Electromechanical delay components during relaxation after voluntary contraction: reliability and effects of fatigue. Issue 6 (24th April 2015)

• Record Type: Journal Article
• Authors: Cè, Emiliano; Rampichini, Susanna; Venturelli, Massimo; Limonta, Eloisa; Veicsteinas, Arsenio; Esposito, Fabio
• Is Part Of: Muscle & nerve. Volume 51:Issue 6(2015:Jun.)
• Page Start: 907
• Page End: 915
• Publication Date: 2015-04-24
• Subjects: Neuromuscular diseases -- Periodicals; Muscles -- Periodicals; Nerves -- Periodicals; 616.74
• DOI: 10.1002/mus.24466
• Languages: English
• ISSNs: 0148-639X

Abstract

<abstract abstract-type="main"> <title>ABSTRACT</title> <sec id="mus24466-sec-0001" sec-type="section"> <title>Introduction</title> <p>Fatigue effects on total relaxation delay (R‐Delay<sub>TOT</sub>) components and measurement reliability were investigated.</p> </sec> <sec id="mus24466-sec-0002" sec-type="section"> <title>Methods</title> <p>Electromyogram (EMG), force (F), and mechanomyogram (MMG) were recorded during maximum voluntary contraction from the biceps brachii muscle before and after fatigue. The delays between EMG cessation and onset of F decay (R‐EMD), between F decay and onset of MMG largest displacement (MMG p‐p) (R‐Δt F‐MMG), from the beginning to the end of MMG p‐p (R‐Δt MMG<sub>p‐p</sub>), and from the end of MMG p‐p to F cessation (R‐Δt MMG‐F<sub>end</sub>) were calculated.</p> </sec> <sec id="mus24466-sec-0003" sec-type="section"> <title>Results</title> <p>R‐Delay<sub>TOT</sub> lasted 366 ± 10 ms. R‐EMD, R‐Δt F‐MMG, R‐Δt MMG<sub>p‐p</sub>, and R‐Δt MMG‐F<sub>end</sub> accounted for 6%, 8%, 59%, and 27% of R‐Delay<sub>TOT</sub>, respectively. After fatigue, R‐Delay<sub>TOT</sub>, R‐EMD, R‐Δt F‐MMG, and R‐Δt MMG<sub>p‐p</sub> increased by 38%, 22%, 40%, 40%, and 38%, respectively (<italic>P</italic> < 0.05). Reliability was very high (0.853–0.960).</p> </sec> <sec id="mus24466-sec-0004" sec-type="section"> <title>Conclusions</title> <p>R‐Δt MMG<sub>p‐p</sub> was the main contributor to R‐Delay<sub>TOT</sub>. Fatigue affected all R‐Delay<sub>TOT</sub> contributors, with a smaller effect on R‐EMD. <italic>Muscle Nerve</italic><bold>51</bold>: 907–915, 2015</p> </sec> </abstract>