J Appl Physiol. 2013 Feb 14. [Epub ahead of print]
Obesity does not impair walking economy across a range of speeds and grades.
Source
1Colorado State University.
Abstract
Despite the popularity of walking as a form of physical activity for obese individuals, relatively little is known about how obesity affects the metabolic rate, economy and underlying mechanical energetics of walking across a range of speeds and grades. The purpose of this study was to quantify metabolic rate, stride kinematics and external mechanical work during level and gradient walking in obese and non-obese adults. Thirty-two obese (18 female, mass = 103.2 (15.8) kg, BMI = 35.0 (4.5) kg•m(-2), mean (SD)) and 19 non-obese (10 female, mass = 64.9 (10.6) kg, BMI = 21.6 (2.0) kg•m(-2)) volunteers participated in this study. We measured oxygen consumption, ground reaction forces and lower extremity kinematics while subjects walked on a dual-belt force-measuring treadmill at eleven speeds/grades (0.50 - 1.75 m•s(-1), -3° to +9°). We calculated metabolic rate, stride kinematics and external work. Net metabolic rate (E(net/kg), W•kg(-1)) increased with speed or grade across all individuals. Surprisingly and in contrast with previous studies, E(net/kg) was 0-6% less in obese compared to non-obese adults (p=0.013). External work, although a primary determinant of E(net/kg), was not affected by obesity across the range of speeds/grades used in this study. We also developed new prediction equations to estimate oxygen consumption and E(net/kg) and found that E(net/kg) was positively related to relative leg mass and step width and negatively related to double support duration. These results suggest that obesity does not impair walking economy across a range of walking speeds and grades.
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