Training apparatuses configured to receive, and conform to, the back of a user's knee and provide varying resistance and tactile feedback to a user performing quadriceps exercises and methods for using such apparatuses are disclosed herein. A preferred embodiment of the training apparatuses for quad sets comprises a solid, deformable, resilient body that includes a non-skid base and a top surface with a recess configured to receive the back of a user's knee. The body of this embodiment is preferably made of open-cell polyurethane foam with a uniform density ranging between 1 lb/ft3 and 8 lbs/ft3, and more preferably between 1.5 lbs/ft3 and 4.5 lbs/ft3. The embodiment provides gradually increasing resistance to compression, e.g. tactile feedback to the user's knee, when the user increasingly pushes his/her knee down against the embodiment, and thus allows dynamic quad setting and strengthening.
