A Tale of Two Runs - Lessons in Heat Management Strategies

Despite being away from home and indulging in some harmless shenanigans with friends last weekend, I still got out for a couple of runs while we were down in the wild blue yonder of Southeastern Michigan. The weather all weekend was fairly stable, and delightful for riding motorcycles: sunny days warm enough to go jacketless even at high speeds.

Good times!

Of course, that meant it would be awfully warm for running. Both times I went out were in similar conditions: near-flat routes, virtually cloudless skies, bright sunshine and temperatures around 24c/75f with fairly low humidity. The results of those two runs were very different, though, and I'd like to examine why.

On Saturday, I departed around 4:15pm for a 12.5km trot just after returning from a group ride that had spanned several hours. My view was rather uninspiring, as the rural areas Southeast of Detroit tend to be.

If you like miles of farm fields and crap pavement, though, have I got a destination for you!

I ran up to Nike Park as one of the only green spaces within reasonable range of the rally's location, and I suffered. The sun was beating me down and the heat was unbearable. I actually had to stop a couple of times just to catch my breath and drink deeply from the water bottles I was carrying. 

Yep, that's about it.

The run wasn't long enough to require any nutrition, so plain water was my only fuel along the way. I got to see one of the funniest signs I've ever encountered:

At Nike Park, by the remote-controlled aircraft flying field

Spotted something that I swore looked like a wooden sculpture of a dragon with a bazooka:

It turns out it's just a lopped off tree, but still..

And I sweated.

KILL ME

We went out for an awesome dinner (Ruby Tuesday FTW!), engaged in some revelry around the fire, and eventually tumbled into bed. On Sunday, we headed out for breakfast, then jammed over to Cabelas where I was able to pick up a tube of electrolyte tablets - I'd neglected to bring any with me, hence using plain water the day before in my bottles. When we got back to the rally site, I did a bit of work on a friend's motorcycle (glad your clutch feels better!) and hung around for awhile before heading out around 6pm for another 9km.

Let's just say I wasn't bored in the meantime.

That run was an entirely different experience, and I want to run down the reasons why so you can learn from my mistakes.

1) Hydration Beforehand

On Saturday, we'd just got back from a ride and I was pressed for time to get the mileage I wanted in before we needed to leave for dinner. I can't drink water while I'm in the saddle, so I ended up leaving for the run dehydrated. It doesn't matter what the weather is like, how long you're running or really any other factors - starting out that way will make for a miserable run. On Sunday I was able to slurp down at least 2L of water in the 2-3hrs before I went out, greatly mitigating the effects of the hot weather.

Though I may have spent some of Sunday night dehydrating myself again..

2) Time of Day

The difference between running between 4:15-5:30pm and running from 6-7pm in early September is the difference between running at the hottest part of the day and taking advantage of a reduction in the sun's intensity and thermal inertia with the onset of evening. While the sun angle is obviously at its highest at mid-day, heat continues to accumulate - it's absorbed and held by the pavement until the sun angle is low enough (as in early evening) that it begins to disperse. I knew I couldn't wait until sunset to head out because there are no streetlights where I was running and I brought a headlamp that isn't up to the task of nighttime running, but I could at least wait until the shadows got longer and the heat began to dissipate.

Not as intolerable.

It's not always possible to dictate the time when you'll be out running (especially if it's a race), but unless you're specifically trying to acclimatize to hot, sunny conditions and you have the option to run in the early morning or late evening, it will make for a far more pleasant experience. If you're doing a workout that requires high intensity intervals (track work or tempo runs), you will likely find it much easier to hit your target paces if you avoid running mid-day.

3) Route Selection

I was also able to choose a better route on Sunday - one that led me through more tree-lined roads around Stony Creek, rather than the wide-open expanses.

Sweet, blissful shade!

The effect of solar radiation on endurance is not to be dismissed. A recent study (April 2016 - Otani / Kaya / Tamaki / Watson / Maughan) showed that the difference in time to exhaustion among a group of cyclists performing trials at 70% of VO2max was reduced by almost 50% on a simluated hot day with intense sun (800 W/m(2) @ 30c/86f ) when compared to a hot day with no solar radiation (0 W/m(2) @ 30c/86f) or a hot, overcast day (250 W/m(2) @ 30c/86f). The sun really does have a sledgehammer, so find yourself a shady place to run if you can!

4) Electrolytes

Remember when I said I was able to pick up some electrolyte tabs on Sunday before I went out running again? I used one in the bottle I carried with me that evening, and was thus better able to keep hydrating myself throughout the run. Sodium in particular facilitates fluid uptake and retention, as well as preserving blood volume and preventing dilution of bodily fluids. Thus, I will usually add some (even just a bit of table salt if you're in a bind, or simply stingy) to my water when running in hot weather even when I won't be out long enough to take in calories. I generally use S!caps for longer runs in hot conditions, but didn't want to risk a sticky situation at the border trying to cross with a bunch of caplets filled with white powder, and forgot to bring a tube of the dissolving tabs with me.

Yes, I'm dumb. Here's a pretty view of Stony Creek.

5) Cooling Technology

Having heard that it was going to be warmer on Sunday than it was Saturday, I saved an additional arrow in my heat management quiver for Sunday's run: a shirt with cooling technology. While several companies have come out with fabrics that are supposed to provide sweat-activated cooling, the specific one I used was part of Columbia's Omni-Freeze Zero line - same as the tubular piece I used to good effect at Iroquoia Trail Test last month.

It's also a bright colour, which should help reflect some solar radiation.

While previous runs in this shirt have proven that (at least for me) "sweat-activated cooling" is not the case, I have found that the fabric does have some effect when soaked in water. Thus, I gave my shirt a rinse under the faucet just before I was about to leave so it would stay wet for the maximum amount of time while I ran. You could get a similar evaporative effect from any shirt, though the Omni-Freeze Zero technology does seem to amplify it somewhat. Despite most of the shirt having dried out by the time I finished, the areas where I was sweating remained wet and provided some welcome relief from the heat.

While Stony Creek provided relief from fields of corn and soybeans.

Conclusion

Sunday's run was much stronger and more enjoyable because I correctly applied heat management strategies that I had - whether through pressures of time or pure idiocy - severely neglected the day before. I hope you'll consider the five-fold approach laid out here the next time you're staring down the barrel of a run on a hot, mercilessly sunny day. Stay cool, my friends!