Lower Extremity and Trunk Electromyographic Muscle Activity During Performance of the Y-Balance Test on Stable and Unstable Surfaces.
Navpreet Kaur, Kunal Bhanot, Germaine Ferreira
PMID 35391869WHAT IT FOUND
Standing on an unstable surface during the Y-Balance Test increased muscle activity in most trunk and leg muscles, but shortened reach distance.
This suggests the unstable version is a more demanding exercise, not a better measure of balance.
Key findings
01Unstable surfaces significantly increased EMG activity in 11 of 15 muscles tested, with moderate to large effect sizes.
02Reach distance was shorter in all three directions (anterior, posterolateral, posteromedial) when performed on the unstable surface.
03Rectus abdominis and anterior tibialis activity did not change significantly between stable and unstable conditions.
STILL TO COME
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What it does not show
The study included only 20 healthy adults, limiting generalizability to injured or clinical populations. Surface EMG is subject to artifacts like skin displacement and cross-talk during dynamic movement. The study measured muscle activity and reach distance, but did not assess long-term training effects or injury risk.
Declared interests
The authors have no conflicts of interest to declare.
The easy way to misread this
Do not interpret the increased muscle activity as proof that the unstable YBT is a superior diagnostic tool. The reduced reach distance indicates it changes the test's mechanics, so it should be used as an exercise progression rather than a standardized assessment of symmetry or stability.