There will often be a large initial curve (due to the elastic build up of tension at the start position of adduction) this will often be followed by a flat portion through range due to neural inhibition.

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The curve will reach a peak before the point where the labrum inhibits the muscles. The inhibition is due to the pain but once beyond the range where the affected part of the labrum is stressed the torque will return giving a second peak. This M shaped curve can be biased towards the beginning or end of the curve dependent on where the damage is.

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