I was 46 when I bought my home in Boulder, CO in 1995 and the heating and cooling systems were like a cabin. When it was cold I chopped wood and built fires in the wood stoves. When it was hot I opened both low and high windows to increase the airflow. About 10 years ago my wife and I decided that getting up when it was only 50F in the house and building fires wasn’t tolerable any more so we put in heat in each room. This year we’ve decided that 85F in the house is too hot and we’re putting in air conditioning next week. As we age we feel less tolerant of the heat. But is loss of heat tolerance inevitable with aging?
Epidemiological Studies
Data collected across large samples of the older population show a correlation between age and hot weather and more heat-related illnesses and deaths. “Older individuals, regardless of how one classifies ‘old’, are the most rapidly growing portion of the population. Statistics from heat waves and other morbidity-mortality data strongly suggest that older persons are at greater risk of developing life-threatening manifestations of heat stress such as heat stroke.” Heat Tolerance, Thermoregulation and Ageing
However, the data are for the general population. It’s not clear the extent to which these heat-related problems are due to chronological aging or due to other factors. These variables change with may age and could affect heat tolerance independent of chronological age.
- Sedentary lifestyle. In the general population physical activity decreases with age. This contributes to the next five factors.
- Decreased aerobic capacity (VO2 max).
- Your body dissipates heat via two basic mechanisms: 1) greatly increasing blood flow to the skin and 2) producing and evaporating sweat. Decreased aerobic capacity means decreased blood flow and therefore less cooling.
- Physical changes such as decreased lean body mass and increased fat tissue. The basal metabolism slows by about 2% per year and this combined with less physical activity results in weight gain.
- Increased prevalence of chronic diseases. Decreased physical activity also increases the occurrence of hypertension, heart disease and diabetes.
- Increased use of prescription medicines. The chronic diseases are often treated with medications that reduce heat tolerance, e.g. diuretics, vasodilators, beta blockers.
- Chronic poor hydration from not drinking enough and/or increased fluid secretion by the kidneys.
If you keep exercising you can greatly reduce the effects of these factors.
Heat Dissipation During Exercise in Warm Conditions
Some physiological changes that affect heat tolerance are inevitable with age:
Decreased cardiac output. How much blood the heart pumps decreases by about 30% between the ages of 20 and 80. Cardiac output is a function of heart rate and stroke volume, how much blood your heart pumps per beat. While your maximum HR inevitably declines, through exercise you can maintain your ability to sustain a reasonably high HR and slow the decrease in the elasticity of your heart, which is what reduces stroke volume.
Decreased skin blood flow. Skin blood flow is 25-40% less in older athletes. The reduced flow is due to changes with the blood vessels in the skin. Staying very fit does not prevent the skin from aging.
Sweating rate. Compared to younger equivalently fit athletes, most older athletes have lower sweating rates. Although the same number of sweat glands are activated each gland produces less sweat. Genetics plays a large role in determining sweating rate and there is wide variability among older athletes. Decreased sweating is more of a problem in hot, dry environments than in humid ones.
Bottom Line
The bottom line is good:
- As athletes get older the capacity to sweat declines although there are exceptions. This does not mean that older athletes are less tolerant of hot conditions.
- Older athletes can acclimate just as well as younger athletes.
- The ability to exercise in hot conditions is primarily a function of physical fitness, especially VO2 max, rather than chronological age.
- One caution is that the sensation of thirst diminishes with age. For athletes the general recommendation is to drink to satisfy thirst but not more because drinking too much fluid risks diluting the blood sodium to a dangerous, potentially fatal level. For older roadies be sure to drink enough whenever you are thirsty. For more information see my column 12 Hydration Myths.
Much of this information is from The Older Athlete: Exercise in Hot Environments.
My eBook Anti-Aging: 12 Ways You Can Slow the Aging Process includes information specifically for older cyclists on all of the different physiological changes with aging and how you can mitigate the changes. The 106-page eBook is available for $14.99.
