Original articles  EXERCISE PHYSIOLOGY AND BIOMECHANICS 

The Journal of Sports Medicine and Physical Fitness 2002 December;42(3):425-30

Copyright © 2009 EDIZIONI MINERVA MEDICA

lingua: Inglese

Effect of low intensity electrical stimulation on quadriceps muscle voluntary maximal strength

Valli P. ¹, Boldrini L. ¹, Bianchedi D. ¹, Brizzi G. ², Miserocchi G. ³

¹ School of Sport Medicine University of Milan, Milan, Italy 2 Sintesi, Linea di Fiorano, Bergamo, Italy 3 University of Milano-Bicocca, Milano, Italy

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Back­ground. Eval­uate the ­effect of low inten­sity ­electrical stim­u­la­tion (ES) ­training on ­strength. We pur­pose­fully ­used a low ES stim­u­la­tion inten­sity to ­have it ­well ­accepted by ­middle ­aged and low per­forming ­people. ­Relate ­strength to meta­bolic param­e­ters.
­Methods. Experi­mental ­design. Pro­tocol 1: ­effects of 11 day low inten­sity ES ­training on quad­ri­ceps ­muscle max­imal vol­un­tary con­trac­tion (MVC). Pro­tocol 2: ­effects of 3 day ­training at low inten­sity ES + vol­un­tary con­trac­tion at 60% of MVC (co-con­trac­tion). Var­i­ables meas­ured: max­imal vol­un­tary ­strength (­FMAX), ­strength ­during ES (FES), ­strength devel­oped ­during co-con­trac­tion (FES-C), ­oxygen con­sump­tion, ­heart ­rate. Experi­mental ­design ­included a ­basal ses­sion, a ­training pro­gram and con­trols of meas­ured var­i­ables ­during and at the end of the ­training pro­gram. Par­tic­i­pants: pro­tocol 1: experi­ments ­were ­done on 13 ­healthy and sed­en­tary sub­jects (6 ­males and 7 ­women, ­mean age 50.6 ­years). Pro­tocol 2: experi­ments ­done on 6 ­healthy sed­en­tary men (­mean age 31.5 ­years).
­Results. Pro­tocol 1: ­FMAX ­increased sig­nif­i­cantly (p<0.05) to 14 and 19% at day 6 and 11, respec­tively. ­During ES, ­oxygen con­sump­tion ­increased by 20%, but no ­change in ­heart ­rate was ­observed. Pro­tocol 2: ­FMAX sig­nif­i­cantly ­increased (­about 5%) in sub­jects who ­trained ­with co-con­trac­tion; con­versely, ­FMAX did not sig­nif­i­cantly ­increase in a con­trol ­group ­matched for age who ­trained ­only ­with vol­un­tary con­trac­tions.
Con­clu­sions. Low inten­sity ES in sed­en­tary and ­poorly per­forming ­people ­increases sig­nif­i­cantly ­FMAX ­during MVC pos­sibly via fac­i­lit­a­tory neu­ro­genic mech­a­nism.