title: Development of lower limb stiffness and its contribution to maximum vertical jumping power during adolescence.
abstract: Maximum power production during multi-joint tasks increases as children grow older. Previous research suggests that in adults, maximum power production in jumping is related to lower limb stiffness. In a developmental context, the question arises as to whether the relationship between maximum power production and lower limb stiffness is age-dependent. The purpose of this study was to investigate the relationship between lower limb stiffness and peak power production in adolescents (AD) and pre-adolescents (PA). With institutional approval, two groups of pre-adults (pre-adolescents: 11-13 years of age, N=43; adolescents: 16-18 years of age, N=30) performed 30 two-legged hops at their preferred frequency and three maximum counter-movement jumps. AD produced significantly greater peak power during the counter-movement jump than PA (t(71)=-5.28, P<0.001) even when body mass was accounted for. Lower limb stiffness was significantly correlated with peak power production during the counter-movement jump in AD (R=0.62, P<0.001) but not in PA (R=0.26, P=0.10). When normalised to body mass, the relationship between lower limb stiffness and peak power also differed between the two age groups (R=0.30, P=0.11 for AD and R=0.02, P=0.88 for PA). In addition, we found that during hopping, both PA and AD behaved like a simple spring-mass system. Our findings highlight the importance of lower limb stiffness in the context of muscular power production during multi-joint tasks. They let us speculate that during adolescence, children acquire the ability to take greater advantage of elastic energy storage in the musculotendinous system when performing maximum counter-movement jumps.
authors.affiliation: Centre for Sports Medicine and Human Performance, Brunel University, Uxbridge, Middlesex, UK. thomas.korff@brunel.ac.uk
authors.forename: Thomas
authors.initials: T
authors.lastname: Korff
authors.forename: Sara L
authors.initials: SL
authors.lastname: Horne
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Cullen
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Blazevich
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D002648:Child; D006801:Humans; D035002:Lower Extremity / Q000033:anatomy & histology / Q000502:physiology; D009068:Movement; D053580:Muscle Strength / Q000502:physiology*; D016059:Range of Motion, Articular