Answer

There are multiple reasons why you may be "pulling" your hamstrings and quadriceps. One possible reason may be that these muscles are tight and not permitting full range of motion at your hip and knee joints. Another possibility may be that you are "over-activating" these muscles when you walk and/or run. Typically, muscles that "over-activate" are compensating from a gait problem such as muscle weakness at adjacent joints, poor balance, etc.

Your physical therapist should be able to evaluate potential causes of your muscle problems and prescribe the appropriate exercises to correct the problem.