• physical activity
• exercise
• heart
• cardiovascular
• coronary heart disease

• CDC/ACSM, Centers for Disease Control and Prevention and the American College of Sports Medicine
• CHD, coronary heart disease
• CVD, cardiovascular disease

The Caerphilly study¹ addresses an important question regarding physical activity and health: how intensely does one need to exercise in order to reduce the risk of premature mortality from cardiovascular disease (CVD)? In this study, 1975 men, aged 49–64 years and free of coronary heart disease (CHD), reported on their leisure time physical activities and were followed for an average of 10.5 years for mortality. The investigators concluded that “only leisure exercise classified as heavy or vigorous was independently associated with reduced risk of premature death from CVD”. When men were categorised into thirds of energy expended on vigorous activities requiring ⩾6 METs, the most active third (expending ⩾24 kcal/day in vigorous activities) experienced a 36% reduction in mortality from CVD compared with the least active third (expending hardly any energy in vigorous activities). However, when men were grouped into thirds of energy expended on light or moderate activities requiring <6 METs, similar rates of CVD mortality were observed in the most and least active thirds of men (expending ⩾343 and ⩽133 kcal/day respectively in light or moderate activities).

“If moderate intensity physical activity does not benefit health, should health professionals bother to prescribe such activities?”

This surely comes as bad news for many, as most people living in developed countries are inactive. In the United Kingdom, only 33% of men and 21% of women meet guidelines for physical activity,² and in the United States, a mere 36% of men and 28% of women engage in regular leisure time physical activity.³ In these largely sedentary societies, persuading those who are inactive to take up moderate intensity physical activity (such as brisk walking) for their health is more likely to meet with success than requiring inactive persons …