Spines are designed to move. However, they are designed to move with control – and in the places we want them to. The easiest way to assess which areas a human body should be getting its movement from is to look at the cross-sectional area of muscle available in each segment.
The areas with the greatest cross-sectional area of muscle are the areas that we can produce the most force, and also the areas where we can exercise the most control. If we look at the torso, the large phasic (force generating) muscles are the latissimus dorsi (lats) and the pectorals, these muscles wrap around the ribcage, and it is this area that we therefore have the ability to produce force through the upper body.
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