Like the old Gershwin tune goes, "Summertime and the livin' is easy." We celebrate the freedom from the confinement and constraints of colder months with new exercise routines, travel and of course, family and friends. But for many of my cardiac patients at St. Mary's Medical Center, our ideas of taking it easy can often put some unique strains on heart muscles.
Your body's cells produce heat in the process of converting sugar to energy. When air temperatures rise, your body compensates in two main ways to cool itself down: radiation and evaporation. Temperature sensors in your body tell blood vessels in your skin to relax and accept more blood. This blood flow radiates heat from inside your body out to the skin, which releases it on to the air.
Sweating also takes heat from the body by turning your liquid sweat into water vapor through evaporation. Evaporating just two teaspoons of sweat can reduce your bloodstream temperature by two degrees. These are amazing systems, but as the heat and humidity climb above body temperature, both radiation and evaporation of heat become increasingly difficult. Rerouting blood forces the heart to work harder. It may move four times as much blood as it would on a cool day and sweating can remove minerals from your body that are needed to maintain a fluid balance.
If you’re a heart patient, older than 50, or overweight, I'd like for you to strongly consider taking special precautions in the heat.
Always check with your doctor or health care professional before starting an exercise routine. Certain heart medications like beta blockers, angiotensin receptor blockers, ace inhibitors, calcium channel blockers and diuretics may contribute to electrolyte imbalances including sodium and potassium depletion which could exaggerate your body’s response to heat. That said, it’s important to keep taking your medications – and take them when you’re supposed to.
Stay Hydrated -
Even older people not on medications need to take precautions in the heat. If you’re over 50, you may not even be aware that you’re thirsty. If you’re going to be outside, it’s important to drink plenty of water often, whether or not you think you need it. Other tips for safe exercise in the heat include:
• Avoiding the outdoors from around noon to 3 p.m. when temperatures are high and the sun is at its strongest. This puts you at a much higher risk for heat-related illnesses.
• Dress for the heat, including well-ventilated shoes, hats and sunglasses.
Wear water resistant sun screen higher than SPF 15. Reapply if you get wet (swimming) or sweat a lot.
• Take breaks! Find a shady spot, stop and hydrate before continuing.
• Utilize the buddy system. It’s safer and much more enjoyable when you share the experience.
Pay attention to your body. Watch for signs you may be in trouble.
Symptoms of heat exhaustion:
• heavy sweating
• cold, moist skin, chills
• dizziness or fainting (syncope)
• a weak and rapid pulse
• muscle cramps
• fast, shallow breathing
• nausea, vomiting or both
Symptoms of heat stroke:
• warm, dry skin with no sweating
• strong and rapid pulse
• confusion and/or unconsciousness
• high fever
• throbbing headaches
• nausea, vomiting or both
If you experience these symptoms, move to a cooler place, stop exercising and cool down immediately by dousing yourself with cold water and rehydrating. You may need to seek medical attention.
Finally, eat light. Choose smaller, simpler meals that don't make your digestive system work so hard. Cold soups, salads, and fruits can help satisfy your hunger and give you extra fluid. Finally, go easy on the alcohol and caffeine. These beverages can contribute to dehydration.
Here's hoping the "livin'" in your summertime is easy – and safe.
-- Dr. Michael Liston is a cardiologist with Kansas City Cardiology at St. Mary's Medical Center and can be reached at 816-525-1600.