Running In Hot Weather: Tips and Precautions

For many people, running in hot weather may be considered a dreaded activity; something they will typically avoid if possible. 

There is no denying that the heat makes most activities more challenging, but with that added challenge also presents an abundance of benefits for the body; so running in high temperatures certainly shouldn't be something you’re running away from!

However, before slipping into your running shoes, it is important to know any warning signs, risks, safety measures to take and also when to stop. We have put together this guide of tips and precautions you can take to stay safe and comfortable when running in hot weather.

We will cover:

• Why is it Difficult To Run in Hot Weather?
• Tips for Running in Hot Weather
• Risks of Running in Hot Weather
• FAQs

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Why Is It Difficult To Run In Hot Weather?

If you're looking to become a running coach, it's important to understand what is happening to the body when running in hot weather. During a run or any exercise, your body temperature increases because your working muscles raise your body temperature. This is where your body’s natural cooling system kicks in. It increases blood flow to the surface of your skin, giving you the infamous red running face, and increases the all important sweat. 

Sweat evaporating from the skin is what cools us down and aids us to keep on going; because high temperatures and humidity puts greater strain on this cooling process. 

Running in hot weather raises the core temperature even higher. The heart rate increases as more blood is pumped to the skin, which means less blood for your working muscles. 

Tips for Running in Hot Weather

#1 Give Yourself Time to Acclimatise  

If there is one tip that all seasoned runners can agree on is the lauded advice to acclimatise and get used to the warmer temperature before heading out on a 10K in 25 degree heat. Not only will this make running in hot weather more comfortable for you, it will improve your  overall performance due to a higher endurance level. 

According to an article published by Gatorade Sports Science Institute, the signs of heat acclimatisation are: a lower heart rate, lower core temperature and a higher sweat rate. These signs make it easier for you to recognise when you’re at less of a risk and can run in hot weather safely. 

Additionally, heat climatisation can be characterised by skin temperatures being lower, sweating starts earlier and you will have a lower overall core temperature.

The good news is, it only takes around two weeks for the body to acclimatise and it adjusts faster in response to heat. Even resting in the heat, or exercising in a temperate environment allows for some limited acclimatisation. 

Spring is an ideal time to start heat running training as the gradual rise in temperature and running regularly on warm days will make the hotter days that more bearable.

#2 Check Temperature and Humidity Levels 

Running in hot, humid weather is even tougher on the body’s cooling system, as higher moisture levels in the air can make it feel even more intense. It’s also more difficult for sweat to evaporate from the skin, which is what works to cool us down.

Not only will the body struggle to lose heat, running in extreme heat and humidity will increase the heart rate even more, with humidity that falls between 50-90% can increase heart rate up to 10 beats per minute.

What this means for your running is that you may find you’re stopping to rest more often and becoming breathless easier, this comes as a result of a higher heart rate negatively impacting the amount of oxygen being pumped around the body and the speed in which it does so.

According to a 2016 study that examined how trained distance runners responded to 31°C at varying relative humidity (RH), the results found that RH had a significant effect on heart rate. During steady-state exercise, the heart rate was significantly higher in the environment of 61% and 71%  humidity, comparable to the 23%  RH trial group.

An increased heart rate puts you at greater risk of overheating and developing a heat-related illness - particularly in those that are always working at a higher heart rate. Therefore, it’s important to remember that cloudy days can be deceiving, so always check both temperature and humidity levels.

#3 Plan a Well-Shaded & Flat Route 

Before running in hot weather, plan a route that will keep you out of direct sunlight, or at least for the majority of your run. 

One of the important tips for running in hot weather is to stay in the shade as much as possible and save those hill climbs for cooler temperatures. With your body working harder than usual, it’s best to stick to flat routes with plenty of rest spots.

The more trees on your route to cool the air, the better. Their canopies intercept sunlight, block heat from reaching the surface and keep you sheltered. When hot weather running, try to take a route through your local park, forest path, or try trail running to get away from urban areas.

Roads and buildings absorb heat and raise the temperatures even higher which, as you can imagine, isn’t ideal for running in 30 degree heat. However, running through rough terrain will also force you to slow down and keep you even cooler. 

#4 Avoid Running In Extreme Heat

Although there isn’t a perfect time of day for running in hot weather, or avoiding the heat and humidity entirely; running closer to sunrise or sunset when temperatures are lower is best during the hotter months. 

It is best to avoid running in high temperatures that tend to fall between 10am and 4pm, as this is when the sun’s intensity is at its greatest. 

If it suits your schedule, rise early to avoid the sweltering heat and improve your mood for the day ahead. When you exercise, your body releases endorphins, also known as ‘happy hormones’. This reduces your perception of pain, boosts self-esteem and triggers a positive feeling.

