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Summer Science Exhibition 2004

Exercise turns back the muscle clock











A little bit of exercise can make older people feel fitter and younger.

Dr Monica Winstanley and Dr Susan Gilchrist.
Biotechnology and Biological Sciences Research Council (BBSRC).

Dr Constantinos Maganaris, Professor Alberto Minetti, Dr Gladys Pearson and Professor Marco Narici.
Manchester Metropolitan University.

As we get older our muscles get smaller and weaker. Commonplace activities like getting out of a chair or climbing a flight of stairs become more difficult and potentially dangerous. Performing even light tasks can require a tremendous effort. Compared to younger people older folk actually use more energy to do the same things.

The conventional theory for age-related muscle weakening suggested that it was caused by reduced muscle mass due to cell death and reduced physical activity. Now researchers from Manchester Metropolitan University (MMU), using sophisticated techniques including ultrasound and magnetic resonance measurements, have shown not only that the muscles of older people are made up of fewer cells, but also that these cells are arranged differently.

Muscle cells, or fibres, in older people are shorter and thinner than those of younger persons. They also tend to run parallel to the direction of the muscle. In addition, as we get older, our tendons stretch more during muscle contraction, making our movements slower - and here is the key to a potentially less frail old age.

On their own, the changes in muscle structure and tendon-stretch characteristics would decrease overall muscle performance. But, in combination, they are nature's way of combating weakness in old age and partially compensate for the reduced muscle performance at the cost of a higher energy use. Unfortunately this also reduces the ability of the muscle to react quickly and recover during a slip or fall, which may have dramatic consequences for older people.

But the effects of ageing can be slowed down or reversed - at least for muscles and tendons. 'We have found that moderateintensity, regular exercise, such as uphill or downhill walking and two muscle-exercise sessions per week, can lengthen muscle fibre and reduce tendon stretch', advise the team of scientists at MMU. 'This substantially counteracts the changes in tissue structure and function. Within months, muscles become considerably stronger and tendon strength is restored to that of young adults. Stronger tendons mean quicker reactions to instability and less likelihood of falling.'

Exercise turns back the muscle clock The Royal Society, London 6-9 Carlton House Terrace London SW1Y 5AG UK