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

The repeatability of energy-expenditure measurements were studied in five c hildren and four adults without disabilities using the Cosmed K4 (high tech nology). 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 childre n 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 o utcome measure was questioned. In addition, 177 children with motor disabil ity were prospectively studied using the Cosmed K4. Previous experience wit h 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 value s of heart rate and oxygen consumption, followed by 10 minutes of continuou s 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 ca rbon-dioxide sensor in the Cosmed K4 has enabled a new group of severely in volved children with cerebral palsy (9%) to be defined. These children have been termed 'physiologically marginal ambulators'.