Running in the afternoons or evenings is also a great option to avoid extreme heat; it’s important to stay safe when running early or later on in the day. So, be sure to wear reflective running attire for hot weather, and take care if running with headphones.

#5 Wear The Right Running Attire For Hot Weather

Running in the hot and humid weather calls for clothing that will aid you and your performance. 

The clothing you wear during any form of training is often overlooked, however we strongly advise opting for loose-fitting, lightweight clothing with light colours to reflect the sunlight, rather than dark colours which will in fact latch on and store heat. 

A lightweight running hat or visor (which you can freeze the night before or dampen with cold water) will keep the sun from your eyes, protect your head and reduce the risk of encountering heat and sun stroke. 

When it comes to materials, look for breathable and moisture-wicking fabrics. They allow hot air to escape, whilst pulling moisture away from your body. This type of fabric enables sweat to evaporate; the best fabrics for running in higher temperatures are nylon, polyester and polypropylene. 

If there is one fabric we suggest staying away from however, it is 100% cotton. Though breathable, cotton absorbs sweat and won’t dry quickly, so it's likely to become uncomfortable and ultimately affect your performance. 

#6 Protect Your Skin And Eyes 

Sunburn is another factor that plays a role in preventing the skin from cooling itself down when running in hot weather, as well as the whole host of other issues it promotes. 

For this reason, we recommend covering all exposed skin in waterproof sunscreen with an SPF 30 or higher 30 minutes before heading out on your run. If you run for longer than an hour, be sure to take some with you to reapply. 

To prevent skin feeling greasy or uncomfortable, look for oil-free, water-resistant and fragrance-free formulas. Sprays or stick sunscreens are great for runners who need quick absorption and easy application. 

It is important to note that sunscreen alone will not completely protect you from all of the effects of a hot summer day, so to be extra precautious, it’s best to wear clothing that covers your skin. 

If this has got you wondering should you run in hot weather when the sun is shining? The best advice when running during the summer months is to spend time in the shade to reduce exposures or, and wear sunglasses; this will assist in preventing headaches and work as a visual aid. If you follow all safety measures, then we still encourage you to partake in your usual running routine without hesitation.

Chafing and heat rash from running are caused by friction, sweating and clogged sweat glands. These tips for running in the heat should also prevent these issues from happening, particularly the tips regarding sunscreen use, loose clothing, hydration and keeping your skin cool. 

Another tip is applying moisturisers and balms, as this can also keep skin comfortable and friction-free. 

#7 Keep Yourself Cool

Running in hot weather puts your body to the test and it can often feel challenging to cool down, but what can you do to support your body’s cooling system? 

A great tip is to freeze your bottle of water the night before, and take it out the freezer 15-20 minutes before you run. The ice will thaw in time for your run and the water will stay colder. 

Don’t overdo your warmup, with the temperatures being higher, your muscles will warm up quicker. A 5-10 minute walk before you start running will help you adjust to the temperature without overheating.

Whilst running, pause to splash water on your head, back of the neck, under arms and insides of your wrists. Be careful not to get your feet wet - blisters are the last thing you need!

#8 Stay Hydrated

One of the most important tips for running in the heat, and simply running in general, is hydration, and this includes ensuring your body is well hydrated before you even head out.

If you’re wondering about how to run in hot weather safely, the first measure to take is to start with a full glass of water and to then continue to drink regularly throughout the day, especially if you are running in the afternoon or later that evening. 

Ensure you take a bottle of water on your run to top yourself up. Drinking sips of water approximately every 10 minutes will keep you hydrated efficiently.

Stick to water, sports drinks, diluted fruit juices and teas during the summer months for the best advantages of hydration. Avoid drinking alcohol or coffee before or after your run as they increase the rate of dehydration. 

#9 Adjust Your Expectations  

Running in the heat and humidity affects performance. It can be frustrating, but we recommend adjusting your expectations and fitness goals when running in hot weather. Save your fitness challenges for cooler months.

Slowing down will help you produce less heat and improve your endurance. As you begin to acclimatise and feel more comfortable running in hot weather, you can gradually increase your pace and duration if it feels right. 

If your running is goal-driven, try running without a measuring device to let your body guide you. The focus for hot weather running should be a steady and endurable pace to avoid overheating. 

#10 Take Breaks & Incorporate Interval Training 

We’ve covered the safety measures for running in hot weather, but what about how to run in hot weather? 

Running at a continuous, steady pace and for long intervals causes your heart rate to increase. Your body is consequently working harder to regulate your core temperature, which can in turn - lead to overheating.

The practice interval training can be useful, as by variating paces of exercises gives you a chance to recover and cool down during the lower intensity durations.

