Building up muscles in later life

Prof Steve Iliffe has spent several years studying the exercise habits of people in later life.

He discusses the pros and cons of physical activity as you get older, suggesting it is never too late to start exercising.

But Prof Iliffe advises that gradual increases in activity may be the best way to begin.

"You can't jump straight into vigorous activity without training yourself otherwise you will do considerable harm," he told BBC News.