Here we are, in the middle of the summer, and with that comes training in the heat. If you ask me in December or January I’m likely to tell you that I can’t wait for July and training in the warm weather. Now that it’s here, I feel like I’ve changed my mind…again, and I'm looking forward to the cooler temperatures already..
Since summer seems to keep coming around each year, it’s valuable to think about how training will change, how to best plan for training in the heat, and what physiological changes you can expect, especially for runs longer than an hour or so. Most of us won’t be able to avoid the heat training with so many races coming up in the fall, and many of us may have races that have a high chance for warm or even hot conditions. So since we can’t really avoid it, what steps can we take to still make sure the sessions are valuable, hopefully a little less uncomfortable, and most importantly, gaining some adaptations to make it all worth while. Let's dig in.
First, and most importantly, safety is critically important and you should always make a decision on training in the heat with your safety in mind. Always have plenty of fluids for the duration of the planned event, including more than you would take on a cooler day. Consult a doctor if you have any medical questions or concerns and always listen to what your body is telling you. No adaptation is worth risking your personal safety.
Training in the heat, whether in dry or humid climates, comes with its own set of challenges. As you may have noticed already, when compared to training in cooler temperatures, heat training will elicit a higher heart rate for a given level of effort. For athletes training based on heart rate. you may notice slower paces for a given training zone, and sometimes feel more labored or struggling to breath normally. This is not abnormal and should be anticipated, so don't try to force a pace, For athletes training based on Rate of Perceived Exertion (RPE), you can also expect slower paces for a given RPE. Again, stick with the plan in the workout but expect the pace to be slower. It may seem frustrating at times, but once a cooler day comes around, you'll likely feel incredible, so enjoy the results when they come.
I'll touch on hydration just briefly, with plans for a more detailed post in the future. Of course, hydration is always important and can mean the difference between a great workout/race, or everything from limiting your potential results to needing medical care to address severe dehydration. One of the struggles I have with hydration (and nutrition) guidelines, is they're just that...guidelines. To really understand your needs, there are a few things you can do to better understand your personal hydration requirements. One free option, is to fill out a sweat rate calculator on a regular basis, at different environmental conditions, determine how much sweat you lose per hour, and determine a more accurate personal hydration strategy. If you want a copy of the spreadsheet I use, send me an email and I'll happily share it.
For a fee, there are labs that can perform sweat tests which may include sweat loss, but perhaps a more valuable metric is salt loss. These results can not only help you line out your hydration strategy, but also how much electrolyte you need to consume to maintain the important salt balance in your system. While the sweat tests will cost a bit of money, salt loss doesn't change drastically over time so it doesn't need to be repeated very often.
Even with your hydration and electrolyte numbers nailed down, that doesn't mean you're necessarily going to feel like you've escaped the heat. Anecdotally, here are some things that I've noticed and try to think about on a planned run, especially a long run, in the heat.
- You may have brought the right volume of water and electrolytes for your long run, but if you can't drink them, they're not providing any value. These fluids, especially if stored in a vest, can get pretty warm...so warm sometimes, that you actually may not want to drink them. Consider using an insulated cover for your the bottles or hydration bladders, or create an aid station at home or with your car where you can keep the fluids in a cooler or on ice and plan a loop course to refresh with cold fluids at regular intervals.
- Nutrition can suffer from the same problem as liquids, they can get real warm. Personally, thinking about downing a chocolate flavored gel that's warm, is completely unappetizing. I'd rather go for a berry, citrus, or neutral flavor in the heat, but pick the flavors that you can stomach, or nutrition that isn't as impacted by the heat. Similar to hydration, you can always plan an aid station and keep the nutrition at a temperature more conducive to eating.
- Always wear plenty of sunscreen, and follow the directions for reapplying at high sweat rates. Protect your skin!
- Pick you clothing colors carefully and try to wear yellow or white if possible, which will reflect more of the solar energy. Wear clothing that's comfortable, breathable, and hopefully wicks moisture. Keep in mind though, once a piece of clothing is saturated, even if it's moisture wicking, it's likely not cooling any differently than a non-wicking material, as the evaporative cooling is happening more on the material, not the skin.
- Be prepared for possible chaffing. Even if you don't chafe in cooler temperatures, you may suddenly notice it on warmer runs, likely when you get in the shower (ouch!). There are several great products to help prevent chaffing, try several and find the one that works for you. And don't be too light when applying. Trying to finish the last 5 miles of a long run while chafing is definitely not a pleasant experience, and I can tell you stories.
- If available, consider pouring cold water over your head and body on occasion, or add ice to arm sleeves, your vest, or an ice bandana or hat.
- There are plenty of other options as well, so experiment and see what works for you.
The last topic I'll touch on here, is what happens physiologically. With all the challenges of running in the heat, there's some good news if you're planning to run a race that has the potential to be hot, or if you're just continuing to train in hot conditions. The chart below shows the body's adaptations over time with implementing a heat training strategy. Some adaptations can be realized pretty quickly, but to get the maximum effect, an athlete generally needs 10 to 14 days.
The diagram below, provides some additional information for heat acclimation and acclimatization strategies that can be employed to achieve the adaptations.
Both charts taken from "Exercise Under Heat Stress: Thermoregulation, Hydration, Performance Implications and Mitigation Strategies", Julien D. Period et al., 2021 https://doi.org/10.1152/physrev.00038.2020
So as the summer temperatures continue, for a couple of more months at least, try to look at the bright side of heat training and implement ways to ensure you're ready for that hot race. Feel free to reach out if you have any questions.
-Brian