Due to variations in these factors across the population, the rate of progression and the threshold at which muscle loss becomes apparent is variable.
Other factors that can increase the rate of progression of sarcopenia include decreased nutrient intake, low physical activity, or chronic disease.
[2] Additionally, epidemiological research has indicated that early environmental influences may have long-term effects on muscle health.
For example, low birth weight, a marker of a poor early environment, is associated with reduced muscle mass and strength in adult life.
[16] Aging sarcopenic muscle shows an accumulation of mitochondrial DNA mutations, which has been demonstrated in various other cell types as well.
[18] An apparent protective factor preventing cells' buildup of damaged mitochondria is sufficient levels of the protein BNIP3.
[citation needed] Multiple diagnostic criteria have been proposed by various expert groups and continues to be an area of research and debate.
[22] Sarcopenia can be diagnosed when a patient has muscle mass that is at least two standard deviations below the relevant population mean and has a slow walking speed.
[22] Hand grip strength alone has also been advocated as a clinical marker of sarcopenia that is simple and cost effective and has good predictive power, although it does not provide comprehensive information.
[36] Progressive resistance training in older adults can improve physical performance (gait speed) and muscular strength.
[42] Other medications under investigation as possible treatments for sarcopenia include ghrelin, vitamin D, angiotensin converting enzyme inhibitors, and eicosapentaenoic acid.
[47] Older adults may not utilize protein as efficiently as younger people and may require higher amounts to prevent muscle atrophy.
[48][49] Ensuring adequate nutrition in older adults is of interest in the prevention of sarcopenia and frailty, since it is a simple, low-cost treatment approach without major side effects.
[50] A component of sarcopenia is the loss of ability for aging skeletal muscle to respond to anabolic stimuli such as amino acids, especially at lower concentrations.
However, aging muscle retains the ability of an anabolic response to protein or amino acids at larger doses.
Supplementation with larger doses of amino acids, particularly leucine has been reported to counteract muscle loss with aging.
[41] β-hydroxy β-methylbutyrate (HMB) is a metabolite of leucine that acts as a signalling molecule to stimulate protein synthesis.
[52][53][54] More research is needed to determine the precise effects of HMB on muscle strength and function in this age group.
Loss of lean body mass is also associated with increased risk of infection, decreased immunity, and poor wound healing.
This includes elucidation of the molecular and cellular mechanisms of sarcopenia, further refinement of reference populations by ethnic groups, validation of diagnostic criteria and clinical tools, as well as tracking of incidence of hospitalization admissions, morbidity, and mortality.