title: Objectively measured sedentary time and physical activity time across the lifespan: a cross-sectional study in four age groups.
abstract: BACKGROUND
  From a health perspective it is suggested to promote a positive balance between time spent in light intensity physical activity (LIPA) and sedentary behaviour (SB) (i.e. spending more time in LIPA than time spent in SB). However, no studies have reported prevalence rates of the LIPA-SB balance yet. The aim of this study was to objectively investigate the time spent in SB, in LIPA and moderate-to-vigorous intensity physical activity (MVPA) in four Belgian age groups and to explore which proportion of the population had a favorable balance between LIPA and SB and combined this with recommended amount of MVPA.
  
  
  METHODS
  Accelerometer data from 7 cross-sectional studies (N=2083) in four age groups (preschoolers, primary schoolchildren, secondary schoolchildren and adults) were aggregated. Differences in SB and PA between age groups and between men and women were determined by two-way MANCOVA. LIPA-SB balance was calculated and participants were categorized into one of four groups: (1) positive LIPA-SB balance (LIPA> SB) & sufficient MVPA (2) negative LIPA-SB balance & sufficient MVPA (3) positive LIPA-SB balance & insufficient MVPA (4) negative LIPA-SB balance & insufficient MVPA.
  
  
  RESULTS
  For the total sample, 55% of the waking time was spent in SB, 39% in LIPA and 6% in MVPA. Differences in SB between age groups was dependent from gender (p<0.001). Further, a positive LIPA-SB balance was assessed in 18% of the total sample and only 10% combined this positive balance with recommended amount of MVPA. Secondary schoolgirls were most at risk, with only 1% of the sample combining a positive LIPA-SB balance with sufficient MVPA. Another risk group was the large proportion (43%) of adult men who combined sufficient MVPA with a negative LIPA-SB balance.
  
  
  CONCLUSIONS
  A high proportion of the Belgian population is at risk if taking into account both SB and PA levels. Secondary schoolgirls have the unhealthiest SB and PA profile and are therefore an important target group for interventions both increasing MVPA and decreasing SB. In men more attention should be given in promoting a positive LIPA-SB balance independently from their compliance with the MVPA guidelines.
authors.affiliation: Department of Movement and Sport Sciences, Faculty of Medicine and Health Sciences, Ghent University, Watersportlaan 2, Gent, 9000, Belgium.
authors.forename: Heleen
authors.initials: H
authors.lastname: Spittaels
authors.forename: Eveline
authors.initials: E
authors.lastname: Van Cauwenberghe
authors.forename: Vera
authors.initials: V
authors.lastname: Verbestel
authors.forename: Femke
authors.initials: F
authors.lastname: De Meester
authors.forename: Delfien
authors.initials: D
authors.lastname: Van Dyck
authors.forename: Maïté
authors.initials: M
authors.lastname: Verloigne
authors.forename: Leen
authors.initials: L
authors.lastname: Haerens
authors.forename: Benedicte
authors.initials: B
authors.lastname: Deforche
authors.forename: Greet
authors.initials: G
authors.lastname: Cardon
authors.forename: Ilse
authors.initials: I
authors.lastname: De Bourdeaudhuij
mesh_terms: D061725:Accelerometry / Q000379:methods*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000886:Anthropometry; D001530:Belgium; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D017408:Guidelines as Topic; D006801:Humans; D008875:Middle Aged; D009043:Motor Activity; D015995:Prevalence; D012307:Risk Factors; D012574:Schools; D057185:Sedentary Behavior; D011795:Surveys and Questionnaires; D055815:Young Adult