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Physiological alterations of maximal voluntary quadriceps activation by changes of knee joint angle
Author(s) -
Becker Roland,
Awiszus Friedemann
Publication year - 2001
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.1053
Subject(s) - isometric exercise , knee joint , knee flexion , physical medicine and rehabilitation , turnover , joint (building) , medicine , range of motion , electromyography , orthodontics , physical therapy , anatomy , mathematics , surgery , architectural engineering , management , engineering , economics
Abstract The purpose of this study was to investigate the influence of different angles of the knee joint on voluntary activation of the quadriceps muscle, estimating the ability of a subject to activate a muscle maximally by means of voluntary contraction. Isometric torque measurement was performed on 6 healthy subjects in 5° intervals between 30° and 90° of knee joint flexion. Superimposed twitches at maximal voluntary contraction (MVC) and at a level of 60% and 40% of the MVC were applied and the voluntary activation estimated. At between 30° and 75° of knee flexion, the maximal extension torque increased at an average rate of 2.67 ± 0.6 Nm/degree, followed by a decline with further flexion. However, throughout the joint‐angle range tested, voluntary activation increased on average by 0.37%/degree with a maximum at 90° of flexion. Due to the influence of joint position it is not possible to generalize results obtained at the knee joint angle of 90° of flexion, which is usually used for the quadriceps twitch‐interpolation technique. Consequently, it is useful to investigate voluntary activation deficits in knee joint disorders at a range of knee joint angles that includes, in particular, the more extended joint angles used frequently during daily activity. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 667–672, 2001