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Cited by 148Lower Extremity Biomechanics and PathologiesKnee injuries and reconstruction techniquesOsteoarthritis Treatment and Mechanisms

Patellofemoral joint kinetics while squatting with and without an external load

Wallace, David A., Salem, George J., Salinas, Ruben, Powers, Christopher M.·2002·Journal of Orthopaedic & Sports Physical Therapy
DOI 10.2519/jospt.2002.32.4.141
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Abstract

STUDY DESIGN: Single-group repeated measures design. OBJECTIVE: To quantify patellofemoral joint reaction forces and stress while squatting with and without an external load. BACKGROUND: Although squatting exercises in the rehabilitation setting are often executed to a relatively shallow depth in order to avoid the higher joint forces associated with increased knee flexion, objective criteria for ranges of motion have not been established. METHODS AND MEASURES: Fifteen healthy adults performed single-repetition squats to 90 degrees of knee flexion without an external load and with an external load (35% of the subject's body weight [BW]). Anthropometric data, three-dimensional kinematics, and ground reaction forces were used to calculate knee extensor moments (inverse dynamics approach), while a biomechanical model of the patellofemoral joint was used to quantify the patellofemoral joint reaction forces and patellofemoral joint stress. Data were analyzed during the eccentric (0-90 degrees) and concentric (90-0 degrees phases of the squat maneuver. RESULTS: In both conditions, knee extensor moments, patellofemoral joint reaction forces, and patellofemoral joint stress increased significantly with greater knee flexion angles (P < 0.05). Peak patellofemoral joint force and stress was observed at 90 degrees of knee flexion. Patellofemoral joint stress at 45 degrees, 60 degrees, 75 degrees, and 90 degrees of knee flexion during the eccentric phase, and at 75 degrees and 90 degrees during the concentric phase, was significantly greater in the loaded trials versus the unloaded trials. CONCLUSION: The data indicate that during squatting, patellofemoral joint stress increases as the knee flexion angle increases, and that the addition of external resistance further increases patellofemoral joint stress. These findings suggest that in order to limit patellofemoral joint stress during squatting activities, clinicians should consider limiting terminal joint flexion angles and resistance loads.

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  • Squatting with the hip externally rotated 30° to 50° increases hip adductor activity compared to a neutral stance by 17% and 23% respectively (neutral: 13% MVIC vs. 17% and 23% MVIC for 30° and 50° rotation, respectively).

    “However, squatting with the hip externally rotated 30° to 50° has been reported to increase hip adductor activity compared to a neutral stance by 17% and 23% respectively (neutral: 13% of maximum voluntary isometric contraction [MVIC] vs. 17% and 23% MVIC for 30° and 50° rotation, respectively).24”

    From A Biomechanical Review of the Squat Exercise: Implications for Clinical Practice. (2024) · cites this paper as [24]

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Authors
Wallace, D. A., Salem, G. J., Salinas, R., & Powers, C. M.
Affiliations
University of Southern California (US)
ORCID
Venue
Journal of Orthopaedic & Sports Physical Therapy
Publisher
Journal of Orthopaedic & Sports Physical Therapy (JOSPT)
Published
2002-04
Volume
32
Issue
4
Pages
141-148
ISSN
  • 0190-6011 (ISSN-L)
  • 1938-1344
DOI
10.2519/jospt.2002.32.4.141
OpenAlex
W2165177300
Cited by
148
References
26
Citations by year
2026: 6 · 2025: 10 · 2024: 8 · 2023: 15 · 2022: 10 · 2021: 5 · 2020: 7 · 2019: 4 · 2018: 7 · 2017: 7 · 2016: 3 · 2015: 12 · 2014: 5 · 2013: 4 · 2012: 11
FWCI
2.38
Type
journal article
Language
en
Open access
closed
Locations
  • Journal of Orthopaedic and Sports Physical Therapy (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Physical Sciences › Engineering › Biomedical Engineering › Lower Extremity Biomechanics and Pathologies
  • Health Sciences › Medicine › Surgery › Knee injuries and reconstruction techniques
  • Health Sciences › Medicine › Rheumatology › Osteoarthritis Treatment and Mechanisms
Keywords
patellofemoral joint, squatting, external load, knee flexion angle, joint reaction forces, joint stress, knee extensor moment, squat depth, exercise rehabilitation, knee biomechanics
MeSH terms
Adult, Analysis of Variance, Biomechanical Phenomena, Female, Humans, Knee Joint, Male, Prospective Studies, Reference Values, Stress, Mechanical, Exercise, Range of Motion, Articular, Weight-Bearing

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