WALKING TO HEALTH

Walking is a rhythmic, dynamic, aerobic activity of large skeletal mus cles that confers the multifarious benefits of this with minimal adver se effects. Walking, faster than customary, and regularly in sufficien t quantity into the 'training zone' of over 70% of maximal heart rate, develops and sustains physical fitness: the cardiovascular capacity a nd endurance (stamina) for bodily work and movement in everyday life t hat also provides reserves for meeting exceptional demands. Muscles of the legs, limb girdle and lower trunk are strengthened and the flexib ility of their cardinal joints preserved; posture and carriage may imp rove. Any amount of walking, and at any pace, expends energy. Hence th e potential, long term, of walking for weight control. Dynamic aerobic exercise, as in walking, enhances a multitude of bodily processes tha t are inherent in skeletal muscle activity, including the metabolism o f high density lipoproteins and insulin/glucose dynamics. Walking is a lso the most common weight-bearing activity, and there are indications at all ages of an increase in related bone strength. The pleasurable and therapeutic, psychological and social dimensions of walking, whils t evident, have been surprisingly little studied. Nor has an economic assessment of the benefits and costs of walking been attempted. Walkin g is beneficial through engendering improved fitness and/or greater ph ysiological activity and energy turnover. Two main modes of such actio n are distinguished as: (i) acute, short term effects of the exercise; and (ii) chronic, cumulative adaptations depending on habitual activi ty over weeks and months. Walking is often included in studies of exer cise in relation to disease but it has seldom been specifically tested . There is, nevertheless, growing evidence of gains in the prevention of heart attack and reduction of total death rates, in the treatment o f hypertension, intermittent claudication and musculoskeletal disorder s, and in rehabilitation after heart attack and in chronic respiratory disease. Walking is the most natural activity and the only sustained dynamic aerobic exercise that is common to everyone except for the ser iously disabled or very frail. No special skills or equipment are requ ired. Walking is convenient and may be accommodated in occupational an d domestic routines. It is self-regulated in intensity, duration and f requency, and, having a low ground impact, is inherently safe. Unlike so much physical activity, there is little, if any, decline in middle age. It is a year-round, readily repeatable, self-reinforcing, habit-f orming activity and the main option for increasing physical activity i n sedentary populations. Present levels of walking are often low. Fami liar social inequalities may be evident. There are indications of a se rious decline of walking in children, though further surveys of their activity, fitness and health are required. The downside relates to the incidence of fatal and non-fatal road casualties, especially among ch ildren and old people, and the deteriorating air quality due to traffi c fumes which mounting evidence implicates in the several stages of re spiratory disease. Walking is ideal as a gentle start-up for the seden tary, including the inactive, immobile elderly, bringing a bonus of in dependence and social well-being. As general policy, a gradual progres sion is indicated from slow, to regular pace and on to 30 minutes or m ore of brisk (i.e. 6.4 km/h) walking on most days. These levels should achieve the major gains of activity and health-related fitness withou t adverse effects. Alternatively, such targets as this can be suggeste d for personal motivation, clinical practice, and public health. The a verage middle-aged person should be able to walk 1.6 km comfortably on the level at 6.4 km/h and on a slope of 1 in 20 at 4.8 km/h, however, many cannot do so because of inactivity-induced unfitness. The physio logical threshold of 'comfort' represents 70% of maximum heart rate, T rials across the age span are required in primary care and community p rogrammes to evaluate such approaches, and the benefits and costs more generally of possible initiatives towards more walking. Walking, by q uantity and pace, is under-researched, particularly in the middle-aged and elderly. Randomised controlled trials art: required of its physio logical effects on blood pressure, thrombogenesis, immune function; an d of walking in the prevention and/or treatment of non-insulin depende nt (type II) diabetes mellitus. osteoporosis, anxiety and depression a nd back pain. Low levels of walking are a major factor in today's wide spread waste of the potential for health and writ-being that is due to physical inactivity, This waste is manifest in impaired functional ca pacities, overweight, disease, disability, premature death and the con comitant human and economic costs. This review seeks to assemble evide nce of the health pains of walking as a resource for the multifarious professionals and students, practitioners, investigators and policy ma kers.