Although the production of heat is much greater during interval training, rests between each interval allows your body to lose some excess heat. So welcome those stationary rests in the shade, or take a break by walking; you’ll still keep your heart rate up all the while.

#11 Cool Down Post-Run And Aid Recovery

Congratulations! You successfully completed your endeavour of running in hot and humid weather. It’s time to seek a cool, shaded area to stretch, drink water, and allow your heart rate and breath to return to a normal rhythm. 

Firstly, we suggest taking a shower as soon as possible following your run and avoid sitting around in sweaty clothes - this can result in bacteria build-up and cause infections or skin issues. If you can’t shower immediately, have a change of clothing with you. 

Your body will need longer to recover when it’s very hot, so be sure to have plenty of rest days or choose alternative exercises that you can do indoors out of the sun. Further, the digestion of stodgy foods such as this, can use alot of your energy alone; therefore you’ll become fatigued more easily.

If you suffer from diarrhea after running in the heat, pay attention to what you eat prior to setting off. For instance, high-fibre or high-fat foods could be the culprit causing a problem as fibre carries water-absorbing properties, which makes passing a lot easier.

#12 - Fill Up On Vitamins and Minerals 

Not only does the heat make running harder, it can also hamper recovery. Valuable vitamins and minerals are lost through sweat and muscle repair in hot weather. Therefore, it’s important to get enough of the right nutrients to support your recovery and replace any necessary nutrients that you are losing. 

Running in hot weather means more sweat and less electrolytes. Electrolytes are elements such as: sodium chloride (salt), potassium, magnesium and calcium. Below are other key vitamins that can be lost in hot weather, and what you can eat to replace them.

• Sodium Chloride: salted nuts, trail mix, crackers, popcorn, pickles, jerky
• Potassium: bananas, melons, oranges, grapefruit, kiwi
• Magnesium: pumpkin seeds, figs, cashews, peanuts
• Calcium: dairy products such as milk, yogurt and cheese, dairy-free milk drinks with added calcium, green leafy vegetables
• Iron: red meat, beans and pulses, nuts, dried fruits such as apricots, fortified breakfast cereals
• Vitamin C: citrus fruits, peppers, berries, broccoli, potatoes 
• Zinc: meat, shellfish, dairy foods, bread, fortified breakfast cereals

Risks Of Running In Hot Weather

Following our tips will help with the prevention of heat-related illness, such as: after-running heat exhaustion, heat cramps or heat stroke while running. Nevertheless, it is still important to know the signs so you can recognise if you or anyone else is encourneting any weather-related issues after a run.

#1 Heat Exhaustion

While heat exhaustion does not present a serious issue if you cool down within 30 minutes, if you were to continue running beyond the point of it occurring, you could be at risk of encountering heat stroke if not treated.

Symptoms of heat exhaustion include:

• Headaches
• Dizziness and confusion
• Loss of appetite and feeling sick/vomiting
• Excessive sweating and pale, clammy skin
• Muscle cramps in the arms, legs and stomach
• Fast breathing or pulse
• A high temperature of 38°C or above
• Dehydration and feeling very thirsty 

If you experience these symptoms, it’s time to stop and cool down. Seek shade, drink plenty of water and splash water on yourself to cool down your skin. It also helps to lie down and raise your feet slightly. You should begin to feel better within 30 minutes. 

#2 Heat Cramps

Heat cramps are painful, brief muscle cramps that cause the muscles to spasm or jerk involuntarily. These can occur during exercise in a hot environment or begin a few hours later. 

They’re a result of lost salt and water throughout the body after or during exercise and can often be prevented by an adequate amount of fluids before you commence your run, look out for the following to stay safe:

Symptoms:

• Painful
• Involuntary
• Brief
• Intermittent
• Usually go away on their own

If the symptoms do not go away with rest or after restoring fluid and electrolytes, seek medical attention. 

To stay safe, check out the best running water bottles to keep you hydrated here.

#3 Heatstroke

Heatstroke is a serious, potentially life-threatening form of heat illness that needs medical attention as soon as possible. Your body’s cooling system completely shuts down at this point, sweating ceases, and your skin becomes very hot and dry. 

Advice from the NHS is to call 999 if you or someone else have any signs of heatstroke

Symptoms: 

• Still feeling unwell after 30 minutes of resting in a cool place and drinking plenty of water
• Not sweating even while feeling too hot
• A high temperature of 40°C or above
• Fast breathing and shortness of breath
• Feeling confused
• Seizures
• Loss of consciousness
• Not responsive 
• Neurological symptoms such as delusions, hallucinations, irritability or odd behaviour 

FAQs

• Is running in hot weather bad for you? 

Should you run in hot weather? The answer will depend on your own health and fitness levels. Knowing your limits and listening to your body will help you avoid the consequences. 

