title: Effects of a daily school based physical activity intervention program on muscle development in prepubertal girls.
abstract: This 12-month prospective controlled intervention evaluated the effect of a general school based physical activity program on muscle strength, physical performance and body composition in prepubertal girls. Fifty-three girls aged 7-9 years involved in a school based exercise program [40 min/day of general physical activity per school day (200 min/week)] were compared with 50 age-matched girls who participated in the general Swedish physical education curriculum (mean 60 min/week). Body composition (DXA), isokinetic peak torque (PT) of the knee extensors and flexors at 60 and 180 degrees /s, and vertical jump height (VJH) were assessed at baseline and 12 months. The annual gain in weight was similar between the groups, but there was a greater increase in total body and regional lean mass (P < 0.05) and fat mass (P < 0.01) in the exercise group. Mean gains in knee extensor PT at 60 and 180 degrees /s were 7.0-7.6% greater in the exercise group (P ranging <0.05-<0.001). No significant differences were detected in VJH. In conclusion, increasing school based physical education to at least 3 h/week provides a feasible strategy to enhance the development of muscle strength and lean mass in prepubertal girls.
authors.affiliation: Clinical and Molecular Osteoporosis Research Unit, Department of Clinical Sciences, Lund University, Lund, Sweden.
authors.forename: Susanna
authors.initials: S
authors.lastname: Stenevi-Lundgren
authors.forename: Robin M
authors.initials: RM
authors.lastname: Daly
authors.forename: Christian
authors.initials: C
authors.lastname: Lindén
authors.forename: Per
authors.initials: P
authors.lastname: Gärdsell
authors.forename: Magnus K
authors.initials: MK
authors.lastname: Karlsson
mesh_terms: D015992:Body Mass Index; D015519:Bone Density / Q000502:physiology; D002648:Child; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D009043:Motor Activity / Q000502:physiology*; D024510:Muscle Development / Q000502:physiology*; D011446:Prospective Studies