Academic journal article Research Quarterly for Exercise and Sport

Exercise versus Heart Attack: Questioning the Consensus?

Academic journal article Research Quarterly for Exercise and Sport

Exercise versus Heart Attack: Questioning the Consensus?

Article excerpt

We, all of us-fellow investigators, practitioners, teachers, and students alike - are indebted to Blair and Connelly (1996) for a model review. Their analysis updates Powell, Thompson, Caspersen, and Kendrick (1987) in its authoritative statement of the position now reached in this heterogeneous field. The findings of our own British studies differ in some respects from what seems to be emerging as the orthodox view. On protection against coronary heart disease (CHD), they do not confirm the benefits of "moderate amounts and intensifies of physical activity" as such. I fancy, therefore, that I can most usefully contribute to this forum by an account of our work and the thinking behind it, now extending over close to half a century.

Throughout this commentary, my concern is restricted to physical activity as possible prevention of the first occurrence of clinical CHD, heart attack, in men of middle and early old age. The multifarious other benefits - physical, psychological, and social - for health (see Bouchard, Shephard, & Stephens, 1994) that do indeed require other exercise prescriptions are not considered here.

I will be dealing essentially with two prospective surveys of men in the executive, middle-management grade of the British civil service. This is a narrow population group, homogeneous in education (subuniversity) and income (modest), of the middle class, engaged in sedentary or physically light office work. The hypothesis we drew from previous occupational studies (Morris & Crawford, 1958; Morris, Heady, Raffle, Roberts, & Parks, 1953) stated simply that the aggregate of physical activity in leisure-time of these men, physically inactive at work, would be related to their incidence of CHD: Those with high totals would suffer less CHD than comparable men with low totals.

Disappointingly, despite exhaustive search, we could find no evidence of this in our survey, launched after much methodological effort, in 1968 of approximately 18,000 men aged 40-64 years. For example, the first 214 coronary cases were compared with 428 closely matched controls. In them, vigorous exercise alone showed the postulated relationship with CHD (Morris et al., 1973; Morris, Everitt, & Semmence, 1987; Morris, Pollard, Everitt, & Chave, 1980). Figure 1 is a sample of findings: There was no association of CHD with total activity scores or with moderate levels of activity. As cases accumulated, eventually over 1,100 first "coronaries," these observations were confirmed. It also became clear that vigorous activity was associated with lower rates of CHD at all ages studied (40-72 years) and in all first clinical presentations: as sudden death, nonfatal or fatal myocardial infarction, angina pectoris, or coronary insufficiency.

Vigorous Exercise

Vigorous exercise had been postulated at the outset as that liable to reach peaks of energy expenditure of 7.5 kcal (31.5 kj) per minute and so enough typically to induce and maintain a training, conditioning effect in such men. As we might now say, this was an attempt to combine at the population level both high absolute intensifies of activity and intensifies high enough, on average, relative to the individual fitness levels and requirements of the men. These activities were, of course, the most energetic reported.

As we wrote at the time, our middle-aged participants, occupationally and otherwise settled in their ways, including their exercise (there was much information), "were little given to track-racing, competitive games, cross-country skiing and the other delights of sports physiologists." The commonest vigorous sport in both surveys was swimming, as such scored 6 METs by Ainsworth et al. (1993). Others included tennis, soccer, hockey, mostly coaching and refereeing, hill climbing, and jogging, approximately 7 METs. Vigorous, yes, but scarcely athletic!

A New Survey

A fresh survey, now of 9,400 men aged 45-64 years and again free of diagnosed CHD, was mounted directly to test the new hypothesis and to apply what had so painfully been learned. …

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