Relationship Between Beats Above Baseline Index (BABI) and Physiological Cost Index (PCI) During Walking with Leg Length Discrepancy

Abstract

The purpose of this study was to assess the criterion-referenced validity of the beats above baseline index (BABI) in relation to physiological cost index (PCI) by having subjects walk with leg length discrepancy and to evaluate the need to supplement shoe height to compensate for leg length discrepancy based on the changes in BABI and PCI in 8 healthy men. The exercise task in the experiments was continuous walking of a 200-m distance along a figure “8”-shaped path, each circle of which was 30 m long. The degree of task difficulty varied among 5 different gaits with leg length discrepancies of 0 cm to 4 cm under two conditions: comfortable walking speed and maximal walking speed. The criterion-referenced validity of BABI in relation to PCI was high at r=0.85-0.89, demonstrating that BABI can be applied to walking tasks. There were no significant differences between time for task completion, walking speed, stride length or cadence at the two walking speeds when leg length discrepancy was no more than 4 cm. At the comfortable walking speed, however, there were significant individual differences between BABI and PCI at differences in leg length of 4 cm and 0 cm, of 4 cm and 1 cm, and of 4 cm and 2 cm. When gait withleg length discrepancies is considered from the standpoint of task difficulty assessed by BABI and energy expenditure assessed by PCI, supplementing shoe height is considered necessary at leg length differences of 4 cm or more