Although stroke patients exhibited mixed size changes in foot-ankle structures, the dissociation between structural changes and balance function suggests that dysfunction is primarily attributable to central nervous system damage rather than to peripheral structural alterations.
Stroke patients showed significantly reduced peroneus longus muscle size compared to healthy controls.
Stroke patients showed significantly reduced tibialis anterior muscle size compared to healthy controls.
Stroke patients showed significantly reduced flexor hallucis brevis muscle thickness compared to healthy controls.
Stroke patients showed significantly increased plantar fascia thickness in both the middle and posterior segments compared to healthy controls.
In healthy controls, foot muscle parameters strongly correlated with balance metrics, with flexor hallucis brevis thickness showing significant negative correlation with mediolateral displacement under eyes-closed conditions.
No significant correlations between structural parameters and balance metrics were observed in stroke patients after false discovery rate correction, indicating a structural-functional dissociation.
The authors concluded that balance dysfunction in stroke patients is primarily attributable to central nervous system damage rather than peripheral structural alterations.
This research suggests that while stroke survivors show measurable changes in the size of foot and ankle muscles and tissues — including shrinkage in key muscles like the peroneus longus and tibialis anterior, and thickening of the plantar fascia — these physical changes do not appear to be what drives their balance problems. The study compared 90 stroke patients (measured 3-12 months after their stroke) to 95 healthy individuals using ultrasound imaging to measure foot structures and a force platform to measure balance during standing. In healthy people, larger foot muscles were associated with better balance, but in stroke patients, no such relationship was found even after rigorous statistical correction. This disconnect between structure and function — which the researchers call 'structural-functional dissociation' — suggests that the balance difficulties stroke survivors experience are driven primarily by damage to the brain and nervous system, not by the physical deterioration of foot muscles themselves. Even when muscles change in size after a stroke, those changes don't explain why a person struggles to maintain their balance. This research suggests that rehabilitation programs for stroke survivors may be more effective if they prioritize retraining the nervous system's ability to control movement — known as neuromuscular control training — rather than focusing mainly on building muscle size or strength in the foot and ankle. The findings point to the brain, not the foot, as the primary target for improving balance after stroke.
Zhang X, Wu Y, Liu G. (2026). Foot Muscle Size and Balance in Stroke: Evidence of Structural-Functional Dissociation.. Journal of foot and ankle research. https://doi.org/10.1002/jfa2.70206