Sarcopenia: an overview and analysis of molecular mechanisms

Evaluating the SarQoL® Questionnaire as a Screening Tool for Sarcopenia among Korean Older Adults

BACKGROUND/OBJECTIVES

Sarcopenia, characterized by the progressive loss of muscle mass and strength, poses significant risks to physical health, leading to a reduced quality of life (QoL), increased disability, and higher mortality rates among older adults. Early detection and intervention are crucial to prevent the cascading effects of sarcopenia, including falls, fractures, and hospitalization. This study determined an optimal cut-off point of the SarQoL® score that can serve as an effective screening tool among community-dwelling Korean older adults.

METHODS

The study involved 451 South Korean older adults, assessing the correlation between SarQoL® scores and sarcopenia as defined by the Asian Working Group for Sarcopenia (AWGS) criteria. Participants completed the Korean version of the SarQoL questionnaire.

RESULTS

Findings revealed that individuals diagnosed with sarcopenia had significantly lower SarQoL® scores compared to non-sarcopenic participants, with a cut-off score of ≤58.5 providing good diagnostic accuracy (AUC = 0.768, sensitivity = 69.3%, specificity = 75.2%).

CONCLUSIONS

These results underscore the questionnaire's reliability and validity in screening for sarcopenia-related QoL impairment and its potential utility as a clinical tool. Implementing the SarQoL® in routine assessments could improve clinical outcomes by enabling earlier and more precise identification of sarcopenia.

Age-related changes in isolated mouse skeletal muscle function are dependent on sex, muscle, and contractility mode

The present study aimed to simultaneously examine the age-related, muscle-specific, sex-specific, and contractile mode-specific changes in isolated mouse skeletal muscle function and morphology across multiple ages. Measurements of mammalian muscle morphology, isometric force and stress (force/cross-sectional area), absolute and normalized (power/muscle mass) work-loop power across a range of contractile velocities, fatigue resistance, and myosin heavy chain (MHC) isoform concentration were measured in 232 isolated mouse (CD-1) soleus, extensor digitorum longus (EDL), and diaphragm from male and female animals aged 3, 10, 30, 52, and 78 wk. Aging resulted in increased body mass and increased soleus and EDL muscle mass, with atrophy only present for female EDL by 78 wk despite no change in MHC isoform concentration. Absolute force and power output increased up to 52 wk and to a higher level for males. A 23–36% loss of isometric stress exceeded the 14–27% loss of power normalized to muscle mass between 10 wk and 52 wk, although the loss of normalized power between 52 and 78 wk continued without further changes in stress ( P > 0.23). Males had lower power normalized to muscle mass than females by 78 wk, with the greatest decline observed for male soleus. Aging did not cause a shift toward slower contractile characteristics, with reduced fatigue resistance observed in male EDL and female diaphragm. Our findings show that the loss of muscle quality precedes the loss of absolute performance as CD-1 mice age, with the greatest effect seen in male soleus, and in most instances without muscle atrophy or an alteration in MHC isoforms.

Emerging molecular mediators and targets for age-related skeletal muscle atrophy

The age-associated decline in muscle mass has become synonymous with physical frailty among the elderly due to its major contribution in reduced muscle function. Alterations in protein and redox homeostasis along with chronic inflammation, denervation, and hormonal dysregulation are all hallmarks of muscle wasting and lead to clinical sarcopenia in older adults. Reduction in skeletal muscle mass has been observed and reported in the scientific literature for nearly 2 centuries; however, identification and careful examination of molecular mediators of age-related muscle atrophy have only been possible for roughly 3 decades. Here we review molecular targets of recent interest in age-related muscle atrophy and briefly discuss emerging small molecule therapeutic treatments for muscle wasting in sarcopenic susceptible populations.