Using rubber instead of dead weight helps protect ligaments because rubber dampens shock. Ligaments are thin strings that connect each end of a muscle cell to the bone. Ligaments release from the bone when the muscle is overshocked to prevent the muscle itself from tearing. This is a good thing but it is quite painful when it happens, and it happens all too often when lifting freeweights. Ligaments can take weeks to reattach. Freeweight fanatics, well known for their brawn, accept tendonitis as an unavoidable part of pumping iron. They should be pumping rubber instead. The shock absorbing feature of Soloflex is particularly useful when rehabilitating injuries.