Smoking Speeds Up Muscle Loss

Researchers at The University of Nottingham have just given people another reason to kick the butt by finding that smokers lose more muscle mass in old age than non-smokers.

This finding adds to a series of other dangers posed by smoking such as cancer, heart attacks and strokes.

Though earlier research had established that smokers tend to have a lower muscle mass than non-smokers, for the first time Michael Rennie, a Professor of Clinical Physiology, and Dr Philip Atherton, a Research Fellow, both from the university's School of Graduate Entry Medicine and Health at Derby, have, with collaborators in Denmark and the USA, discovered that smoking impairs the day to day upkeep of muscle by speeding up a condition known as sarcopenia - the loss of muscle mass with ageing which is linked to poor balance, gait speed, falls, and fractures.

As a part of their study the researchers analysed 16 people in their mid sixties who were selected because of their similar lifestyles in terms of alcohol consumption and physical activity.

They were all considered to be healthy, with no symptoms of lung disease. They were studied in two equal groups: heavy smokers, who had smoked at least a pack of 20 cigarettes a day for at least 20 years: and non-smokers.

To measure the synthesis of muscle protein they were given an intravenous infusion of blood with a tagged amino acid (one of the building blocks of protein). Samples of muscle were taken from their thighs before and after the infusion to follow how much had "stuck" in muscle protein.

This measured the rate of synthesis of muscle protein which contributes to the daily maintenance of the muscle mass. The researchers found that it was substantially less in smokers than non-smokers.

During extensive studies, carried out in collaboration with Washington University, St Louis and Copenhagen University, Professor Rennie and Dr Atherton discovered that the amounts of myostatin, a muscle growth inhibitor and MAFbx enzyme, which breaks down muscle protein, were higher in smokers than non-smokers.

Dr Philip Atherton said: "From our tests, we can conclude that smoking slows the muscle protein synthesis machinery - probably impairing day to day upkeep of muscle. We are all well aware of the ill affects of smoking on the lungs but our study reveals yet another cause of ill-health associated with smoking. Hopefully the UK smoking ban will encourage people to quit while they are still young, helping them to keep in good health in later life".

Their research is being presented by Dr Atherton at Life Sciences 2007, the first joint meeting of the Biochemical Society, the British Pharmacological Society and The Physiological Society.

The study has been published on line in American Journal of Physiology.

Source-ANI
JAY/M