Data from: Body acceleration as indicator for walking economy in an ageing population

Background: In adults, walking economy declines with increasing age and
negatively influences walking speed. This study aims at detecting
determinants of walking economy from body acceleration during walking in
an ageing population. Methods: 35 healthy elderly (18 males, age 51 to 83
y, BMI 25.5±2.4 kg/m2) walked on a treadmill. Energy expenditure was
measured with indirect calorimetry while body acceleration was sampled at
60Hz with a tri-axial accelerometer (GT3X+, ActiGraph), positioned on the
lower back. Walking economy was measured as lowest energy needed to
displace one kilogram of body mass for one meter while walking (WCostmin,
J/m/kg). Gait features were extracted from the acceleration signal and
included in a model to predict WCostmin. Results: On average WCostmin was
2.43±0.42 J/m/kg and correlated significantly with gait rate (r2 = 0.21,
p<0.01) and regularity along the frontal (anteroposterior) and
lateral (mediolateral) axes (r2 = 0.16, p<0.05 and r2 = 0.12,
p<0.05 respectively). Together, the three variables explained 46%
of the inter-subject variance (p<0.001) with a standard error of
estimate of 0.30 J/m/kg. WCostmin and regularity along the frontal and
lateral axes were related to age (WCostmin: r2 = 0.44, p<0.001;
regularity: r2 = 0.16, p<0.05 and r2 = 0.12, p<0.05
respectively frontal and lateral). Conclusions: The age associated decline
in walking economy is induced by the adoption of an increased gait rate
and by irregular body acceleration in the horizontal plane.