title: Effect of obesity onset on pendular energy transduction at spontaneous walking speed: Prader-Willi versus nonsyndromal obese individuals.
abstract: OBJECTIVE
  To compare the mechanical external work (Wext ) and pendular energy transduction (Rstep ) at spontaneous walking speed (Ss ) in individuals with Prader-Willi syndrome (PWS) versus subjects with nonsyndromal obesity (OB) to investigate whether the early onset of obesity allows PWS subjects to adopt energy conserving gait mechanics.
  
  
  METHODS
  Wext and Rstep were computed using kinematic data acquired by an optoelectronic system and compared in 15 PWS (BMI = 39.5 ± 1.8 kg m(-2) ; 26.7 ± 1.5 year) and 15 OB (BMI = 39.3 ± 1.0 kg m(-2) ; 28.7 ± 1.9 year) adults matched for gender, age and BMI and walking at Ss .
  
  
  RESULTS
  Ss was significantly lower in PWS (0.98 ± 0.03 m s(-1) ) than in OB (1.20 ± 0.02 m s(-1) ; P < 0.001). There were no significant differences in Wext per kilogram between groups (PWS: 0.37 ± 0.04 J kg(-1) m(-1) ; OB: 0.40 ± 0.05 J kg(-1) m(-1) ; P = 0.66) and in Rstep (PWS: 69.9 ± 2.9%; OB: 67.7 ± 2.4%; P = 0.56). However, Rstep normalized to Froude number (Rstep /Fr) was significantly greater in PWS (6.0 ± 0.6) than in OB (3.8 ± 0.2; P = 0.001). Moreover, Rstep /Fr was inversely correlated with age of obesity onset (r = -0.49; P = 0.006) and positively correlated with obesity duration (r = 0.38; P = 0.036).
  
  
  CONCLUSIONS
  Individuals with PWS seem to alter their gait to improve pendular energy transduction as a result of precocious and chronic adaptation to loading.
authors.affiliation: Institute of Sport Sciences of University of Lausanne (ISSUL), Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
authors.forename: Davide
authors.initials: D
authors.lastname: Malatesta
authors.forename: Luca
authors.initials: L
authors.lastname: Vismara
authors.forename: Francesco
authors.initials: F
authors.lastname: Menegoni
authors.forename: Graziano
authors.initials: G
authors.lastname: Grugni
authors.forename: Paolo
authors.initials: P
authors.lastname: Capodaglio
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D016022:Case-Control Studies; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000503:physiopathology*; D011218:Prader-Willi Syndrome / Q000503:physiopathology*; D016138:Walking / Q000502:physiology*; D055815:Young Adult