Original articles  EXERCISE PHYSIOLOGY AND BIOMECHANICS 

The Journal of Sports Medicine and Physical Fitness 2002 September;42(3):282-8

Copyright © 2009 EDIZIONI MINERVA MEDICA

language: English

Is muscle power related to running speed with changes of direction?

Young W. B., James R., Montgomery I.

From the School of Human Movement and Sport Sciences, University of Ballarat, Ballarat, Victoria, Australia

Back­ground. The pur­pose of ­this ­study was to iden­tify the rela­tion­ships ­between leg ­muscle ­power and ­sprinting ­speed ­with ­changes of direc­tion.
­Methods. Experi­mental ­design: the ­study was ­designed to ­describe rela­tion­ships ­between phys­ical qual­ities and a com­po­nent of ­sports per­for­mance. Set­ting: ­testing was con­ducted in an ­indoor ­sports ­hall and a bio­me­chanics labor­a­tory. Par­tic­i­pants: 15 ­male par­tic­i­pants ­were ­required to be ­free of ­injury and ­have ­recent expe­ri­ence com­peting in ­sports ­involving ­sprints ­with ­changes of direc­tion. Meas­ures: sub­jects ­were ­timed in 8 m ­sprints in a ­straight ­line and ­with var­ious ­changes of direc­tion. ­They ­were ­also ­tested for bilat­eral and uni­lat­eral leg ­extensor ­muscle con­cen­tric ­power ­output by an iso­ki­netic ­squat and reac­tive ­strength by a ­drop ­jump.
­Results. The cor­re­la­tions ­between con­cen­tric ­power and ­straight ­sprinting ­speed ­were non-sig­nif­i­cant ­whereas the rela­tion­ships ­between reac­tive ­strength and ­straight ­speed ­were sta­tis­ti­cally sig­nif­i­cant. Cor­re­la­tions ­between ­muscle ­power and ­speed ­while ­changing direc­tion ­were gen­er­ally low and non-sig­nif­i­cant for con­cen­tric leg ­power ­with ­some mod­erate and sig­nif­i­cant (p<0.05) coef­fi­cients ­found for reac­tive ­strength. The par­tic­i­pants who ­turned ­faster to one ­side ­tended to ­have a reac­tive ­strength dom­i­nance in the leg respon­sible for the ­push-off ­action.
Con­clu­sions. The rela­tion­ships ­between leg ­muscle ­power and ­change-of-direc­tion ­speed ­were not con­sis­tent. Reac­tive ­strength as meas­ured by the ­drop ­jump ­appears to ­have ­some impor­tance for lat­eral ­change-of-direc­tion ­speed, pos­sibly ­because of sim­ilar ­push-off ­actions. It was con­cluded ­that reac­tive ­strength of the leg ­extensor mus­cles has ­some impor­tance in ­change-of-direc­tion per­for­mance but the ­other tech­nical and per­cep­tual fac­tors ­than influ­ence ­agility per­for­mance ­should ­also be con­sid­ered.