Elucidation of abductor digiti minimi activity in chronic ankle instability.
Yutaro Hyodo, Takumi Jiroumaru, Noriyuki Kida and 7 others
PMID 35291477WHAT IT FOUND
In men with chronic ankle instability, the abductor digiti minimi was underactive during toe extension tasks without load, while the peroneus longus and tibialis anterior were overactive.
This intrinsic-extrinsic muscle imbalance disappeared when weight was added.
Key findings
01Abductor digiti minimi activity was significantly lower on the unstable side during maximal toe extension/abduction with both ankle dorsiflexion and plantarflexion.
02Peroneus longus and tibialis anterior activity were significantly greater on the unstable side during toe extension/abduction tasks without load.
03No significant difference in abductor digiti minimi activity was found between sides during one-leg standing or toe-standing with loads.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included only 12 adult males, so findings may not apply to females, children, or older adults. Measurements were taken in static or controlled positions; the study did not assess muscle activity during dynamic tasks like landing or turning, which are common mechanisms for ankle injury. The sample size is small, and the comparison is within-subject (CAI vs non-CAI side in the same person), which may not reflect differences between individuals with CAI and healthy controls. No specific clinical outcomes (like pain or function) were measured, only muscle electrical activity.
Declared interests
None declared.
The easy way to misread this
Do not assume that the muscle imbalance seen in unloaded toe extension exercises persists during weight-bearing activities. The study found no significant difference in abductor digiti minimi activity during standing or loaded toe-standing tasks, suggesting the pattern of dysfunction is task-specific.