How to Run in Hot, Humid Weather: 6 secrets to handling the worst kind of heat
You are one hot runner! Unfortunately you probably aren't hot in the way you wish you were. In my other post I talk about running in desert-like heat that sucks the moisture out of you. I have spent a lot of time running in both dry and humid heat and it will likely come as no surprise that running in high humidity is the worst.
It's Hot! What's Wrong With You?
Wet, Wet Sweat
For beginning runners, one of the main problems with running in hot, humid weather is evaporation, or really, the lack of it. Your body is desperate to cool itself down so it sweats bucket loads but the sweat doesn't go anywhere. It just sits on your skin, soaking into your clothes, stinging your eyes and filling your shoes. To make matters worse, it acts as an insulator contributing to the feeling of your body being too hot. Hang on for solutions!
Everything Is In The Wrong Place
Your body doesn't just sweat to cool down. As the outside temperature increases, your body sends more blood away from its core to the skin. That is why certain parts of your body look "flushed" when you are working out hard in the heat. New runners may not notice the impact of this shift much beyond looking red in the face but as you run further and for longer periods of time you will.
The main issue here is not the blood itself but what's in the blood. All that blood going away from your muscles, toward your skin is taking away oxygen. Your muscles need large amounts of oxygen when they are working hard and they can't get it if the blood doesn't arrive.
The first symptom of this is early fatigue. You may have been able to sprint up that hill last week when it was 70F (21C) impressively passing little old ladies thus impressing everyone along the way but now that it is 90F (32C) and humid you feel out of breath and spent half way up. The further you run, the worse it can get. Oxygen-starved muscles begin to cramp, which is annoying at first, but can eventually slow you to a walking pace.
#1 Wear the right clothing
Less is more in this case. The more hot skin you can expose to the fresh air, the cooler you will feel when you run. The type of material also makes a difference.
Cotton is not a true friend in this heat. Most cotton t-shirts are medium and heavy weight. Instead of assisting with evaporation they hold moisture against your skin which heats up, as mentioned above, increasing discomfort.
The number one piece of clothing I recommend for running in sticky heat is a synthetic material singlet. (A "singlet" is what non-runners would call a "tank top." BTW, be sure to insert the word "singlet" at least once in conversations with other runners. It will increase your street cred immensely!) Ideally you want to avoid cotton altogether but if you have a thin cotton, or better yet 50-50 blend, tank top in your shirt drawer already it's still better than wearing a thick cotton t-shirt.
For women who prefer a one-piece support solution, look for a breathable synthetic material sports top with as few layers as possible. Remember that the goal is to get fresh air into everywhere you can.
Going lower, let's assume that you are already smart enough not to wear tight leggings when it's humid so I can skip two paragraphs of rants (lucky you).
For shorts, you have two basic options: compression shorts or traditional running shorts. I'll start by saying that some people swear by compression shorts so if you are one of those, I respect your opinion. However, that gallon of sweat pouring out your leg openings can be avoided.
Do I have a beef with compression shorts? Yes. I have tried three different brands and all of them made my legs feel like they had to work harder to move no matter what the temperature was. When I run, one of the functions of my clothing should not be to slow me down. On top of that, in summer, I constantly felt prickly hot in the nether regions. Last is simply aesthetic and my own sense of propriety. Compression shorts on men don't leave much to the imagination. You either have meat and two veg running toward you or spandex-covered watermelons running away from you. Either way, it's not pleasant.
Traditional running shorts get a thumbs up for both men and women. There are a lot of choices out there but I like the shorts from Road Runner Sports. They fit well, have well-placed pockets for bandaids and other essentials and they are much less expensive than shorts from Nike, New Balance, etc. Also, skip the second underlayer. Most running shorts come with a liner. Some runners cut out the liner and wear their favorite undergarments so don't be afraid to do this if it works for you. You're in good company. I find that a good liner cuts down on chaffing and more of the all-important airflow I mentioned above.
Continuing our downward trend, socks make a difference too. Running without socks may seem like a "cool" idea but when your feet sweat they slide. If your shoes have any give, your feet will twist and turn uncontrollably.
Forget cotton! Wear your cotton socks to your mother's house, not out running. Believe it or not, I wear the same socks year round — allow me to clarify that: I wear the same TYPE of socks year round. My favorites are ankle-high and made mostly of wool (check out Darn Tough socks). I can comfortably wear them when it's zero or 90 F (32C). There are also some good synthetic socks on the market that perform well.
But why not cotton? Cotton socks act like sponges when you sweat or run through water. Holding onto moisture isn't what you want. Your socks should pull the moisture away from your feet as efficiently as possible. Wool is surprisingly cool because of its wicking properties. Also check out toe socks, like Injinji. Each toe sits in its own pocket that helps them feel dryer and some people love them.
