ORIGINAL ARTICLES   

The Journal of Sports Medicine and Physical Fitness 1998 September;38(3):194-200

Copyright © 1999 EDIZIONI MINERVA MEDICA

lingua: Inglese

The effects of superimposed electrical stimulation of the quadriceps muscles on performance in different motor tasks

Strojnik V.

Faculty of Sport, University of Ljubljana, Slovenia

Back­ground. ­Some exam­ples are pre­sent­ed to ­show how super­im­posed electri­cal stim­u­la­tion of mus­cles dur­ing max­i­mum vol­un­tary ­effort can be ­used to ­enable sub­jects to ­achieve great­er ­joint ­torque, ­rate of ­joint ­torque devel­op­ment, and the ­joint angu­lar veloc­ity as ­when per­form­ing ­only vol­un­tar­i­ly ­with max­i­mum ­effort.
Meth­ods. Par­tic­i­pants: Ten stu­dents of phys­i­cal edu­ca­tion not ­involved ­into a reg­u­lar ­sport train­ing par­tic­i­pat­ed the ­study.
Inter­ven­tions: The sub­jects per­formed iso­met­ric and con­cen­tric ­knee exten­sions and ­squat ­jumps, with­out and ­with super­im­posed electri­cal stim­u­la­tion of the quad­ri­ceps mus­cles.
Meas­ures. A ­knee ­torque and angu­lar dis­place­ment ­were ­observed dur­ing iso­met­ric and con­cen­tric ­knee exten­sion. Dur­ing the jump­ing, a ver­ti­cal com­po­nent of the ­ground reac­tion ­force was meas­ured.
­Results. ­Results ­showed ­that the max­i­mal ­knee ­torque, as ­well as a ­torque ­rise, ­were high­er in iso­met­ric ­knee exten­sion ­trials ­with super­im­posed electri­cal stim­u­la­tion. The ­same was ­observed in con­cen­tric ­knee exten­sions, ­where great­er ­knee ­torque dur­ing super­im­posed electri­cal stim­u­la­tion ­also result­ed in high­er angu­lar veloc­ity and a ­more extend­ed ­knee at the end of the move­ment. In ­squat ­jumps, the appli­ca­tion of the super­im­posed electri­cal stim­u­la­tion result­ed in poor­er per­for­mance.
Con­clu­sions. It was con­clud­ed ­that super­im­posed electri­cal stim­u­la­tion was effec­tive in ­some sim­ple ­motor ­tasks, but not in ­more com­plex ­tasks ­where a co-ordi­na­tion of mul­ti­ple mus­cles of dif­fer­ent ­groups was nec­es­sary for ­improved per­for­mance.