Childhood muscle morphology and strength: alterations over six months of growth.
BACKGROUND
The purpose of this study was to establish the nature and stability of the strength-size relationship for the knee flexors and extensors across a 6-month period of childhood growth.


METHODS
Nineteen typically developing children aged 5-11 years underwent lower limb magnetic resonance imaging (MRI) and dynamometry strength assessments on 2 occasions, 6 months apart. Muscle volume (MV) and maximum anatomical cross-sectional area (aCSA) for the knee flexors and extensors were determined using MRI analysis software. Isokinetic dynamometry determined corresponding isometric and isokinetic strength.


RESULTS
Strong correlations were found between muscle size and strength for both the knee flexors and extensors (r = 0.84-0.90; P < 0.01). Furthermore, the ratio of strength to muscle size remained consistent across 6 months of prepubescent growth.


CONCLUSIONS
Increases in thigh muscle strength were relative to those in muscle size, suggesting that muscle growth may play an important role in the development of strength during childhood.
School of Sport Science, Exercise and Health, M408, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia.
Christian A
CA
Pitcher
Catherine M
CM
Elliott
Sîan A
SA
Williams
Melissa K
MK
Licari
Alex
A
Kuenzel
Peter J
PJ
Shipman
Jane P
JP
Valentine
Siobhán L
SL
Reid
D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000254:growth & development