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Habitual exercise and lifespan

I indicated last week that lifelong exercisers live longer than their more sedentary friends.  Is it ever too late to start? The answer is a qualified no because the effect on longevity takes a while to kick in. It probably takes several years of high levels of activity to increase your lifespan.

A cohort of more than 315,000 Americans aged 50 to 71 had their exercise habits tracked and were followed up for 20 years. Unsurprisingly the mortality during FU was about 35% lower in the habitually active group than in those who took little exercise. Surprisingly, however, was the finding that those who took up exercise later in life and then maintained it had a similar reduction in mortality. The critical word is “maintained” which meant for several years. As the Times reported “It is never too late to get off the sofa and extend your life.”

Exercise and Physical fitness

The more exercise you take the fitter you are likely to be – there is a clear relationship between increasing habitual exercise and increasing physical fitness.

Physical fitness and lifespan

Numerous studies have confirmed the relationship between physical fitness and life expectancy – indeed physical fitness in the middle aged is the best predictor bar none of what age you will achieve, and that includes blood cholesterol, presence of obesity, high blood pressure or diabetes or even pre-existent heart disease and cigarette smoking. Only increasing age is a better predictor of how many years are left to you. The reduction in mortality in the fit compared with the unfit is largely due to lower rates of cardiovascular disease and cancer.

A summary of the results of 33 studies which compared physical fitness and mortality was published in 2009. The population included over 100,000 people without heart disease, diabetes, high blood pressure or high blood cholesterol. The subjects had all had an initial exercise test to measure their fitness and were then followed for a mean of 11 years. Fitness was  divided into three categories – low, intermediate and high.  There was a clear correlation between fitness level and mortality – the risk of dying being 70% higher in the low fitness group than in the high fitness group. Moreover for every 1 MET increase in fitness (equivalent to an increase in walk/jog speed of 1km per hour) there was a 13% decrease in risk of dying.

This is illustrated by the histogram above. CRF, on the horizontal x axis, is cardiorespiratory fitness (low, intermediate and high). Age related mortality, on the vertical y axis, is the age adjusted death rate per 10,000 people. It shows clearly that if you are unfit you are much more likely to die prematurely than if you are fit.

The greatest benefit between being fit and being very fit was found in the over 70s, confirming the effectiveness and importance of exercise in older people.

Risk scores

The most used score to predict future heart disease and subsequent mortality is the QRisk3. Google it and you will be asked to fill in all your details such as age, gender, smoking habit, blood pressure, blood cholesterol etc. Even your post code is included. Where you don’t know the answer the form will give you an average reading. What is missing is any question about your fitness level or even any measure of how much exercise you take. Bizarre!

When is it too late to start increasing fitness?

As with taking up exercise later in life, older individuals who improve their fitness also improve their life expectancy. In a large epidemiological study involving older male veterans (age, 65–92 years) with an 8-year median follow-up, an inverse and graded association between  exercise capacity (in METs – see glossary)) and survival was noted. Mortality risk was 12% lower for every 1-MET increase in exercise capacity, regardless of age. The biggest relative benefit was found for the higher fitness groups.

The facts are clear. Low levels of exercise and low physical fitness are both predictors of premature mortality and shortening of total lifespan. Low fitness levels has been calculated to account for 16% of premature deaths, substantially more than any other risk factor including, as I indicated above, cigarette smoking, diabetes, obesity, raised blood cholesterol, or hypertension. And we should not be surprised that other measures of physical performance are also associated with longer life, including grip strength and balance and also leg muscle strength.

PS

I forgot to add these  to the list I gave last week of the effective exercise types for increasing lifespan.
1. Regular swimming may be particularly effective in postponing mortality.
2. Active commuting to work. A study of more than half a million adults aged 40 to 69, followed up for five years, found that those who cycled to work had about half the risk of dying during this time as those who used public transport.