Tag Archives: sweating

Tales of Forgotten Subsystems, Part IV: The Sweating Mechanism.

The sweating mechanism is truly one of the most forgotten parts of the human body. Its influence in our athletic performance is so great that it’s really a mystery to me why more emphasis isn’t placed on training and developing it.

In a big way, our sweating mechanism is one of the things that sets us humans apart from the rest of the animal world. (The second sweatiest animal, the horse, only has about one-fifth of the sweat glands, per unit of skin, that we do). There must be a good reason we have a five-hundred percent sweating advantage over the next-best sweater in the animal world.

And yet, not only do we gloss over this massive mechanism to focus on sexier components of athletic training, but we actively shun it in society. We deride people who sweat a lot, and turn the very act of sweating into a social faux-pas.

Discussing that irony is an essay in itself.

Sweating is one of the things that makes us human. It is intricately tied to a multitude of other traits that identify us among animals: why we have little to no hair covering our bodies, why we have big brains, and even why we stand erect.

In Waterlogged, Timothy Noakes explains how these traits all come together in the human animal. As desert endurance hunters, it was necessary for humans to have big brains, in order to think abstractly and plan pursuits that would last for many hours into the future. But big brains aren’t enough. The air that’s closest to the ground (where most four-legged animals live) is also the hottest. In that hot air, the human brain—our supercomputer, the reason we outclass every other animal on the plains and otherwise—will overheat, and force the body to halt all athletic activity.

So how did we get around this problem?

In two ways: First, by standing up. This not only takes our center mass outside of the hottest part of the terrain, but it also puts our body in a vertical position, meaning that, during the hottest part of the day, we have much less surface area exposed to direct sunlight (than say a deer). Second, by dramatically increasing the amount of sweat glands, we can take advantage of the wind. Because our skin is uncovered, sweat lets the wind take heat directly from our skin, resulting in massive convective heat loss that other animals just can’t match.

From "Waterlogged: The Serious Problem of Overhydration in Endurance Sports" (Noakes, 2012).
From “Waterlogged: The Serious Problem of Overhydration in Endurance Sports” (Noakes, 2012).

(When an animal’s skin is covered by fur, the majority of their body heat remains trapped in that fur layer, and never gets exposed to the wind). In other words, while most animals were “designed,” if you will, for heat retention, we humans were “designed” for heat loss. Talk about natural athletes.

Thanks to this confluence of extraordinary adaptations, we can bring the rest of the features of the human body—our pack dynamics, our nimble physique, our massive aerobic engine, and the supercomputer that allows for productive, recursive symbolic manipulation (the human brain)—to bear on the hunt.

Given all of this, it’s amazing that we think of ourselves as frail, sedentary creatures. We are the athletes of the animal world, being able to run down just about every ungulate but camelids (llamas, camels, etc.) because we can’t drink saltwater (while most desert ungulates can), because we choose slow (and relatively inefficient) two-legged propulsion over quick and efficient four-legged propulsion, and because we play hardball with the desert climate—betting our internal water on the idea that we’ll be able to chase down that deer and still be able to replenish the water we lost. We take all of these apparent disadvantages and use them to our advantage.

And we can run down these “athletic” animals because our brains use 20% of our oxygen and 16% of our energy. (Comparatively, the brains of other mammals use between 2 and 10% of their total energy).

The powerful sweating mechanism lets humans act like that annoying poker player a lot of us know—while everyone else at the table is betting in a friendly, conservative manner, they’re changing the rules, out to make money, constantly going all-in.

Our sweating mechanism lets us fundamentally change the game. While other animals are stuck playing conservatively, trying to lower their body heat in a body designed for scarcity—a body that is all about water retention and heat retention (to save energy in the long run)we humans exploit this conservative game: we force animals to play by our rules.

It’s just like that poker game: because other animals can’t spend water fast enough, we humans play our aggressive game, betting that they’ll run out of chips before we do.

Next time we run in the heat, let’s remember this. When it’s so hot that running becomes uncomfortable, let’s remember that by unlocking our sweating capacity—by training the sweating mechanism just like we’d train any other muscle—we’re developing a crucial component of our athletic potential. Also, we’re getting in touch with one of the very things that makes us human.

Running in the heat (Part 1)

Here, I begin to answer a comment from this post, by Liliana Gutierrez Mariscal:

What makes running difficult for me?

Running in the heat

No matter what you do, it will be more difficult to run in the heat than in cool weather. But if you do take the time and trouble to run in the heat, it’ll really be worth your while.

I’ll devote another blog post to a very innovative idea that’s been put forth by a wealth of authors and scientists: the idea that we evolved into what we are now by chasing down four-legged animals in the heat of the african desert, (in other words, that we are desert endurance runners). But let’s not be tricked into thinking that achieving that level of expression will be an easy task.