Running in hot, humid weather comes with health risks, such as heat exhaustion and heat stroke, but with enough preparation, hydration and applying the tips we have mentioned, you can still enjoy running during those hotter months and stay safe at the same time. 

Fortunately, the body will adapt to the warmer climate and learn to cope better overtime. Follow our running in heat tips to help your body adjust, rather than pushing it beyond its limits. 

• Does running in hot weather burn more calories? 

There are many variables which will affect how many calories a person burns when working out. Some factors are genetic and out of our control, but running in hot weather feels more difficult, so does that mean we burn more calories? 

The answer is yes - you can burn more calories when running in the heat, and even when resting, because the cardiovascular system (heart, lungs, veins and arteries) is working harder to cool itself down and maintain a steady body temperature. 

The Medicine and Science in Sports and Exercise published two studies examining the relationship between temperature and exercise. In one study, nine male subjects cycled for 90 minutes in ambient temperatures of -10, 0, 10 and 20°C. During the two colder temperatures, more carbohydrate was used for fuel and less fat was burnt during the warmer temperatures. 

In a second study, eight male cyclists rode to exhaustion in four different temperatures of approximately 4, 10, 20 and 30°C. Exercise duration was shortest at 30.5°C and longest at 10.5°C. This shows that cycling was best performed in moderate temperatures, because the cyclists rode for the least amount of time in very cold and very hot temperatures. 

Both studies show that the best environment for; exercising for long periods of time, burning more fat and more calories, are in moderate to warm temperatures. Without the extra heat, you can achieve better results and burn more calories, because you can run for longer durations without the health risks and added stress on the body. 

• Is it better to run when it’s hot or cold?

If you are mentally and physically comfortable during a run, you will notice improved performance and results. This is why runners may find it both easier and better to run in the cold and cooler temperatures as opposed to the heat - as lower temperatures tend to reduce stress on the body. 

Research performed by London Winter Run tested this theory using six athletes. They carried out 40 minute runs at 22°C and 8°C. The results found that warmer conditions were more challenging for the body and runners’ heart rates were on average 6% higher.  

Whether you’re training for an event or running for enjoyment, you may find colder conditions better. Your heart rate and the body’s dehydration levels are lower and the body needs less water on a cold day than in warm weather. 

Exercise also already warms up the body, so it’s much easier for the body to warm up than to cool down during a run. With all that being said, the benefits of running in heat are vast and though it may present more of a challenge, it is certainly worth it in our opinion.

• What are the benefits of running in hot weather? 

If you follow these running in heat tips to avoid danger and discomfort, heat running training comes with many benefits if committed to. It can ultimately make you run faster and more efficiently in all temperatures.

The benefits include:

• Improved cardiovascular fitness
• Decreased heart rate
• Increased oxygen consumption
• Your body gets better at maintaining a healthy core temperature
• The body sweats sooner and contains less salt, maintaining electrolyte balance and cooling you down faster. 

Chris Minson, a professor of human physiology at the University of Oregon, studies heat acclimation responses in athletes. According to his research, heat training can expand blood plasma volume. Plasma is the liquid component in your blood and if the volume is increased, the body can send blood to cool your skin - without lowering the supply of oxygen to your muscles. 

Before You Go!

You may not be able to run at the same pace or cover the same distance as you do in cooler climates, but remember, the body is working harder than normal to keep you going. 

Make it easier and safer for yourself by enabling your body to cope and adjust, and you’ll be set for a great summer ahead of running. If you’re an avid runner, gym goer or just an all round fitness fanatic; why not check out our L3 PT Diploma. You can also browse our range of CPD courses here to expand your knowledge in the industry.

References

1. Michael N. Sawka, Julien D. Périard, Sébastien Racinais, Heat Acclimatization to Improve Athletic Performance in Warm-Hot Environments. Gatorade Sports Science Institute (2016).
2. Ahmad Munir Che Muhamed, Kerry Atkins, Stephen R. Stannard, Toby Mündel, and Martin William Thompsond, The effects of a systematic increase in relative humidity on thermoregulatory and circulatory responses during prolonged running exercise in the heat. Temperature (Austin) (2016).
3. Joseph D Layden, Mark J Patterson, Myra A Nimmo, Effects of reduced ambient temperature on fat utilization during submaximal exercise. Medicine and Science in Sports and Exercise (2002).
4. S D Galloway, R J Maughan, Effects of ambient temperature on the capacity to perform prolonged exercise in man. Medicine and Science in Sports and Exercise (1997). 
5. Santiago Lorenzo, John R. Halliwill, Michael N. Sawka, Christopher T. Minson, Heat acclimation improves exercise performance. Journal of Applied Physiology (2010).