How do we know that walking does more good than harm?
One source of evidence is that the people who walk say that walking makes them feel, and look, good. But this does not prove that walking is beneficial or, as is said when new medical treatments are evaluated, that it does more good than harm. It might be that people who feel good about themselves and who are healthy, walk more than people who are depressed or unwell, and there is probably some truth in that
A second method is to question people with a problem such as heart disease or depression about their lifestyle before they became ill, and compare their answers with the results of interviews of another group of people chosen because they are identical to the group that is ill – for example, same gender, same social class, same job – in fact being as similar to the people with the disease as possible except for the fact that they do not have the disease. This approach produces scientific evidence but, like all scientific methods, has its flaws. For example, one study of four questionnaires used in interviewing people about their exercise habits demonstrated that very different results were obtained, depending on which questionnaire was used. The answers given by the same people ranged from 81 minutes in response to one questionnaire to 242 minutes in response to another.
Pedometers do away with the problem of both memory and questionnaires, but you cannot go backwards in time so studies of walking, and other forms of exercise, have to rely on memory as well as questionnaires, and both are unreliable
In spite of these difficulties, there is now a large amount of evidence about the benefits of walking.
A drug has indications and contra-indications. The indications are the reason why a drug should be prescribed, the contra-indications are reasons why it should not be prescribed. For example, bacterial infection of the tonsils is an indication for penicillin, but allergy to penicillin is a contra-indication. There are many indications for walking, but what about the contra-indications? Some people with chronic conditions worry about taking more exercise, but there are no chronic conditions or diseases for which walking is contra-indicated. Walking has been shown to be beneficial for many diseases, including:
- heart disease
- intermittent claudication;
- lung diseases;
- psychological problems
One reason why walking is helpful in so many chronic diseases is that it tackles a complication common to all chronic conditions – loss of fitness. Disease has direct and indirect effects. The disease directly affects certain parts of the body. In coronary heart disease, for example, the arteries to the heart itself are affected; in neurological disease it is the brain. However, many chronic conditions also have indirect psychological and physical effects, most commonly depression and loss of fitness
A vicious cycle develops. The disease causes inactivity and the inactivity itself increases joint stiffness and the loss of muscle power, making the person feel even more depressed.