Preventing frailty – how much is enough?

Sincere apologies to all my readers. This blog is one week late – but I have an excuse. I have been away and my laptop, which should have enabled the publication of this edition, let me down. Now I am back home with my trusty desk-top, so here we go.

In September I mentioned the DoH recommendation of 150 minutes of moderate exercise per week – or 75 minutes of vigorous exercise – in bouts of ten minutes or more. Another take on this is around 40 minutes of  exercise, enough to make you somewhat sort of breath, three of four times per week. Some people like to use a pedometer to build up to 10,000 paces per week. This goal was recommended by a Japanese company to promote their pedometers and, although an entirely untested figure with no evidence backing at the time,  subsequent studies have confirmed it to be a surprisingly appropriate suggestion.

Another view

The first person to define the amount of exercise needed for health benefit was Professor Gerry Morris of the London School of Hygiene and Tropical Medicine. It was Gerry who conducted the London Busmen Study and subsequently The Whitehall Study. The former showed the lower rate of coronary disease in bus conductors compared to drivers. The latter, which is ongoing, has found that physical activity, including walking pace and leisure time activity, is associated with a lower risk of mortality from a range of causes, including cardiovascular disease, cancer, and respiratory disease. 

Today’s illustration shows the relationship between the amount of exercise taken and the health benefits to be gained as envisaged by Professor Morris. The curve looks the same for all the measures of exercise – how often, how hard and how long the exercise may be. As soon as you increase from doing nothing to doing something there are benefits and these increase as the quantity (exercise time, exercise frequency and exercise intensity) increases. Beyond a certain point the curve begins to flatten off progressively. The recommended amount of exercise is usually taken at an arbitrary point between the early, steep part of the curve and the later more gradual flattening of the curve. Note also the lower curve – that of increasing risks and harms of exercise with increasing amounts of exertion.

How Often?

The recommended range is between 3 and 5 times per week. The risks of exercising more frequently are mainly related to exercise induced muscle and joint pain and injury.

How hard?

The recommended range lies between 70 and 85% of maximum heart rate. This roughly equates to the effort needed to make you “somewhat breathless” up to that need to make you “definitely short of breath”. This is between  4 and 7 on the “Borg” score which assess exercise intensity using a scale of “0” to “10”. The risk of doing more is an increasing chance precipitating a cardiac event, mainly in older exercisers.

How long?

The recommended duration of exercise is between 30 and 50 minutes per session. The risk of going on for longer is the increasing risk of muscle and joint injuries – as it is with increases of frequency.

The overview

So a reasonable recommendation for total amount of exercise is three or four times per week for between 30 and 50 minutes at an intensity which makes you noticeably short of breath. It does not matter what exercise you choose. And remember that if the recommendations are more than you can stomach, doing anything still has benefits – and that the steepest part of the curve is going from doing nothing to doing a bit!  If you want to do more you will continue to get increasing benefits but the risk of injuries also increases – a common problem, for instance, for long-distance runners.