Reliability and Reproducibility of Physiological Cost Index (PCI) as an Energy Expenditure Index among Asian Individuals

Abstract

Introduction: Physical activity and energy expenditure are important markers of wellbeing. Energy expenditure index can be assessed by bicycle ergometer and treadmill test but they are costly and are not suitable for physically challenged ones. Hence, simpler and straightforward tests like Physiological Cost Index can be useful in a broader perspective. However, it is not known whether they are reliable and reproducible in Asian population.

Methods: A total of 10 young randomly selected healthy individuals performed 50m, 100m and 150m walking test at their self-selected preferred speed. The test was repeated three times on each distance. The resting measurements were taken and their Physiological Cost Index during exercise was calculated using MacGregor's equation.

Results: The mean age was 24.8 years (22-39 years). The mean speed of walking was 65m/min. The mean body mass index was 20.68.Their mean PCI values for 50, 100 and 150m distance walks at self-selected, preferred speed did not show statistically significant difference from each other. On a reproducibility test, irrespective of the distance walked, the first test (Test I) had statistically significant higher PCI values than Test II and Test III (p<0.05) for the respective distance walked.

Conclusion: Physiological Cost Index can be estimated using MacGregor's equation with walking varying distances (50m, 100m and 150m) at a self-selected and preferred speed. The first test tends to overestimate PCI as compared to the second and third tests on the same distance. However, the second and third tests (trials) seem consistent