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Phase Angle Is a Useful indicator for Muscle Function in Older Adults.
M Yamada1, Y Kimura, D Ishiyama
1Minoru Yamada, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 3-29-1 Otsuka, Bunkyo-ku, Tokyo 112-0012, JapanTel: +81-3-3942-6863, Fax: +81-3-3942-6895, Email address: m-yamada@human.tsukuba.ac.jp.
The Journal of Nutrition, Health & Aging
|March 2, 2019
Summary
Phase angle (PhA) is a key indicator of skeletal muscle health in older adults. Lower PhA values correlate with reduced muscle mass and function, particularly in sarcopenia and dynapenia.
Area of Science:
- Gerontology
- Muscle Physiology
- Biophysics
Background:
- Skeletal muscle health declines with age, impacting mobility and quality of life.
- Bioelectrical impedance analysis (BIA) provides unique physiological variables, including phase angle (PhA).
- Phase angle (PhA) is a sensitive indicator of cell membrane integrity and cellular hydration, reflecting skeletal muscle status.
Purpose of the Study:
- To investigate the relationship between PhA and muscle mass/quality in older adults.
- To determine the diagnostic value of PhA for identifying poor muscle function.
- To establish cutoff values for PhA indicative of sarcopenia and dynapenia.
Main Methods:
- A cross-sectional study involving 1009 community-dwelling Japanese older adults (285 men, 724 women).
- Participants were categorized into normal, presarcopenia, dynapenia, and sarcopenia groups based on established criteria.
- Measurements included PhA via BIA, muscle quantity/quality via ultrasonography, muscle strength, and physical performance.
Main Results:
- Significant differences in PhA were observed across the four groups in both men and women (P<0.05).
- Lower PhA values were significantly associated with dynapenia and sarcopenia compared to the normal group.
- Receiver-operating characteristic curve analysis identified optimal PhA cutoff values (men: 4.05°, women: 3.55°) for discriminating sarcopenia and dynapenia.
Conclusions:
- Phase angle (PhA) is a valuable and accessible biomarker for assessing skeletal muscle function in older populations.
- PhA can effectively differentiate individuals with sarcopenia and dynapenia from those with normal muscle status.
- The established PhA cutoff values provide practical tools for clinical screening and management of age-related muscle decline.
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