Running in the heat

Mar 29, 2021
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image of charlie egan jogging

We have been lucky enough to have some fantastic weather over lockdown and this week is set for more sunshine and soaring temperatures in the UK and Europe.

Sometimes work can get in the way of our busy training schedules (or is it the other way around?!)

So this led me to be out running at midday a few weeks ago in baking heat with little shade; it was a tough run but only in my perception and certainly challenged my body to adapt. 

Do you avoid the hot sun?

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It got me thinking about why we try not to train in the heat; heading out for a run early before the sun really starts to share it’s heat or later in the evening. Whilst in the heat it does challenge our body, and certainly, the perceived rate of exercise may appear higher; we simply can’t avoid training in the heat if we then expect our bodies and mind to be able to cope and feel comfortable racing in some far-flung sunny country. Whilst it is true that there are many factors that come into play when we look at training and racing in the heat; one thing is for sure we need to actually get out there and get uncomfortable and get used to what it feels like. You wouldn’t buy a new bike, never ride it then turn up to a race expecting that it will be the perfect fit and feel comfortable, would you? So we can’t simply expect that without specifically training in certain conditions that we can adapt or at least get used to being uncomfortable and knowing how your body reacts. Usually, adaptation takes 14 days; but we can start to adapt to new conditions such as heat, humidity and altitude within 5-7 days. 

You may be missing a trick!

Running when it is hot is actually the perfect time to perform a sweat test and record how much fluid you lose in an hour; accounting for any fluid drunk. It may also be worth noting any symptoms or clues to your sodium losses too. You may find that your sweat stings your eyes, that you white marks on your clothing or that you don’t feel quite right with general fatigue and a loss of concentration. Collecting data in different conditions is always useful and then making informed decisions about what to put in place to make sure that you perform at your best.

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What’s Different about Running in Hot Conditions?

Remember that when we train our body produces heat; for every 100W of energy we produce we produce 400W as heat! Sweating is one way our body tries to cool us down to keep the core temperature within range. We know that being hypohydrated; or under-hydrated makes us feel the effects of heat even more as our body tries to cool itself. It is also with the knock-on effects from dehydration that we see an interplay with other systems in the body. The cardiovascular system is put under strain as the blood plasma volume decreases affecting blood pressure coupled with an increase in heart rate. This obviously leads to effects on the delivery of oxygen to working muscles; as the body tries to thermoregulate coupled with less efficient removal of substrates (Nybo et al 2014). We also feel fatigue; in fact, it is actually termed as central fatigue, the brain’s functions alter in the heat with a direct effect on specific neurotransmitters in the brain. 

From a nutrition and hydration perspective ; it isn’t just the fluids lost or sodium depletion that we need to think about either. Not many athletes are aware of the needs for carbohydrates and how our requirements for carbohydrate are increased. When it is hot there is a significant shift in substrate utilization towards the oxidation and usage carbohydrates (Burke et al 2001) and an increase in metabolites produced. 

Using the Heat to our Advantage

So when it is hot outside and you have a race booked that may be rocketing to soaring temperatures or is humid; take the plunge and get out there and collect some data! Remember the data you collect is only as good as what you choose to do with it; so bring it back and work out your strategy and how you may be able to help prepare for that hot race; as best you can before you get to the start line! 

If you are struggling with getting your nutrition and hydration strategy right get in touch!

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