NEUROMUSCULAR ADAPTATIONS OF THE ANKLE WITH STABILITY TRAINING: REFLEX CHANGES

Introduction and Aims: Stability training on a wobble board is a common method of rehabilitation from lower limb injuries. Injury prevention represents a relatively new application of this exercise but the neural mechanisms underlying its success remain unknown. We hypothesised that a three-week period of wobble board training will result in a decrease in the reflex response in the muscles crossing the left ankle joint. Method: Fourteen moderately trained university students were randomly assigned to a control and training group. The training group underwent 10-, 20-minute sessions of wobble board training over three weeks. Pre- and post-testing was conducted on an ankle perturbation rig and involved applying various levels of plantar torque to a stable (1DOF) and unstable (3 DOF) footplate. Nine potentiometers measured the position of the footplate, a force transducer measured the applied torque and a dorsiflexing perturbation could be given. Electromyographic data was recorded from four superficial muscles crossing the ankle joint to determine stretch reflex profiles for each muscle. Data was displayed in bar graphs and a two-way ANOVA was used. Results: No significant difference in the stretch reflex amplitude was noted between the training and control groups in medial gastrocnemius, lateral gastrocnemius, soleus or peroneus longus. A reduction in the amplitude of the stretch reflex in the experimental group was recorded after wobble board training in medial gastrocnemius (35% reduction), lateral gastrocnemius (25% reduction), soleus (15% reduction), and peroneus longus (40% reduction) during post-testing (significant at p Conclusion: Presynaptic inhibition represents the most likely neural mechanism responsible for the observed reduction in the stretch reflex amplitude after a brief period of wobble board training. This neuromuscular adaptation may offer dynamic protection prior to and during heel contact, helping to prevent inversion sprains.