Avoid the compression obsession. Leave your compression socks, leg wraps (bands) and arm wraps at home. Not only do they make you feel a lot hotter, the jury is still out on whether they do anything beneficial. See http://www.ncbi.nlm.nih.gov/pubmed/24911991.
My last advice on hot weather clothing is the most optional and down to personal preference. Unless it is the dead of winter, I always run with a well-ventilated running cap which looks like a baseball cap (ball cap, truckers cap, etc) except that the main material in synthetic and very light weight with high breathability. The bill of mine is flexible instead of rigid like a baseball cap so that I can bend it to deflect more or less of the sun from my face and also fold it up to stick in my waistband. The one drawback is that if you have thick hair, your head is going to feel hotter which is contrary to this entire thread. Other runners have gone with a visor instead which does a great job of deflecting the sun without keeping in the heat but still allows the sun to bake the crown of your head. If you have ever had a sunburned scalp you'll know how uncomfortable it can be. So hat on or hat off? If your running route offers very little shade, wear something with a visor. If you have few folicles on your dome, wear something with a visor and full head coverage. Outside of that you will probably feel cooler leaving the running cap at home.
#2 Slow down
As mentioned above the combination of heat and humidity quickly saps your energy. When the heat is at its worst, accept that your pace will be slower and take it easy from the start. If your normal running route includes hills, plan an alternate route. If you have a choice between running for distance or running for a set time, it's safer to go for the set time. Going for a set distance may keep you out in the high temps longer than you are used to as you fight to achieve your goal. If you are going to run for a set time, understand that your body is working a lot harder than normal and make it shorter than the time you run for on cooler days. Finally, you should choose a route that provides a shortcut back to your starting point. Running a twisting route around your neighborhood that is never more than a few blocks from your house in a straight line allows you to safely call it quits and get home to you're AC. If you run an "out and back" route when it's much hotter than normal you might find yourself stranded miles from your starting point if the heat gets to be too much.
#3 Hydrate enough but not too much
This one is the trickiest of all the advice. Many runners mistakenly overhydrate which can become a dangerous problem when the heat is on. Understanding when to drink water (or sports drink if you really really really must) is the key. On short runs you typically don't need to take water. You are sweating buckets, sure, but when it's humid the sweat isn't going anywhere fast so your body doesn't expend as much fluid trying to cool you down as it would if you were running in dry heat. The trick is to pay attention to the right signs. Recent studies have shown that the "drink before you are thirsty" rule can put people at risk of flushing out too much sodium from their bodies (hyponatremia - See http://journals.lww.com/cjsportsmed/Citation/2015/07000/Preventing_Deaths_Due_to_Exercise_Associated.1.aspx). If you do take water, drink when you are thirsty. You may not even feel thirsty until you get back home. Most of the time you are better off squirting that water over your head and face during a short run. Salty water (think sweat) evaporates more slowly so dumping fresh water over your hot head slightly increases the evaporation rate thus cooling you down more.
#4 Pick your running times carefully
Some runners can only find time at lunch, but at that point you are usually hitting the hottest time of the day. If you're fighting the work schedule to get in your run, try running at night. By 9pm even the hottest days have cooled down some. The humidity is still there but it won't feel quite as bad when you don't have the sun beating down on you at the same time.
If you can pick any time of the day or night to run, early morning is your best bet. The air temperature and humidity are usually at their lowest. But, the window is narrow. My personal experience is that once the sun gets involved the temperature/humidity ratio can feel even worse in mid-morning than it does in mid-afternoon.
#5 Location, location, location
Most of us can't just fly somewhere less humid for the summer. We are stuck where we are but, wherever you are, it's possible that some runs are more comfortable when it's hot than others. If there's a trail with a lake or stream nearby try that (unless you are in central Florida then there is no hope). Avoid black asphalt at all costs and stick to the shade if you are running during the day. This sounds like duh! But we runners are creatures of habit. If we have a run we like we stick to it because we know the distance, the incline, etc. It's likely that your favorite run that you found in the early spring isn't the best one when summer becomes a hotbox.
This is the slowest of the recommendations to show results but it's still effective. Get out there and run, no matter what the weather. As the year moves from spring into summer, running most days of the week will gradually get you used the uncomfortable conditions as the air gets hotter and more humid. By the time you hit the height of summer, your body will be working efficiently as it can in the heat and you will notice that it doesn't affect you as much.
You'll notice that I didn't bring up the topic of sunscreen or sunglasses. Neither of those things play a part in making it more comfortable
If you disagree with any of this or have more ideas about coping with humid heat while running, leave a comment below. Just keep the flame wars to a minimum. It's hot enough already.