I’m really interested in this too as I’m a total gym freak. I’ve been told it’s to do with rising your heart rate too. Nurse said at the two week check you may get cleared for light legs like gentle spin/incline treadmill walks, but nothing at all strenuous’ until after the 6 week check. My surgeon said I may be able to start short runs again at 6 weeks- I run marathons and do 40 miles training practically every week, so this time not training is going to be so tough for me, but all SO worth it in the scheme of things!! Xx