Karen Blood, clinical associate professor of physical therapy, warned that excessive heat can have adverse effects on the human body.

“Increased heat acts as a stressor on the body. The body will try to push the heat toward the skin so that it can evaporate and does this by vasodilating — or widening the blood vessels. With vasodilation, we are more prone to drops in blood pressure and increased swelling in the legs which may lead to dizziness or fainting,” said Blood.

While this process is crucial to restoring normal body temperature, there can be negative effects if exposed to high temperatures for excessive periods of time.

“The body needs to work overtime in an attempt to cool down. This process can lower blood pressure, which makes the heart have to pump faster to ensure adequate circulation. Sweating, although a needed process to help with cooling, burns more energy and also makes the body fatigue faster,” said Blood.

The CDC reports that heat-related deaths have increased 124% in the past quarter century, from 1,069 in 1999 to 2,415 in 2024.

Stephen Straub, associate dean of academic operations and finance and professor of health and exercise science, warns of the major conditions that can result from high temperatures.

“The biggest concern is that these high temperatures lead to heat stroke,” said Straub. “This is typically defined as when the core body temperature rises to approach 104 to 105 degrees Fahrenheit (compared to a typical 98.2 degrees). This leads to a breakdown of heart muscles cells and blood vessels, along with damage to internal organs.”

In addition to the temperatures, it is also crucial to understand how factors like humidity and UV radiation can magnify these symptoms.

Humidity describes the amount of moisture present in the air. The term “relative humidity” is more commonly used to describe how close the air is to being fully saturated with water, he added.

“The more water that is in the air, the harder it is for sweat to evaporate from your skin. Therefore, there is less heat loss from evaporation, and you are more likely to get an increase in your core temperature,” said Straub.

Many weather services will use the term “heat index,” which is a combination of air temperature and humidity. This value typically provides a better estimate of the heat risk on any given day.

In addition to humidity, understanding the impact of UV radiation from the sun is crucial to reducing your risk of cancers and other conditions.

“On the positive end, UV radiation is essential for Vitamin D production. On the other end, UV radiation is a major risk factor for skin cancer, cataracts and skin damage. UV rays are scored on a scale of one to 15. 1-2 is low and eight or more is very high,” said Straub.

Wearing sunscreen can help reduce your risk of these conditions when the UV is higher.

“SPF stands for Sun Protection Factor which looks at the ability of the sunscreen to protect your skin from UVB rays,” said Straub. “The Environmental Protection Agency recommends a minimum SPF of 15 which will block 93% of UVB rays. SPF 15 means it will take 15% more UV exposure to cause skin redness.”

For Blood, who is a certified geriatric clinical specialist and serves as co-chair for the Geriatric Special Interest Group of the American Physical Therapy Association’s Connecticut chapter, it is especially important for older adults to take precautions during major heat waves.

“Older adults are more susceptible to heat illnesses. With aging, there is a decline in homeostasis and the ability for the body to adequately control temperature because of changes to the skin, changes in blood flow and impaired sweating function. Because of these changes, older adults are not as able to adjust to sudden external temperature changes like younger people are,” said Blood.  

Additionally, older adults are more likely to have other risk factors that could increase the chance of heat illness.

“Older adults are more likely to have chronic conditions that affect the lungs and kidneys which can make the body work harder at rest and present more difficulty adapting to temperature changes,” said Blood. “Medications including diuretics (which may be taken for high blood pressure) or sedative medications can make it more difficult for the body to cool itself. The risk for heat related illnesses will rise with the more medications that a person takes.”

Blood recommends that older adults who are on medications, especially diuretics, should communicate with their doctor during times of high heat and humidity.

“These individuals often limit their water intake and may need guidance on how they should safely increase their intake during times of increased temperature. Dehydration can lead to shock, seizures, muscle cramps and falls, so it is important to know how to adequately maintain hydration when on medications that alter fluid output,” said Blood.

There are two main categories of heat illness to watch out for during heat waves: the less severe heat exhaustion and the more severe heat stroke — a true medical emergency.

“Heat exhaustion is less severe; there is a decrease in blood plasma volume, and the body is reacting to and trying to accommodate to the heat. In contrast, heat stroke is the body moving past the ability to accommodate the heat and results in a large increase in body core temperature,” said Straub. “Both can result in flushed skin, rapid heart rate and breathing, headache, nausea and dizziness. Classic descriptions of heat stroke will say that the skin will be hot and dry — this is not always true. People can be sweating and wet and still suffering from heat stroke.”

While these conditions are dangerous and worrisome, there are measures that can be taken to reduce your risk of suffering from heat exhaustion or heat stroke.

“To stay safe, the number one thing that people can do is stay hydrated, keeping in mind that caffeinated and alcoholic beverages should be avoided,” said Blood. “People should also keep their living spaces cool by using air conditioners or fans and keeping blinds and shades drawn during the day. In the event that the home cannot be kept cool, older adults should try to seek shelter elsewhere during the hottest parts of the day such as a mall, library or senior center to limit exposure to high heat.”

For those who do enjoy staying physically active during the summer, Straub recommends being flexible in the timing of your workouts. Specifically, avoiding the outdoors during the hottest time of the day — between 10 a.m. and 4 p.m. — can reduce your risk of illness.

“You may have to change the time, the intensity or the modality of your workout. If your body is telling you something, you have to listen,” said Straub.

Taking care of your body once you have finished your physical activity is just as important as caring for your body during the workout.

“Be sure to cool down afterward. Take a cold shower or hop in the pool; this will help your body regulate quicker after exercise,” said Straub.

While you may want to limit intense physical activity outdoors during these heat waves, it is still important to remain active once the temperatures drop again.

“People of all ages who are obese are also at a higher risk of morbidity and mortality from heat-related illnesses. This fact highlights the importance of healthy eating and increasing physical activity during times of normal temperature to improve resilience to heat-related events,” said Blood.