title: Effects of an obesity-specific marker set on estimated muscle and joint forces in walking.
abstract: BACKGROUND
  The accuracy of muscle and joint contact forces (JCF) estimated from dynamic musculoskeletal simulations is dependent upon the experimental kinematic data used as inputs. Subcutaneous adipose tissue makes the measurement of representative kinematics from motion analysis particularly challenging in overweight and obese individuals.
  
  
  OBJECTIVE
  The purpose of this study was to develop an obesity-specific kinematic marker set/methodology that accounted for subcutaneous adiposity and to determine the effect of using such a methodology to estimate muscle and JCF in moderately obese adults.
  
  
  METHODS
  Experimental kinematic data from both the obesity-specific methodology, which utilized digitized markers and marker clusters, and a modified Helen Hayes marker methodology were used to generate musculoskeletal simulations of walking in obese and nonobese adults.
  
  
  RESULTS
  Good agreement was found in lower-extremity kinematics, muscle forces, and hip and knee JCF between the two marker set methodologies in the nonobese participants, demonstrating the ability for the obesity-specific marker set/methodology to replicate lower-extremity kinematics. In the obese group, marker set methodology had a significant effect on lower-extremity kinematics, muscle forces, and hip and knee JCF, with the Helen Hayes marker set methodology yielding larger muscle and first peak hip and knee contact forces compared with the estimates derived when using the obesity-specific marker set/methodology.
  
  
  CONCLUSIONS
  This study demonstrates the need for biomechanists to account for subcutaneous adiposity during kinematic data collection and proposes a feasible solution that may improve the accuracy of musculoskeletal simulations in overweight and obese people.
authors: 1School of Biomedical Engineering, Colorado State University, Fort Collins, CO; and 2Department of Health and Exercise Science, Colorado State University, Fort Collins, CO.
authors: Zachary F
authors: ZF
authors: Lerner
authors: Wayne J
authors: WJ
authors: Board
authors: Raymond C
authors: RC
authors: Browning
mesh_terms: D050154:Adiposity / Q000502:physiology; D000328:Adult; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D009765:Obesity / Q000503:physiopathology*; D013647:Task Performance and Analysis; D016138:Walking / Q000502:physiology*