title: Greater vertical loading rate in obese compared to normal weight young adults.
abstract: BACKGROUND
  Obesity is a risk factor for knee osteoarthritis. Altered gait biomechanics are common in obese individuals, and may contribute to the development of knee osteoarthritis. Research has focused on older obese adults with knee osteoarthritis, and it is unclear if young obese individuals display similar aberrant biomechanics. The purpose of this study was to compare gait biomechanics between normal-weight and obese young adults.
  
  
  METHODS
  15 normal-weight (body mass index=21.5 (1.1)) and 15 obese (body mass index=33.5 (3.7)) young adults were recruited and categorized by body mass index. Lower extremity kinematics and kinetics were collected while participants walked at standardized (1m/s) and self-selected speeds. Analysis of variance (group by condition) was used to compare peak vertical ground reaction force, vertical loading rate, peak internal knee extension moment, peak internal knee abduction moment, peak knee flexion angle, and knee flexion excursion between groups.
  
  
  RESULTS
  Gait biomechanics did not differ between groups during walking at a self-selected speed. When walking at a standardized speed, obese subjects displayed greater instantaneous vertical loading rates (46.2 vs. 35.0 N/s, P<0.001), and lesser knee flexion excursion (5.5° vs. 7.7°, P=0.04). Instantaneous vertical loading rate was greater during walking at a self-selected speed compared to a standardized speed in the obese (P=0.007) and normal weight groups (P=0.001).
  
  
  CONCLUSIONS
  As greater loading rates are related to cartilage degeneration, these results suggest that obesity may contribute to knee osteoarthritis. Prospective studies are needed to identify the influence of higher loading rates on knee osteoarthritis.
authors.affiliation: Department of Kinesiology, California State University, Fullerton, 800 N State College, Fullerton, CA 92831, USA; Department of Exercise and Sport Science, The University of North Carolina at Chapel Hill, 209 Fetzer Hall, Chapel Hill, NC 27599-8700, USA; Curriculum in Human Movement Science, The University of North Carolina at Chapel Hill, Bondurant Hall, Suite 3000, Chapel Hill, NC 27599-7135, USA. Electronic address: dpamukoff@fullerton.edu.
authors.forename: Derek N
authors.initials: DN
authors.lastname: Pamukoff
authors.affiliation: Department of Exercise and Sport Science, The University of North Carolina at Chapel Hill, 209 Fetzer Hall, Chapel Hill, NC 27599-8700, USA; Curriculum in Human Movement Science, The University of North Carolina at Chapel Hill, Bondurant Hall, Suite 3000, Chapel Hill, NC 27599-7135, USA; Division of Physical Therapy, The University of North Carolina at Chapel Hill, Bondurant Hall, Suite 3000, Chapel Hill, NC 27599-7135, USA. Electronic address: michael_lewek@med.unc.edu.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Lewek
authors.affiliation: Department of Exercise and Sport Science, The University of North Carolina at Chapel Hill, 209 Fetzer Hall, Chapel Hill, NC 27599-8700, USA; Curriculum in Human Movement Science, The University of North Carolina at Chapel Hill, Bondurant Hall, Suite 3000, Chapel Hill, NC 27599-7135, USA; Department of Orthopedics, The University of North Carolina at Chapel Hill, 209 Fetzer Hall, Chapel Hill, NC 27599-8700, USA. Electronic address: troyb@email.unc.edu.
authors.forename: J Troy
authors.initials: JT
authors.lastname: Blackburn
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D015992:Body Mass Index; D005684:Gait / Q000502:physiology*; D006801:Humans; D007717:Knee / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology*; D020370:Osteoarthritis, Knee / Q000209:etiology*; D012307:Risk Factors; D016138:Walking / Q000502:physiology; D055815:Young Adult
keywords: Biomechanics; Gait; Obesity; Osteoarthritis; Walking