Age-related changes in mechanical and metabolic energy during typical gait

Abstract

The purpose of the study was to investigate and report age-related changes in walking energy expenditure using different methods of energy estimation. For 81 children and 16 adults (3-35 years) energy expenditure was investigated by using the following methods: analysis of energy changes of the centre of body mass (external and internal mechanical work), sum of segmental energies, sum of net joint work and gross and net metabolic cost, as well as net non-dimensional oxygen cost. Different methods of energy estimation not only show different outcome results but also different age-related changes. Significant changes were found for negative net joint work, external mechanical work and recovery as well as sum of segmental energies, until 9, 11 and 19 years respectively. Positive net joint work showed no differences between age groups and the differences for internal work did not suggest development. Metabolic energy showed significant changes until adult age. Gross cost decreases with increasing age in children and, although more gradually, still in adolescents. Net and net non-dimensional cost shows a more constant decrease with increasing age until adulthood. Therefore, the choice of estimation method and the use of age-related reference data when evaluating young patients should be carefully considered. For interpretation of oxygen consumption in children the use of net is superior to gross cost, but even after net non-dimensional normalization, age-related reference data should be used.

Mechanical energy estimation during walking: Validity and sensitivity in typical gait and in children with cerebral palsy

“…W j was higher in child_CP, compared to adult_TG and child_TG, who did not differ from each other. This is in agreement with Van de Walle et al, where W j did not differ from adult values after the age of 9 years and both W SSE and net O 2 -cost showed a decrease by increasing age until adult ages [7]. O 2 -cost was sensitive enough to discriminate between pathology as well as development.…”

“…Typical subjects (18 children, 11 adults) were selected from a previous study [7] when aged <12 years or >20 years and when three trials with valid bilateral kinetics and full visibility for total body kinematics as well as O 2 -consumption measurement were available (Table 1).…”

“…Child_CP walked barefoot, typical subjects performed GA barefoot and measurement of O 2 -consumption with their normal shoes. Mechanical energy: During GA, total body kinematics and kinetics were collected while walking on a 10-m walkway at self selected comfortable walking speed (speed comf ) using an eight-camera VICON System (Mx camera-workstation,100 Hz, PlugInGait marker set, VICON, Oxford Metrics, Oxford, UK) and two embedded force plates (0.4 m  0.5 m, 1500 HZ, Advanced Mechanical Technology Inc., Watertown, MA) [7].…”

“…However, it can only be assessed over a steady state period of walking, and therefore only detect overall EE without any specific information on causes of increased EE. The clinical use of metabolic measurements in CP is further restrained by its limited reproducibility [5,6] and high variability in pediatric typical gait [7,8]. Mechanical energy estimations could provide valuable additional information in pathological gait, as they can be plotted over the gait cycle.…”

“…All three approaches are sensitive enough to detect developmental changes in typical gait [7,21]. Furthermore McDowell et al found that W SSE , allowing inter-segmental transfer, was able to discriminate between levels of spina bifida [20].…”