Beat the heat with these hydration tips

This post was written by Dr. Bob Murray, co-author of Food & Fitness After 50, and hydration and exercise expert.

Famed baseball player Satchel Paige’s career spanned from 1924 to 1966, incredible longevity for any athlete.  In addition to being an amazing pitcher, Satchel’s unique perspective on life produced many memorable quotes, including “Age is a question of mind over matter.  If you don’t mind, it don’t  matter.”  Also, “How old would you be if you didn’t know how old you were?”  Both quotes speak to the importance of maintaining an optimistic, positive attitude about aging, although our bodies naturally change as we age.  Some of those changes influence our ability to stay well hydrated, especially so during the hot summer weather.

What does staying hydrated mean?

It is important to point out that staying hydrated—drinking enough each day to prevent significant dehydration and its consequences—is usually not a problem for the vast majority of older adults.  Although it is true that our thirst mechanism becomes less sensitive as we age, that change does not typically increase the risk of dehydration.  That may sound counterintuitive but it turns out that humans of any age do not rely solely on thirst as the primary gauge for when to drink.

Drinking at meals accounts for most of our daily fluid intake, along with the spontaneous drinking that occurs throughout the day—stopping at the water fountain and drinking coffee, tea, bottled water, and soft drinks at work or while watching TV are examples of spontaneous drinking.  The fact is that thirst plays a minor role in our daily fluid intake and that is especially true for those older adults who are inactive.  For those reasons, the reduced thirst sensitivity that occurs as we age does not have a major influence on our day-to-day hydration.  However, as with all things in life, there are exceptions.

The dangers of dehydration

When older adults fall ill, suffer immobilizing injuries, or fight diseases, the loss of thirst sensitivity can contribute to dehydration because normal drinking at meals and spontaneously throughout the day is completely disrupted.  Age-related loss of thirst sensitivity can also be a problem during heat waves or with prolonged sweating during endurance exercise, long hikes, and yard work when sweating results in dehydration.

Periodic heat waves cause a disproportionate number of deaths among adults over age 50, deaths that occur mostly from heart failure, not from heat stroke.  Prolonged exposure to the heat creates enormous strain on the heart and blood vessels to deliver much more blood to the skin to aid in heat loss. Dehydration makes matters worse because the sweating and inadequate drinking that lead to dehydration reduce the total volume of blood, placing even greater strain on the heart.  For those with preexisting heart, lung, or kidney disease, that strain can simply be too much to handle, resulting in death.  Older adults who are ill, out of shape, lack air conditioning, and have limited access to fluids are at greatest risk during heat waves.

         On June 8, 1982, Leroy “Satchel” Paige died of heart failure and emphysema at age 75.  Satchel’s death occurred after a power failure at his home in Kansas City.  Although there was no heat wave at that time in Kansas City, the maximum temperature that day was 86℉  and the maximum relative humidity was 93%, a combination that would make it feel like 108℉.

Aging not only reduces our thirst sensitivity and prolongs the time it takes us to fully rehydrate after we become dehydrated as a result of physical activity or heat exposure, we also sweat less, our heart’s capacity to pump blood is less, we deliver less blood to the skin, and we are less able to divert blood from our internal organs into the main circulation, all of which makes it tougher to cope with the heat.

How to win at hydration

While that may sound like uniformly bad news, we can avoid the dire consequences by staying physically fit, acclimating to the heat, and reminding ourselves of the importance of drinking more, particularly whenever we sweat.  Getting outdoors in warm weather may initially feel uncomfortable, but our bodies will gradually acclimate over time.  That acclimation improves our sweating and our hydration because acclimation prompts us to drink more throughout the day.

Additional good news is that for maintaining hydration, virtually all fluids count.  Okay, that advice does not include shots of tequila or other liquors, but mixed drinks do count toward daily hydration, as do coffee, tea, colas, energy drinks, beer, and wine.  As with food, consuming a wide variety of fluids during the day is important for overall nutrition and for hydration, both of which are vital for good health. Summer fruits and veggies are high in water content, so snacking on grapes, watermelon, cantaloupe, berries, summer squash, tomatoes, and cucumbers deliver both water and nutrients.

For more on the importance of hydration and a guide to finding your individual hydration needs, see Dr. Murray’s chapter on hydration in Food & Fitness After 50.