Despite fashions for aerobics classes and gym membership, the UK has experienced a 30 year decline in routine physical activity - the energy expended as part of everyday life. At the same time, there has been a rise in serious disease and disability that impairs quality of life and causes unnecessary suffering. It also costs the NHS and businesses billions of pounds annually, and that doesn't include a range of problems associated with obesity.

Health studies reveal that inactivity is as bad as smoking or unhealthy diets. For study purposes, a physically active lifestyle is one that includes just 30 minutes of moderate exercise (brisk walking, climbing stairs, dancing) on 5 days a week. An inactive lifestyle is one that contains no exercise. Inactive people are found to be at far greater risk of premature death and chronic illnesses such as heart disease, stroke, diabetes and cancer.

Meaning that, when you talk about the known health benefits of exercise, you are really talking about the health risks of not exercising.

To encourage people to adopt more active lifestyles, health campaigns suggest activities that can be easily included in regular daily routines. Frequent short bursts of moderate activity are more effective than infrequent bouts of vigorous exercise - they provide the greatest benefit to the least active people, and are more likely to be continued over the long term. Because 43% of everyday journeys are less than 2 miles, and 65% are less than 5 miles, walking and cycling are promoted as ideal ways to adopt regular physical activity permanently.

There are many good reasons to walk and cycle more often: personal ones like practicality, convenience, time and money savings, and fun; and social ones like business productivity, better transport systems, and environmental gains. Those are described elsewhere, below is a run through of the most firmly established health benefits of adopting a more physically active lifestyle.

Cardiovascular disease (heart and blood vessels)

Inactivity and low fitness are major risk factors: inactive, unfit people have double the risk of dying from heart disease. Physically active lifestyles help prevent strokes and high blood pressure, and combat cholesterol. Note that the 30 minutes of moderate exercise does not have to be taken in one dose - three 10 minute bouts are just as effective, and more likely to lead to greater activity in the long term.

Obesity/overweight (affects all aspects of general health and well-being)

Calorie-cutting diets don't work, they are a recipe for failure. Exercise alone can produce modest weight loss of a few pounds a month. But combining diet and exercise achieves the best results: preserving muscle tissue while maximising fat loss, fitness gains and health benefits. There are two main reasons for this.
1) Because movement expends energy, any activity counts as exercise. Adopting a more active lifestyle can be as effective for weight loss as a structured exercise programme (joining a gym or aerobics class), and is more likely to be maintained.
2) Surprisingly, the bulk of calorie expenditure goes on simply keeping our bodies alive. Even modest exercise raises the body's metabolic rate, and leaner bodies have higher resting metabolic rates anyway. So as you get leaner, you can eat more food without it turning to fat, and exercising becomes easier and more effective. This is why inactive and unfit people gain the most from adopting a more active lifestyle.

Diabetes

Inactivity is a major risk factor for developing type 2 diabetes, also linked with obesity. Some people are at greater risk than others, but increasing activity significantly reduces their risk, as well as reducing risk for the general population. Because of metabolic improvements, physical activity aids the management of type 2 diabetes, and greatly reduces the risk of premature death.

Mental health and psychological well-being.

Mental illnesses such as stress, depression, anxiety, sleep disorders and fatigue are increasingly prevalent. Trends suggest that by 2020 depression will be the 2nd most prevalent disabling illness, with associated consequences including marriage or relationship break-ups, unemployment, and drug or alcohol abuse. But people who lead active lifestyles have reduced risk of clinical depression.

Physical activity helps people 'feel' better by reducing anxiety, alleviating stress, improving sleep and enhancing self-perception. Exercise can be as effective as psychological therapy and medication. However, there is no clear mechanism that explains the positive effect of exercise on psychological well-being. It varies from person to person, and for different activities: competitive sports benefit people who are already accustomed to them; group games benefit just about everybody; and rhythmic aerobic exercises, such as walking, jogging, cycling, swimming and dancing, are the most consistently effective.

'Enhancing self-perception' is an important and under-appreciated benefit. It means that exercise improves self-esteem and sense of worth; every little success is a positive change that gives encouragement and increases motivation, making people more likely to sustain a more active lifestyle.

Cancer

Physical activity is associated with a reduction in overall risk of cancer, and large reductions in risk of colon cancer, breast cancer in post-menopausal women, and possibly lung cancer. Prevention of obesity also reduces cancer risks.

Overall

While specific illnesses can be combated individually, physical activity provides a strength of effect over a range of common diseases. As well as being an effective therapy for many conditions, physical activity has its strongest effects in prevention, and it offers protection against almost all diseases, all the time.

Patrick Simpson