Associate Prof Sheard, of the university physiology department, made that point last night in a talk as part of the ''Thirst for Knowledge'' series.
''The decline in physical ability as we age is an issue most of us prefer not to think about, and something we consider inevitable.''
But Prof Sheard disagreed with that view.
Even a 10% increase in physical activity would deliver big benefits for ageing muscles.
''Any increase in your amount of physical activity is going to be helpful.
''It might be gardening, it might be walking, it might be swimming,'' he said.
Some muscle loss did result from ageing, but even a modest increase in physical activity would help boost overall physical fitness, generate health benefits, and result in more muscle mass being retained in older people.
He explained, at the cellular level, how muscle mass and function was lost with age and urged people to ''not only think about but also act to delay this process''.
