Muscle function and physical activity in pre-pubertal school children
Author
Summary, in English
Materials and Methods: The participants in this thesis were collected from the Pediatric Osteoporosis Prevention (POP) cohort. A school-curriculum-based exercise intervention programme comprising 40 minutes of physical education per school day was initiated and 68 boys and 53 girls aged 6 to 8 from one school were included in the intervention group. Age- and gender-matched children in the control group (46 boys and 50 girls) from three neighbouring schools were assigned to the general Swedish school curriculum of 60 minutes of physical education per week. When evaluating the effect of the mode of school transportation, comparisons were made between children who reported to have walked or cycled to school, and those who had commuted by bus or car. Physical activity was measured objectively by accelerometers worn for four consecutive days. Accelerometer measurements, however, were not done until two years after study start. In the cross-sectional normative data report (paper IV) 246 boys and 190 girls aged 6 to 12 in Tanner stages I and II were included.
Measurements were conducted before any intervention was initiated. Neuromuscular function was assessed by concentric isokinetic peak torque of the knee extensors and flexors at 60° and 180°/s and with vertical jump height test. Total body soft tissue composition was evaluated by dual energy X-ray absorptiometry and body mass and stature by standard measurements. Level of physical activity was subjectively estimated through questionnaires. In the prospective part of the study (papers I, II and III), neuromuscular and soft tissue development was followed for one year in the intervention group and control group.
Results: The normative evaluation reported improved performance and higher values in all anthropometric measurements with advancing ages, and with no constant gender differences across the age groups. Both boys and girls with increased school-based physical educational classes had higher annual gains in different muscle strength indices, but not in vertical jump height, than the control group. Walking or cycling to school was not associated with beneficial gain in muscle strength indices or vertical jump height in either boys or girls. The level of physical activity measured by accelerometers was so high in these children that all reached the level recommended by the United Kingdom Expert Consensus Group of 60 minutes of moderate-to-vigorous daily physical activity.
Conclusion: Normative gender-specific data on muscle strength, lean and fat mass and vertical jump height show that in Swedish children aged 6 to 12 in Tanner stage I and II there seems to be an increase with age and no structural gender differences. Daily physical education classes in school could be used in pre-pubertal boys and girls as a strategy to increase muscle strength, at least in the short term. These findings suggest increased physical education in pre-pubertal children as one possible strategy to improve neuromuscular function on a population level in society. In contrast, the mode of school transportation seems not to influence the measured traits, at least not in young children with a generally high level of everyday physical activity.
Department/s
Publishing year
2011
Language
English
Publication/Series
Lund University Faculty of Medicine Doctoral Dissertation Series
Volume
2011:32
Document type
Dissertation
Publisher
Lund University
Topic
- Orthopedics
Keywords
- children
- physical activity
- exercise
- isokinetic muscle strength
- vertical jump height
- normative
- intervention
- school transport
- DXA
- anthropometry
- fat mass
- lean mass
- weight
- height
- body mass index
- girls
- boys
- pre-pubertal
Status
Published
Research group
- Orthopedics - Clinical and Molecular Osteoporosis Research
Supervisor
- Magnus Karlsson
- Karin Ringsberg
ISBN/ISSN/Other
- ISSN: 1652-8220
- ISBN: 978-91-86671-80-8
Defence date
28 April 2011
Defence time
09:00
Defence place
Föreläsningssalen, plan 5 Ing 25b, Ortopediska kliniken SUS, Malmö
Opponent
- Roland Thomeé (Docent)