Suppose we truly did evolve for the purpose of being runners, and more importantly, thanks to that activity. That being the case, we can make the argument that, running in hot weather in particular constitutes a very important part of the physical and physiological (and no doubt cognitive and emotional) expression of a human being.

Perhaps one of our most natural forms of expression (if not the most natural) is to run in the heat.

This argument comes from an evolutionary-systemic point of view. If you use a particular system for the very activity that it was developed to do in the first place (by first making it capable of operating at that level), then that system is very likely to manifest functions (or an efficiency of function) that it can’t express by performing any other activity.

Ultrarunning—the sport of putting the body through an irresponsible amount of miles—may tap into that level of expression. We already know that people sign up to run across the Sahara Desert, Death Valley, or to do back-to-back marathons in the desert summer as is the case with the Comrades Marathon.

But you don’t need to look that far for some idea that running was not created equal to other sports: Answer in the comments if you’d ever heard of a “golfer’s high,” or a “cyclist’s high.” It’s not that these cognitive states don’t happen in those sports. But the associations between running and favorable cognitive states are that much higher. They are so high, in fact (or so I argue), that people still sign up by the hundreds of thousands to run 26.2 miles despite the near-certainty that they will end the day with a significant injury.

Why do we still do it? As Christopher McDougall argues: it’s because we were born for it.

Those are the ultimate reasons for why you should run in the heat.

But I’ll give you a more proximate reason: you can make bigger gains in performance. I’m going to paraphrase a chapter-long argument in Tim Noakes’ book Waterlogged: The Serious Problem of Overhydration in Endurance Sports.

There are two important numbers in this story: 98.6° Fahrenheit and 104° Fahrenheit.

The first number, 98.6°, is of course, our normal core temperature. 104° is the temperature at which the body’s functioning becomes compromised. (This is a severe emergency).

What this means is that there are still, say, 2½ degrees of “give” between normal core temperature and the temperature at which things start getting too close to the danger zone (which starts at around 101º).

Take your typical runner stepping out into 100º heat for the first time: the body feels the heat and decides that no way is it going to let core temperature rise. It’s not accustomed to that environment—and more importantly, it doesn’t have a sweating system powerful enough to bring core temperature down, in case it needs to.

The cooling system of this average runner is fighting the environment heroically, struggling for every single tenth of a degree. That has a huge metabolic cost: the cooling systems go into overdrive, and the runner experiences fatigue in order to force a reduction in activity. Maintaining core temperature at a level that the body is comfortable with has become the most important thing—far more important than athletic performance.

But as that runner continues to train in the heat, the body begins to adapt over time: its sweating mechanism becomes more powerful, its able to more effectively circulate blood from the core to the skin—and furthermore, it knows that it’s still got those 2½ degrees of “give” between normal core temperature and the 101°, where its really beginning to skirt close to the danger zone. The runner experiences incrementally less and less fatigue; running becomes easier and easier.

As sweating system becomes more powerful, the body gives itself a little bit of rope. It’s getting used to that heat, so it lets core temperature rise a tenth of a degree, then another, and another. This isn’t a problem—it’s still in the safe zone.

What’s happening? It no longer has to fight the environment to cool those three-tenths of a degree.

In other words, the body developed a more powerful cooling system, and yet, because it developed that system, it no longer needs to use it that much!

Becoming accustomed to the heat lets you increase your level of performance in two ways: you can keep exercising at a higher core temperature, and with a more powerful sweating system. Suppose you increase your metabolic rate to tax the sweating system (which has now become more powerful) just as much as you used to tax it when you had only just started running in the heat: now you’ll be running at a much greater speed—and none of this has to do with your muscle power.

This brings us back to the argument that I was making earlier: by running in the heat, you can manifest physiological functions (heat tolerance) and psychological functions (lessened fatigue) that can’t be manifested under any other conditions.

The argument I make in this post is very similar to the argument I made in yesterday’s blog post. Just like having stronger muscles makes you a faster and safer runner at the same time, having a stronger sweating system does two things, instead of just one.

All this said, training in the heat means that we’re going to be playing with dangerous forces. Too much heat really will kill us. If we do choose to train that way, let’s do so with humility and care.

This will become a recurring topic. Soon, I’ll post a few exercises and training ideas that we can use to safely develop our heat tolerance. Also, I’ll post about the physiological aspects of the human body, that make us such good heat runners.

Remember, even though running in the heat might be really difficult, in a very deep way, it is what you do. If you gain that ability, you probably won’t regret it.

Happy running!