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Influence of Infrapatellar and Suprapatellar Straps on Quadriceps Muscle Activity and Onset Timing During the Body-Weight Squat

Straub, Rachel K.; Cipriani, Daniel J.

Journal of Strength & Conditioning Research: July 2012 - Volume 26 - Issue 7 - p 1827–1837
doi: 10.1519/JSC.0b013e318234e81d
Original Research

Abstract: Straub, RK and Cipriani, DJ. Influence of infrapatellar and suprapatellar straps on quadriceps muscle activity and onset timing during the body-weight squat. J Strength Cond Res 26(7): 1827–1837, 2012—The use of knee braces for the treatment of patellofemoral pain syndrome (PFPS) is widely documented, yet the mechanism by which such braces alleviate knee pain remains unclear. This study attempted to clarify this issue by simplifying the brace to the level of only straps. The effectiveness of an infrapatellar strap for PFPS remains controversial, and the use of a suprapatellar strap has not yet been studied. Quadriceps muscle activity and onset timing parameters were measured with surface electromyography (EMG) during a body-weight squat in 19 healthy subjects during 4 different knee-strapping conditions (infra, supra, both, and none). No differences in normalized mean or peak EMG activity in any part of the quadriceps were found. The onset timing of the vastus lateralis (VL) was significantly delayed when using an infrapatellar strap (p < 0.05) or both straps (p < 0.05) and marginally delayed when using a suprapatellar strap (p < 0.10) in comparison with the no-strap (control) condition. No differences in the vastus medialis oblique (VMO) onset timing or VMO-VL onset timing difference were found among the strapping conditions, although an improvement in timing was noted with the suprapatellar condition. The results provide novel evidence that the application of an infrapatellar strap, suprapatellar strap, or both straps improves quadriceps muscle timing imbalances by delaying VL onset. Because the largest delay in VL onset occurred when wearing both straps, the combined application of an infrapatellar and suprapatellar strap may be the most beneficial in managing patellofemoral pain. Knee straps, unlike braces, are cost effective, nonrestrictive, and can be universally fitted to any knee and based on the results deserve further study in the patellofemoral pain population.

1Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, California

2Department of Physical Therapy, Chapman University, Orange, California

Address correspondence to Rachel K. Straub, rstraub@usc.edu.

© 2012 National Strength and Conditioning Association