From the time you are born to around the time you turn 30, your muscles grow larger and stronger. But at some point in your 30s, you begin to lose muscle mass and function, a condition known as age-related sarcopenia or sarcopenia with aging. People who are physically inactive can lose as much as 3% to 5% of their muscle mass per decade after age 30. Even if you are active, you will still experience some muscle loss.
Although there is no generally accepted test or specific level of muscle mass for sarcopenia diagnosis, any loss of muscle mass is of consequence, because loss of muscle means loss of strength and mobility. Sarcopenia typically accelerates around age 75 -- although it may happen in people age 65 or 80 -- and is a factor in the occurrence of frailty and the likelihood of falls and fractures in older adults.
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Symptoms of muscle loss include musculoskeletal weakness and loss of stamina, which can interfere with physical activity. Reduced physical activity, in turn, further reduces muscle mass.
Although sarcopenia is mostly seen in people who are inactive, the fact that it also occurs in people who stay physically active throughout life suggests there are other factors involved in the development of sarcopenia.
Researchers believe the following factors play a role:
Age-related reduction in nerve cells responsible for sending signals from the brain to the muscles to initiate movement
A decrease in the concentrations of some hormones, including growth hormone, testosterone, and insulin-like growth factor
A decrease in the body's ability to synthesize protein
Inadequate intake of calories and/or protein to sustain muscle mass
Treatments for Sarcopenia
The primary treatment for sarcopenia is exercise. Specifically, resistance training or strength training -- exercise that increases muscle strength and endurance with weights or resistance bands -- has been shown to be useful for both the prevention and treatment of sarcopenia.
Resistance training has been reported to positively influence the neuromuscular system, hormone concentrations, and protein synthesis rate. Research has shown that a program of progressive resistance training exercises can increase protein synthesis rates in older adults in as little as two weeks.
For optimal benefits with minimal risk of injury, the proper number, intensity, and frequency of resistance exercise is important. For that reason, you should work with an experienced physical therapist or trainer to develop an exercise plan.
Although drug therapy is not the preferred treatment for sarcopenia, a few medications are under investigation. They include:
Urocortin II. This peptide has been shown to stimulate the release of a hormone called adrenocoticotropic hormone (ACTH) from the pituitary gland. Intravenous urocortin II has been shown to prevent muscle atrophy from being in a cast or taking certain medications; it has also been shown to cause muscle growth in healthy rats. But its use for building muscle mass in humans has not been studied and is not recommended.
Hormone Replacement Therapy (HRT). When a woman's production of hormones is diminished at menopause, hormone replacement therapy has been shown to increase lean body mass, reduce abdominal fat short-term, and prevent bone loss. However, in recent years there has been controversy surrounding the use of HRT due to increased risk of certain cancers and other serious health problems among HRT users.
Other treatments under investigation for sarcopenia include testosterone supplementation, growth hormone supplementation, and medication for treatment of metabolic syndrome (insulin-resistance, obesity, hypertension, etc.). If found useful, all of these would complement the effects of resistance exercise, not replace them.