Original articles   

The Journal of Sports Medicine and Physical Fitness 2001 March;41(1):46-53

Copyright © 2009 EDIZIONI MINERVA MEDICA

lingua: Inglese

Strength capabilities of knee extensor muscles in junior speed skaters

Kanehisa H., Nemoto I., Fukunaga T.

From the Department of Life Sciences (Sports Sciences) University of Tokyo, Tokyo, Japan * Research Institute of Physical Fitness, Japan Women’s College of Physical Education, Tokyo, Japan

Background. The ­present ­study ­aimed to inves­ti­gate the gen­der- and age-relat­ed pro­files of jun­ior ­speed skat­ers in ­strength capa­bil­ities dur­ing ­both sin­gle and repet­i­tive max­i­mal con­trac­tions.
Methods. The sub­jects ­were 19 ­male (age= 17.1±0.2 ­years, X±SE) and 13 ­female skat­ers (16.9±0.2 ­years). Isokinetic ­knee exten­sion ­torque (T) devel­oped con­cen­tri­cal­ly in a sin­gle con­trac­tion at ­three con­stant veloc­ities of 1.05, 3.14 and 5.24 rad/sec and 50 repet­i­tive max­i­mal con­trac­tions at 3.14 rad/sec was meas­ured ­using an iso­ki­net­ic dyna­mom­e­ter. In addi­tion, a B-­mode ultra­sound appa­ra­tus was ­used to deter­mine the ­cross-sec­tion­al ­area (CSA) of the quad­ri­ceps fem­or­is mus­cle at mid-­thigh.
Results. For the jun­ior skat­ers, T val­ues at ­three veloc­ities of 1.05, 3.14 and 5.24 rad/sec and the ­mean val­ue of iso­ki­net­ic ­torque (MT) for eve­ry ­five con­sec­u­tive ­trials in the ­first 25 max­i­mal con­trac­tions ­were sim­i­lar in ­both gen­ders ­when ­they ­were ­expressed rel­a­tive to the pro­duct of the ­cross-sec­tion­al ­area (CSA) of the quad­ri­ceps fem­or­is mus­cle and low­er ­limb ­length, T/­CSAL and MT/­CSAL, respec­tive­ly. However, the ­males ­showed sig­nif­i­cant­ly high­er MT/­CSAL val­ues ­than the ­females in the ­last 25 rep­e­ti­tions of the endu­rance ­test. In the com­par­i­sons ­between jun­ior and ref­er­ence sen­ior skat­ers, T/­CSAL for ­both gen­ders and MT/­CSAL for the ­females ­showed lit­tle age-relat­ed dif­fer­ence. For the ­males, how­ev­er, MT/­CSAL val­ues in the ­first 15 rep­e­ti­tions of the endu­rance ­test ­were sig­nif­i­cant­ly low­er in the jun­ior skat­ers ­than in the sen­ior ­ones.
Conclusions. The ­present ­results indi­cate ­that the ­strength capa­bil­ities of jun­ior ­speed skat­ers in a sin­gle max­i­mal con­trac­tion ­will be sim­i­lar in ­both gen­ders ­when the dif­fer­ence in mus­cle ­size is nor­mal­ized. However, the jun­ior ­male skat­ers may be ­less fat­i­gu­able ­than the jun­ior ­female ­ones in repet­i­tive max­i­mal con­trac­tions. Moreover, the com­par­i­son ­between jun­ior and sen­ior skat­ers sug­gests ­that, in ­postado­les­cence, ­males ­might be ­more train­able ­than ­females to ­improve ­torque out­put dur­ing ­short-­term repet­i­tive max­i­mal con­trac­tions ­beyond ­that ­achieved dur­ing ado­les­cence.