title: A 3-year school-based exercise intervention improves muscle strength - a prospective controlled population-based study in 223 children.
abstract: BACKGROUND
  Intense physical activity (PA) improves muscle strength in children, but it remains uncertain whether moderately intense PA in a population-based cohort of children confers these benefits.
  
  
  METHODS
  We included children aged 6-9 years in four schools where the intervention school increased the school curriculum of PA from 60 minutes/week to 40 minutes/school day while the control schools continued with 60 minutes/week for three years. We measured muscle strength, as isokinetic Peak Torque (PT) (Nm) of the knee flexors in the right leg at speeds of 60°/second and 180°/second, at baseline and at follow-up, in 47 girls and 76 boys in the intervention group and 46 girls and 54 boys in the control group and then calculated annual changes in muscle strength. Data are provided as means with 95% confidence intervals.
  
  
  RESULTS
  Girls in the intervention group had 1.0 Nm (0.13, 1.9) and boys 1.9 Nm (0.9, 2.9) greater annual gain in knee flexor PT at 60°/second, than girls and boys in the control group. Boys in the intervention group also had 1.5 Nm (0.5, 2.5) greater annual gain in knee flexors PT at 180°/second than boys in the control group.
  
  
  CONCLUSIONS
  A 3-year moderately intense PA intervention program within the school curriculum enhances muscle strength in both girls and boys.
authors.affiliation: Clinical and Molecular Osteoporosis Research Unit, Department of Orthopedics and Clinical Sciences, Skåne University Hospital, SE-205 02 Malmö, Sweden. fredrik.detter@med.lu.se.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Detter
authors.forename: Jan-Åke
authors.initials: JÅ
authors.lastname: Nilsson
authors.forename: Caroline
authors.initials: C
authors.lastname: Karlsson
authors.forename: Magnus
authors.initials: M
authors.lastname: Dencker
authors.forename: Björn E
authors.initials: BE
authors.lastname: Rosengren
authors.forename: Magnus K
authors.initials: MK
authors.lastname: Karlsson
mesh_terms: D015992:Body Mass Index; D002648:Child; D003479:Curriculum; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007717:Knee / Q000502:physiology; D008019:Life Style; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D010806:Physical Education and Training / Q000379:methods*; D011446:Prospective Studies; D012574:Schools