Crazy Runners. You know the ones I'm talking about. The ones who are out there running in the most adverse conditions, seemingly oblivious to it all. They take the United States Postal Service motto to heart, as if it were there own personal motto: Neither rain, nor snow, nor heat, nor gloom of night stays these couriers from the swift completion of their appointed rounds. I know this because not only do I run with crazy runners, but I am a crazy runner, and I've been known to run in all sorts of less-than-ideal conditions.
There are some (okay, many) who would ask "Why bother? Why not just hop on a treadmill when the weather is bad?" There are times when a treadmill or indoor track is a better choice - when the weather is dangerous (lightning, heavy storms, extreme heat or cold), or when the roads are bad (heavy snow, plowed snow along the sides of the road, or ice on the roads). But for the most part, it's really preferable to run outside in all sorts of conditions for the simple reason that whatever race(s) you're training for will not be postponed or canceled for anything short of dangerous conditions. To be well-prepared for anything that is thrown at you on race day, it is important to train in all sorts of conditions. Even if you don't run races, there are training benefits to running in adverse conditions - it can provide an increased training effect, similar to running at high altitude.
Given that the temperatures here in lovely Central Illinois have soared to over 90°F in the last few days, I think now is an appropriate time to talk about running in the heat and humidity of summer. These are difficult conditions to run in, no doubt about it. And there's a fine line between being just a crazy runner and being a crazy runner with heat stroke, so it's especially important to train smart when it's hot.
Let's start with a discussion on what happens to the body when it's hot and humid. As soon as you step outside, your body's core temperature begins to rise. Then as you start to run, your temperature increases more rapidly, and your body responds by increasing blood flow to your extremities and skin, carrying heat away from your core. This means there's an increase in heart rate over and above your normal exercising heart rate. Since blood is being diverted to your skin, that means less blood is reaching your working muscles, so they aren't able to work as hard. Additionally, you begin to sweat sooner and in greater quantity, quickly depleting your fluid stores and expelling electrolytes from your body. As you lose fluid through sweating, your blood becomes more viscous (thicker) and therefore more difficult to pump, so your heart must work even harder. The net effect of all of this is that, all things being equal (pace, route, elevation changes, etc), your run will feel significantly more difficult on a hot day than on a cool day.
Let's look at an example of this. I run 3 miles every Monday afternoon. It's an easy run (or at least it's supposed to be easy), and I generally don't worry about my pace so much as keeping my heart rate low. Let's compare the run data from my 3 mile run yesterday (when it was 95° with the humidity factored in) and a week prior to that (when it was 60 and cloudy).
May 17, 3-mile run
Weather: 60°F, cloudy, occasional light drizzle
Average Pace: 11:06
Average Heart Rate: 152
May 24, 3-mile run
Weather: 91°F, sunny, humid, heat index of 95°F
Average Pace: 11:24
Average Heart Rate: 162
As you can see, when it was hot, I ran slower and with a higher average heart rate than during the cooler run a week ago. I typically try to keep my heart rate under 155 for easy runs. Yesterday, I just couldn't seem to do that. I could have slowed down even more, but I was torn between wanting to keep my heart rate down and wanting to get the run over with faster. So I allowed myself to run at a slightly more elevated heart rate just so I could get back to my wonderfully air-conditioned house sooner. Even though it was only a 3-mile run, it was exceptionally difficult, especially the last mile or so. The good news is that the more I run in the heat, the easier it will get. Maybe "easy" isn't the right word. Running in the heat is never really easy. But it becomes more tolerable as the body adapts (and the body does adapt over time, by increasing sweat production, decreasing electrolyte concentrations in sweat, and retaining more water over the course of the day in anticipation of hot-weather activity).
And there are steps runners can take to ensure a safer and more comfortable hot-weather run. Here are some tips I've gathered from various sources:
1. Hydrate! This should be pretty obvious, but not only is important to hydrate while running, it's important to be well-hydrated before you even set foot out the door to run. It's also important to replace electrolytes, particularly on long runs. Sports drinks, gels, chews, etc are all good ways to do this.
2. Go easy. Especially the first few times you run in the heat. Acclimating to hot-weather running is gradual, so it's important to ease into it. This will probably mean slowing down, perhaps substantially. If you monitor your heart rate, focus on staying below a certain heart rate rather than focusing on pace. Don't go out on the first 90° day of summer and do a 6-mile tempo run with 6 sets of strides. In fact, super-hard workouts like this should be avoided completely on hot days. If you must do speedwork, go indoors. The risks of running hard in the heat outweigh the benefits.
3. Dress appropriately. Wear lightweight, loose-fitting running clothes made of moisture-wicking technical fabrics. Remember, cotton is the devil. Avoid it. Wear a wide-bill hat or visor to protect your face, and sunglasses to protect your eyes.
4. Wear sunscreen. Studies have shown that runners logging as few as 25 miles per week are more likely than non-runners to develop malignant skin cancers. This is likely because a lot of us think we are immune to such things (I run marathons! I can't get cancer!) and fail to protect our skin from sun damage. Olympic marathoner Deena Kastor has been diagnosed with malignant melanoma three times - and as much as I'd like to be like Deena Kastor, this is one way I do not! So let's all vow to slather it on. Sunscreen has an added benefit in that it provides a mild evaporative cooling effect - every little bit helps when it's really hot outside! Use a sweatproof sunscreen designed for athletes, such as Bullfrog Marathon Mist.
5. Run early in the morning or later in the evening. It may still be hot, but it may be more bearable if the sun isn't beating down on you. In the morning, it is usually cooler, but more humid. In the evening, it's generally hotter, but less humid. It's not always practical to run at these times, but I think it's particularly important during long runs to avoid the hottest time of day (typically around 4pm) and the peak hours for UV exposure (11am - 2pm).
6. Bring water, but not just for drinking. Pouring water over your head, face and neck during a hot run can bring immediate and wonderful relief. Try it. You'll thank me.
With all that said, it's most important to listen to your body. As you become acclimated to the heat, you may be able to dial up the intensity or pace of your runs, but always be mindful of your hydration, sweat rate, respiration, heart rate, etc.
As for How To Be A Crazy Runner, Parts Two and beyond... well, at some point, I suppose I'll address the other facets of the Postal creed: rain, snow and gloom of night. But I don't think I'll be talking about running in the snow anytime soon. *fans self vigorously*
Peace. Love. Train.