But the study also finds that even decades spent meeting the minimum requirements for exercise (150 minutes of moderate intensity exercise, or 75 minutes of vigorous intensity exercise a week) will not continue to protect you if you ease off in later life.  The benefits to longevity and health diminish sharply if an active lifestyle is not maintained. 

It’s well established that in most people exercise improves health to the point where there is a significant reduction in the risk of dying prematurely from any cause, as well as from specific causes such as cardiovascular disease and cancer.  Physical activity has a systemic, “polypill”, effect with benefits throughout the body, benefiting the muscles, brain, immune system, even fat cells. 

The JAMA study, led by Pedro Saint-Maurice of the National Cancer Institute, used data from the National Institutes of Health and AARP who in 1995-96 recorded details of the exercise histories of more than 315,000 people.  The NIH and AARP asked participants, who were then aged between 50 and 71, how much physical exercise they’d had in four main periods of their lives – adolescence, early life, early middle age and later life.  The data gathered was compared by Dr Saint-Maurice and his colleagues with the National Death Index, revealing which of the participants had died from all causes, cardiovascular disease, or cancer up to the end of 2011.

Perhaps not surprisingly, people who had been physically inactive all the way from adolescence until later adulthood (40 – 61 years of age) were the most likely to have died, from any cause but in particular from cardiovascular disease.  In comparison, those who’d been active since adolescence had a 29% to 36% lower risk of death from any cause and around 40% lower risk of dying of cardiovascular disease. 

However, the finding with implications for millions of people with long records of sedentary behavior was that increasing exercise during middle age was associated with reduced risk of all-cause mortality of between 32% and 36%, an outcome for health similar to that of people who’d exercised all their lives. 

It doesn’t matter if you’re overweight or obese: increasing physical activity can significantly reduce the risk of death from the diseases associated with being an unhealthy weight.  A recent study has suggested that increasing exercise is a more practical and effective way of reducing the risk of mortality than attempting to lose weight (see article: Want To Reduce Your Risk Of Death?  Fitness Matters More Than Weight Says A New Study).

The findings did rely on the memory, and honesty, of the thousands taking part, and what they could recall of how much formal exercise they took as well as the activities and chores of daily life.  Although effects on health and longevity such as weight and smoking were corrected for in the calculation of risks, there are many factors – including the income of individual participants and their genetic makeup – that could also influence longevity.  The study doesn’t prove cause and effect either: it shows instead that exercise is associated with longer and healthier lives.