Squat & Knee

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Squat & Knee

Postby Canuck Singh » Tue Jul 08, 2008 6:34 pm

Deep Squatting
Deep squatting tends to get a bad rap for the possibility of causing knee injuries. However, no research has substantiated this, and deep squatting may be the most effective exercise for targeting the gluteal (buttock) muscles.

Researchers from Furman University in Greenville, South Carolina had 10-highly trained men perform squats at partial, parallel and full depths with 100%-125% of their body weight. Special electrodes placed on the skin measured the activity and contribution of the muscles involved, such as the gluteals, quadriceps and hamstrings.

The deeper the athlete squatted, the more the gluteus maximus (the largest buttock muscle) was activated. This muscle contributed significantly during the "push" (concentric) phase.

Deep squatting takes great skill. Take time to perfect your form and control your decent, and this exercise will increase your overall squatting strength and add new strength to other leg exercises.


ref: Medicine and Science in Sports and Exercise 32(5): S56, 2000
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Effect of Knee Position on Hip and Knee Torques During the Barbell Squat

ANDREW C. FRY1, 2, J. CHADWICK SMITH1, and BRIAN K. SCHILLING1

1. Human Performance Laboratories, The University of Memphis, Memphis, Tennessee 38152, 2. Address correspondence to Dr. Andrew C. Fry, E-mail: afry@memphis.edu
* ANDREW C. FRY
* J. CHADWICK SMITH
* BRIAN K. SCHILLING

Some recommendations suggest keeping the shank as vertical as possible during the barbell squat, thus keeping the knees from moving past the toes. This study examined joint kinetics occurring when forward displacement of the knees is restricted vs. when such movement is not restricted. Seven weight-trained men (mean ± SD; age = 27.9 ± 5.2 years) were videotaped while performing 2 variations of parallel barbell squats (barbell load = body weight). Either the knees were permitted to move anteriorly past the toes (unrestricted) or a wooden barrier prevented the knees from moving anteriorly past the toes (restricted). Differences resulted between static knee and hip torques for both types of squat as well as when both squat variations were compared with each other (p < 0.05). For the unrestricted squat, knee torque (N·m; mean ± SD) = 150.1 ± 50.8 and hip torque = 28.2 ± 65.0. For the restricted squat, knee torque = 117.3 ± 34.2 and hip torque = 302.7 ± 71.2. Restricted squats also produced more anterior lean of the trunk and shank and a greater internal angle at the knees and ankles. The squat technique used can affect the distribution of forces between the knees and hips and on the kinematic properties of the exercise. Practical applications: Although restricting forward movement of the knees may minimize stress on the knees, it is likely that forces are inappropriately transferred to the hips and low-back region. Thus, appropriate joint loading during this exercise may require the knees to move slightly past the toes.

Reference Data:Fry, A.C., J.C. Smith, and B.K. Schilling. Effect of knee position on hip and knee torques during the barbell squat.
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Re: Squat & Knee

Postby Canuck Singh » Tue Jul 08, 2008 6:35 pm

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

APPLIED SCIENCES
Medicine & Science in Sports & Exercise. 33(9):1552-1566, September 2001.
ESCAMILLA, RAFAEL F.; FLEISIG, GLENN S.; ZHENG, NAIQUAN; LANDER, JEFFERY E.; BARRENTINE, STEVEN W.; ANDREWS, JAMES R.; BERGEMANN, BRIAN W.; MOORMAN, CLAUDE T. III

Abstract:
ESCAMILLA, R. F., G. S. FLEISIG, N. ZHENG, J. E. LANDER, S. W. BARRENTINE, J. R. ANDREWS, B. W. BERGEMANN, and C. T. MOORMAN, III. Effects of technique variations on knee biomechanics during the squat and leg press. Med. Sci. Sports Exerc., Vol. 33, No. 9, 2001, pp. 1552-1566.


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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