Summer Bundle for all roadies regardless of age.
The 65-page summer riding bundle includes four eArticles:
- Cycling in the Heat, Part 1: Ride Management is 19 pages and covers how to acclimate to hot conditions, how to train in hot months, what to wear, eat and drink, how to cool down if you overheat, and how to deal with heat-related problems.
- Cycling in the Heat, Part 2: Hydration Management is 21 pages and covers how to determine how much you should drink depending on your physiology and sweat rate, how best to replace your fluids and electrolytes, the contents of different sports drinks, how to make your own electrolyte replacement drinks, how to rehydrate after a ride, and how to deal with hydration-related problems.
- Preventing and Treating Cramps, 10 pages. A detailed look into the causes of cramps, prevention techniques, and tips (both on-bike and off-bike, including photos) for breaking and flushing cramps.
- Eating and Drinking Like the Pros, 15 pages. What pro riders consume before, during and after a stage and the benefits for cyclists at all levels. Eating and drinking like the pros offers recreational riders the same nutritional benefits, which you can customize to your own needs at a fraction of the cost of commercial sports food and drink, if you choose to make our own. I worked with a professor of nutrition and an expert on hydration and electrolytes (both experts are cyclists) in creating recipes for both sports drinks and food.
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Coach John Hughes earned coaching certifications from USA Cycling and the National Strength and Conditioning Association. John’s cycling career includes course records in the Boston-Montreal-Boston 1200-km randonnée and the Furnace Creek 508, a Race Across AMerica (RAAM) qualifier. He has ridden solo RAAM twice and is a 5-time finisher of the 1200-km Paris-Brest-Paris. He has written over 40 eBooks and eArticles on cycling training and nutrition, available in RBR’s eBookstore at Coach John Hughes. Click to read John’s full bio.
My heat tolerance has substantially increased with age – now (61) I tolerate heat much better than 40 year ago and not worse that 10 years ago.
Tell me about it in 11 or so years. I was increasing at your age. And until 70. Then hit the wall, or it hit me. Now I’m OK at 85° but not taking chances above that and I have to wear a shell and maybe leggings below the high 70°s.
Tuesday was a long ride with some climbing but mostly climbing dew points and temperature. Knowing it was going to be a hot day, I weighed myself just before getting on the bike and then when I got home. I lost 6.8 lb. out of 174 (3 kg out of 79) for a nearly 4% loss. And that was while taking in about 130 oz. of fluid over the 113 miles (4.6 liters in 182 km). I also took in a lot of salt, knowing what the day was going to be like. My shorts were dappled white by the time I got home even with the high humidity (usually the sweat in the short fabric hides the salt).
I never felt thirsty at any time and could have drunk more, I guess, but I doubt I could have taken in another 55 oz. (2 liters) of fluid to keep my weight loss within the magic 2% figure you hear is needed to prevent performance loss. And yes, the second half of the ride did demonstrate “performance loss.” I was purposely taking it easy as the only known way to deal with the heat but I couldn’t have gone much faster even if I wanted to.
I’m 75 & when I was younger I used to love riding in the heat. Temps up to 90F didn’t bother. This gradually changed over the years & now I struggle in temps of about 84+ F. I have become more tolerant of riding in the cold. Temps of 20F don’t bother me at all & I’ll ride if the roads are clear of snow & ice. This switch took place in my late 60s.
I have been taking several maintenance medications since my mid 40’s, including a diuretic and a beta blocker to control blood pressure. This evidently affects my heat tolerance, both for short rides in hot weather and for longer rides (50+ miles) in any weather. This is basic reality for me, and most of my riding friends simply cannot understand – they suggest I need to be mentally tougher about heat. They just don’t get it.
I am 70 and I enjoy riding in the above 90° weather we have been having.
