10 Tips for Running in Humidity + How Humidity Effects Running
Running in humidity is dreaded by just about every runner. For runners who live in a mild climate, humidity can take them by surprise when travelling. Runners who live in tropical climates or areas with changing seasons often despise running in the thick of summer.
Heat and humidity pose difficult conditions for runners of all ability levels. Running in high humidity can make a moderate or warm day feel absolutely miserable.
Why is it harder to run in humidity?
Humidity can be deceiving. Cool temperatures with high humidity can still make running feel difficult, and it often takes runners by surprise. Hot weather with high humidity is nearly impossible to navigate. So why is it so hard to run in humidity?
Ultimately, the higher the percentage of humidity, the more saturated the air is relative to the temperature. With more moisture in the air, it’s harder for sweat to evaporate. Breathing while running in humidity can also feel more difficult, as you’re taking in more moisture with the air.
Running in high humidity means that the body has to work harder to cool down. On days with high heat and humidity, the heart rate can be anywhere from 10 – 30 bpm higher with the same level of exertion.
What is humidity?
Humidity refers to the amount of moisture in the air. In most weather apps and forecasts, humidity is recorded as a percentage. The percentage of humidity measures how saturated the air is with moisture.
The difficulty with humidity is that the measurement is relative to the temperature – the higher the temperature, the more moisture the air can hold. When the measurement is not absolute, it is difficult to compare. 90% humidity will feel entirely different in 50-degree temperatures as compared to 80 degrees.
Does running in humidity make it harder to breathe?
In many cases, running in high humidity can make it feel like it’s difficult to breathe. Some runners describe the feeling as trying to run through water, while others just struggle to catch their breath or settle into a rhythm throughout their run.
The reason it might feel more difficult to breathe in high temperatures with high percentages of humidity is that the air is more saturated with water. With each breath, you take in more water and less oxygen than on days with low humidity.
Will humidity slow down the running pace?
Running in humidity may or may not slow down your pace, depending on a variety of factors. The biggest contributing factors are the percentage of humidity and the actual temperature. Conditions are considered “ideal” when humidity is between 30-50%. When humidity creeps above 50%, running might begin to suffer.
Humidity above 70% is sure to slow most runners down. According to Runner’s World, the average decrease in pace is about 30 – 90 seconds per mile when running in high humidity.
Runners who have already acclimated to a humid climate will find it easier to sustain their typical pace, whereas travelling runners who are thrown into humid conditions for a single run or few days will likely experience a decline in performance.
10 Tips for Running in Humidity
1. Run early – beat the heat.
The best way to navigate running in humidity during the hottest months of the year is to run early. The earlier you get started, the cooler the temperature will be. Not only will cooler temperatures make it easier to manage humidity, but the percentage of water the air can absorb will be lower, and the sun won’t be nearly as intense.
2. Reduce your intensity.
Accepting the fact that running in humid conditions is going to affect your performance will help make the necessary adjustments during training.
Rather than pushing yourself to the point of exhaustion, reduce your intensity to make running more comfortable. Remind yourself that the continued effort in humid conditions will pay off when the weather changes in the fall.
3. Wear appropriate gear.
Since running in humidity makes it harder for sweat to evaporate, it’s important to dress appropriately. Dressing in light clothing that is loose fitting will give your skin extra room to breathe when it needs it most.
Aim for shorts and tank tops, or as minimal as you feel comfortable dressing, to keep your skin exposed in the air.
4. Try a visor instead of a hat.
Speaking of giving your body room to breathe, an easy switch to make when it’s humid is to wear a visor instead of a hat. Hats keep air trapped at the top of your head, and dark colours can absorb heat from the sun.
Opting for a visor instead of a hat will provide protection from the sun on your face, without creating extra heat on your head.
5. Take time to acclimatize.
The best way to navigate running in heat and humidity for a long duration of time is to acclimatize to the conditions. Giving your body plenty of opportunities to get outside in the conditions when resting or giving minimal effort will help it adjust and prepare for the harder effort of running.
6. Hydrate with cool water.
It might sound counterintuitive – taking in more water when your body is unable to release much sweat – but staying hydrated is essential when it’s humid.
A simple way to help stay cool is to make sure your water is as cold as possible each time you go to take a drink. Try adding ice or freezing half of it to take on your run.
7. Take breaks when needed.
Trusting your progress and listening to your body is key to maintaining peace of mind when running in humidity. Remember that the same amount of effort when it’s humid might result in a slower pace, but is still building the same amount of fitness.
If you’re struggling during a humid run, allow yourself to take a break. Stop completely or slowly to a walk to give your body time to recover. It’s important to take breaks as needed to avoid any serious issues or complications from the heat.
8. Plan a route through the shade.
High humidity doesn’t always mean that it’s hot and sunny, but any extra heat can really increase the difficulty during a run.
Take the time to plan a route ahead of time that will take you through as many shaded areas as possible to ensure you avoid any extra exposure to the elements – which might make things even more miserable on the run.
9. Check the heat index.
Being prepared is key to successfully navigating running in humidity. Checking the weather conditions ahead of time will allow you to make any adjustments to gear, route or timing.
Be sure to check the heat index and ‘real feel’ temperatures as opposed to the actual temperature. These indexes are adjusted based on all of the conditions and will give you a more accurate representation of what to expect during your run.
10. Listen to your body.
Above all, listening to your body is key when it’s humid. If you’re struggling to keep going, don’t ignore it. Educate yourself about the signs of heat stroke and any other conditions that could result from high heat and humidity.
