European Journal of Applied Physiology and Occupational Physiology

, Volume 76, Issue 3, pp 253–259

The effects of antagonist moment on the resultant knee joint moment during isokinetic testing of the knee extensors

  • E. Kellis
  • V. Baltzopoulos

DOI: 10.1007/s004210050244

Cite this article as:
Kellis, E. & Baltzopoulos, V. Eur J Appl Physiol (1997) 76: 253. doi:10.1007/s004210050244


The purpose of this study was to examine the effects of moment of antagonistic muscle on the resultant joint moment during isokinetic eccentric and concentric efforts of the knee extensors. Ten males performed maximum eccentric and concentric knee extension and flexion efforts on a Biodex dynamometer at 0.52 rad · s−1 (30° · s−1). Electromyographic (EMG) activity of vastus medialis and biceps femoris (hamstrings) was also recorded. The antagonistic moment of the hamstrings was determined by recording the integrated EMG (iEMG)/moment relationship at different levels of muscle effort. The iEMG/moment curves were fitted using second-degree polynomials. The polynomials were then used to predict the antagonistic moment exerted by the hamstrings from the antagonist iEMG. The antagonistic moment had a maximum of 42.92 Nm and 28.97 Nm under concentric and eccentric conditions respectively; paired t-tests indicated that this was a significant difference (P < 0.05). These results indicate that the resultant joint moment of knee extensors is the result of both agonist and antagonist muscle activation. The greater antagonist muscle activity under concentric activation conditions may be partly responsible for the lower resultant joint concentric moment of knee extensors compared with the corresponding eccentric activation. The antagonist moment significantly affects comparisons between the isokinetic moments and agonist EMG and in vitro force measurements under different testing (muscle action and angular velocity) conditions.

Key words Isokinetic dynamometryCoactivationKneeElectromyography

Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • E. Kellis
    • 1
  • V. Baltzopoulos
    • 2
  1. 1.Division of Sport and Recreation, University of Northumbria at Newcastle, Newcastle upon Tyne NE1 8ST, UKGB
  2. 2.Department of Exercise and Sport Science, Manchester Metropolitan University, Crew and Alsager Faculty, Hassal Road, Alsager ST7 2HL, UKGB