Effects of obesity on the biomechanics of walking at different speeds.
OBJECTIVE
Walking is a recommended form of exercise for the treatment of obesity, but walking may be a critical source of biomechanical loads that link obesity and musculoskeletal pathology, particularly knee osteoarthritis. We hypothesized that compared with normal-weight adults 1) obese adults would have greater absolute ground-reaction forces (GRF) during walking, but their GRF would be reduced at slower walking speeds; and 2) obese adults would have greater sagittal-plane absolute leg-joint moments at a given walking speed, but these moments would be reduced at slower walking speeds.


METHODS
We measured GRF and recorded sagittal-plane kinematics of 20 adults (10 obese and 10 normal weight) as they walked on a level, force-measuring treadmill at six speeds (0.5-1.75 m.s(-1)). We calculated sagittal-plane net muscle moments at the hip, knee, and ankle.


RESULTS
Compared with their normal-weight peers, obese adults had much greater absolute GRF (N), stance-phase sagittal-plane net muscle moments (N.m) and step width (m).


CONCLUSIONS
Greater sagittal-plane knee moments in the obese subjects suggest that they walked with greater knee-joint loads than normal-weight adults. Walking slower reduced GRF and net muscle moments and may be a risk-lowering strategy for obese adults who wish to walk for exercise. When obese subjects walked at 1.0 versus 1.5 m.s(-1), peak sagittal-plane knee moments were 45% less. Obese subjects walking at approximately 1.1 m.s(-1) would have the same absolute peak sagittal-plane knee net muscle moment as normal-weight subjects when they walk at their typical preferred speed of 1.4 m.s(-1).
Browning
Raymond C
RC
Locomotion Laboratory, Department of Integrative Physiology, University of Colorado, Boulder, CO, USA. ray.browning@uchsc.edu
Kram
Rodger
R
D000054:Acceleration; D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D019245:Compressive Strength / Q000502:physiology; D005080:Exercise Test; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008297:Male; D009765:Obesity; D020370:Osteoarthritis, Knee; D016138:Walking / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology