Patellofemoral joint kinetics during squatting in collegiate women athletes

  • George J. Salem
    Corresponding author
    Musculoskeletal Biomechanics Research Laboratory, Department of Biokinesiology and Physical Therapy, University of Southern California, 1540 E. Alcazar Street, CHP-155, Los Angeles, CA 90033, USA
    Search for articles by this author
  • Christopher M. Powers
    Musculoskeletal Biomechanics Research Laboratory, Department of Biokinesiology and Physical Therapy, University of Southern California, 1540 E. Alcazar Street, CHP-155, Los Angeles, CA 90033, USA
    Search for articles by this author


      Objective. To characterize the biomechanics of the patellofemoral joint during squatting in collegiate women athletes.
      Design. Repeated measures experimental design.
      Background. Although squatting exercises are required components of most intercollegiate resistance-training programs and are commonly performed during rehabilitation, the effects of various squatting depths on patellofemoral joint stress have not been quantified.
      Methods. Anthropometric data, three-dimensional knee kinematics, and ground reaction forces were used to calculate the knee extensor moment (inverse dynamics approach) in five intercollegiate female athletes during squatting exercise at three different depths (approximately 70°, 90° and 110° of knee flexion). A biomechanical model of the patellofemoral joint was used to quantify the patellofemoral joint reaction force and patellofemoral joint stress during each trial.
      Results. Peak knee extensor moment, patellofemoral joint reaction force and patellofemoral joint stress did not vary significantly between the three squatting trials.
      Conclusions. Squatting from 70° to 110° of knee flexion had little effect on patellofemoral joint kinetics. The relative constancy of the patellofemoral joint reaction force and joint stress appeared to be related to a consistent knee extensor moment produced across the three squatting depths.Relevance
      The results of this study do not support the premise that squatting to 110° places greater stress on the patellofemoral joint than squatting to 70°. These findings may have implications with respect to the safe design of athletic training regimens and rehabilitation programs.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Clinical Biomechanics
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Ferretti A.
        Epidemiology of jumper's knee.
        Sports Med. 1986; 3: 289-295
        • Ferretti A.
        • Papandrea P.
        • Conteduca F.
        Knee injuries in volleyball.
        Sports Med. 1990; 10: 132-138
        • Molnar T.J.
        • Fox J.M.
        Overuse injuries of the knee in basketball.
        Clin. Sports Med. 1993; 12: 349-362
      1. National Collegiate Athletic Association Injury Surveillance System. Overland Park, KS: National Collegiate Athletic Association; 1994

        • Zelisko J.A.
        • Noble H.B.
        • Porter M.
        A comparison of men's and women's professional basketball injuries.
        Am. J. Sports Med. 1982; 10: 297-299
        • DeHaven K.E.
        • Linter D.M.
        Athletic injuries: comparison by age, sport, and gender.
        Am. J. Sports Med. 1986; 14: 218-224
        • Arendt A.E.
        Orthopaedic issues for active and athletic women.
        Clin. Sports Med. 1994; 13: 483-502
      2. Holloway JB, Gater D, Ritchie M. Position paper on strength training for female athletes. Colorado Springs, CO: National Strength and Conditioning Association Position Paper; 1990

        • Hunter L.Y.
        • Andrews J.R.
        • Clancy W.G.
        • et al.
        Common orthopaedic problems of female athletes.
        Instr. Course Lect. Am. Acad. Orthop. Surg. 1982; 31: 126-151
        • Knapik J.J.
        • Bauman C.L.
        • Jones B.H.
        • et al.
        Pre-season strength and flexibility imbalances associated with athletic injuries in female collegiate athletes.
        Am. J. Sports Med. 1991; 19: 76-81
      3. Calliet R. Knee pain and disability. 2nd ed. Philadelphia, PA: F.A. Davis Co; 1990. p. 61

      4. Griffin LY. Rehabilitation of the knee extensor mechanism. In: Fox JM, Del Pizzo W, editors. The patellofemoral joint. New York: McGraw-Hill; 1993. p. 279–90