A question…Many years ago, I loved hot weather. It was great when it was so hot that I began to sweat just crossing the street. Then we had a very hot summer…90+ degrees days, day after day all summer. I pushed hard riding until one day I was exhausted and said, “OK. I quit. I can’t do this anymore until it cools off!” Ever since then I feel fairly heat intolerant and hate riding if the temperature is even above 85 let alone 90. Is it possible to get overly stressed in the heat and then loose the ability to be tolerant or is it all in my head?
In my younger days, if it was 60F, low wind and the sun was shining, I would leave early in the morning on a long bike ride with bare arms and legs. Now that I am 75, that 60F has worked its way into the upper 60s before I am comfortable with bare arms and legs. My first job out of college was in Phoenix and I worked 3rd shift at times. I would come home from work early morning, sleep until noon and then go for a training ride in the afternoon – in 100+ temperatures. I can’t imagine doing that now.
I am 73 and I can no longer tolerate the cold,ie, any temp below the upper 60’s. Heat is a balm. I shudder to think of my decades riding in VT!
What is this “heat” of which you speak? (I am from Seattle.)
I see from the comments that this article first appeared in 2018. About cooling your house. Now that your live in the mountains, you probably don’t need air conditioning. Boulder is different. To anyone needing AC, please consider evaporative cooling in contrast to refrigerated AC if you live in an arid climate. Evaporative cooling takes by some accounts only 25% as much electricity as AC, is mechanically simpler so you can do a lot of the maintenance yourself, and promotes fresh air as the windows must be opened for it to function effectively.
Outstanding article!!!! Posted two years ago but timely every summer.
So much “coaching” advice out there is just plain WRONG for the older athlete. Only ‘drinking to thirst’ may work OK for folks in their 20’s, but a proper hydration PLAN for long rides in the heat becomes increasingly important as we age. Weighing yourself before and after exercise (like Kerry mentioned) is a good tip to help guide fluid intake for specific conditions.
The aging athlete is slower to recover from overheating for all those physiologic factors you mention. A recent local incident reminded me that AVOIDANCE of heat illness also becomes increasingly important as we age. During a hot ride, the line between recoverable heat stress and life-threatening heat stroke can become much narrower. Trust me- you do NOT want to step on the wrong side of that line.
The role of thermal mass must be considered here. Think how long it takes a block of ice to melt versus an ice cube, or how children and infants don’t tolerate heat or cold as well as adults, or my wife who swelters while in the heat while I take a bike ride in it.
In my mid-70s I still ride from just above freezing to avoid frostbite to 95 where thermal mass is an advantage. Sweating like a pig in low humidity is another advantage in the heat. I also find that using sun sleeves on my arms and legs and a neck gaiter also cools me better than bare skin plus adds the benefit of protection from the sun. Consider Bedouins in the desert as portrayed in the movie “Lawrence of Arabia”..
Lots of interest in this topic. I rode a 40 miler last week. The second half of the ride was 90F. The road temp was hotter. I drank liberally, but my heart rate was about 10-15 bpm higher than usual for my perceived level of effort on a cooler day. I suspect spending more time indoors on hot days has affected my heat tolerance, along with some of the other factors noted in the article.
My wife and I (72 and 70) generally ride unless the temperature is above 95 without any problem.
I’m 86 and have been cycling for “only” the last 26 years. My residence is in Oro Valley, AZ near Tucson where the temps have been typically in the 100+ for the last 45 days and I summer in Longmont, CO for the last 8 years where the temps have been a cool 90+ for the same time period. My experience is that it isn’t the heat that is the problem – but the heat plus the humidity. The evaporative cooling effect in either location has it’s advantages over the much more humid locations.. I’ve had riders from more humid climates such as NC and KS tell me they don’t sweat as much in AZ and therefore don’t have to hydrate as much as at home. Tell me if I’m wrong, but I think one sweats as much, but the evaporation because of the low humidity keeps one cooler and dupes one into thinking he/she is not sweating as much..
My target is 20 oz of fluid per hour when the temp is 75+ and I know that is an arbitrary figure.