The overall objective of this project is to compare the three home-managed treatment regimens for PFPS: neuromuscular electrical stimulation (NMES), transcutaneous electrical nerve stimulation (TENS), and NMES combined with TENS to a standard home exercise program (HEP). Each of the three treatment arms will be supplemented by HEP and compared to a group receiving standard HEP alone. The central hypothesis is that the combination of NMES with TENS will show significantly greater improvements in muscle strength, mobility, pain, daily activity and quality of life (QOL) than HEP alone.