title: The influence of minimum sitting period of the ActivPAL™ on the measurement of breaks in sitting in young children.
abstract: BACKGROUND
  Sitting time and breaks in sitting influence cardio-metabolic health. New monitors (e.g. activPAL™) may be more accurate for measurement of sitting time and breaks in sitting although how to optimize measurement accuracy is not yet clear. One important issue is the minimum sitting/upright period (MSUP) to define a new posture. Using the activPAL™, we investigated the effect of variations in MSUP on total sitting time and breaks in sitting, and also determined the criterion validity of different activPAL™ settings for both constructs.
  
  
  METHODS
  We varied setting of MSUP in 23 children (mean (SD) age 4.5 y (0.7)) who wore activPAL™ (24 hr/d) for 5-7 d. We first studied activPAL™ using the default setting of 10 s MSUP and then reduced this to 5 s, 2 s and 1 s. In a second study, in a convenience sample of 30 pre-school children (mean age 4.1 y (SD 0.5)) we validated the activPAL™ measures of sitting time and breaks in sitting at different MSUP settings against direct observation.
  
  
  RESULTS
  Comparing settings of 10, 5, 2 and 1 s, there were no significant differences in sitting time (6.2 hr (1.0), 6.3 hr (1.0), 6.4 hr (1.0) and 6.3 hr (1.6), respectively) between settings but there were significant increases in the apparent number of breaks - (8(3), 14(2), 21(4) and 28 (6)/h) at 10, 5, 2 and 1 s settings, respectively. In comparison with direct observation, a 2 s setting had the smallest error relative to direct observation (95% limits of agreement: -14 to +17 sitting bouts/hr, mean difference 1.83, p = 0.2).
  
  
  CONCLUSIONS
  With activPAL™, breaks in sitting, but not total sitting time, are highly sensitive to the setting of MSUP, with 2 s optimal for young children. The MSUP to define a new posture will need to be empirically determined if accurate measurements of number of breaks in sitting are to be obtained.
authors: School of Medicine, University of Glasgow, Glasgow, United Kingdom.
authors: Zubaida
authors: Z
authors: Alghaeed
authors: John J
authors: JJ
authors: Reilly
authors: Sebastien F M
authors: SF
authors: Chastin
authors: Anne
authors: A
authors: Martin
authors: Gwyneth
authors: G
authors: Davies
authors: James Y
authors: JY
authors: Paton
mesh_terms: D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D018670:Monitoring, Ambulatory / Q000295:instrumentation* / Q000379:methods; D009043:Motor Activity; D009068:Movement; D011187:Posture; D057185:Sedentary Behavior; D014741:Video Recording
references: Mov Disord. 2010 Oct 15;25(13):2114-20
references: 20721926
references: Exerc Sport Sci Rev. 2004 Oct;32(4):161-6
references: 15604935
references: Arch Dis Child. 1995 Jul;73(1):17-24
references: 7639543
references: Med Sci Sports Exerc. 2012 Nov;44(11):2243-52
references: 22648343
references: Arch Dis Child. 1995 Jul;73(1):25-9
references: 7639544
references: Med Sci Sports Exerc. 2012 Jun;44(6):1081-7
references: 22143113
references: Med Sci Sports Exerc. 2012 Apr;44(4):761-8
references: 21983077
references: Int J Behav Nutr Phys Act. 2011 Oct 28;8:120
references: 22035260
references: Age Ageing. 2012 Jan;41(1):111-4
references: 21749993
references: Med Sci Sports Exerc. 2009 May;41(5):998-1005
references: 19346988
references: Diabetes. 2007 Nov;56(11):2655-67
references: 17827399
references: Exerc Sport Sci Rev. 2010 Jul;38(3):105-13
references: 20577058
references: Prev Med. 2010 Nov;51(5):357-60
references: 20816693
references: Lancet. 1986 Feb 8;1(8476):307-10
references: 2868172
references: Br J Sports Med. 2006 Dec;40(12):992-7
references: 16980531
references: Diabetes Care. 2008 Apr;31(4):661-6
references: 18252901
references: Med Sci Sports Exerc. 2005 Oct;37(10):1800-5
references: 16260984
references: Int J Behav Nutr Phys Act. 2012 Feb 19;9:15
references: 22340137
references: Physiol Meas. 2012 Nov;33(11):1913-21
references: 23111301
references: Med Sci Sports Exerc. 2012 Jun;44(6):1075-80
references: 22215180
references: Gait Posture. 2010 Jan;31(1):82-6
references: 19854651
references: Pediatr Exerc Sci. 2011 Nov;23(4):468-76
references: 22109774