Pain at the front of the knee is a common condition treated by physical therapists. Treatment may consist of generalised strengthening exercises directed at the quadriceps muscle or specific retraining aimed at restoring motor control at the knee. This study compared these two exercise programs in a group of people who were painfree at the time to evaluate their effect on motor control. It was hypothesised that only the motor retraining program would influence motor control at the knee.

Inclusion Criteria:

• aged between 16-40 years, with the upper age limit to reduce the likelihood of osteoarthritic changes in the patellofemoral joint
• a self-reported history of anterior or retropatellar knee pain with insidious onset of symptoms and with at least one episode of pain in the past 12 months where pain was aggravated by at least two of the following: prolonged sitting, stairs, squat, running, kneeling and hopping/jumping
• currently asymptomatic for at least 8 weeks prior to assessment
• delay in the onset of VMO EMG relative to that of VL of greater than 10 ms during either the ascent or descent of a stair stepping task

Exclusion Criteria:

• current knee pain
• history of knee surgery or other knee injury in previous 12 months
• physiotherapy treatment for knee pain in the past 12 months
• history of patellar dislocation/subluxation
• clinical evidence of meniscal lesion, ligamentous instability, traction apophysitis around the patellofemoral complex, patellar tendon pathology, chondral damage, osteoarthritis and spinal referred pain
• current lower limb pathology affecting their ability to satisfactorily complete the testing or exercise protocol
• current use of non-steroidal anti-inflammatory or corticosteroid drugs
• inability to communicate and comprehend written or verbal instructions in English