High- or low-technology measurements of energy expenditure in clinical gait analysis?

Abstract

The repeatability of energy-expenditure measurements were studied in five children and four adults without disabilities using the Cosmed K4 (high technology). The ability to detect change in measurements was compared between this instrument and the Physiological Cost Index (PCI; low technology). The results of repeatability (95% range) for oxygen cost were 13.1% in children and 13% in adults. In contrast, the SD of PCI was 6 to 72% of the mean in adults and wider in children (91%; 95% range). The validity of PCI as an outcome measure was questioned. In addition, 177 children with motor disability were prospectively studied using the Cosmed K4. Previous experience with the Cosmed K2 (intermediate technology) helped to develop a practical and repeatable protocol for testing children with disability using the Cosmed K4. The protocol commenced with 5 minutes of rest to achieve baseline values of heart rate and oxygen consumption, followed by 10 minutes of continuous walking at a self-selected speed on a 10-metre level oval walking track. The test concluded with 5 minutes of rest to monitor the return to baseline values. Ninety-one percent of the children with disability quickly reached a steady-state of oxygen consumption and carbon-dioxide production. The carbon-dioxide sensor in the Cosmed K4 has enabled a new group of severely involved children with cerebral palsy (9%) to be defined. These children have been termed 'physiologically marginal ambulators'.

Prediction of mechanical efficiency from heart rate during stair-climbing in children with cerebral palsy

“…Another study concluded that PCI reproducibility and its relationship tȯ VO 2 were only moderate [24] in children with CP. The validity of PCI as an outcome measure was also questioned by Boyd et al [25] after a study in children and adults with physical disabilities. Keefer et al [26] also re-evaluated the use of HR per walking speed for a group of hemiplegic children and found low correlations between this index and absolute and netVO 2 .…”

A stair-climbing test for ambulatory assessment of children with cerebral palsy

“…Because brain lesions and formation abnormalities in children with CP can alter many of these variables and neurodevelopmental therapy emphasizes improvement of all of these variables, the measurement ofVO 2 and EC can indicate subtle changes following neurodevelopmental therapy. The use of EC measurements has increased over the past decade in the assessment of rehabilitation intervention [19][20][21]. However, frequently an index derived from heart rate and walking velocity is still used because of the difficulty of treadmill testing in this population.…”

Ankle dorsiflexion fMRI in children with cerebral palsy undergoing intensive body‐weight‐supported treadmill training: a pilot study

“…Walking velocity and the 6-minute walk are valid and reliable measures of walking ability in children with or without neuromuscular disability. 10,11 TRAINING PROTOCOL Participants were fitted in a harness suspended from a hydraulic weight-support system (LiteGait I system; Mobility Research, AZ, USA) and positioned over a motor-driven treadmill with variable speed control. The 12-session training protocol occurred twice daily (one morning, one afternoon session), 6 days a week for 2 consecutive weeks.…”