Muscle mass impacts more than just muscles

July 17, 2018
/ Muscle, Research, Sarcopenia

Twenty years ago, the term “sarcopenia” – Greek for “poverty of flesh” – was coined to describe the muscle wasting that occurs with aging.

Often unnoticed, this condition can dramatically impact quality of life and independent living. Experts propose that muscle mass, strength and function should be assessed to diagnose sarcopenia.

Awareness of sarcopenia – affecting at least a third of older Australians – is slowly gaining momentum. So too are its wide-ranging effects on health, including its potential to cause type 2 diabetes.

New research suggests it could impact lung function and breast cancer risk.

Sarcopenia and lung function

Poor lung function can lead to respiratory complications like pneumonia and bronchitis as well as broader problems like heart disease and death.

Lungs rely on healthy muscles in the respiratory system, particularly the diaphragm, to help breathe in oxygen and expel carbon dioxide.

Handgrip strength is an easy, quick measure of muscle strength. The test involves simply squeezing a small object as hard as possible to measure the strength of your grip.

Handgrip strength is a useful indicator of general health, and has been related to nutrition status and walking ability. Also a useful indicator of low muscle mass, hand-grip strength can be used to diagnose sarcopenia.

Weak lung function has been linked to poor handgrip strength in hospitals or nursing homes. Korean researchers wanted to test if handgrip strength could predict lung function, measured using standard pulmonary (lung) function tests, in a national population study of healthy community-dwelling women aged 65-79.

They found that as handgrip strength declined, so did lung capacity – after adjusting for several other factors like age, education and physical activity levels.

The researchers suggest handgrip strength could be a useful public health tool for identifying potential impairment in lung function.

Muscle mass and breast cancer mortality

Sarcopenia and excess fat have been previously related to higher risk of mortality from metastatic (secondary) breast cancer.

Researchers from the United States and Canada recently investigated whether this was the case with nonmetastatic (primary) breast cancer. They measured muscle mass, muscle quality and fat in 3,241 women with stage 2 or 3 breast cancer, i.e. cancer that has not spread to other organs, and followed them up for at least 6 years.

A third of patients had sarcopenia, and they were 41 percent more likely to die early than those without sarcopenia. Women with highest amounts of fat were 35 percent more likely to die early than those with low fat levels.

Women who had lower muscle mass and higher levels of fat were 89 percent less likely to survive. Interestingly, body mass index (BMI; height/weight ratio) was not associated with survival.

It is possible, the researchers say, that women with more aggressive cancer may have lost more muscle mass early in their cancer as a result. Women with higher muscle mass may also have had healthier lifestyle habits more generally.

They suggest, however, that clinical measures of muscle mass and fat might help provide prognostic information to help guide treatment.

Staying strong

These studies build on evidence that says muscle matters – more than we might realise. Better health outcomes with aging can be achieved with simple lifestyle habits that embrace physical activity and good nutrition to prevent loss of muscle mass.