The Great Equalizers: Heat and Humidity

“It’s so hot out that I tried to pee and it was just steam!” - Overheard at the KEYS 100 Ultramarathon, May 2016: 100-mile individual runner talking to his crew

We are in the dog days of summer. For those of us living in hot and humid places, it seems like there is no end in sight. I live and train in the southeast, splitting time between Chapel Hill, North Carolina and Charleston, SC. I also used to work summer jobs (outside in the heat) in Oklahoma and Texas, and I lived full-time in Houston, TX for a while. I like to think I know a bit about heat and humidity. Very few people genuinely look forward to this time of the year in the southeast (as it relates to training). In fact, I know a lot of folks who decrease mileage or only do maintenance miles over the summer, race rarely, and only begin to ramp up training at the end of summer heading into fall.

Helpful definitions from NOAA’s National Weather Service Glossary

Humidity: Generally, a measure of the water vapor content of the air. Popularly, it is used synonymously with relative humidity.

Relative Humidity: A dimensionless ratio, expressed in percent, of the amount of atmospheric moisture present relative to the amount that would be present if the air were saturated. Since the latter amount is dependent on temperature, relative humidity is a function of both moisture content and temperature. As such, relative humidity by itself does not directly indicate the actual amount of atmospheric moisture present. See dew point.

Dew Point: A measure of atmospheric moisture. It is the temperature to which air must be cooled in order to reach saturation (assuming air pressure and moisture content are constant). A higher dew point indicates more moisture present in the air. It is sometimes referred to as Dew Point Temperature, and sometimes written as one word (Dewpoint).

In April and May of most years, I usually train for the KEYS 100 Ultramarathon in the Florida Keys. As race-specific training (simulating or training in conditions like those you will race in) is critically important, I train during the hottest times of the day during April and May. I’ll even wear long pants and long shirts to get ready for the heat/humidity of the Keys. This is certainly effective to train for the pure heat of the race, but it is nearly impossible to simulate humidity. Actually, humidity may be the key to the entire hot weather thing (hmmmm?). Anyway, once I run the race at the end of May, I spend the rest of the summer trying my hardest to avoid running during the worst parts of the day.

Like me, most runners find the summer is a long slog of trying to avoid the sun and heat at all costs. This typically involves getting up very early in the morning or running late in the evening or at night. This can be very effective for missing the hot sun and UV Rays, but these times are generally the WORST for humidity. For me, I usually get the best (worst?) of both worlds. For a variety of work/life reasons, I generally run in the late afternoon/early evening; starting my runs somewhere around 5:30-6 and finishing by 8 or later. In addition, I’m fair-skinned with lots of freckles, so I target these times of the day so I don’t have to put a thick coat of sunscreen on, but also don’t have to wear a reflective vest and/or blinking lights. Lucky for me, this means I get to experience both the heat of the sun and the increasing humidity as the sun goes down. This makes for many miserable moist miles. I sweat a lot too, so it only takes a mile or two for me to be totally covered in sweat. Usually by the end of each run, my socks and shoes are totally soaked too. Hooray!

*Warning, Tangential paragraph: Obviously there are exceptions, like the folks who train for and race “Badwater.” Badwater, or the Badwater 135 Ultramarathon, takes place in Death Valley, CA in July, where temperatures regularly reach 125F and above. Additionally, the race is 135-miles long and features many significant climbs, unforgiving pavement, and there is literally NO shade for 99% of the race. Good times. The training those folks do to prepare for that race is basically nuts. N-U-T-S. Anyway, the sun (UV Rays) and heat are one of the biggest challenges of Badwater, but the humidity is usually non-existent. In these ultra-low humidity and very high heat conditions, sweat can evaporate from a runner’s body so quickly that many don’t even realize they are sweating (extreme danger for dehydration!!). There are SO many aspects of hydration/dehydration that we can’t get into this now, but this high heat, low-humidity situation MAY be the only time where “drinking beyond your thirst” might be appropriate (disclaimer: I’m not a Medical doctor and this is not medical advice; this is my opinion. Also, if you seriously needed that disclaimer, you may be in all sorts of other trouble).

So, back to the point of the blog post. On two recent back-to-back runs (Saturday and Sunday) the real temperature was about the same each day: 93-95F. However, the humidity was drastically lower on Sunday. The difference was so dramatic that I was bouncing through my Sunday run like a little kid who was just released from school for the summer. It was so great and I felt like a million bucks! Woohoo! My miles were way faster than Saturday, with what seemed to be much less effort. This is especially important because this was the 6th day of a 6-day training week, when my legs should’ve been the most fatigued and I should’ve been exhausted. That was actually the reason why I wanted to discuss heat and humidity here.

Anyway, after these long wandering paragraphs, I have a few points:

  1. Training is all about variables, and that’s why I truly believe focusing on Perceived Effort during training is very important, especially through the summer months (some refer to it as perceived exertion). Perceived effort relates specifically to intensity, or how hard you’re working (or how hard you think you’re working). I recommend this to anyone training anytime, but I think it’s most important for those of us in humid (and hot) environments. It can also be very important for mountain runners and those running on really tough, technical terrain. For focused workouts (all workouts should have a defined purpose!), you really need to think hard about the times you’re aiming for and then ADJUST those according to the environmental conditions, and keep adjusting once you begin your warm-up, and even during the main part of the workout. Warning: Don’t adjust yourself into a totally different workout! This is also very important when it comes to your confidence and what you deem a “successful” workout. For example, you may have run a quick marathon last Spring and want to target 6 tempo miles at 7:25-7:30 pace for a hot July afternoon workout. However, it’s 92F with a BUNCH of humidity, so the “Real Feel” is somewhere around 105-110F. You do your first tempo mile (after a good 1.5-3 mile warmup) at 7:45 pace and you stop your watch, hunch over, and do everything you can to avoid vomiting on (in?) your own shoes. Well, this probably could have been avoided a number of ways, but mainly using Perceived Effort to measure intensity and adjusting your workout to fit the conditions of the day. Situations like these are also total confidence killers and can even cause total abandonment of a workout (bad news all around). So, in summary: be SMART!
  2. You are not alone and I totally feel your pain. Training during the summer can totally suck! However, you can certainly minimize how much it SUCKS by: 1. measuring intensity by perceived effort, 2. targeting the times of the day to train that are BEST for YOU (everyone is different), 3. being super adaptable, 4. keeping a constant eye on the weather (relates to #3 and A.) – you can adjust your workout schedule to the upcoming forecast, and 5. by resting - rest is always so very important, but you need to be more cognizant of it during summer training, since there is usually a TON of stuff to do that impacts your rest/recovery (vacation, social activities, non-running sports, barbeques, etc.).
  3. Try to remember that this all should be fun! For 99.9% of us, running is not our career or the way we support ourselves and our families. Obviously, having goals and nailing those goals can definitely be fun too, but the process of training shouldn’t be a total drag all of the time. Remember to smile and think about why you are doing this!

Thanks for reading and enjoy training in the HEAT (but cross your fingers for low humidity)! Hooray! Also, a just took a look at the forecast and a COLD FRONT is coming through! YESSSSSSS!!!!!!!!!!!

“But really, I did pee and it was the color of black coffee.” - Same runner as mentioned above from the KEYS 100

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