The Tanner Hill - Wellness

Sarcopenia which is associated with physical disability, regardless of your ethnic group, age, morbidity, income etc., has raised public and academic awareness recently. In the process of sarcopenia, the change in muscle composition, contractile and functioning of the tendon will result in the progressive loss of skeletal muscle mass and strength. It may even happen in younger adult in some situations.

In healthy muscle, protein and amino acid turn over regularly in a balanced manner. Nevertheless, this balance is typically disrupted with up to a 30% decrease in the production of muscle protein in senior citizens. Besides, during aging, the Type II (fast twitch) muscle fibers, which are characterized by higher force and low endurance, will be converted more into slow Type I (slow twitch) muscle fibers, which are characterized by low force and high endurance. This will lead to the loss of muscle power which is necessary for performing daily activities, such as rising from a chair or climbing steps. The consequence is not hard to imagine: fall and fracture.

Apart from falling or the consequential fracture, sarcopenia also increases the risk of functional impairment and physical disability and lead to failure to perform activities including activities of daily living (ADLs) and instrumental activities of daily living (IADLs). ADLs relate to the personal care tasks like bathing and washing, dressing, feeding, getting in and out of bed, and from the toilet; IADLs refer to domestic tasks such as shopping, laundry, vacuuming, cooking, and handling personal affairs. Professor Baumgartner and colleagues reported that the likelihood of having disability is approximately four times greater in sarcopenic men and women, as compared to older persons with normal muscle mass.

Efforts have been made these years to better define sarcopenia, and various methods have been introduced to measure skeletal muscle mass such as bioelectrical impedance analysis (BIA), dual-energy X-ray absorptiometry (DEXA), magnetic resonance imaging, computer tomography, positron emission tomography and functional magnetic resonance imaging. Nevertheless, most of these tools are costly and not always available in the clinical setting. The most cost-effective and easy-to-apply measuring methods are DEXA and BIA.

BIA is a non-invasive, rapid, easy-to-perform, reproducible and safe method to analyse body composition. It helps determine percentage of body fat and lean tissue and estimate volume of fat and lean body mass. It is a portable alternative to DEXA for estimating muscle mass.

Another indicator of sarcopenia is muscle strength. Many institutions use handgrip strength for assessment.

Physical function or performance is the third important factor to detect sarcopenia. Simple and easy tests such as get-up-and-go test or stair-climb power test are used to determine if there is any severe mobility limitation and mortality.

In the coming sessions, we will look into other details about sarcopenia.

Dr Liu Kin-wah
Specialist in Geriatric Medicine

Continuous reading:
Sarcopenia – What is It? (Part 1)