Accepted for/Published in: JMIR Aging
Date Submitted: Dec 22, 2025
Open Peer Review Period: Dec 22, 2025 - Feb 16, 2026
Date Accepted: Aug 10, 2026
(closed for review but you can still tweet)
Warning: This is an author submission that is not peer-reviewed or edited. Preprints - unless they show as "accepted" - should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
Domain-specific associations of physical activity with phase angle and extracellular water-to-total body water ratio in middle-aged or older adults
ABSTRACT
Background:
The phase angle (PhA) and extracellular water (ECW)-to-total body water (TBW) ratio serve as indicators of cell membrane integrity and body fluid balance in older adults.
Objective:
This study examined the domain-specific associations of physical activity (PA) with PhA and the ECW/TBW ratio.
Methods:
A nationally representative sample of 5,211 adults aged ≥ 50 years was analyzed. Weekly amounts of moderate-to-vigorous physical activity (MVPA) in leisure-time, occupational, and transport-related domains were assessed using the Global Physical Activity Questionnaire. A bioelectrical impedance analyzer was employed to measure PhA (°) and the ECW/TBW ratio (%). Linear regression analyses were conducted.
Results:
For leisure-time PA, compared with 0 min/week, participating in 150–299 min/week and ≥300 min/week of MVPA was associated with 0.08 (95% confidence interval [CI]: 0.02, 0.14) and 0.13 (95% CI: 0.06, 0.20) degrees higher PhA, respectively. Additionally, compared with 0 min/week, engaging in 150–299 min/week and ≥300 min/week of MVPA was associated with –0.11 (95% CI: –0.19, –0.03) and –0.15 (95% CI: –0.22, –0.07) percentage points lower ECW/TBW ratio, respectively. For transport-related PA, compared with 0 min/week, engaging in ≥300 min/week of MVPA was negatively associated with the ECW/TBW ratio (β: –0.07; 95% CI: –0.14, –0.01). Occupational PA showed no clear associations with PhA or the ECW/TBW ratio.
Conclusions:
The association between PA and both PhA and ECW/TBW ratio substantially differs across PA domains. The findings suggest beneficial associations of PA with cellular membrane integrity and body fluid balance are primarily attributable to leisure-time PA.
Citation
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Copyright
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