Insulin-like growth factor in muscle growth and its potential abuse by athletes
Authors: G R Adams
Journal: British Journal of Sports Medicine (2000)

in his poem, To my honoured kinsmen, writes: "The wise for a cure on exercise depend".This is good advice that the NHS is only just beginning to take seriously.Current policy has rightly focused its attention on improving services to treat the big killers: coronary heart disease, stroke, and cancer.The challenge to reduce premature mortality from these diseases is huge-for example, the National Service Framework on Coronary Heart Disease, 1 published earlier this year, has created a blueprint both for improving quality of services (from prevention to palliative care), and for improving access to these services across the country.In the drive to modernise the NHS more emphasis is being placed on the important role that prevention and early intervention can play.Many are aware of the risk to health from smoking, but far fewer realise that the relative risk from physical inactivity is of a similar order.People who are physically inactive carry twice the risk of coronary heart disease and three times the risk of stroke as their more active counterparts. 2 If it is to bring continued health benefits, physical activity needs to be embedded in the daily lives of many more people.Six out of ten men and seven out of ten women in England, between the ages of 16-74, are not physically active enough to benefit their health. 3 The recently published National Diet and Nutrition Survey of 4-18 year olds has shown that children are becoming less active. 4 About 40% of boys and 60% of girls spent, on average, less than an hour a day in activities of at least moderate intensity and therefore failed to meet our recommendation for young people's participation in physical activity. 5 Moreover, participation in physical activity-such as, sports and walking, is strongly related to household income.However, this association between socioeconomic group and physical activity is partly oVset by the higher levels of occupational activity in manual social classes.As a result, approximately 50% of men in social classes IV and V do not meet current recommendations in levels of physical activity, compared to two thirds of men in classes I and II.Overall, the picture for women is worse.In social classes IV and V, nearly 80% of women fail to achieve the recommended level of physical activity.Although activity levels in class I are not significantly diVerent, levels for social classes II and non-manual III are slightly higher.Physical activity must be one of the most undervalued interventions to improve public health.Its benefits are great.Physical activity is closely associated with better health and reduced all cause mortality, including reduced mortality from coronary heart disease, stroke, colon cancer, and reduced fatality after a heart attack.Exercise helps to reduce blood pressure and hypertension, and can protect against the development of type II diabetes mellitus.It is a vital component of weight control.Weight bearing activity helps to maintain bone mass density and to reduce the risk of osteoporosis; and physical activity generally helps with improved balance, coordination, and endurance in older people.It has an important role in helping people to manage chronic conditions-such as, asthma and arthritis.It also has psychological benefits, including improved self esteem, and lower risk of mild to moderate depression. 6 It is not surprising that exercise has