Is physical activity advisable only for people in the prime of life and not for the elderly? Is it unnecessary for children who already burn up too much energy on normal activities? The answer on both counts is a firm 'No'. The next time someone tells you that physical exercise is an expensive proposition involving equipment, special shoes and clothes, turn around and "move" your way to better health.

These are just some of the myths and beliefs that the World Health Organization (WHO) is trying to correct as it observes World Health Day on April 7. Several public awareness programs are being launched to publicize the theme for 2002 - "Move for Health".

It is common knowledge that physical activity like walking, riding a bike, dancing or playing makes you feel better. In addition to a feeling of well being, however, regular physical activity brings about many health benefits. Regular exercise is known to reduce the risk of death from cardiovascular diseases, prevent or reduce hypertension – which affects one-fifth of the world's population – and helps prevent or control tobacco, alcohol or other substance use, especially among children and young people.

According to WHO figures, regular physical activity reduces the risk of developing heart disease or colon cancer by up to 50 per cent. It also helps to prevent and lower the chances of osteoporosis, reducing the risk of hip fracture by up to 50 per cent in women.

In many countries, a significant proportion of health spending is due to costs related to lack of physical activity and obesity. Thus, promoting physical activity can be a highly cost-effective and sustainable public health intervention, say health experts.

The lack of physical activity is a major underlying cause of death, disease and disability, say experts. Preliminary data from a WHO study on risk factors suggest that inactivity or a sedentary lifestyle is one of the 10 leading global causes of death and disability. More than two million deaths each year are attributable to physical inactivity.

In countries around the world, between 60 and 85 per cent of adults are simply not active enough to benefit their health. Sedentary lifestyles increase all causes of mortality, double the risk of cardiovascular disease, diabetes and obesity and substantially increase the risks of colon cancer, high blood pressure, osteoporosis, depression and anxiety, stresses the study.

Recent studies have also shown that children around the world are becoming increasingly sedentary, especially in poor urban areas. Time and resources devoted to physical education are being cut and computer games and television are replacing physically active pastimes.

It is estimated that in many countries, both developed and developing, more than two-thirds of the young people are insufficiently active. WHO warns that inadequate physical activity in children can have life-long health consequences. WHO is also assessing the global burden of disease from 22 health risk factors, including physical inactivity. The results of this research will be published in the World Health Report 2002.

The preventive approach is especially relevant for a country like India, which would have to invest heavily to effectively tackle epidemics of life-threatening diseases, thereby creating a perceptible dent in its precious resources, says obesity specialist and Diabetologist Dr Suneet Khanna.

He emphasizes that contrary to widespread misconceptions, physical activity can be done almost anywhere and requires no equipment. At least 30 minutes of moderate physical activity each day such as brisk walking is enough to bring about many of the beneficial effects, says Khanna, who runs Westside Clinic, a super-specialty polyclinic in West Delhi.

As Khanna and other specialists' point out, there is no need to go to a gym, swimming pool or other special sports facility to sweat out the extra calories and tone up the muscles. Carrying groceries, wood, books or children are good complementary physical activities, as is climbing stairs.

Walking, which is perhaps the most practiced and most highly recommended physical activity, is absolutely free and any park, waterfront or other pedestrian areas are ideal for walking, running or playing.

While "earlier the better" is preferable to get the benefits of physical activity, it is never too late to begin. The benefits of physical activity can be enjoyed even if regular practice starts late in life. According to Nidhi Raj Kapoor of HelpAge India, the number of people over 60 years of age is projected to double in the next 20 years and a majority of them will be living in developing countries.

Reducing and postponing age-related disability is an essential public health measure and physical activity can play an important role in creating and sustaining well-being at all ages, she says. Towards this objective, HelpAge India has organized a series of physical events for senior citizens including golf tournaments and walkathons.

Major General Pratap Narain, at 91 years easily the oldest contestant in the recent golf tournament, perhaps sums it up neatly when he says: "Golf and physical activity are very good for the elderly as it makes old bones work. And even more than that, it makes your mind work so you don't lapse into gaga-land."

But in the rapidly growing cities of the developing world crowding, poverty, crime, traffic, poor air quality and a lack of parks, sidewalks, sports and recreation facilities make physical activity a difficult choice.

In this context, WHO urges countries to formulate policies which include planning for safe sidewalks, cycling paths and parks. The health, education and sports sectors should take the leading role in organizing specific physical activity programs in health services and strengthening national policies related to physical education, physical activity and "Sports for All" in schools.