Roosen P.1, Willems T.1, De Mits S.1, Vanrenterghem J.1, De Ridder R.1
1University Ghent, Rehabilitation Sciences and Physiotherapy, Ghent, Belgium
Background: Sensorimotor training is one of the most frequently used interventions in musculoskeletal injuries especially in the prevention and rehabilitation of ankle sprains and chronic ankle instability. But balance training protocols are different in time, frequency, used materials and progression. During training different types of surfaces can be used. Nowadays there is no consensus in literature about the progression.
Purpose: The first purpose of this study was to evaluate the effect of foot positioning in relation to the axis of a uni-axial balance board on muscle activation. The second aim was to evaluate the effect of uni-axial and multi-axial materials on the activity of the stabilizing muscles of the ankle. Based on these results a sensorimotor training protocol for patients with ankle complaints could be developed.
Methods: For the foot orientation study 69 healthy subject werd included. For the patient study 28 patients with chonic ankle instability were included. In the corrected unilateral stands position subjects were asked to maintain their equilibrium on different surfaces (Airex balance pad, Bosu and uni-axial balance board) or with the foot in 4 different positions on the uni-axial balance board. Muscle activity of the m. tibialis anterior, m. peroneus longus and brevis, m. gastrocnemius medialis and lateralis was measured by means of surface electromyography with a measuring frequency of 1000 Hz. The EMG data were analysed with MyoResearch XP Master Edition. Raw data were first rectified and smoothed with a RMS. Mean EMG values were calculated based on 3 good trials. Statistical analysed was performed with SPSS 20. For the foot position study a repeated ANOVA was used with a posthoc Bonferroni correction. For the patient study a mixed model analysis was used for each muscle and for the muscle ratio, followed with a Holm-Bonferroni correction. The significance level was set at p 0,05.
Results: For all muscles the least muscle activity was measured when de training was performed on a flat hard surface. The m. tibialis anterior activity was maximally challenged along the oblique axis. The m. peroneus longus and brevis were most active when trained along the frontal axis or on the Bosu. For a maximal focus on the peroneus longus with a low tibialis anterior/peroneus longus ratio, a uni-axial balance board must be used with the foot positioned along the frontal axis.
Conclusion(s): Statistical analysis showed a significant effect of foot orientation and surface on muscle activity.
Implications: A uni-axial balance board can be used to focus on specific ankle stabilizers and the foot orientation can be adapted in function of the patients needs. A uni-axial balance board offers the best possibility to control the agonist-antagonist coactivation. For patients with chronic ankle instability a graded progression can be build in the therapy based on muscle activation and cocontraction.
Funding acknowledgements: No funding was received for this study.
Topic: Musculoskeletal: lower limb
Ethics approval: This study was accepted by the Ethical Committee of the Ghent University Hospital.
All authors, affiliations and abstracts have been published as submitted.
