Patellofemoral Joint Force and Stress during the Wall Squat and One-Leg Squat

ESCAMILLA, RAFAEL F.1; ZHENG, NAIQUAN2; MACLEOD, TORAN D.3; BRENT EDWARDS, W.4; IMAMURA, RODNEY5; HRELJAC, ALAN5; FLEISIG, GLENN S.6; WILK, KEVIN E.7; MOORMAN, CLAUDE T. III8; ANDREWS, JAMES R.6,9

Medicine & Science in Sports & Exercise:
doi: 10.1249/MSS.0b013e31818e7ead
Applied Sciences
Abstract

Purpose: To compare patellofemoral compressive force and stress during the one-leg squat and two variations of the wall squat.

Methods: Eighteen subjects used their 12 repetition maximum (12 RM) weight while performing the wall squat with the feet closer to the wall (wall squat short), the wall squat with the feet farther away from the wall (wall squat long), and the one-leg squat. EMG, force platform, and kinematic variables were input into a biomechanical model to calculate patellofemoral compressive force and stress as a function of knee angle. To asses differences among exercises, a one-factor repeated-measure ANOVA (P = 0.0025) was used.

Results: During the squat ascent, there were significant differences in patellofemoral force and stress among the three squat exercises at 90° knee angle (P = 0.002), 80° knee angle (P = 0.002), 70° knee angle (P < 0.001), and 60° knee angle (P = 0.001). Patellofemoral force and stress were significantly greater at 90° knee angle in the wall squat short compared with wall squat long and one-leg squat, significantly greater at 70° and 80° knee angles in the wall squat short and long compared with the one-leg squat and significantly greater at 60° knee angle in the wall squat long compared with the wall squat short and one-leg squat.

Conclusions: Except at 60° and 90° knee angles, patellofemoral compressive force and stress were similar between the wall squat short and the wall squat long. Between 60° and 90° knee angles, wall squat exercises generally produced greater patellofemoral compressive force and stress compared with the one-leg squat. When the goal is to minimize patellofemoral compressive force and stress, it may be prudent to use a smaller knee angle range between 0° and 50° compared with a larger knee angle range between 60° and 90°.

Author Information

1Department of Physical Therapy, California State University, Sacramento, CA; 2Department of Mechanical Engineering and Engineering Science, The Center for Biomedical Engineering, University of North Carolina, Charlotte, NC; 3Department of Physical Theraphy, Center for Biomedical Engineering Research, University of Delaware, Newark, DE; 4Department of Kinesiology, Iowa State University, Ames, IA; 5Kinesiology and Health Science Department, California State University, Sacramento, CA; 6American Sports Medicine Institute, Birmingham, AL; 7Champion Sports Medicine, Birmingham, AL; 8Duke Sports Medicine Center, Duke University Medical Center; Durham, NC; and 9Andrews-Paulos Research and Education Institute, Andrews Institute, Gulf Breeze, FL

Address for correspondence: Rafael F. Escamilla, Ph.D., P.T., C.S.C.S., F.A.C.S.M., Professor, Department of Physical Therapy, California State University, 6000 J Street, Sacramento, CA 95819-6020; E-mail: rescamil@csus.edu.

Submitted for publication July 2007.Accepted for publication September 2008.

©2009The American College of Sports Medicine