Wavelet analysis of quadriceps power spectra and amplitude under varying levels of contraction intensity and velocity. Issue 5 (16th September 2014)

• Record Type: Journal Article
• Authors: Croce, Ronald; Miller, John; Chamberlin, Kent; Filipovic, David; Smith, Wayne
• Is Part Of: Muscle & nerve. Volume 50:Issue 5(2014:Nov.)
• Page Start: 844
• Page End: 853
• Publication Date: 2014-09-16
• Subjects: Neuromuscular diseases -- Periodicals; Muscles -- Periodicals; Nerves -- Periodicals; 616.74
• DOI: 10.1002/mus.24230
• Languages: English
• ISSNs: 0148-639X

Abstract

<abstract abstract-type="main"> <title>ABSTRACT</title> <p> <italic>Introduction</italic>: We investigated the effect of contraction intensity [100%, 75%, 50%, and 25% maximum voluntary contraction (MVC)] and movement velocity (50°, 100°, 200°, and 400°/s) on surface electromyography root mean square amplitude (SEMG_RMS) and median frequency (SEMG_MDF) of rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM). <italic>Methods</italic>: SEMGs during knee extension were resolved into their respective frequencies using wavelet transformations. <italic>Results</italic>: RF, VL, and VM muscles displayed increased SEMG_MDF as contraction intensity increased from 25% to 50% MVC and from 75% to 100% MVC, and each muscle displayed its own unique frequency shifting patterns. The SEMG_MDF was not influenced by movement velocity. SEMG_RMS increased in all 3 muscles as contraction intensity increased and was influenced by movement velocity, with the highest values observed at 400° and 200°/s. <italic>Conclusions</italic>: We infer that increasing contraction intensity facilitates greater recruitment of fast‐twitch muscle fibers, but there are differing responses in RF, VL, and VM muscles. <italic>Muscle Nerve</italic><bold>50</bold>: 844–853, 2014</p> </abstract>