title: Excess body weight and gait influence energy cost of walking in older adults.
abstract: OBJECTIVE
  The objective of this investigation is to study how excess body weight influences the energy cost of walking (Cw) and determine whether overweight and obese older adults self-select stride frequency to minimize Cw.
  
  
  METHODS
  Using body mass index (BMI), men and women between the ages of 65 and 80 yr were separated into normal weight (NW, BMI ≤24.9 kg·m(-2), n = 13) and overweight-obese groups (OWOB, BMI ≥25.0 kg·m(-2), n = 13). Subjects walked at 0.83 m·s on an instrumented treadmill that recorded gait parameters and completed three 6-min walking trials; at a preferred stride frequency (PSF), at +10% PSF, and at -10% PSF. Cw was determined by indirect calorimetry. Repeated-measures ANOVA was used to compare groups, and associations were tested with Pearson correlations, α = 0.05.
  
  
  RESULTS
  OWOB had 62% greater absolute Cw (301 ± 108 vs 186 ± 104 J·m, P < 0.001) and 20% greater relative Cw(kg) (3.48 ± 0.95 vs 2.91 ± 0.94 J·kg(-1)·m(-1), P = 0.046) than NW. Although PSF was not different between OWOB and NW (P = 0.626), Cw was 8% greater in OWOB at +10% PSF (P < 0.001). At PSF, OWOB spent less time in single-limb support (33.1% ± 1.5% vs. 34.9% ± 1.6 % gait cycle, P = 0.021) and more time in double-limb support (17.5% ± 1.6% vs 15.4% ± 1.4% gait cycle, P = 0.026) than NW. In OWOB, at PSF, Cw was correlated to impulse (r = -0.57, P = 0.027) and stride frequency (r = 0.51, P = 0.046).
  
  
  CONCLUSIONS
  Excess body weight is associated with greater Cw in older adults, possibly contributing to reduced mobility in overweight and obese older persons.
authors.affiliation: 1Department of Kinesiology, University of New Hampshire, Durham, NH; 2Department of Physical Therapy and Occupational Therapy, São Paulo State University, Marília, SP, BRAZIL; and 3Department of Physical Education, São Paulo State University, Rio Claro, SP, BRAZIL.
authors.forename: Dain P
authors.initials: DP
authors.lastname: Laroche
authors.forename: Nise R
authors.initials: NR
authors.lastname: Marques
authors.forename: Heidi N
authors.initials: HN
authors.lastname: Shumila
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Logan
authors.forename: Robyn St
authors.initials: RS
authors.lastname: Laurent
authors.forename: Mauro
authors.initials: M
authors.lastname: Gonçalves
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D015992:Body Mass Index; D001835:Body Weight; D004734:Energy Metabolism; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D009765:Obesity / Q000503:physiopathology; D050177:Overweight / Q000503:physiopathology*; D010101:Oxygen Consumption; D011659:Pulmonary Gas Exchange; D016138:Walking / Q000502:physiology*