Exercising In Hot Weather: How To Train Safely This Summer

Published on

28/8/2026

In most cases you don't need to give up exercise in hot weather - you need to move it. Train in the early morning or the evening rather than the hottest part of the day, ease off strenuous effort when it is very warm, drink regularly, and build up gradually. Stop and rest if symptoms appear.

Summer is one of the easiest times of year to be more active, and it is worth doing. The British Heart Foundation puts the reduction in risk of heart and circulatory diseases from being physically active at up to 35% [1], and recommends that adults do at least 150 minutes of moderate intensity exercise per week [1].

Heat doesn't cancel that. It changes how you go about it, and makes one or two things worth checking before you push harder.

Why Does Hot Weather Make Your Heart Work Harder?

Because cooling you down takes effort. Hot weather means your body has to work harder to keep its core temperature at a normal level, which can put extra strain on your heart, lungs and kidneys [2]. It does this by opening your blood vessels wider than normal - vasodilation - while your heart beats quicker to help pump blood around your body [2].

The British Heart Foundation also notes that some types of exercise, such as running and football, can make you very hot and dehydrated, and will put extra pressure on your heart during hot weather [2]. So if your usual run feels harder in August than in April, that is your body doing what it should - a reason to adjust the session, not to abandon it.

Should You Stop Exercising When It Is Hot?

For most people it is a case of moving the activity rather than cancelling it. GOV.UK advises limiting the amount of strenuous physical activity you do during the hottest part of the day, and planning it for cooler times such as the early morning or the evening [3]. The British Heart Foundation advises staying out of the sun during the hottest part of the day, between 11am and 3pm [2].

On days of extreme heat the advice tightens. NHS heatwave guidance is to stay in the shade especially between 11am and 3pm, and to avoid exercise or activity that makes you hotter [4]. That is heatwave advice: scale right back on those days rather than giving up activity for the summer.

How Should You Adjust Your Training In The Heat?

Beyond timing, small changes do most of the work. These are general principles from NHS, GOV.UK and British Heart Foundation guidance, not personal advice.

Start low and slow - a session could be as little as 5 or 10 minutes [5], and a brisk walk counts. If you're beginning a new activity, build up gradually [6].
Use the talk test: at a moderate intensity your breathing rate has increased but you are still able to talk and continue exercising comfortably [6].
Start and finish at a slower pace to allow your body to prepare and recover [6].

How Much Should You Drink When You Exercise In The Heat?

Regularly, rather than waiting until you are thirsty. GOV.UK advises drinking fluids regularly throughout the day, especially if you are physically active, and drinking enough that your pee is a pale straw colour [3]. Water, diluted squash and lower-fat milk all count, with alcohol limited [3]. Our article on fuelling your exercise covers what to eat and drink around a session more generally.

Who Should Take Extra Care Exercising In Hot Weather?

Some people are more affected by heat than others. The British Heart Foundation lists adults over 75, very young children, people with long-term heart or circulatory conditions, and people with kidney problems or diabetes [2]. GOV.UK adds people aged 65 and over, children under 5, people with breathing problems, mobility problems or Parkinson's disease, and pregnant women [3].

Medicines matter too: NHS guidance names people on multiple medicines, or medicines that may make them more likely to be badly affected by hot weather [4]. A GP or pharmacist can tell you whether that applies to yours. The British Heart Foundation also advises speaking to your doctor before beginning any physical activity for the first time [5].

What Is Worth Getting Checked Before You Push Harder?

A few symptoms are worth taking seriously rather than training through. The British Heart Foundation puts it plainly: you should not start any exercise if you are currently feeling symptoms, and should stop and rest if you notice them during your exercise [5]. Its guidance for people exercising with a heart condition adds a stop list - stop exercising if you experience any chest pain, palpitations, dizziness or light-headedness [6]. These are reasons to get something looked at, not predictions of disease.

Chest pain that comes on with exertion. The NHS notes that angina pain is often brought on by exercise, stress, emotion or cold temperatures, and advises getting help from NHS 111 for chest pain or other symptoms of angina that come and go [7]. More on chest pain.
Breathlessness that is unusual for you. The NHS advises seeing a GP if your shortness of breath gets worse when you've been doing your normal activities, or when you lie down - and adds that you're not wasting anyone's time by getting it checked out [8]. More on breathlessness.
Palpitations. The British Heart Foundation includes palpitations - the feeling that your heart is pounding or skipping a beat - among the symptoms to stop exercising for [5][6]. The NHS advises seeing a GP if they keep coming back, last longer than a few minutes, or you have a heart condition or a family history of heart problems [9]. More on palpitations.
Fainting or blacking out. This one is different. The NHS lists having fainted while exercising among the situations in which to call 999 [10]. If you have fainted and recovered, it still advises seeing a GP to get it checked [10]. More on blackouts and loss of consciousness.
Dizziness or light-headedness during activity. On the stop list above [6], and worth assessing if it keeps happening. More on dizziness.
Unusual tiredness. Tiredness has many causes, most of them not related to the heart. The NHS does list feeling weak, light-headed or very tired, particularly after moving or doing physical activity, among the symptoms of heart failure [11], so a change that persists is worth raising. More on tiredness and fatigue.

LivingCare is a specialist outpatient service and is not an emergency care facility. If your symptoms are sudden or severe, call 999.

Frequently Asked Questions

Is it safe to exercise in hot weather?

For most healthy adults it is manageable with sensible adjustments - training when it is cooler, easing off strenuous effort in the middle of the day, and drinking regularly [3]. Heat does make your heart work harder [2]. On heatwave days, NHS advice is to avoid activity that makes you hotter [4].

How do I know if I am working too hard in the heat?

The talk test is a useful guide: at a moderate intensity your breathing rate increases but you can still talk and keep going comfortably [6]. If you develop chest pain, palpitations, dizziness or light-headedness, the advice is to stop and rest [6].

When should I see a cardiologist about symptoms during exercise?

If you notice new chest pain on exertion, breathlessness that is unusual for you, palpitations, dizziness or a blackout, it is worth having them assessed before you increase your activity [5][6]. If you have fainted while exercising, the NHS advises calling 999 [10].

Book A Cardiology Assessment

LivingCare's consultant cardiologists provide private cardiology assessment in Leeds and Sheffield - at Thorpe Park Clinic in Leeds and Canon Medical Arena in Sheffield. If something has been niggling when you exercise, you can be seen quickly and find out what is behind it: no GP referral needed, self-pay or insurance. Exceptional care, without the wait.

If you are building towards an event this summer, cardiac screening for sport and events is another route in.

Book a cardiology assessment