Training in Heat and Cold

Quick Intro

In the heat, slow down, drink to thirst and build up gradually, since the body takes a couple of weeks of regular exposure to adapt. Stop and cool down at the first signs of heat exhaustion, such as dizziness, nausea, heavy tiredness or a headache. In the cold, warm up longer and keep warm between efforts, because cold muscles lose some of their power, and cover your mouth in very cold air.

This article gives practical, non-medical guidance for both. If you have a heart or lung condition, asthma or another health condition, follow your own medical advice.

Training in the Heat

Hot weather makes the same effort feel harder, because your body is working to cool itself as well as to move.

Your body adapts. Regular exercise in the heat brings real adaptations over roughly one to two weeks: you sweat more readily and the heat feels more manageable. Sports bodies build training up gradually over the first two weeks in hot conditions for this reason.

Practical tips:

Lower your pace or effort on hot days, and expect to go slower than usual.
Train at cooler times, such as early morning or evening.
Seek shade and choose routes with water available.
Wear light, loose, breathable clothing and a hat in the sun.
Drink before, during and after, guided by thirst, and a little more on very hot days or long sessions.
Build up gradually if you are new to the heat or have travelled somewhere hot.

Warning Signs of Heat Exhaustion

Stop exercising, move somewhere cool, loosen clothing and drink if you notice:

heavy tiredness or weakness,
dizziness, light-headedness or feeling faint,
headache,
nausea or vomiting,
muscle cramps,
a fast heartbeat,
pale, clammy skin.

If symptoms do not improve quickly once you have cooled down, or if someone becomes confused, stops making sense or collapses, get emergency help. Heat stroke is a medical emergency and can come on without much warning.

Training in the Cold

Cold weather brings different challenges. Muscles work less well when they are cold: jump and sprint performance and strength all fall as muscle temperature drops. In one study, a light walk after sitting in the cold was not enough to restore muscle temperature or jumping performance.

Practical tips:

Warm up longer and a little harder than usual, until you feel properly warm. Do I really need a warm-up and a cool-down? gives a simple warm-up.
Keep warm between efforts. Avoid long pauses in the cold, and put a layer back on if you stop.
Dress in layers you can remove as you warm up, with gloves and a hat.
Protect your airways. Breathing very cold air can make the airways narrow, especially in people prone to it. A scarf or face covering over the mouth warms the air.
Watch the ground. Ice and wet leaves raise the risk of slips. Shorten your stride and slow down on slippery surfaces.
Be seen. Winter days are short, so wear bright or reflective clothing in low light.

Indoor Options

On days that are too hot, cold or icy to train safely outside, an indoor session works just as well. A bodyweight circuit, stair climbing or a class keeps you going without the weather. Getting fit at home with no equipment has a routine.

Who This Applies To

This guidance suits most healthy adults. Older adults, children, people with heart or lung conditions, people with asthma and anyone taking medication that affects temperature or fluid balance may be more affected by heat and cold and should follow advice from their doctor.

FAQ

How much should I drink when exercising in the heat?

Let thirst guide you, drinking before, during and after the session, with a little extra on very hot days or long efforts.

Is it safe to run in freezing weather?

For most healthy people, yes, with a good warm-up, warm layers, a covering over the mouth in very cold air and care on icy ground. People with asthma should follow their own medical advice.

How long does it take to get used to exercising in the heat?

Usually around one to two weeks of regular, gradually increasing exercise in the heat.

Can I exercise during a heatwave?

You can, with care. Train at the coolest time of day, lower your effort, choose shade or an indoor space and stop at the first warning signs. On the hottest days, an easy session or a rest day is a sensible choice.

Why do I feel weaker in the cold?

Cold muscles produce force less well. A longer warm-up and keeping warm between efforts help.