The purpose of this study was to investigate usefulness of physiological cost index(PCI) with correlation to the heart rate, walking speed, O₂ rate and O₂ cost responses of individuals with hemiplegia to resting and comfortable walking. We measured the physiological energy expenditure using the portable oxygen consumption monitor(K2, COSMED, Rome, Italy).

Twenty hemiplegic patients and twenty able-bodied control subjects participated.
Results
showed that the hemiplegic group required significantly high O₂ cost and PCI during comfortable walking. In the hemiplegic group, there was statistically positive correlation between O₂ rate and heart rate, O₂ cost and PCI and negative correlation between walking speed and PCI, and O₂ cost and walking speed. In the control group, there was statistically positive correlation between O₂ rate and heart rate, O₂ rate and PCI, and heart rate and PCI. According to the above results, it could be concluded that hemiplegic group required higher energy consumption during comfortable walking compared to the control group, and PCI is an easy and comfortable index to estimate energy expenditure during ambulation.