J Neurophysiol (March 1, 2003). 10.1152/jn.00863.2002
Submitted on Submitted 28 February 2002; accepted in final form 26 October 2002

Vibration-Induced Changes in EMG During Human Locomotion

 ¹Motor Control Laboratory, Department of Kinesiology, Faculteit Lichamelijke Opvoeding en Kinesitherapie, Katholieke Universiteit, 3001 Leuven, Belgium;  ²Gait Laboratory, University Hospital UZ Pellenberg, Belgium;  ³Department of Medical Physics and Biophysics, K.U. Nijmegen;  ⁴Sint Maartensclinic Research, 6500 Nijmegen, The Netherlands

Verschueren, Sabine M. P., Stephan P. Swinnen, Kaat Desloovere, and Jacques Duysens. Vibration-Induced Changes in EMG During Human Locomotion. J. Neurophysiol. 89: 1299-1307, 2003. The present study was set up to examine the contribution of Ia afferent input in the generation of electromyographic (EMG) activity. Subjects walked blindfolded along a walkway while tendon vibration was applied continuously to a leg muscle. The effects of vibration were measured on mean EMG activity in stance and swing phase. The results show that vibration of the quadriceps femoris (Q) at the knee and of biceps femoris (BF) at the knee enhanced the EMG activity of these muscles and this occurred mainly in the stance phase of walking. These results suggest involvement of Ia afferent input of Q and BF in EMG activation during stance. In contrast, vibration of muscles at the ankle and hip had no significant effect on burst amplitude. Additionally, the onset time of tibialis anterior was measured to look at timing of phase transitions. Only vibration of quadriceps femoris resulted in an earlier onset of tibialis anterior within the gait cycle, suggesting involvement of these Ia afferents in the triggering of phase transitions. In conclusion, the results of the present study suggest involvement of Ia afferent input in the control of muscle activity during locomotion in humans. A limited role in timing of phase transitions is proposed as well.