The Health Education Authority (HEA) report found that elderly women do less exercise than men and are more likely to lose the ability to climb stairs, go for walks or to wash their own hair comfortably.

The report's authors said it illustrated that a lot of old age disability is the result of disuse rather than disease, and that older people must keep fit if they want to maintain their skills.

This way they will be able to live a long, independent life, the authority said.

Key findings

The report - called Physical Activity in Later Life - found that:

• 40% of men and women aged 50 and over are sedentary - meaning they are moderately active for at least 30 minutes less than once a week
• Among those classified as sedentary, 52% of men and 57% of women thought they were doing enough exercise to keep fit
• One in four men and one in six women over 50 were active enough to benefit their health - doing some activity five times a week
• Among over 70s, one in four men and one in three women were unable to walk a quarter of a mile on their own
• 26% of men and 37% of women over 70 said they had trouble washing their hair comfortably
• When it came to climbing a 30cm step unaided, 93% of men aged 50-74 felt confident they could do it compared with 72% of women the same age

"What is most worrying is the large discrepancy between how fit older people think they are compared with how active or inactive they really are.

"Health professionals will have a hard task to convince people to be more active if they feel they are doing enough exercise already.

"These findings reinforce the message that a lot of disability associated with old age is a result of disuse, not disease.