title: Associations of Monitor-Assessed Activity with Performance-Based Physical Function.
abstract: The purpose of this study was to investigate the cross-sectional associations of monitor-derived measures of sedentary time and physical activity with performance-based physical function in healthy Australian adults. Data from 602 participants (mean age 58.1±10.0 years; 58% female) from the 2011/12 wave of the Australian Diabetes, Obesity and Lifestyle (AusDiab3) study were analyzed. The thigh-worn activPAL3™ monitor (7-days continuous wear) was used to derive time during waking hours spent: sitting/reclining; standing; and, stepping (overall, and separately as light [<3 METs] and moderate-to-vigorous physical activity [MVPA; ≥3 METs]), and number of sit-stand transitions. Associations of these (in hours/day, or 15 transitions/day) with physical function measures (8ft Timed Up and Go [TUG-8; log-transformed seconds] and Knee Extensor Strength [KES; kg]) were tested via linear regression, adjusting for confounders. Interactions by sex and age-category (<45; 45-54; 55-64; ≥65 years) were tested. In all participants, KES was significantly (p<0.05) associated with stepping and MVPA stepping only; none of the activity measures were associated with TUG-8. However, subgroup analysis revealed that in older adults (≥65 years), TUG-8 was associated with stepping and MVPA stepping (both p<0.05). All associations with sitting time, standing, sit-stand transition and sex interactions were not statistically significant. In summary, sitting time was not significantly associated with impaired muscle strength or gait/mobility in Australian adults aged 36-80 years, but light- to moderate activity (stepping) was positively associated with muscle strength, and gait/mobility in older adults aged ≥65 years. The direction of causation is not known and remains important to investigate considering the high prevalence of both poor function and limited activity in older age.
authors.affiliation: School of Public Health, The University of Queensland, Brisbane, Australia.
authors.forename: Natasha
authors.initials: N
authors.lastname: Reid
authors.affiliation: Centre for Physical Activity and Nutrition Research, Deakin University, Melbourne, Australia.
authors.forename: Robin M
authors.initials: RM
authors.lastname: Daly
authors.affiliation: School of Public Health, The University of Queensland, Brisbane, Australia.
authors.forename: Elisabeth A H
authors.initials: EA
authors.lastname: Winkler
authors.affiliation: School of Public Health, The University of Queensland, Brisbane, Australia.|Mater Research Institute, The University of Queensland, South Brisbane, Australia.|Centre for Research in Geriatric Medicine, The University of Queensland School of Medicine, Brisbane, Australia.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Gardiner
authors.affiliation: School of Public Health, The University of Queensland, Brisbane, Australia.
authors.forename: Elizabeth G
authors.initials: EG
authors.lastname: Eakin
authors.affiliation: School of Public Health, The University of Queensland, Brisbane, Australia.|Baker IDI Heart and Diabetes Institute, Melbourne, Australia.|Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia.|Department of Medicine, Alfred Hospital, Monash University, Melbourne, Australia.
authors.forename: Neville
authors.initials: N
authors.lastname: Owen
authors.affiliation: School of Public Health, The University of Queensland, Brisbane, Australia.|Centre for Physical Activity and Nutrition Research, Deakin University, Melbourne, Australia.|Baker IDI Heart and Diabetes Institute, Melbourne, Australia.|Department of Medicine, Alfred Hospital, Monash University, Melbourne, Australia.|School of Public Health & Preventive Medicine, Monash University, Melbourne, Australia.|School of Sport Science, Exercise and Health, The University of Western Australia, Perth Australia.
authors.forename: David W
authors.initials: DW
authors.lastname: Dunstan
authors.affiliation: School of Public Health, The University of Queensland, Brisbane, Australia.|Baker IDI Heart and Diabetes Institute, Melbourne, Australia.|Mary MacKillop Institute of Health Research, Australian Catholic University, Melbourne, Australia.|School of Physiotherapy, Curtin University, Perth, Australia.
authors.forename: Genevieve N
authors.initials: GN
authors.lastname: Healy
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D009043:Motor Activity / Q000502:physiology*; D057185:Sedentary Behavior