To evaluate the time-course of stretching-induced changes in mechanical properties of the muscletendon unit (MTU), 11 participants (age 22 +/- 1 yr; body mass 77 +/- 5 kg; stature 1.78 +/- 0.05 m; mean +/- SD) underwent tetanic electrical stimulations of the medial gastrocnemius muscle before and after (up to 2 h) stretching administration. During contractions, surface electromyogram (EMG), mechanomyogram (MMG) and force were recorded simultaneously. From MMG, peak-to-peak (p-p) and root mean square (RMS) were calculated during the on-phase and plateau phase of tetanic contraction, respectively. After stretching: (i) no differences were found in EMG parameters; (ii) MMG p-p and slope decreased (-16% and -10%, respectively; P < 0.05) and remained depressed for the entire recovery period; (iii) MMG RMS increased (+20%; P < 0.05), returning to pre-stretching values within 15 min; and (iv) peak force (pF), with its first (dF/dt) and second (d(2)F/dt(2)) derivative, decreased significantly by 32%, 35% and 54%, respectively, and remained depressed for the entire recovery period. The lack of MMG p-p and pF recovery could be ascribable to a reduced muscle force generating capacity due to persisting changes in viscoelastic characteristics of series elastic components. The early return of MMG RMS to pre-stretching values suggests that changes in viscoelastic parallel components recovered after few minutes.
Time course of stretching-induced changes in mechanomyogram and force characteristics / F. Esposito, E. Limonta, E. Cè. - In: JOURNAL OF ELECTROMYOGRAPHY AND KINESIOLOGY. - ISSN 1050-6411. - 21:5(2011 Oct), pp. 795-802.
|Titolo:||Time course of stretching-induced changes in mechanomyogram and force characteristics|
ESPOSITO, FABIO (Primo)
LIMONTA, ELOISA MARIA GUGLIELMINA (Secondo)
CE', EMILIANO (Ultimo)
|Parole Chiave:||EMG; MMG; recovery; electrical stimulation|
|Settore Scientifico Disciplinare:||Settore BIO/09 - Fisiologia|
|Data di pubblicazione:||ott-2011|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1016/j.jelekin.2011.07.012|
|Appare nelle tipologie:||01 - Articolo su periodico|