chair
The reason is that the fitball’s surface is unstable, and you can only sit comfortably on it if you have a straight back and no lumbar arch. In this position,…
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Adviсe
A fitball instead of a regular chair
The reason is that the fitball’s surface is unstable, and you can only sit comfortably on it if your back is straight and not arched. In this position, the stabilizer…