title: Plyometrics' trainability in preadolescent soccer athletes.
abstract: Plyometric training (PT) is a widely used method to improve muscle ability to generate explosive power. This study aimed to determine whether preadolescent boys exhibit plyometric trainability or not. Forty-five children were randomly assigned to either a control (CG, N = 21, 10.6 ± 0.5 years; participated only in regular soccer practice) or a plyometric training group (PTG, N = 24, 10.6 ± 0.6 years; participated in regular soccer practice plus a plyometric exercise protocol). Both groups trained for 12 weeks during the in-season period. The PT exercises (forward hopping, lateral hopping, shuffles, skipping, ladder drills, skipping, box jumps, low-intensity depth jumps) were performed twice a week. Preadolescence was verified by measuring Tanner stages, bone age, and serum testosterone. Speed (0-10, 10-20, 20-30 m), leg muscle power (static jumping, countermovement jumping, depth jumping [DJ], standing long jump [SLJ], multiple 5-bound hopping [MB5]), leg strength (10 repetition maximum), anaerobic power (Wingate testing), and soccer-specific performance (agility, kicking distance) were measured at baseline, midtraining, and posttraining. The CG caused only a modest (1.2-1.8%) increase in speed posttraining. The PTG induced a marked (p < 0.05) improvement in all speed tests (1.9-3.1% at midtraining and 3-5% at posttraining) and vertical jump tests (10-18.5% at midtraining and 16-23% at posttraining), SLJ (2.6% at midtraining and 4.2% at posttraining), MB5 (14.6% at midtraining and 23% at posttraining), leg strength (15% at midtraining and 28% at posttraining), agility (5% at midtraining and 23% at posttraining), and kicking distance (13.6% at midtraining and 22.5% at posttraining). Anaerobic power remained unaffected in both groups. These data indicate that (a) prepubertal boys exhibit considerable plyometric trainability, and (b) when soccer practice is supplemented with a PT protocol, it leads to greater performance gains.
authors.affiliation: Department of Physical Education and Sport Sciences, Democritus University of Thrace, Komotini, Greece.
authors.forename: Yiannis
authors.initials: Y
authors.lastname: Michailidis
authors.forename: Ioannis G
authors.initials: IG
authors.lastname: Fatouros
authors.forename: Eleni
authors.initials: E
authors.lastname: Primpa
authors.forename: Charalampos
authors.initials: C
authors.lastname: Michailidis
authors.forename: Alexandra
authors.initials: A
authors.lastname: Avloniti
authors.forename: Athanasios
authors.initials: A
authors.lastname: Chatzinikolaou
authors.forename: José C
authors.initials: JC
authors.lastname: Barbero-Álvarez
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Tsoukas
authors.forename: Ioannis I
authors.initials: II
authors.lastname: Douroudos
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Draganidis
authors.forename: Diamanda
authors.initials: D
authors.lastname: Leontsini
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Margonis
authors.forename: Fani
authors.initials: F
authors.lastname: Berberidou
authors.forename: Antonios
authors.initials: A
authors.lastname: Kambas
mesh_terms: D000704:Analysis of Variance; D000886:Anthropometry; D054874:Athletic Performance / Q000502:physiology*; D002648:Child; D005080:Exercise Test; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D010806:Physical Education and Training / Q000379:methods*; D059385:Plyometric Exercise; D012916:Soccer / Q000502:physiology*; D018709:Statistics, Nonparametric; D013739:Testosterone / Q000097:blood
chemical_list: D013739:Testosterone