Association between oxygen consumption and stepping exercise standardized with a triaxial accelerometer

Abstract

Objective

According to the current American College of Chest Physicians (ACCP) guideline, a cardiopulmonary exercise test (CPET) is indicated in patients with lung cancer being considered for lung surgery. The measurement of maximum oxygen consumption ($\mathop V\limits^{ \cdot } O_{2}$ max) is not sufficiently prevalent because it requires special technical equipment. Considering that stepping is a simple and common exercise, we aimed to establish a simple and reproducible test with standardization of exercise intensity using a triaxial accelerometer.

Methods

Twenty healthy volunteers (10 male, 10 female) were included in the study. The subjects were obliged to step on the same spot at the rate of 80 and 110 counts for 1 min each and then step as quickly as possible for the last minute. Oxygen consumption ($\mathop V\limits^{ \cdot } O_{2}$) (mL/kg/min) for every breath was continuously measured during the exercise. A triaxial accelerometer was attached to the hip of test subjects whereby metabolic equivalents (METs) at each test level were measured.

Results

The mean age of the study subjects was 42.9 ± 11.4 (mean ± SD). The mean value of $\mathop V\limits^{ \cdot } O_{2}$ at each level increased linearly along with the stepping level in each individual but varied among subjects. Using METs instead of step counts minimized the difference in regression lines among subjects. A receiver operating characteristic analysis revealed the possibility of $\mathop V\limits^{ \cdot } O_{2}$ prediction for the critical values of 10 and 20 mL/kg/min using METs.

Conclusion

A simple and reproducible stepping test was suggested as applicable to standardizing the intensity of exercise using a triaxial accelerometer.