Resumen de The influence of maturation on sprint performance in boys over a 21-month period
Robert W. Meyers, Jon L. Oliver, Michael G. Hughes
AB Purpose: This study examined how the characteristics of maximal overground sprint performance are affected by the period of peak height velocity (PHV) in boys. Methods: One hundred eighty-nine school-age boys completed two assessments of maximal sprint performance, separated by a 21-month period. Kinematic characteristics of sprint performance were collected during a 30-m sprint using a floor-level optical measurement system, with modeled force and stiffness characteristics also calculated. Participants were grouped according to maturation using a noninvasive predictive equation. Individuals whose maturity offset was <-0.5 yr in both assessments were classed as "pre-PHV" (n = 67), whereas those whose maturity offset developed from <-0.5 to >0.5 yr in test two were classed as "pre-to-post PHV" (n = 39). Participants with a maturity offset between >-0.5 and <0.5 yr at test 2 were removed from analysis (n = 67) to ensure that the entire pre-to-post-PHV group had experienced the PHV spurt. Results: The pre-to-post-PHV group experienced significantly greater increases in speed (10.4% vs 5.6%) and relative vertical stiffness (12.1% vs 5.6%) compared with the pre-PHV group. Step frequency declined (-2.4%) and contact time increased (2.3%) in the pre-PHV group, whereas step frequency increased (2.7%) and contact time decreased (-3.6%) in the pre-PHV to post-PHV group. Changes in relative measures of vertical stiffness, maximal force, and leg stiffness accounted for 79% and 83% of the changes in speed between assessments for pre-PHV and pre-to-post-PHV groups, respectively. Conclusions: As boys experience PHV, there are greater increases in maximal sprint speed compared with those who remain pre-PHV. Furthermore, measures of relative stiffness and relative maximal force appear to exert an important influence on the development of maximal sprint speed in boys, regardless of maturity. (C) 2016 American College of Sports Medicine
