Does the weakening of intrinsic foot muscles cause the decrease of medial longitudinal arch height?
Kazunori Okamura, Shusaku Kanai, Sadaaki Oki and 6 others
PMID 28626309WHAT IT FOUND
Fatiguing the abductor hallucis and flexor hallucis brevis did not lower the arch during standing or walking.
Arch height slightly increased, and rear foot rolled outward less. In healthy men, this does not support arch collapse from intrinsic foot muscle weakness.
Key findings
01Fatigue of the abductor hallucis and flexor hallucis brevis increased arch height during standing.
02The same fatigue increased maximum arch height during walking.
03Four of the 20 men were excluded because the fatigue criteria were not met.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Four of the 20 men were excluded because the toe muscles did not reach the fatigue criteria, so the analysis included 16. All participants were healthy young men, not people with foot pain or diagnosed arch collapse. The walking test was at a normal speed, while arch-related overuse injuries often occur during running or higher-intensity activity. The study did not measure the activity of flexor hallucis longus, a large toe muscle that could have helped during the task. The authors state the observed changes were small, so they do not show what happens with repeated fatigue or in injury.
The easy way to misread this
Do not read the small increase in arch height after toe fatigue as evidence that toe exercises raise the arch. The study tested healthy men once, walked at a normal speed, and measured immediately after a fatigue task, so it does not show long-term effects or what happens in people with foot pain.