title: Physiological adaptations to resistance training in prepubertal boys.
abstract: OBJECTIVE
  The purpose of this study was to investigate the physiological adaptations of resistance training (RT) in prepubertal boys.
  
  
  METHODS
  Eighteen healthy boys were divided into RT (n = 9, Mage = 10.4 ± 0.5 years) and control (CTR; n = 9, Mage = 10.9 ± 0.7 years) groups. The RT group underwent a resistance training during 12 weeks, 3 times per week, performing 3 sets of 6 to 15 repetitions at intensities ranging from 60% to 80% of maximal dynamic strength (1-repetition maximum [1-RM] values). Before and after the training, the groups were assessed in their body mass and composition (dual-energy X-ray absorptiometry), isokinetic dynamometry, 1-RM, and ergoespirometry. Moreover, force per unit of muscle volume was calculated by the quotient between 1-RM and lean mass.
  
  
  RESULTS
  Both groups presented statistically significant (p < .05) increases in the 1-RM and force per unit of muscle volume in the knee extension and elbow flexion, but these strength increases were statistically significantly greater in the RT group (effect size [ES] = 2.83-9.00) than in the CTR group (ES = 0.72-1.00). Moreover, both groups statistically significantly increased in lean body mass variables (ES = 0.12-0.38). However, increases in the fat mass variables occurred only in the CTR group (ES = - 0.01-0.50), whereas no changes were observed in the RT group. Furthermore, there were statistically significant increases in all bone mineral content variables (ES = 0.13-0.43), without differences between groups. No cardiorespiratory changes were observed.
  
  
  CONCLUSIONS
  Twelve weeks of RT was effective in improving strength and force per unit of muscle volume and prevented fat mass increases in boys.
authors.affiliation: a Federal University of Rio Grande do Sul.
authors.forename: Giovani Dos Santos
authors.initials: Gdos S
authors.lastname: Cunha
authors.forename: Marcelo Morganti
authors.initials: MM
authors.lastname: Sant'anna
authors.forename: Eduardo Lusa
authors.initials: EL
authors.lastname: Cadore
authors.forename: Norton Luis de
authors.initials: NL
authors.lastname: Oliveira
authors.forename: Cinara Bos Dos
authors.initials: CB
authors.lastname: Santos
authors.forename: Ronei Silveira
authors.initials: RS
authors.lastname: Pinto
authors.forename: Alvaro
authors.initials: A
authors.lastname: Reischak-Oliveira
mesh_terms: D000222:Adaptation, Physiological; D001823:Body Composition; D015992:Body Mass Index; D015519:Bone Density; D002648:Child; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology; D011627:Puberty; D011659:Pulmonary Gas Exchange; D055070:Resistance Training; D019415:Torque
keywords: children's sports; exercise prescription; pediatric exercise; strength