However, scientists at Manchester Metropolitan University have discovered that by the age of 75, people have between 30 and 50 per cent fewer nerves controlling the muscles in their legs.
This leaves large areas of the muscle disconnected from the nervous system – which acts as an electricity supply and communication link to the brain. Without the connection the muscle areas wither away and die.
Dr Mathew Piasecki, the study lead author who has since taken up a position at the University of Nottingham, said: “One of the earliest attempts at research similar to ours showed results from a small group of older people who apparently had just a couple of surviving nerves feeding into a foot muscle.
“We were very sceptical of the old data, however, now that we have tested a couple of hundred men we think the early observation was probably correct. We have also observed some very old muscles with just a few dozen nerves left, where young and healthy adults have hundreds.”
The researchers used MRI scans to gain a detailed look at the muscle tissue in more than 200 men, followed by enhanced electromyography to record the electrical activity passing through the muscle to estimate the numbers and the size of surviving nerves available to rescue muscle fibres.
Professor Jamie McPhee, the senior author on the research, commented on the significance of the findings: “Our challenge now is to find ways to increase the success of nerve branching to rescue detached muscle fibres and thereby reduce the numbers of older people in our neighbourhoods with low muscle mass and muscle weakness.
“Our research helps to explain why muscles decline with advancing age and this new knowledge will help in the search for effective countermeasures.”
Last week, researchers at King’s College London and the University of Birmingham discovered that older people who cycled regularly had managed to conserve their muscle mass and strength.
Professor Janet Lord, Director of the Institute of Inflammation and Ageing at the University of Birmingham, said: “Hippocrates in 400 BC said that exercise is man’s best medicine, but his message has been lost over time and we are an increasingly sedentary society.
“Our findings debunk the assumption that ageing automatically makes us more frail.”
The research was published in the Journal of Physiology.