Exercise intensity

Exercise intensity refers to how hard your body is working during physical activity. The right intensity for you depends on your health and fitness goals as well as your current fitness level. Intensity is usually described as low, moderate, or vigorous.

For the most health benefits, the aim is to work hard but not too hard, which is generally described as moderate intensity. A common recommendation is to aim for at least 30 minutes of moderate-intensity activity on most days, alongside the broader message to move more and sit less.

Screening before you start#

Pre-exercise screening is used to identify people with medical conditions that may put them at higher risk of a health problem during physical activity. Think of it as a filter or “safety net” that helps you weigh the potential benefits of exercise against the risks. It is worth working through a self-screening checklist before you begin any new activity or exercise program.

The advice here applies equally to women and men.

See your doctor for a check-up before starting a new exercise program if you have a medical condition, are above a healthy weight, are over 40, or have not exercised in a long time. Your heart rate target range may need to be recalculated by a professional to account for your health and fitness. Some medications can change how your heart rate responds to exercise, so discuss any medicines you take and how they might affect your plans. If you take certain medications, you may need to use a method other than heart rate to gauge intensity.

There are several ways to measure exercise intensity. You may need to experiment to find the method that suits you best.

Three ways to measure intensity#

1. Target heart rate#

Your body has a built-in intensity gauge: the heart. Your heart rate rises in proportion to how hard you are working, so you can track and guide intensity using your Target Heart Rate (THR) range.

For moderate-intensity activity, your THR should be about 50 to 70 per cent of your maximum heart rate. Maximum heart rate is based on age and can be roughly estimated as 220 beats per minute (bpm) minus your age. Because this is only an estimate, use it with caution.

• If you are new to regular exercise, keep your heart rate at the lower end of your range and build up gradually as your fitness improves.
• Keep your heart rate in the lower ranges during warm-up and cool-down.
• A heart rate monitor makes tracking easy, or you can take your pulse by hand.

As a rough guide, the moderate-intensity target range (50–70% of maximum heart rate) falls at roughly 100–140 bpm at age 20, around 90–126 bpm at age 40, and around 80–112 bpm at age 60, decreasing with age.

Taking your pulse#

Checking your pulse at intervals tells you whether you are working within your target range. A simple routine is:

• Take your pulse before you warm up.
• Take it again after about 5–10 minutes of exercise.
• Continue checking at regular intervals.

The radial pulse is on the inner wrist. To measure it, place the first three fingers of one hand on the inner wrist of the other, just below the thumb, and press lightly into the hollow next to the tendon, where the artery lies just beneath the skin. Using a watch with a second hand, count the beats for 15 seconds and multiply by four to get beats per minute. (For example, 31 beats in 15 seconds equals 124 bpm.) You can also feel the carotid pulse by pressing gently on either side of your windpipe.

Exercise is not the only thing that affects heart rate. Beats per minute can also be raised by factors such as hot weather, caffeine, time of day, hormonal changes, stress or anxiety, smoking, and some medications.

2. The talk test#

The talk test is a simple and reliable way to judge intensity:

• If you can talk and sing without puffing at all, you are at a low level.
• If you can talk comfortably but not sing, you are at moderate intensity.
• If you cannot say more than a few words without gasping, you are at vigorous intensity.

3. The exertion rating scale#

This method is based on observing your body’s physical signs during activity, including a faster heart rate, faster breathing, more sweating, and muscle fatigue. On a 0–10 scale, the signs build from no effort and no sensation, through light sweating and warmth in the middle range, up to heavy sweating and an inability to talk at the top.

To stay at moderate intensity, aim for a rating of roughly 3 to 7, where you notice stronger sensations of movement and light to moderate sweating but can still talk. Keeping a diary of your exertion ratings lets you track your progress. As you get fitter, the same activity feels easier and your rating drops, which tells you it is time to increase your effort.

At moderate intensity, your body’s normal responses include a faster heart rate, faster breathing, feeling warmer, slight swelling of the hands and feet, and mild to moderate sweating. You may also feel mild muscular aches for a day or two afterwards, especially if you are not used to the activity.

When to stop and seek help#

Becoming aware of how hard you are working helps you exercise at the right intensity for your goals. Stop exercising and seek medical help if you experience warning signs such as:

• extreme breathlessness
• breathing problems such as wheezing or coughing
• chest pain or pressure
• extreme sweating
• dizziness or fainting
• severe muscle pain or cramps
• nausea
• severe pain in any muscle or joint
• extreme or long-lasting fatigue after exercising

Key points#

• Exercise intensity is how hard your body works, and is usually described as low, moderate, or vigorous.
• For general health, aim for moderate-intensity activity: working hard but not too hard.
• You can gauge intensity using your target heart rate, the talk test, or the exertion rating scale.
• Screen yourself before starting, and see a doctor first if you have a medical condition, are over 40, or have not exercised in a while.
• Stop and seek help if you develop chest pain, severe breathlessness, dizziness, or other warning signs.

Where to get help and trusted information#

For evidence-based global health guidance, see Source: World Health Organization (WHO).