European Journal of Applied Physiology and Occupational Physiology

, Volume 77, Issue 3, pp 212–216

Bilateral deficit in plantar flexion: relation to knee joint position, muscle activation, and reflex excitability

  • Yasuo Kawakami
  • Digby G. Sale
  • J. Duncan MacDougall
  • John S. Moroz
ORIGINAL ARTICLE

DOI: 10.1007/s004210050324

Cite this article as:
Kawakami, Y., Sale, D., MacDougall, J. et al. Eur J Appl Physiol (1998) 77: 212. doi:10.1007/s004210050324

Abstract

Six male subjects made maximal isometric plantar flexions unilaterally (UL) and bilaterally (BL), with the knee joint angle positioned at 90° and 0° (full extension) and the ankle joint kept at 90°. Plantar flexion torque and electromyogram (EMG) of the lateral gastrocnemius (LG) and the soleus (Sol) muscles were recorded. There was a deficit in torque in BL compared to UL (P<0.05), and the deficit was greater when the knee was extended than when bent to 90° (13.9% vs 6.6%). The integrated EMG (iEMG) of UL and BL did not differ when the knee was at 90°. On the other hand, when the knee was extended iEMG of LG was smaller for BL than for UL, suggesting that the larger bilateral deficit when the knee was extended was due to a reduced activity of the LG motor units. In addition, the H-reflex recorded from Sol when the contralateral leg was performing a maximal unilateral plantarflexion was reduced. This would indicate that the force deficit was associated with a reduction of motoneuron excitability.

Key words Unilateral and bilateral contractionsGastrocnemius and soleus musclesH-reflex

Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Yasuo Kawakami
    • 1
  • Digby G. Sale
    • 2
  • J. Duncan MacDougall
    • 2
  • John S. Moroz
    • 2
  1. 1.Department of Life Sciences (Sports Sciences), The University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153, JapanJP
  2. 2.Department of Kinesiology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, CanadaCA