title: The effect of sitting and calf activity on leg fluid and snoring.
abstract: Prolonged sitting may promote leg fluid retention that redistributes to the neck during sleep and contributes to snoring. This could be attenuated by calf activity while sitting. In 16 healthy non-obese subjects we measured leg fluid volume (LFV) below the knees using bioelectrical impedance while sitting for 4h, snoring using a portable BresoDx™ device, and Mallampati grade. Using a double cross-over study design, subjects were randomized to one of two arms and crossed-over one week later: control arm - no calf exercise while sitting; intervention arm - calf contraction against a pedal resistance while sitting. The effects of sitting±calf activity on LFV and snoring were compared. We found that LFV increased by 216±101.0ml (p<0.0001) after sitting. Calf activity while sitting attenuated LFV by 53.8ml (p<0.0001) and, in all five subjects with severe upper airway narrowing (Mallampati grade IV), reduced snoring duration (from 357±132.9 to 116.2±72.1s/h, p=0.02) suggesting reduced overnight rostral fluid shift to the neck.
authors.affiliation: Sleep Research Laboratory, University Health Network, Toronto Rehabilitation Institute, 550 University Avenue, Toronto, ON M5G 2A2, Canada; Department of Pulmonary Physiology & Sleep Medicine, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, WA 6009, Australia; Faculty of Science, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia; West Australian Sleep Disorders Research Institute, QEII Medical Centre, Hospital Avenue, Nedlands, WA 6009, Australia. Electronic address: bhajan.singh@health.wa.gov.au.
authors.forename: Bhajan
authors.initials: B
authors.lastname: Singh
authors.affiliation: Sleep Research Laboratory, University Health Network, Toronto Rehabilitation Institute, 550 University Avenue, Toronto, ON M5G 2A2, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College St, Toronto, ON M5S 3G9, Canada. Electronic address: Azadeh.Yadollahi@uhn.ca.
authors.forename: Azadeh
authors.initials: A
authors.lastname: Yadollahi
authors.affiliation: Sleep Research Laboratory, University Health Network, Toronto Rehabilitation Institute, 550 University Avenue, Toronto, ON M5G 2A2, Canada. Electronic address: Owen.Lyons@uhn.ca.
authors.forename: Owen
authors.initials: O
authors.lastname: Lyons
authors.affiliation: Sleep Research Laboratory, University Health Network, Toronto Rehabilitation Institute, 550 University Avenue, Toronto, ON M5G 2A2, Canada. Electronic address: Hisham.Alshaer@uhn.ca.
authors.forename: Hisham
authors.initials: H
authors.lastname: Alshaer
authors.affiliation: Sleep Research Laboratory, University Health Network, Toronto Rehabilitation Institute, 550 University Avenue, Toronto, ON M5G 2A2, Canada; Centre for Sleep Medicine and Circadian Biology, University of Toronto, 27 King's College Cir, Toronto, ON M5S, Canada; Department of Medicine, University Health Network, Toronto General Hospital, 585 University Ave, Toronto, ON M5G 2N2, Canada. Electronic address: douglas.bradley@utoronto.ca.
authors.forename: T Douglas
authors.initials: TD
authors.lastname: Bradley
mesh_terms: D000328:Adult; D000368:Aged; D001826:Body Fluids / Q000502:physiology*; D018592:Cross-Over Studies; D017097:Electric Impedance; D004576:Electromyography; D015444:Exercise; D005260:Female; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011187:Posture / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D012913:Snoring / Q000503:physiopathology / Q000534:rehabilitation*; D016896:Treatment Outcome
keywords: Bioelectrical impedance; Calf activity; Leg fluid volume; Rostral fluid shift; Sitting; Snoring