Segmental extracellular-to-intracellular water resistance ratio and physical function in older adults.

OBJECTIVES: This study aimed to investigate the association between whole-body (WB), arm, and leg extracellular-to-intracellular water resistance (Recw/Ricw) ratios and various physical functions of each segment and muscle mass using segmental multifrequency bioelectrical impedance analysis. METHODS: In total, 988 community-dwelling older adults were included in the analysis. Physical function was assessed using hand grip, 5-repetition sit-to-stand, 5-m habitual walk, Timed Up and Go, and single-leg balance with eyes open tests. Each segmental Recw/Ricw ratio and muscle mass were assessed at 5 and 250 kHz resistances using a segmental multifrequency bioelectrical impedance analysis device. Pearson's correlation between the segmental Recw/Ricw ratio and muscle mass and physical function was calculated, and the difference in correlation coefficients was tested using Bonferroni correction. Multiple linear regression analysis was conducted using physical function as the dependent variable and the segmental Recw/Ricw ratio as the independent variable, adjusting for sex, age, body mass index, and segmental muscle mass. RESULTS: WB and leg Recw/Ricw ratios were significantly positively correlated with good hand grip performance, gait speed, mobility, balance, and standing power (p < 0.05), after adjusting for sex, age, body mass index, and muscle mass. Furthermore, the leg Recw/Ricw ratio was positively associated with lower extremity physical function compared with WB and arm Recw/Ricw ratios and muscle mass (p < 0.01). Conversely, WB muscle mass was more strongly related to grip strength than WB, arm, and leg Recw/Ricw ratios (p < 0.01). CONCLUSIONS: The Recw/Ricw ratio is useful for identifying older adults with worse physical function. The Recw/Ricw ratio allows for easy and timely screening of older adults with worse physical function in clinical settings.

Association of 24-h movement behaviors with phase angle in community-dwelling older adults: a compositional data analysis.

BACKGROUND: Phase angle (PhA) is an indicator of cellular conditions. Recent studies have suggested that PhA supports healthy aging. Identifying modifiable lifestyle factors for PhA is important. The associations of PhA in 24-h movement behaviors, including physical activity (PA), sedentary behavior (SB), and sleep, have not been studied in older adults. OBJECTIVES: We investigated the cross-sectional associations between 24-h movement behaviors and PhA in community-dwelling older adults while appropriately considering the co-dependent nature of daily time use using compositional data analysis. METHODS: The participants were 113 healthy older adults. PhA was measured using a bioelectrical impedance device. Time spent in light-intensity PA (LPA), moderate- to vigorous-intensity PA (MVPA), and SB was measured using a tri-axial accelerometer. Sleep duration information was self-reported in a questionnaire. Compositional multiple linear regression and compositional isotemporal substitution were performed to examine the associations of 24-h movement behaviors with PhA and hypothetical time reallocation in movement behaviors with PhA, respectively. RESULTS: Even after adjusting for potential confounders, relative to other behaviors more time spent in MVPA was significantly associated with higher PhA (p < 0.001). The 30 min/day of time reallocation from the other behaviors (SB, LPA, and sleep) to MVPA was predicted to be 0.12 higher PhA (corresponding to 2.3% increase; 95% CI 0.01, 0.24). CONCLUSIONS: Our results suggest that increasing or maintaining the daily time spent in MVPA is important for managing PhA in older adults, regardless of the other behaviors time consumed instead.

Cross-sectional and longitudinal study of the relationship between phase angle and physical function in older adults.

AIM: Although the validity of the assessment in older adults has been supported by several studies, cross-sectional and longitudinal relationships between phase angle (PhA) and physical function by sex have not been clarified. This study aimed to examine (i) cross-sectional relationships and (ii) longitudinal relationships between PhA and physical function in older adults. METHODS: A total of 816 and 445 community-dwelling older adults were included in cross-sectional and longitudinal analyses, respectively. We evaluated their physical function using grip strength, 5-repetition sit-to-stand test (5-STS), 5-meter habitual walk, Timed Up and Go test (TUG), single-leg balance with eyes open, and sit-and-reach test. A multifrequency bioelectrical impedance analyzer was used to determine the PhA at 50 kHz as well as the participants' body composition. RESULTS: In the cross-sectional analysis, a higher PhA was significantly associated with higher grip strength, sit-and-reach, single-leg balance with eyes open, 5-STS and lower TUG in women, as well as higher grip strength, single-leg balance with eyes open, lower 5-STS and TUG in men, adjusting for age, body mass index and muscle mass. In the longitudinal analysis, there was a significant interaction between PhA and year in the TUG test (B = -0.08; 95% CI, -0.136 to -0.025; P = 0.005) in men. There was no significant interaction between the PhA value and year for the other physical functions. CONCLUSIONS: The PhA is a useful indicator for assessing physical function in both older men and women. Furthermore, the PhA may be able to predict mobility limitation in older men. Geriatr Gerontol Int 2023; 23: 141-147.