Characteristics of lower limb skeletal muscles of community-dwelling, elderly women and their relationships with gait function and daily physical activity: a fundamental study for early detection of sarcopenia using quantitative and qualitative evaluations of lower limb skeletal muscles by ultrasonography.

Abstract

Objective: This study examined the relationships among lower limb skeletal muscle characteristics, walking function, and daily physical activity in community-dwelling, independently living older women. This serves as a fundamental study for the prevention and early detection of sarcopenia, using ultrasonography-based muscle mass and quality assessment.

Patients and methods: The participants were 53 community-dwelling women aged 66-89 years, who were independent in activities of daily living (ADL). Age, physical characteristics (height, weight, body fat percentage, skeletal muscle mass, and skeletal muscle index [SMI]), walking function, physical activity level, fall occurrence in the past month, and gastrocnemius muscle parameters (muscle thickness, fascial thickness, and muscle echo intensity) were assessed. Correlation analyses were conducted and intra-examiner reliability was confirmed using the intraclass correlation coefficient.

Results: The participants' median age was 77.0 years, height was 150.3 cm, weight was 51.0 kg, body fat percentage was 30.6%, and SMI was 6.5 kg/m². Overall, 11.3% of participants had an SMI below the sarcopenia threshold. The gastrocnemius muscle parameters showed the strongest correlations; muscle thickness had weak positive correlations with SMI, walking function, and physical activity, but negative correlations with age and total movement time. Fascial thickness correlated positively with weight and body fat percentage but negatively with walking function. Muscle echo intensity was positively correlated with age and negatively correlated with SMI, walking speed, step count, and housework time.

Conclusion: Although all the participants lived independently, 11.3% had an SMI below the sarcopenia threshold, highlighting the need for early prevention. Gastrocnemius muscle parameters were significantly associated with age, physical characteristics, walking function, and activity level. Reduced physical activity may contribute to muscle degeneration and impaired walking even in independent individuals. Combining muscle echo intensity and fascial thickness may enhance muscle quality assessment, aiding in the prevention and early detection of sarcopenia.