The human body is like a car: it becomes more gas-guzzling with age
That's according to scientists at Manchester Metropolitan University who observed that active pensioners may not be getting enough calories to cope with increased "fuel loss".
Exercise scientists compared the walking abilities of a group of septuagenarians (average age 74) with those of people in their late 20s and found the former using more than 30% more energy to walk 100 yards at a set speed.
The increased ‘cost’ in calorific consumption is due to muscles overworking to support unstable joints and tendons and is, the researchers found, irreversible.
They also said tendons in the elderly were like an "old elastic band" - overstretching and not springing back into shape - and this too was causing over-usage of muscles.
Professor Marco Narici, coordinator of the European-funded Better Ageing research project, said: "The elderly participants had too many muscles switched on at the same time and were seeping energy like an old car with its engine out of tune.
"They were quite inefficient and this is due in the main to muscles overcompensating for weak joints."
He said the result was that the elderly tended to take smaller, more frequent steps, and tend to drag their feet; a walking pattern that makes them more vulnerable to trips and falls.
The scientists, from MMU’s Institute for Biophysical and Clinical Research into Human Movement, also examined whether a 12-month programme of exercise could offset the effects of walking efficiency loss. But they found that after the training programme, the older volunteers were just as uneconomical.
Added Professor Narici: "Exercise can help build muscle mass and strength but the fitter people still consumed the same amount of energy. This, we believe, is because the main key is the way the muscles are controlled by the nervous system and not the size or bulk of the muscles per se."
They found no difference between the walking efficiency loss between men and women.
Peer reviewed publication and references:
The findings have been published in Acta Physiologica and the European Journal of Applied Physiology. - The authors were Professor Marco Narici, Dr Omar Mian and Professor Alberto Minetti at the Institute for Biophysical and Clinical Research into Human Movement, Manchester Metropolitan University.