RT Journal Article
SR Electronic
T1 Biomechanical analysis of the single-leg decline squat
JF British Journal of Sports Medicine
JO Br J Sports Med
FD BMJ Publishing Group Ltd and British Association of Sport and Exercise Medicine
SP 264
OP 268
DO 10.1136/bjsm.2006.032482
VO 41
IS 4
A1 J Zwerver
A1 S W Bredeweg
A1 A L Hof
YR 2007
UL http://bjsm.bmj.com/content/41/4/264.abstract
AB Background: The single-leg squat on a 25° decline board has been described as a clinical assessment tool and as a rehabilitation exercise for patients with patellar tendinopathy. Several assumptions have been made about its working mechanism on patellar load and patellofemoral forces, but these are not substantiated by biomechanical evaluations. Aim: To investigate knee moment and patellofemoral contact force as a function of decline angle in the single-leg squat. Methods: Five subjects performed single-leg eccentric squats at decline angles of 0°, 5°, 10°, 15°, 20° and 25° (with/without a backpack of 10 kg), and 30° on a board that was placed over a forceplate. Kinematic and forceplate data were recorded by the Optotrak system. Joint moments of ankle, knee and hip were calculated by two-dimensional inverse dynamics. Results: Knee moment increased by 40% at decline angles of 15° and higher, whereas hip and ankle moment decreased. Maximum knee and ankle angles increased with steeper decline. With a 10 kg backpack at 25° decline, the knee moment was 23% higher than unloaded. Both patellar tendon and patellofemoral forces increased with higher decline angles, but beyond 60°, the patellofemoral force rose steeper than the tendon force. Conclusions: All single-leg squats at decline angles >15° result in 40% increase in maximum patellar tendon force. In knee flexions >60°, patellofemoral forces increase more than patellar tendon forces. Higher tendon load can be achieved by the use of a backpack with extra weight.