{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T21:02:55Z","timestamp":1790629375487,"version":"4.1.0"},"reference-count":43,"publisher":"JMIR Publications Inc.","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JMIR Aging"],"abstract":"Abstract<\/jats:title>\n \n Background<\/jats:title>\n The phase angle (PhA) and extracellular water (ECW)\u2013to\u2013total body water (TBW) ratio serve as indicators of cell membrane integrity and body fluid balance in older adults.<\/jats:p>\n <\/jats:sec>\n \n Objective<\/jats:title>\n This study examined the domain-specific associations of physical activity (PA) with PhA and the ECW-to-TBW ratio.<\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n A nationally representative sample of 5211 adults aged 50 years and older was analyzed. Weekly amounts of moderate-to-vigorous PA (MVPA) in leisure-time, occupational, and transport-related domains were assessed using the Global Physical Activity Questionnaire. A bioelectrical impedance analyzer was used to measure PhA (\u00b0) and the ECW-to-TBW ratio (%). Linear regression analyses were conducted.<\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n For leisure-time PA, compared with 0 min\/week, participating in 150 to 299 min\/week and \u2265300 min\/week of MVPA was associated with 0.08 (95% 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 to 299 min\/week and \u2265300 min\/week of MVPA was associated with \u20130.11 (95% CI \u20130.19 to \u20130.03) and \u20130.15 (95% CI \u20130.22 to \u20130.07) percentage points lower ECW-to-TBW ratio, respectively. For transport-related PA, compared with 0 min\/week, engaging in \u2265300 min\/week of MVPA was negatively associated with the ECW-to-TBW ratio (\u03b2=\u20130.07, 95% CI \u20130.14 to \u20130.01). Occupational PA showed no clear associations with PhA or the ECW-to-TBW ratio.<\/jats:p>\n <\/jats:sec>\n \n Conclusions<\/jats:title>\n While the observed associations were modest, the associations of PA with both PhA and the ECW-to-TBW ratio differed across PA domains. Specifically, leisure-time PA was positively associated with PhA and inversely associated with the ECW-to-TBW ratio. These findings highlight the potential role of leisure-time PA in improving bioelectrical markers of cellular health and fluid distribution.<\/jats:p>\n <\/jats:sec>","DOI":"10.2196\/90158","type":"journal-article","created":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T20:22:07Z","timestamp":1790626927000},"page":"e90158-e90158","source":"Crossref","is-referenced-by-count":0,"title":["Domain-Specific Associations of Physical Activity With Phase Angle and Extracellular Water\u2013to\u2013Total Body Water Ratio in Middle-Aged or Older Adults: Cross-Sectional 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