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But it’s too hot to run today!

This article has been contributed by our blogging friend fishcounter. Check out his blog for more about his running adventures.

July is nearly over and August is upon us. Two things are going to happen that runners here in Taiwan love: The first is the increase in glorious races available to us. The second is a glorious drop in temperature. There is a correlation between these two.

Training in the heatMany race directors don’t want to plan a race in this kind of heat unless they are organized by some kind of sociopath who enjoys seeing aching bodies lug themselves toward free t-shirts and medals (don’t forget to sign up for Taiwan Beast Runner events!) But come October, the difference between the people who are huffing over the finish line then curling up into a fetal position, and the ones who bound through the line like a baby gazelle and stand on the podium proudly is one thing:

Did you train in the heat?
Running in heat sucks, but the heat has some great effects on your body. Like all good training, it doesn’t come easy.

When you’re doing your training in the heat, things change. Your body starts to pump more blood closer to the surface of your skin in order to radiate out the heat that is deep within you, wringing out sweat which is evaporated for heat loss. This makes you feel slower because all that oxygen and glycogen-laden blood could certainly be used other places like your vital organs, muscles, heart, and brain.

This sucks for two reasons:

1: With less blood going through the heart, and more being devoted to cooling your body through sweat evaporation, you actually decrease your overall volume of blood that is pumped because it’s being re-routed elsewhere. New highways are built, and the concentration between your heart and muscles decreases. With not as much blood going to your muscles, your heart picks up the slack by pumping at an increased rate.
2: The other reason is because your body makes changes to the composition of your blood to accommodate the transportation of electrolytes and water. Blood plasma decreases in the muscles and viscosity (thickness of red blood cell counts) increases. This literally thickens your blood, giving extra stress on your heart and vessels to move that dense stuff through.

Energy-use changes, too. Runners need oxygen to be transported directly to their muscles. That’s how we move. When you are training and trying to cool your body at the same time, you split the load, and either your muscles or your ability to cool yourself is going to suffer. Most likely, less oxygen is going to make it to your muscles, and your body is going to have to rely on anaerobic (without oxygen) modes of producing energy. This energy then has to come instead from the glycogen stored in your muscles and liver. Lactic acid builds up more quickly in your muscles due to the energy conversion, making your legs feel stiff and heavy, and when energy stores are depleted, you start lipid-induced fat burning–or fat burning.

Sounds lovely, right? Burn that fat. Kill it. Give me those abs. But it’s not that easy. With great change comes with great cost, and running on lipid stores when all energy has been drained from your body is what runners often refer to as “hitting the wall.” It’s miserable, and it can be dangerous, especially when you have all of these other things to worry about while running in the heat.

We also see marked decreases in VO2 max, the maximum amount of oxygen that the body can take in and use to fuel working muscles, which is the benchmark for measuring fitness. Essentially it feels like you are out of shape, when really you’re totally okay.

Now remember, when your body senses all of these changes, it increases sweating to cool it down. Water goes into the air, and you’re left with this chilly refreshing feeling.

Problem solved, right?

This is the hard part because Taiwan is known for being pretty humid, with weeks lasting 32 degrees, direct sunlight and 80% humidity. The humidity is pretty much just air saturated with water–air that cannot take on more water through evaporation. So while you might be dripping in sweat, none of it goes through that crisp, lovely phase change that leaves your body dry and cool.

I’m not really selling this whole running-in-heat thing, am I? Sounds like you should just stay indoors, run on a treadmill under an air conditioner.


Change does happen. Your body will adjust. You will increase VO2 max, and that translates to huge payouts later in overall fitness when the weather is nice. Restricted blood flow creates new capillary highways to transport blood, and strength of your heart and lungs will make you fast when the weather does finally drop. Your blood plasma composition will adjust to flow more easily in your heart. You will receive a free puppy. Okay, that last one isn’t true.

Don’t get too excited about these gains and push too hard too early, though. Heat exhaustion is real, as I highlighted a story I wrote in April. It can also lead to heat cramps in newer runners while your body transports blood away from the vital organs and to the skin, creating a competition for electrolytes. You can faint, as blood flow moves too quickly away from the brain. Hyponatremia, or overhydration, can occur as sodium levels in the blood wash away, and you guzzle water trying to fix a perceived lack of hydration. Your free puppy could fall off a cliff.

Here’s what you do:

You need to wear light clothing with tech fabric, run in the morning and night and hydrate well. Find shady spots to run, don’t run on the road at high noon. Drink water early and often. Your body needs you to soak your cells in water that it will need later, not just fill your tummy before you run. And obviously, when you get home, drink more.

The benefits outweigh the costs. The riverside biking paths are full of runners right now who will be signing up for races in the fall and winter, and they will be the ones who are acclimated to the heat. Don’t give them that advantage. They are going to be laughing while they stand on the podium and overheated runners are still shuffling over the line.

Go run now, so you can stand on the podium and laugh with them.

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