Physical activity for adults: how much you need and why it matters

Physical activity is linked to better long-term health. This review explains what physical activity is, how much is recommended, what it does for the body and mind, and how to begin safely. It draws on the World Health Organization (WHO) and the US Centers for Disease Control and Prevention (CDC).

1. Introduction

WHO defines physical activity as any movement of the muscles that uses energy. It includes exercise and sport, but also walking or cycling to get somewhere, active work, housework and play ^[1]. Both moderate and vigorous activity improve health ^[1].

Many people are not active enough. WHO reports that about 31% of adults worldwide, around 1.8 billion people, do not reach 150 minutes of moderate activity a week, and that women are on average less active than men ^[1]. Insufficiently active people have a 20% to 30% higher risk of death than people who are active enough ^[1].

2. How much activity do adults need?

The CDC adult guidance sets out a clear weekly target ^[2]:

• At least 150 minutes of moderate activity, such as brisk walking. This could be 30 minutes a day on 5 days.
• Or at least 75 minutes of vigorous activity, such as jogging or running.
• Or an equal mix of the two, spread across at least 2 days.
• Muscle-strengthening activity on at least 2 days a week, working all the main muscle groups: legs, hips, back, abdomen, chest, shoulders and arms.

The CDC gives 75 minutes of vigorous activity as the alternative to 150 minutes of moderate activity, or an equivalent mix of the two ^[2]. Doing more than the minimum gives extra benefit ^[2]. WHO's message is simple: any activity is better than none, all activity counts, and everyone should limit the time they spend sitting ^[1].

3. Why activity matters

Heart and circulation

The CDC states that at least 150 minutes a week of moderate activity lowers the risk of heart disease and stroke, and that regular activity can lower blood pressure and improve cholesterol levels ^[3]. It also lowers the risk of type 2 diabetes and of metabolic syndrome, a cluster of problems such as raised blood pressure and blood sugar that increase heart risk ^[3].

Mind and sleep

Some brain benefits start straight after a session. Regular activity can reduce short-term feelings of anxiety, help keep thinking and judgement skills sharp with age, and lower the risk of depression and anxiety ^[3]. Activity also helps people sleep better ^[3].

Weight, bones and muscles

Weight depends on both eating and activity. The CDC notes that working up to 150 minutes a week helps with keeping weight steady, while losing weight and keeping it off usually needs more activity or changes to eating as well ^[3]. Muscle-strengthening activity helps keep muscle mass and strength, which matters more as we age, and activity lowers the risk of falls and hip fractures in older adults ^[3].

Cancer and long-term illness

Regular activity lowers the risk of at least eight types of cancer, and for people who have had cancer it can improve quality of life and fitness ^[3]. WHO adds that in adults, activity is linked with lower risk of death, high blood pressure, type 2 diabetes and falls ^[1].

4. The risk of sitting too much

WHO uses the term sedentary behaviour for low-energy time awake spent sitting, reclining or lying down ^[1]. In adults, more sedentary time is linked with higher risk of death from any cause, from heart disease and from cancer, and with more cases of heart disease, cancer and type 2 diabetes ^[1]. The CDC notes that adults who sit less and do any amount of moderate or vigorous activity gain some benefit ^[2].

5. Getting started and staying active

Practical ideas drawn from the sources ^{[1, 2, 3]}:

• Spread activity across the week rather than doing it all in one day.
• Break the total into smaller blocks of time, for example short brisk walks.
• Count everyday activity: walking or cycling to work or the market, climbing stairs, gardening, dancing and active play with children.
• Add muscle-strengthening on 2 days, for example lifting weights, and gradually increase the weight and repetitions.
• Remember that moderate activity such as brisk walking is generally safe for most people.

6. Special groups

WHO guidelines also cover children and adolescents, older adults, pregnant and postpartum women, and people with long-term conditions or disabilities, with advice for each group ^[1]. WHO notes that in pregnant and postpartum women, activity is linked with lower risk of pre-eclampsia (a pregnancy problem involving high blood pressure), gestational diabetes and postpartum depression, and that it does not raise the risk of stillbirth or harm birthweight ^[1]. WHO notes that inactivity increases in both men and women after age 60 ^[1]. The CDC says that for older adults, a mix of aerobic, muscle-strengthening and balance activities improves physical function and lowers the risk of falls ^[3]. Anyone in these groups should ask their own doctor which activities are right for them.

7. When to see a doctor

Most adults can start with gentle activity such as walking. Speak to a doctor first if you have a long-term condition such as heart disease, diabetes, high blood pressure or joint problems, if you are pregnant, if you are older and have not been active for a long time, or if you are unsure what is safe for you. Stop and seek medical advice if exercise brings on chest pain or pressure, severe breathlessness, dizziness or fainting, or unusual pain.

In an emergency, call your local emergency number (112 in India, 911 in the United States).

8. Conclusion

Regular physical activity supports the heart, brain, bones, muscles and sleep, and the guidance for adults is clear: aim for 150 minutes of moderate activity a week, or the vigorous equivalent, with muscle-strengthening on 2 days and less time sitting. Benefits start with small steps, and any activity is better than none. Build up gradually, and talk to your doctor if you have a health condition or any worry about starting.