      5. Kisner C, Colby LA. Therapeutic exercise: foundations and techniques. Philadelphia, PA: F.A. Davis Co; 1990. p. 345–84

      6. Chandler JY, Stone MH. The squat exercise in athletic conditioning: a position statement and review of the literature. Colorado Springs, CO: National Strength and Conditioning Association Position Paper; 1992

        • Dahlqvist N.J.
        • Mayo P.
        • Seedhom B.B.
        Forces during squatting and rising from a deep squat.
        Eng. Med. 1982; 11: 69-75
        • Hattin H.C.
        • Pierrynowski M.R.
        • Ball K.A.
        Effect of load, cadence, and fatigue on tibio-femoral joint force during a half squat.
        Med. Sci. Sports Exerc. 1989; 21: 613-618
        • Hungerford D.
        • Barry M.
        Biomechanics of the patellofemoral joint.
        Clin. Orthop. 1979; 144: 9-15
        • Fleck S.J.
        • Kraemer W.J.
        Designing resistance training programs. Human Kinetics, Champaign, IL1987
        • Stone M.H.
        • O'Bryant H.S.
        Weight training: a scientific approach. Burgess International Group Inc, Edina, MN1987
      7. Fulkerson JP, Shea KP. Mechanical basis for patellofemoral pain and cartilage breakdown. In: Ewing JW, editor. Articular cartilage and knee joint function: basic science and arthroscopy. New York: Raven Press; 1990. p. 93–101

        • Grana W.
        • Kriegshauser L.
        Scientific basis of extensor mechanism disorders.
        Clin. Sports Med. 1985; 4: 247-257
        • Moller B.N.
        • Moller-Larsen F.
        • Frich L.H.
        Chondromalacia induced by patellar subluxation in the rabbit.
        Acta. Orthop. Scand. 1989; 60: 188-191
        • Reilly D.T.
        • Martens M.
        Experimental analysis of quadriceps muscle force and patello-femoral joint reaction force for various activities.
        Acta. Orthop. Scand. 1972; 43: 126-137
        • Huberti H.H.
        • Hayes W.C.
        Patellofemoral contact pressures: the influence of Q-angle and tendofemoral contact.
        J. Bone Joint Surg. 1984; 66A: 715-724
        • Lesuer D.A.
        • McCormick J.H.
        • Mayhew J.L.
        • et al.
        The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift.
        J. Strength Cond. Res. 1997; 11: 211-213
        • Dempster W.T.
        • Gabel W.C.
        • Felts W.J.L.
        The anthropometry of manual work space for seated subjects.
        Am. J. Phys. Anthrop. 1959; 17: 289-317
        • Winter D.A.
        Biomechanics and motor control of human movement. Wiley, New York1990
        • van Eijden T.M.
        • Weijs W.A.
        • Kouwenhoven E.
        • et al.
        forces acting on the patella during maximal voluntary contraction of the quadriceps femoris muscle at different knee flexion/extension angles.
        Acta. Anat. 1987; 129: 310-314
      8. Brechter JH. Quantification of patellofemoral joint stress in persons with patellofemoral pain. Dissertation, Los Angeles: University of Southern California; 2000

        • van Eijden T.M.
        • Kouwenhoven E.
        • Verburg J.A.
        Mathematical model of the patellofemoral joint.
        J. Biomech. 1986; 19: 219-229
        • McLaughlin T.M.
        • Dillman C.J.
        • Lardner T.J.
        A kinematic model of performance in the parallel squat by champion powerlifters.
        Med. Sci. Sports Exerc. 1977; 9: 128-133
        • McLaughlin T.M.
        • Lardner T.J.
        • Dillman C.J.
        Kinetics of the parallel squat.
        Res. Q. 1979; 49: 175-188
        • Steinkamp L.A.
        • Dillingham M.F.
        • Markel M.D.
        • Hill J.A.
        • Kaufman K.R.
        Biomechanical considerations in patellofemoral joint rehabilitation.
        Am. J. Sports Med. 1993; 21: 438-444
        • Scott S.H.
        • Winter D.A.
        Internal forces at chronic running injury sites.
        Med. Sci. Sport Exerc. 1990; 22: 357-369