Health & Wellbeing

Working Out When It's Hot Outside

With a summer that promises to be the hottest on record, above-average temperatures are also putting the heat on your training regime. Heat and humidity combine to place extra stress on the body as we work out in warmer weather, making a hard training session even tougher. That said, there’s no need for rising mercury to put a stop to your training and in fact warm weather may even boost performance by naturally increasing training intensity. Here’s how to exercise safely in the summer heat…

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WHAT HAPPENS WHEN WE WORK OUT IN WARM TEMPERATURES?

Perspiration is the body’s natural cooling system – when we train hard, we sweat hard. As we exercise, our core body temperature rises and the body works to counter this by drawing heat from our muscles into the blood vessels. This excess heat then circulates to our skin where evaporating sweat draws heat from the blood capillaries, and cooler blood then circulates back around the body – reducing our core body temperature.

When we exercise in warm weather this effect is magnified as air temperature and humidity push up core body temperature even further. This puts extra stress on the body as the body’s cooling system kicks in and the body sweats harder. Blood volume and pressure decrease, as the body sends more blood to circulate through the skin. This means the heart has to work harder, increasing heart rate and effort, in turn bringing on exhaustion faster. This could potentially bring an early end to your session and make it impossible to sustain your usual training intensity.

So, how can we counter this effect?

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HYDRATE, HYDRATE AND HYDRATE

Staying hydrated is crucial to the evaporative cooling process. On average, we lose a litre of water through sweating per hour of exercise, and exercising in warm temperatures can increase that to up to 3 litres! If we don’t replace fluids lost during exercise, the body’s natural cooling system fails - dehydration occurs and the body overheats. This can reduce training performance by between 20 and 30%, or worse, will increase the likelihood of heat related illness such as cramps, heat exhaustion and even heatstroke.

Make sure to hydrate throughout the day and pre, during and post exercise, avoiding caffeine, alcohol and high sugar drinks. While exercising in warm weather, you should rehydrate around every 15-20 minutes, and it’s important not to wait until you feel thirsty - if you feel thirsty you’re already dehydrated.

At the same time, it’s important not to drink too much, as this can lead to the potentially dangerous condition hyponatremia. You can monitor your hydration levels by checking your urine – it should be the colour of pale straw. The darker it is, the more dehydrated you are.

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WORK TO EFFORT - NOT METRICS

As the body sends blood to the capillaries to aid cooling, blood volume drops - meaning the heart has to work harder to maintain workload. That means that your relative intensity and effort level will increase, and you’ll max out faster.

This means you’ll need to reduce intensity to be able to complete your session safely. Forget your usual training metrics such as maintaining a target pace and instead concentrate on feel and effort – this is working to your perceived intensity. A heart rate monitor can be particularly useful here in definitively gauging how hard you’re working.

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WEAR LIGHT, BREATHABLE CLOTHING

The body’s cooling process only works if moisture evaporates from skin. That means that fabrics such as cotton that cling onto sweat and actively hinder evaporation really are an absolute no in warm weather. Always wear lightweight, breathable fabrics that wick moisture away from the skin. Extra ventilation will also help this cooling effect – look for mesh panels in key heat areas such as under the arms, at the lower back or behind the knees, as well as in-shoe cooling systems that release heat. Our gym store is the perfect place to start!

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WATCH OUT FOR HUMIDITY

Grey, humid days and stuffy gyms are equally as potent as direct sunshine. Humidity makes it harder for sweat to evaporate because the air is already saturated with water. That means that even though you’re sweating, there is no cooling effect and you are just as likely to overheat. Keep a close eye on your effort levels on very humid days and adjust your intensity accordingly.

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TIME IT RIGHT

It goes without saying to avoid exercising at the hottest time of day. Avoid training between 12 and 3pm when the sun is at its hottest - and if you’re exercising outside, always wear a protective barrier of sun screen against UV rays. If you can, try to exercise in the early morning or late evening to avoid the worst of the heat.

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KNOW WHEN YOU ARE OVERHEATING

It’s important to know the early signs of heat exhaustion and when you must stop your training session immediately. Early symptoms can include heavy sweating, tiredness, thirst and muscle cramps, which can then develop into weakness, dizziness, headaches, cool and moist skin, nausea or vomiting.

At the first sign of any of these symptoms, immediately stop your training session, get out of the heat and drink water or a sports drink. If you’re not feeling better within an hour, seek medical advice. At the first sign of heatstroke, seek emergency medical attention. Symptoms include fever, red hot, dry skin, rapid shallow breathing, weak pulse, confusion and a loss of consciousness.

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WHAT ABOUT AIR CON?

When it’s hot, an air-conditioned gym can seem like a godsend. Put simply, air conditioning cools air temperature and reduces humidity which has the effect of cooling core body temperature. This increases productivity and results in an effective, comfortable training session. But, there are disadvantages to air con too. Cooler temperatures mean less energy, it takes longer to warm up properly and the risk of injury is increased.

There are also potential performance benefits to exercising outside in warm weather or inside a non-air-conditioned gym. One study conducted by the University of Oregon found that heat acclimation exposure boosted performance in highly trained cyclists by improving the body’s ability to control body temperature and blood flow through the skin and expanded blood volume. There is also evidence to suggest that there is increased calorie burn from working out in warmer conditions, as the heart works harder to pump blood around the body. The downside is that increased effort makes it harder to sustain intensity and may cut a training session short.

Ultimately, when working out in the summer heat it’s important to listen to your body and to exercise safely. Take precautions, reduce intensity and monitor your effort - and at the first sign of heat related symptoms, know when it’s time to stop.

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