Think Fit. Be Fit.

If you’ve been attuned to conventional fitness wisdom, at some point you’ve been advised to avoid certain exercises, like leg extensions, at all costs.  Why?  Because of the noxious shear stress that may damage your knees.  Do you too have the Fear of Shear? Shear is a type of force that arises when adjacent structures move in opposing directions, and frankly, it occurs in most joint motion. So, if that’s the case, why does its presence ring so many alarm bells in the heads and hearts of physical therapists, trainers, doctors and fitness enthusiasts? Well, it might have something to do with a paper published in the early 1990’s by members of the esteemed Mayo Clinic that found significantly higher levels of shear at the ACL in an open chain vs closed chain condition.  Their unambiguous conclusion?  Avoid open chain exercises, like leg extensions, if you are rehabbing an injured or newly reconstructed ACL.  Of course, that translates into “avoid leg extensions at all costs, period.” So, is this settled wisd