion and stroke. Most people take a look at the temperature before going outside, more so to see what they should be wearing for their workout. Moisture wicking shirt, no shirt, etc. Did you know that the humidity and dew point can cause the outside temperature to feel totally different than the number you are looking at? Here are the differences:
Oxford Dictionary:
Temperature: the measurement in degrees of how hot or cold a thing or place is
Humidity: the amount of water in the air
Dew Point: the temperature at which air can hold no more water. Below this temperature the water comes out of the air in the form of drops.
Although humidity and dew point seem similar, they are very different. One a warm day with high humidity you could feel like you are running a PR through some fog and haze, but on a warm day with high dew point you could feel like you’re dragging your feet on the ground and barely moving. With a high dew point the ability for your body to sweat and evaporate to cause a cooling effect is reduced. With moisture already in the air your sweat is less likely to evaporate off of your skin. You start to form an outer layer of water on your body causing you to heat up faster. It is similar to being wrapped in saran wrap, no air in or out. With the increase in heat your body temperature goes up and the dangerous effects of overheating can occur. Lightheaded, dehydration, fatigue, nauseous, heart palpitations, and worse. Knowing these three numbers before heading out for a workout is key to your safety. The chart below shows how to adapt your workout based on dew point.
Without these adaptations to your workout you are causing more stress to your cardiovascular system. The extra strain on your heart and its ability to pump blood through your system is what can cause heart attacks. Make sure you are smart during the heat of the summer and pay attention to your symptoms. Take a lot of water as well as electrolyte replenishments to avoid overheating and loosing too many important nutrients. Paying attention to the heat, your hydration and ways to cool your body (i.e. running at the coolest part of the day, wearing proper breathable clothing) will help set appropriate expectations for your daily exercise habits.