Prof. Mc.Gill sir, my respects to you. I am Lakshman and am from India. I am your fan and have your back pain book on kindle. I have a question on a term you use in this video. The term used is "Sets become clinical" (@ around 6.00minutes into the interview). what does it mean.
I think you are referring to his comment saying 'facet's become clinical'. He is talking about the facet joints of the lumbar spine, and becoming clinical means that they start to become sensitised and may cause pain/issues. Hope that helps :)
