Sarcopenia: 2020

• J Nutr Health Aging . 2021;25(3):278-280

Over the last 20 years sarcopenia has been recognized as a major geriatric syndrome with its own ICD-10-CM billable code (M62:84) (1) Numerous societies have recognized it should be diagnosed by having a low measurement of muscle strength, e.g., grip strength, as well as a low fat free mass (2–5). Sarcopenia should be screened for using the SARC-F (6). A number of papers have found that SARC-F is highly specific at identifying persons with sarcopenia that have poor outcomes (7–12). When SARC-F is combined with a measurement of calf circumference (SARC-CalF) it has better sensitivity (13, 14). In over 10,000 older persons sarcopenia was present in 42.9% of persons (15). Only 5.3% of frail persons were non-sarcopenic. In a younger population utilizing the SARC-F as part of the Rapid Geriatric Assessment mobile APP, 15.1% were sarcopenic (16). In persons with a positive SARC-F exercise for 12 months returned the SARC-F score to the normal range (17) (Figure 

Cawthon et al (18) showed that the D3-Creatine dilution method was better at predicting functional activity and mortality compared to DEXA-measured appendicular lean mass/height. Madden et al (19) showed that point of care of ultrasound is an excellent measure of vastus medialis mass and correlates well with muscle strength.

Osteosarcopenia is defined as a low bone and muscle mass and strength (20). It is associated with an increase in frailty, falls, hospitalizations and mortality. In persons with sarcopenia high-intensity resistance training over a year increased leg press strength and lumbar bone mineral density (21).

2020 was the year that demonstrated the importance of physical therapy for treating sarcopenia (22). The Izquierdo group clearly demonstrated that 2 sessions daily of an exercise program in hospital improves muscle power and functional outcomes (23, 24). A meta-analysis confirmed that exercise interventions in acutely older adults in hospital enhanced physical performance and functional independence (25, 26). Wang et al (27) showed that a hospital exercise program enhanced gait speed. Exercise therapy in hospital also improves cognition (28). In a meta-analysis of over 2,900 older persons, exercise decreased falls and improved physical and cognitive function (29). For persons with sarcopenia higher intensity resistance exercise is the treatment of choice (30).

Neuromuscular electric stimulation (NES) increased muscle mass and improved the Timed Up and Go test (TUG) (31). NEMS reduced muscle mass loss in critically ill patients (32). A meta-analysis found that vibration therapy in older persons improved strength, five times sit to stand and TUG (33).

It is recognized that high protein intake improves muscle mass in older persons (34). In persons with COPD in the NOURISH study betahydroxy-beta-methylbutyrate improved hand grip strength and reduced death in undernourished older hospital patients (35). Fortetropin, a food derived from egg yolk, increased muscle protein synthesis in older persons (36). Unlike in animals it did not reduce myostatin.

A number of drugs have improved muscle mass and strength compared to placebo but have not been compared to physical exercise (37). Bimagrumab, and activin II receptor inhibitor, failed to improve physical function compared to an adequate diet and exercise (38).

2020 was the year of COVID-19 (39, 40). Lockdown lead to increasing sarcopenia (41, 42). Exercise (ViviFrail) prevented functional decline in older persons in nursing homes (43). Persons with fatigue with long term Covid-19 were at increased risk for developing sarcopenia (44). The increased cytokines in COVID-19 resulted in severe muscle weakness as part of a cachexia syndrome (45, 46).

Of particular interest this year was the work on sestrin-1 (47). Sestrin-1 is low in muscle in old and frail humans. Muscle knockout of sestrins resulted in increased proteolysis in mice. When sestrins were overexpressed, they blocked muscle atrophy in denervated muscles.

• During this time SARC-F became more widely accepted as a screening test for sarcopenia. There was further evidence supporting that D3-creatine dilution is the best measure for muscle. Exercise is the treatment of choice for hospitalized, and institutionalized older persons as well as those who undergo lockdown due to the Covid-19 pandemic. Neuromuscular electrical stimulation may be the treatment of choice for persons with intensive care unit-acquired weakness (critical illness myopathy) and post stroke (48, 49). There is a need to increase the availability of exercise programs for the prevention and treatment of sarcopenia.