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Obesity does not increase external mechanical work per kilogram body mass during walking
Raymond C Browning1, Craig P McGowan, Rodger Kram
1Department of Health and Exercise Science, 215C Moby B Complex, Colorado State University, Fort Collins, CO 80523-1582, USA. browning@cahs.colostate.edu
Journal of Biomechanics
|August 4, 2009
Summary
Obese adults expend more energy walking, but their external mechanical work (W(ext)) per step is similar when normalized for body mass. This suggests W(ext) doesn't explain the higher metabolic cost of walking in obesity.
Area of Science:
- Biomechanics
- Exercise Physiology
- Obesity Research
Background:
- Walking is a key physical activity for obesity management.
- Obese individuals exhibit a higher net metabolic rate during walking.
- The role of external mechanical work (W(ext)) in obesity's metabolic cost is unclear.
Purpose of the Study:
- To compare external mechanical work (W(ext)) between obese and normal-weight adults during walking.
- To investigate the influence of body mass on the biomechanics of walking in different weight groups.
Main Methods:
- Twenty adults (10 obese, 10 normal weight) walked on a force-measuring treadmill at various speeds.
- Three-dimensional ground reaction forces were recorded.
- The individual limb method (ILM) calculated external work (W(ext)) on the center of mass.
Main Results:
- Absolute W(ext) (J/step) was higher in obese adults across all speeds.
- Relative W(ext) (J/step/kg) was comparable between obese and normal-weight groups.
- No significant differences in step frequency were observed.
Conclusions:
- External mechanical work (W(ext)) per kilogram of body mass is similar in obese and normal-weight adults.
- W(ext) does not appear to be the primary driver of the increased metabolic cost of walking in moderately obese individuals.
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