The Effect of Heat on your Pace

Hands up who hates summer training?

Me!!!

The impact that just a slight rise in temperature has on my running is huge, it takes even more effort to maintain my running pace and I forget how much harder it feels to maintain my pace. The good news is that running in the heat does affect your pace, by a considerable amount, just look how much by in the table below.

How temperature effects your pace using a 10 min mile example. (Image reproduced from Runner’s World 2011)

Even moderately warm temperatures can significantly impair your run because heat -

• Increases your heart rate and your blood pressure. This can worsen as you sweat and as your fluid loss starts to exceed 2% of your body weight. This occurs because your overall blood volume starts to decrease as you dehydrate. This means that your heart must work harder to pump a reduced volume of blood to the needed muscles. It’s made even worse as the body shunts blood to the skin to help cool the body so even less blood is available to the working muscles.

• Excessive fluid loss which can lead to dehydration. Most runners will lose some body weight and up to 2% can even be performance enhancing. After the 2%-mark, performance will drop even further. Some studies suggest 4-6% initially which worsens as dehydration continues.

• Every step can feel like you are running through treacle. Most runners don’t like running through the summer months and long for winter training, just acknowledge that it’s hard and part of the training cycle and process. And remember how much you hate summer training when you have to get up in the cold, dark and wet mornings!