Sarcopenia Defined: Symptoms and TreatmentFitness Gear & Equipment
Sarcopenia is defined as age-related loss of muscle mass. In some persons there is excessive loss of muscle, similar to the excessive loss of bone that occurs in osteoporosis.
• Sarcopenia is measured by dual-energy radiograph absorptiometry and calculated as follows: appendicular skeletal mass/height2. A person whose muscle mass is two standard deviations below the level of the sex-specific mean in adults ages 20 to 40 years is considered to have a critical level of sarcopenia. By this definition 12% of persons 60 to 70 years of age have
• Fatty infiltration of muscle leads to myosteatosis and a decline in muscle power. Patients with sarcopenic obesity (also known as the fat frail) have the highest risk of developing future functional disability and an early death. Active obese persons tend to have a lower propensity to develop disability than obese persons who are housebound.
• There are multiple factors involved in the pathogenesis of sarcopenia. These include genetic factors. For example, persons with a single or double I allele for angiotensin-converting enzyme (ACE) generate more power than persons with the D allele. Small babies have been shown to have less strength when they reach 70 years of age than do large babies.
• The major factors in the development of sarcopenia are lack of exercise and excess production of cytokines. Interleukin-6 (the geriatric cytokine) and tumor necrosis factor-α result in activation of the muscle cell death chamber (ubiquitin-proteasome system) resulting in muscle atrophy, decreased strength, and functional decline.
• Anabolic steroids increase protein synthesis, inhibit the ubiquitin-proteasome system, and stimulate satellite cell production from precursor cells while inhibiting production of adipocytes. A number of highly selective androgen-receptor molecules are being developed to specifically treat sarcopenia.
• In older persons, the incorporation of amino acids into muscle protein is reduced. Older persons need higher levels of leucine and creatinine for protein synthesis than do younger persons.
• Insulin resistance leads to increased incorporation of fat into muscle and a decrease in protein synthesis. High levels of angiotensin II seen in diabetic patients stimulate the breakdown of actin and myosin in muscle. Diabetes mellitus is associated with decreased muscle strength, increased falls, and a decline in function.
• Low levels of vitamin D are associated with decreased muscle mass, increased falls, and functional deterioration. 25-hydroxyvitamin D levels in older persons should be greater than 30 ng/dL.
Treatment of Sarcopenia
Exercise (should include all five forms of exercise):
• Water exercise is particularly effective for persons with arthritis. Older persons should be encouraged to increase their spontaneous physical activity, such as getting out of the house once a day and parking as far away from their destination as possible.
• Anabolic steroids (eg, testosterone, nandrolone in males with low testosterone levels).
• Vitamin D at least 800 IU daily. Levels of
25-hydroxyvitamin D needs to be measured; and if lower than 30 ng/dL, higher doses of vitamin D should be given.
• Encourage adequate caloric intake with adequate amounts of protein (1.2 g/kg/d) enriched with leucine (whey protein) and creatine (meat protein). Supplements may be necessary to obtain sufficient amounts of protein and specific amino acids.
• Assess for peripheral vascular disease (Doppler assessment of the ankle-brachial index) and aggressively treat.
• Advise on the use of a cane or walker to reduce the incidence of falls.
• If the patient has hypertension, congestive heart failures, or diabetes mellitus, use an ACE inhibitor, because these agents appear to increase muscle strength.