IT IS the news Jim Royles everywhere have been waiting for.

Scientists have claimed that too much exercise is bad for you - and that doing less could lengthen your life.

But, unfortunately for full-time couch-potatoes, the claims have attracted a healthy scepticism from York's fitness experts.

The researchers behind the study, a retired professor and his GP daughter, say that everybody has a limited amount of "life energy", and how long you live is determined by how fast you use it up.

High-energy activities - running, cycling, working out at the gym - make the body more susceptible to illness and actually accelerate the ageing process, the German researchers argue in a new book.

The Joy Of Laziness: How To Slow Down And Live Longer is written by Dr Peter Axt, retired professor of health science at Fulda University near Frankfurt, and his daughter, Dr Michaela Axt-Gadermann. Both former long-distance runners, their preferred form of exercise is now a gentle walk.

Their book says over-activity can cause the body to produce the hormone cortisone, which can damage brain cells, and lead to memory loss and premature senility.

Those who prefer lounging on the couch to pumping iron in the gym produce fewer "free radicals" in their body, the unstable oxygen molecules which are believed to contribute to ageing.

The Axts also suggest early risers are more prone to stress, and late sleepers live longer because they conserve their energy.

Dr Axt-Gadermann said: "If you lead a stressful life and exercise excessively, your body produces hormones which lead to high blood pressure and can damage your heart and arteries.

"People who would rather laze in a hammock instead of running a marathon, or who take a nap instead of playing squash, have a better chance of living into old age.

"We try to put our own ideas into practice, but this does not mean that we do nothing all day.

"Laziness should not be to the extreme and work is an important part of life, but recreation and relaxation should not be underestimated."

But medical and fitness experts have attacked the Axts' conclusions.

Nigel Davies, health and fitness manager at Fitness First York health club disagreed with the idea that exercise is bad for you. He said: "In my opinion, having done this job for 25 years, physical exercise keeps you healthy, both physiologically and emotionally.

Philippa Press, health improvement manger for Selby and York NHS Primary Care Trust, said: "All the medical evidence indicates that exercise is good for you.

"In those that don't take physical activity, we see increased levels of obesity, which can lead to hypertension and heart disease - things that are more likely to kill you."

Updated: 10:05 Wednesday, January 12, 2005