Inactivity Weakens Muscle Mass for Both Old and Young

By Jane Farrell

Both young and old people lose muscle strength once they become inactive, according to new research.

A study shows that it takes only two weeks of not using their legs for young people to lose a third of their muscular strength, leaving them on par with a person who is 40-50 years their senior. The investigation was conducted by researchers from the Center for Healthy Aging and the Department of Biomedical Sciences at the University of Copenhagen.

“Our experiments reveal that inactivity affects the muscular strength in young and older men equally. Having had one leg immobilized for two weeks, young people lose up to a third of their muscular strength, while older people lose approx. one fourth. A young man who is immobilized for two weeks loses muscular strength in his leg equivalent to aging by 40 or 50 years, ” said Andreas Vigelsø, Ph.D.

Additionally, there can be a “penalty” for people who are fit before they are injured.

“The more muscle mass you have, the more you’ll lose. Which means that if you’re fit and become injured, you’ll most likely lose more muscle mass than someone who is unfit, over the same period of time. But even though older people lose less muscle mass and their level of fitness is reduced slightly less than in young people, the loss of muscle mass is presumably more critical for older people, because it is likely to have a greater impact on their general health and quality of life, ” said researcher Martin Gram.

After two weeks of immobilization, the participants rode bicycles 3-4 times a week for six weeks. But, researchers found, that wasn’t enough to reach pre-immobilization levels. The participants needed weight training as well.

The study was published in the Journal of Rehabilitation Medicine.