September 14, 2021

How To Train Effectively In Hot And Humid Conditions

Learn how to achieve the most comfortable training experience, output and recovery when training in hot and humid environments.

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I first came to Singapore in 2000. 

My parents had just moved here with dad’s work, and I was eager to visit. The minute I stepped off the plane, I was hit by a wall of heat and humidity that I had never experienced, and I knew my training here was gonna be a challenge.

The first race I did in Singapore was a 5k running race at Macritchie. Besides having a monkey drop from a tree onto my shoulder and jumping over a monitor lizard – both new experiences – the weather nearly killed me. Like most athletes new to this environment, I swore I would never race another one. 

That thought didn’t last long, and since that time, I have raced in many running, triathlon, cycling, aquathlon and stair climbing races, and have spent countless hours training and racing here and throughout South East Asia in extreme heat and humidity. I have also coached hundreds of athletes to do the same.

Here’s what I’ve learned.

Train Early Or Later In the Day

To achieve the most comfortable training experience, output and recovery, training earlier or later in the day when the sun is lower in the sky is essential. 

The slightly lower temperatures at these times help to keep your heart rate down and output up. You’ll also sweat a little less, making electrolyte replacement and hydration a little easier during your session and afterwards.

This rule applies to the majority of training sessions. However, if you have a race coming up that will have you racing in the heat of the day, it can be helpful to do a few race-specific sessions when you’ll be racing to condition your body for the demands. Just make sure you fuel the session properly – before, during and after – to ensure sufficient and swift recovery. 

Train Indoors

Besides being time effective, training indoors allows you to swap the heat and humidity for an air-conditioned room. Training in cooler conditions, as discussed above, improves the quality of your session and helps you recover faster afterwards, so training indoors can be beneficial when maximum output is the goal of a session or when you’re exhausted.

While it’s helpful to do some training indoors, make sure you continue to train outside to condition yourself for the heat. After all, you will race out, and you want to be ready.

Cut Race Times, Not Corners.

Racing at your potential and enjoying training is easy when you’re following the right programme.

Hydration Matters

I underestimated the importance of hydration for a long time. I didn’t know precisely what and how much to consume, and for years felt tired and sluggish during training.

Dehydration is cumulative, so you must pay attention and stay on top of your hydration at all times to recover and keep energy levels high.

Heat and humidity cause your body to sweat, and with it, you lose electrolytes. Sodium is the primary electrolyte lost in sweat, so salt supplementation is essential in hot and humid conditions.

As well as maintaining fluid balance, sodium plays a vital role in the absorption of nutrients in the gut, preserving cognitive function, nerve impulse transmission, and muscle contraction.

Individual sodium loss varies considerably between athletes. We’ve seen losses as low as 400 mg/l and as high as 2,000 mg/l amongst athletes we’ve tested in our lab. Based on data from Precision Hydration, who provide our sweat testing, the average athlete loses 949 mg/l, which is not insignificant.

If you’re planning to spend any significant time training and racing in the heat, I strongly encourage you to know your numbers.

Firstly, your sweat rate – that is how much sweat you lose per hour. Second, your sodium loss – how much sodium you lose per litre of sweat. Lastly, the duration and intensity of your training session.

Once you know those numbers, you can easily calculate what you need to consume to stay hydrated and maximise your training.

Cap Your HR For Long Training Sessions

When you’re first adjusting to the heat – and in all long sessions moving forward – train with a heart rate monitor below your Zone 2 (steady) ceiling.

Compared to your ‘cool weather pace’, your pace will slow, but the stress remains constant. Your body is simply working harder to cool itself.

As you adapt to the heat and assuming you fuel your training correctly, you’ll see your output start to increase a little at the same heart rate.

Dress For The Conditions

This point is pretty obvious, but you want to dress for the conditions. Avoid wearing layers and heavy clothing. Wear lightweight and breathable clothing; ideally, that wicks moisture away from your body.

We’ve already discussed how critical hydration is when it comes to training in the heat. Choosing your hydration equipment is equally important. Some hydration vests are heavy and can increase body temperature, so minimal and lightweight vests are essential. They’ll keep you hydrated and also minimise the rate at which your body temperature rises.

Round the waist and handheld options are also helpful.

If you can nail the points above, you’ll radically improve the quality of your training in heat and humidity. Your training experience will also improve because it won’t feel as hard as it used to.

Some of the best races during my career were in intense heat and humidity. It wasn’t that I was faster than the others; I just performed to a higher percentage of my ‘cool weather’ ability because I was acclimated to the conditions and knew what to do to get the best out of myself in hot, humid weather.

You can do the same.

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Ben Pulham

Ben Pulham is the founder of Coached, a personalised training programme that helps runners & triathletes optimise, track and enjoy their training.