Training In The Heat: How To Maximise Your Workout

Training In The Heat: How To Maximise Your Workout

With holiday season here and the heat wave that we’ve all been treated to here in the UK, working out outside can become a little more difficult. While we complain the Winters are too cold and dark to take our workouts outdoors, this Summer is proving that training in the heat isn’t so easy either. So, we’ve addressed some of the most common questions for when it comes to training in the heat to help you maximise your workout outdoors this Summer.

How Long Does It Take To Acclimatise To The Heat?

Like anything in fitness, when it comes to training in the heat and in differing humidity, everyone is different. Generally, it can take around 7 to 10 days of structured training for the body to slowly adapt to different heat levels. During this time you should be aiming to work out for around 45 minutes to 1 hour per session. However, the time it takes to acclimatise to heat can also depend on several other factors including individual hydration and fitness levels. Be sure to stay hydrated during hot conditions and replenish your electrolytes after each session for the best recovery.

What Percentage Of Your Regular Performance Should You Aim To Reach?

Our training performance is based on physiological factors such as heart rate and our individual VO2 max oxygen uptake (how much oxygen you take in during maximum exertion). VO2 max is a measure of how intense exercise is and also a measure for endurance, as your vo2 max increases so does your heart rate. Factors that affect performance include altitude from air pressure and temperature. When training in the heat, it’s 100% normal not to be able to reach that PB or top speed and performance often decreases due to the body adjusting.

What Affect Does Heat Have On The Body When Training?

Heat acts as an additional stressor when training which results in cardiovascular adjustments. Some of these include changes in blood flow, increased sweating, an increase in your heart rate and a lower oxygen uptake. When we are exposed to hot conditions the body will try and cool itself down and regulate temperature through increased sweating, which in turn increases blood flow to the skin’s surface. This means we lose blood flow to the muscles and vital organs during training as well as losing water and electrolytes through sweat.

Because blood flow to the muscles and vital organs is decreased in the heat, the amount of blood pumped from the heart is also decreased and to compensate for this adaptation the heart works harder. This is why heart-rate can increase more quickly despite the workout being less intense!

Not only that but if you are looking to take part in some endurance training, hotter conditions can also alter the way the body creates and burns energy. In order to train at high intensities for longer periods of time the body relies on several sources of fuel, including both fats and carbohydrates. To burn fat as energy, the body needs oxygen, whereas carbohydrate energy stores are an anaerobic source of fuel and don’t require oxygen. When hot conditions cause the blood flow to the heart and muscles to decrease it also decreases the amount of oxygen that is delivered to the muscles and as a result the body is forced to rely on carbohydrates as fuel. However, our carbohydrate stores in the body are limited, therefore you may find in the heat the body will reach exhaustion sooner than usual.

So, How Will My Performance Differ?

The percentage to which you can train in the warm weather can vary again depending on the temperature increase itself and other factors such as altitude and humidity. Not only that, but dehydration can often come into play when training in the heat to further the disproportional intensity effect that you’ll see. So don’t be disheartened! Not being able to hit your PB and max speed is totally normal until the body adapts and even then you need to pay close attention to hydration and replenishing electrolytes.

What Should I Eat and Drink Before, During And After Training In The Heat?

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Nutrition pre, intra and post-workout is important regardless of the training conditions but when it comes to staying safe in hot conditions pay close attention to losing salts and water.


Before training be sure to keep hydrated during the day, or if training early in the morning make sure you have consumed enough water (around 600ml) two hours prior to working out when possible. If you need a caffeine fix in the morning, taking a pre-workout supplement is a great option. Sadly coffee can actually decrease blood flow and dehydrate the body so definitely stick to water or pre-workout supplements over your usual cup!

The best meals to consume include a healthy balance of protein and high carbohydrate foods. Some great options are a hearty bowl of porridge with a scoop of protein powder or peanut butter, banana and toast! If eating during the day, try to consume a balanced meal with protein and complex carbohydrates like potatoes, rice or pasta 1-2 hours before training. Avoid too much sugar as it may cause insulin spikes and an energy crash during your workout, whereas complex carbohydrates offer stabilisation of blood sugar levels and sustained release of energy.

Many people choose a pre-workout for increasing performance. The best pre-workout supplements should contain a low level of caffeine with ingredients such as citrulline malate, bcaas, glutamine and beta-alanine which are thought to aid blood flow and carnosine stores to help reduce lactic acid. 

During Your Workout

During a workout, your nutrition depends on the duration for which you are training. If you are training for under 30 minutes then water is the best way to hydrate. If you are looking to focus on endurance and training for prolonged periods of time, then more attention needs to be put on your intra-workout nutrition. In order to prevent the build-up of lactic acid and to prolong fatigue, you need to make sure you stay hydrated and also replenish electrolyte and salt stores.

Many runners swear by carrying packets of salt from restaurants on runs to reduce cramps and train for longer. BCAAs are also a great supplement to consume during prolonged workouts as they prevent muscle being broken down as fuel and can act to increase muscle recovery.

IdealfFit BCAAs have been developed to support the body intra-workout using coconut water powder and added magnesium and calcium to replenish electrolytes as well as bcaas and glutamine for essential muscle repair.

Find out more about BCAAs and why they can help your training goals.


If you have not been replenishing electrolytes intra-workout, then be sure to restore hydration and salts post-workout. This can be done through food alone by consuming foods high in magnesium and potassium like bananas, nuts and pink Himalayan salt or can be done through supplementation. If you have been training at a high intensity for a shorter period of time your post-workout nutrition is important but can be as simple as a light protein shake with a banana and should be taken into account of your whole diet and calorie content.

If you have been training for longer periods of time the body’s energy reserves will need to be restored with a combination of sugars, complex carbohydrates and protein for the best muscle recovery. This can usually be done through a balanced meal using a good protein source such as chicken, carbohydrate sources like sweet potato and brown rice and fat sources such as nuts, seeds, oils or avocados. A lot of runners swear by full-fat milk protein shakes following a workout – which delivers a source of calcium, protein, fat, lactose sugars and carbohydrates.


Sophie Seddon

Sophie Seddon

Lifestyle Editor

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