Establishing Borderline and At-risk Regions for Estimated Skeletal Muscle Mass of Legs Determined with a Body Composition Meter

Abstract

Objective: Sarcopenia, in which decreases in muscle mass occur, may cause walking and motor function disorders among elderly individuals. We noninvasively measured lean skeletal muscle mass of the legs in healthy individuals. Results were corrected with the square of height to determine a corrected leg muscle index (CLMI). Standard deviations (SDs) were determined according to sex and age group and used to establish borderline and at-risk regions for use in preventing sarcopenia.

Subjects: The study participants comprised 5,197 healthy men (mean age, 52±11 years) and 2,237 healthy women (mean age, 50±11 years).

Methods: Leg scores were determined with a body composition meter that uses bioelectrical impedance for measurement. Leg scores were used to calculate leg skeletal muscle based on standard levels in young people. The CLMI, corrected for height, was then used to: 1) evaluate age-related changes in men and women; and 2) set a borderline region as the range1-2 SDs below the mean in subjects 20–39 years old and an at-risk region as >2 SDs below the mean. The proportions of subjects in each age group in these regions were calculated.

Results: The CLMI of persons in their 80s was 88% of that of those in their 20s. The CMLI of women in their 80s was 95% that of subjects in their 20s. Thus, age-related decline in CLMI was more prominent in men. For men, the borderline region was 5.1–5.8 kg/m² and the at-risk region was <5.1 kg/m². For women, these regions were 4.1–4.6 kg/m² and <4.1 kg/m², respectively.

Conclusion: We set borderline and at-risk regions for use in preventing sarcopenia.