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.
Titolo: | Time course of stretching-induced changes in mechanomyogram and force characteristics |
Autori: | 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 |
Rivista: | |
Tipologia: | Article (author) |
Digital Object Identifier (DOI): | 10.1016/j.jelekin.2011.07.012 |
Appare nelle tipologie: | 01 - Articolo su periodico |
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