Reliability of Physiological Cost Index Measurements in Walking Normal Subjects Using Steady-state, Non-steady-state and Post-exercise Heart Rate Recording

Abstract

Summary Energy cost of locomotion is an important parameter in the evaluation of locomotor disability. Use of oxygen uptake to quantify this has been commonly used but is not always practicable in clinical situations. Heart rate (HR) and walking speed have been previously shown to be linearly related to oxygen uptake at sub-maximal exercise levels. Combination of these two parameters yields a single value in beats per metre, the physiological cost index (PCI). This is calculated as Working HR — Resting HR/Walking speed (metres/minute) Previous use of the measure has involved sophisticated continuous monitoring equipment to measure HR. This study investigates whether PCI can be simply assessed using equipment which may be found in the average physiotherapy department; and whether it is a reliable measure under non-steady-state as well as steady-state conditions, as patients with locomotor disability may not always be able to achieve the latter. Low cost HR monitoring is used. Reliability of post-exercise HR was also measured as this would enable PCI to be calculated using manual pulse recording without recourse to continuous monitoring devices. Fifteen female physiotherapy students each walked at individual preferred walking speed on a treadmill, and HR was monitored with a Tunturi pulse meter. Significant (p