Squat vs Leg Press Biomechanics

[Guest guest]

This research project compared the biomechanics of the different ways of

squatting and machine leg pressing.

Med Sci Sports Exerc 2001 Sep;33(9):1552

Effects of technique variations on knee biomechanics during the squat and leg

press

Escamilla RF, Fleisig GS, Zheng N, Lander JE, Barrentine SW, s JR,

Bergemann BW, Moorman CT 3rd.

PURPOSE: The specific aim of this project was to quantify knee forces and

muscle activity while performing squat and leg press exercises with technique

variations. METHODS: Ten experienced male lifters performed the squat, a high

foot placement leg press (LPH), and a low foot placement leg press (LPL)

employing a wide stance (WS), narrow stance (NS), and two foot angle

positions (feet straight and feet turned out 30 degrees ).

RESULTS: No differences were found in muscle activity or knee forces between

foot angle variations. The squat generated greater quadriceps and hamstrings

activity than the LPH and LPL, the WS-LPH generated greater hamstrings

activity than the NS-LPH, whereas the NS squat produced greater gastrocnemius

activity than the WS squat. No ACL forces were produced for any exercise

variation.

Tibiofemoral (TF) compressive forces, PCL tensile forces, and patellofemoral

(PF) compressive forces were generally greater in the squat than the LPH and

LPL, and there were no differences in knee forces between the LPH and LPL.

For all exercises, the WS generated greater PCL tensile forces than the NS,

the NS produced greater TF and PF compressive forces than the WS during the

LPH and LPL, whereas the WS generated greater TF and PF compressive forces

than the NS during the squat. For all exercises, muscle activity and knee

forces were generally greater in the knee extending phase than the knee

flexing phase.

CONCLUSIONS: The greater muscle activity and knee forces in the squat

compared with the LPL and LPH implies the squat may be more effective in

muscle development but should be used cautiously in those with PCL and PF

disorders, especially at greater knee flexion angles. Because all forces

increased with knee flexion, training within the functional 0-50 degrees

range may be efficacious for those whose goal is to minimize knee forces. The

lack of ACL forces implies that all exercises may be effective during ACL

rehabilitation.

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Dr Mel C Siff

Denver, USA

Supertraining/