Email updates

Keep up to date with the latest news and content from TBioMed and BioMed Central.

Open Access Research

Application of neural oscillators to study the effects of walking speed on rhythmic activations at the ankle

Sook-Yee Chong, Heiko Wagner* and Arne Wulf

Author Affiliations

Department of Motion Science, University of Muenster, Horstmarer Landweg 62b, Muenster, 48149, Germany

For all author emails, please log on.

Theoretical Biology and Medical Modelling 2013, 10:9  doi:10.1186/1742-4682-10-9

Published: 13 February 2013

Abstract

Background

Spinal pattern generators (SPG) are neural networks in the spinal cord that do not require a central input from the brain to generate a motor output. We wanted to determine whether SPG can adapt to the changing motor demands from walking at different speeds, and performing silly walks.

Methods

An SPG model consisting of an oscillator made up of two neurons was utilised in this study; one neuron activates the soleus and the other activates the tibialis anterior. The outputs of the SPG model therefore represent the electromyographic measurements from each muscle. Seven healthy subjects were requested to perform silly walks, normal walking at self-selected speed (4.8 ± 0.5 km/h), 3.5 km/h, 4.0 km/h and 4.5 km/h on a treadmill. Loading and hip angles were used as inputs into the model.

Results

No significant differences in the model parameters were found between normal walking at self-selected speed and other walking speeds. Only the adaptation time constant for the ankle flexor during silly walks was significantly different from the other normal walking trials.

Conclusion

We showed that SPG in the spinal cord can interpret and respond accordingly to velocity-dependent afferent information. Changes in walking speed do not require a different motor control mechanism provided there is no disruption to the alternating muscular activations generated at the ankle.

Keywords:
Locomotion; Walking speed; Silly walks; EMG; Spinal pattern generator; Neural network; Sensory afferents; Motor control