Running in the Heat & Heat-Related Injury
Heat Exhaustion
Heat exhaustion is caused by dehydration. The symptoms include chills, lightheadedness, dizziness, headache, and nausea. The body temperature is usually between 100 – 102 degrees and profuse sweating is evident.
Treatment should be to get the individual to a cool shaded area and administer fluids either by mouth if conscious or IV if the individual is unconscious. Seek medical advice.
Heat Stroke (a form of Hyperthermia)
Heat stroke is a serious life-threatening medical emergency. It is caused by a sudden failure of the thermoregulatory system of the body.
It may be fatal. Some consider it to lie on a continuum with heat exhaustion. It initially appears similar to heat exhaustion, but may rapidly progress to manifest more serious neurological symptoms: disorientation, loss of consciousness and seizures. The body temperature may be higher than 105 degrees Fahrenheit.
Genetic susceptibility to hyperthermia increases the risk of this disorder. Sweating is often absent, but the skin may be quite moist from earlier perspiration. The core temperature must be brought down immediately.
In fun runs, perspiration is usually noted, and you do not need the absence of perspiration or a rectal temperature to make the diagnosis. There is usually sinus tachycardia present, with the pulse noted to be faster than 160.
The blood pressure may be low. Kidney damage (acute nephropathy) occurs in about 35 per cent of cases. Rhabdomyolysis (muscle breakdown) occurs and myoglobinuria (excretion of muscle breakdown products) contributes to kidney injury.
Liver damage is also evident when liver enzymes are measured following heatstroke. Disseminated intravascular coagulation also occurs in exertional heat stroke. The individual will often be confused and ataxic. Seizures can occur as well as coma.
Ecchymoses (bruised appearance to the skin), hematuria (blood in the urine) and epistaxis (bloody nose) may also be seen and indicate coagulopathy.
Current treatment includes rapid cooling to get the temperature below 102F. Evaporative assistance may help. Spray water, increase airflow and remove restrictive clothing if present. Ice baths or cooling packs for the armpits, groin and neck may also be used.
These are the individuals who get “packed in ice”. Rapid medical attention is vital.
Avoiding Heat Stress Injury
- Hydration: Drink about 20 – 24 oz of fluid 30 – 45 minutes before exercise and then a cupful (4 – 6 oz) every 20 minutes while exercising. After exercise drink another 24 – 32 oz. of fluid. If you are over 40 your thirst mechanism may not be as effective a gauge of your water needs as you age. Drinking fluid, while exercising and after completion will help speed your recovery. Sport replacement drinks are superior to water at longer distances and times (over 60 – 90 minutes). The electrolytes and carbohydrates in them will also help speed your recovery from the stress of fluid loss and your long-distance run. Somehow they do seem to taste great in the heat and the good taste encourages you to drink more and replace your fluids.
- Gradually build up your tolerance for running in warmer weather.
- Stay Fit and don’t overestimate your level of fitness
- Keep track of your heart rate: Your heart rate should stay within 10 beats of what it would normally be during an easy workout.
- Slow up for safety
- Make sure you are aware of both medical conditions you have and medications that can affect your tolerance to exercise in the heat. Medical conditions affecting your heat tolerance include diabetes, high blood pressure, anorexia nervosa, bulimia, obesity and fever.
- Wear lightweight shorts and a singlet rather than a tea shirt, to permit evaporation of perspiration.
- Stop if you have to. Call it an early day if things don’t feel right.
Hyponatremia
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In longer events, in which competitors are running for much longer than a 10-mile distance and staying out and hydrating themselves over a longer period hyponatremia is a large concern. Of particular concern are events which take longer than 4 hours. This problem was brought to the fore by Dr Tim Noakes who had vast experience with ultra events, particularly the Comrades Marathon.
Hyponatremia is a more dangerous and insidious problem than dehydration. Hyponatremia, by definition, is low blood sodium (below 130 mm/L). In athletes, it most often occurs primarily because of overhydration.
Over the past 20 years, much attention has been paid to proper hydration, in some cases, going over the line into overhydration. The drink till you slosh theory, is a bad one for marathoners. Many years ago salt pills were in vogue for athletes, and then they were called ridiculous.
For runners who are out for 4+ hours, it may be time to rethink this and strongly consider bringing back a bit of salt again. On the other hand, a simple weight check can help keep your hydration under control.
Weigh stations have been proposed. Check your weight at the start, and make sure you aren’t gaining weight as you continue along the race course.
The symptoms of hyponatremia include lightheadedness, a blurring of consciousness, nausea, vomiting, and dizziness. With increasing severity, the athlete may become unconscious, have seizures or stop breathing.
The symptoms of hyponatremia and heat injury are similar and are differentiated by a blood test, aided by keeping in mind the possibility of hyponatremia in long distance, long time, events.
While Gatorade and other sports drinks include more electrolytes than water, they do not include enough to treat hyponatremia.
Dangers of Running in High Humidity
In most scenarios, running in humid conditions is still safe. Runners should stay alert for any possible signals that might point towards the start of a major health issue. These are some of the ones you should be aware of.
- Overheating – goose bumps, feeling faint, dizzy or fatigued
- Heatstroke – hot skin, confusion, exhaustion, high body temperature
- Heat cramps – excess sweating, muscle spasms or twitches
- Heat exhaustion – confusion, weakness, headache, nausea
- Dehydration – lack of urination, thirst, lightheadedness, fatigue, dry skin
