The link between exercise and general health has been appreciated since ancient times. Doctors routinely recommend regular exercise for good health but gathering reliable scientific evidence on the effects of exercise is difficult, not least because of confounding factors such as genetics and lifestyle.
This is typified in two recent studies; one apparently demonstrating very positive effects of exercise on health and the other much more circumspect in its conclusions.
Epidemiological evidence showing the relationship between physical activity and mortality was reported in the classic studies of Jeremy Morris and Ralph Paffenbarger from the 1950s on.
Morris showed incidence of heart disease and sudden cardiac death was lower in London bus conductors compared with bus drivers and attributed the difference to the greater physical activity of conductors. And, in the 1970s, Paffenbarger and collaborators demonstrated an inverse relationship between physical activity and cardiac disease and “all-cause mortality”.
Aerobic exercise – eg walking, cycling and swimming – works the body’s large muscles rhythmically and repetitively, increasing heart rate and body oxygen consumption. Regular exercise reduces the risk of contracting heart disease, diabetes, high blood pressure and high cholesterol.
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Official recommendations, based largely on study participants’ reports of their exercise activity, are that 150–300 minutes of moderate aerobic exercise (eg walking) or 75–150 minutes of vigorous physical activity (VPA) (eg running, swimming) per week is necessary to achieve optimum health results. This is a time commitment of an hour a day in the gym, which people find difficult to maintain and many quickly drop out of aerobic exercise programmes.
However, recent research reported in the European Heart Journal has demonstrated that cumulative intermittent short bouts (two-minute bouts) of VPA, easily integrated even into the busiest schedule, significantly boost health.
The authors concluded that VPAs totalling 15-20 minutes per week, each VPA lasting two minutes, is associated with a 16 to 40 per cent lower mortality rate, with further decreases in mortality rate attainable up to 57 minutes VPA per week – 103,000 adults aged 40–69 participated in the study. Accelerometer data accurately measured physical activity, unlike previous measurements of physical activity relying on fallible memory and affected by personal bias/vanity.
If such short exercise bouts are as powerful at boosting good health as claimed, this discovery is the most important health news announced for a long time. It would mean there is no excuse any more for not exercising sufficiently to dramatically improve your health.
That second study is less positive about exercise. A long-term study of 22,750 Finnish twins with 30 years’ mortality data was published by Anna Kankaanpaa and others in the European Journal of Epidemiology and reviewed by Chuck Dinerstein for the American Council on Science and Health. It examined the association between leisure-time-physical-activity (LTPA) and all-cause mortality. Although physical exercise seems to be generally beneficial, it doesn’t strongly support a causal relationship with mortality.
Twins were divided into four activity categories – sedentary, moderately active, active and highly active. As expected, the most active group showed a 20 per cent lower mortality risk than the sedentary group, but when other lifestyle factors were factored in, mortality risk benefit sank to 7 per cent.
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Moderate LTPA sufficed to achieve the mortality bonus and higher LTPA levels produced no extra improvement. Also, identical-twin studies, each twin having different levels of LTPA, show minimal differences in mortality, suggesting that heredity is the big determinative factor affecting mortality. This would substantially fade the mortality benefits of LTPA. Your genes plus lifestyle habits together seem to shape your ageing and lifespan.
Aristotle said: “Happiness is the meaning and purpose of life, the whole aim and the end of human existence.” We should therefore strive to be happy as well as healthy. Research is revealing many health benefits of happiness including a stronger immune system, improved resilience against stress, less risk of cardiovascular disease, quicker recovery times after illness and even a longer life.
Various practices are recommended as aids to promote happiness, including being kind to others, forgiving those who offend you, focusing on the positive and practising meditation. So, the complete formula for health and longevity could well be – choose your parents carefully, exercise regularly and be happy.
William Reville is an emeritus professor of biochemistry at UCC