Changes in muscle activity in typically developing children walking with unilaterally induced equinus

Area of Science:

• Biomechanics
• Neuroscience
• Orthopedics

Background:

• Differentiating gait changes due to motor control versus equinus adaptations is challenging.
• Understanding muscle activity alterations in equinus gait is crucial for diagnosis and treatment.

Purpose of the Study:

• To identify the threshold degree of equinus that alters muscle activity.
• To characterize muscle activity adaptation patterns in children with induced equinus gait.

Main Methods:

• Ten typically developing children participated.
• A custom orthosis induced varying degrees of equinus (10° dorsiflexion to maximum plantar flexion).
• Muscle activity of key lower limb muscles (rectus femoris, vastus lateralis, hamstring, tibialis anterior, soleus) was recorded in both limbs.

Main Results:

• Significant muscle activation changes occurred from 10° plantar flexion in the affected limb and maximum plantar flexion in the contralateral limb.
• Soleus and tibialis anterior muscles showed altered activation timing and magnitude with increasing equinus.
• Hamstring, vastus lateralis, and rectus femoris activation increased during specific gait phases, with similar contralateral limb changes.

Conclusions:

• Simulated equinus gait induces distinct muscle activity changes.
• These findings offer insights for therapeutic strategies in managing equinus gait.