title: Multilevel Development Models of Explosive Leg Power in High-Level Soccer Players.
abstract: OBJECTIVE
  The aim of the present study was to model developmental changes in explosive power based on the contribution of chronological age, anthropometrical characteristics, motor coordination parameters, and flexibility.
  
  
  METHODS
  Two different longitudinal, multilevel models were obtained to predict countermovement jump (CMJ) and standing broad jump (SBJ) performance in 356 high-level, youth soccer players, age 11-14 yr at baseline. Biological maturity status was estimated (age at peak height velocity [APHV]), and variation in the development of explosive power was examined based on three maturity groups (APHV; earliest < P33, P33 < average < P66, latest > P66).
  
  
  RESULTS
  The best-fitting model for the CMJ performance of the latest maturing players could be expressed as: 8.65 + 1.04 × age + 0.17 × age + 0.15 × leg length + 0.12 × fat-free mass + 0.07 × sit-and-reach + 0.01 × moving sideways. The best models for average and earliest maturing players were the same as for the latest maturing players, minus 0.73 and 1.74 cm, respectively. The best-fitting model on the SBJ performance could be expressed as follows: 102.97 + 2.24 × age + 0.55 × leg length + 0.66 × fat-free mass + 0.16 × sit-and-reach + 0.13 jumping sideways. Maturity groups had a negligible effect on SBJ performance.
  
  
  CONCLUSIONS
  These findings suggest that different jumping protocols (vertical vs long jump) highlight the need for special attention in the evaluation of jump performance. Both protocols emphasized growth, muscularity, flexibility, and motor coordination as longitudinal predictors. The use of the SBJ is recommended in youth soccer identification and selection programs because biological maturity status has no effect on its development through puberty.
authors.affiliation: 1Department of Movement and Sports Science, Ghent University, Ghent, BELGIUM; 2Faculty of Sport Science and Physical Education, University of Coimbra, Coimbra, PORTUGAL; and 3Faculty of Physical Education and Sport, Lusofona University of Humanities and Technologies, Lisbon, PORTUGAL.
authors.forename: Dieter
authors.initials: D
authors.lastname: Deprez
authors.forename: Joao
authors.initials: J
authors.lastname: Valente-Dos-Santos
authors.forename: Manuel Joao
authors.initials: MJ
authors.lastname: Coelho-E-Silva
authors.forename: Matthieu
authors.initials: M
authors.lastname: Lenoir
authors.forename: Renaat
authors.initials: R
authors.lastname: Philippaerts
authors.forename: Roel
authors.initials: R
authors.lastname: Vaeyens
mesh_terms: D000293:Adolescent; D002648:Child; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D015233:Models, Statistical; D009068:Movement / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology*; D011627:Puberty / Q000502:physiology*; D012044:Regression Analysis; D012916:Soccer / Q000502:physiology*