Muscle fibre conduction velocity in motor units of the human anterior tibial muscle: a new size principle parameter.
Article first published online: 1 OCT 1987
© 1987 The Physiological Society
The Journal of Physiology
Volume 391, Issue 1, pages 561–571, October 1, 1987
How to Cite
1987), Muscle fibre conduction velocity in motor units of the human anterior tibial muscle: a new size principle parameter.. The Journal of Physiology, 391 doi: 10.1113/jphysiol.1987.sp016756., , (
- Issue published online: 1 OCT 1987
- Article first published online: 1 OCT 1987
- Cited By
1. Twitch contractions were elicited in human anterior tibial muscle by intramuscular microstimulation of single motor axons with a bipolar needle electrode. The population of stimulated motor units studied was fairly representative for the muscle. 2. The conduction velocity of the fibres in the motor unit was calculated as the ratio between the electrode separation (15 mm) in a tripolar array of surface electrodes and the conduction delay of the motor unit potential along the electrode array. The motor unit conduction velocity ranged from 2.6 to 5.3 m/s with a mean of 3.7 m/s. 3. The contractile properties of the motor units were obtained by averaging the torque developed around the ankle joint. Twitch torques ranged from less than 10(-3) to 16 x 10(-3) N m, with a mean of 5.7 x 10(-3) N m. The twitch torque of the whole anterior tibial muscle was approximately 5 N m. Rise times were 47-80 m/s with a mean of 61 m/s, and half-relaxation times were 40-78 ms with a mean of 60 ms. 4. The mechanical properties of individual motor units were highly correlated (rise time and twitch torque: r = -0.81; rise time and half-relaxation time: r = 0.75; twitch torque and half-relaxation time: r = -0.81). 5. The motor unit conduction velocity was highly correlated to twitch torque (r = 0.87), rise time (r = -0.75) and half-relaxation time (r = -0.66). This indicates that the motor unit conduction velocity can be included in the family of interrelated 'size principle parameters'.