Reliability and Validity of the Zephyr™ BioHarness™ to Measure Respiratory Responses to Exercise

The Zephyr™ BioHarness™ (Zephyr Technology, Auckland, New Zealand) is a wireless physiological monitoring system that has the ability to measure respiratory rate unobtrusively. However, the ability of the BioHarness™ to accurately and reproducibly determine respiratory rate across a range of intensities is currently unknown. The aim of this study was to determine the reliability and validity of the BioHarness™ to measure respiratory rate. Twelve physically active participants attended the laboratory on two separate occasions to perform an incremental treadmill test to volitional exhaustion. Respiratory rate (br.min−1) was measured continuously and simultaneously during both trials using both a Metamax 3b online gas-analysis system (Cortex, Leipzig, Germany) and the BioHarness™. The mean respiratory rate measured by the Metamax 3b and BioHarness™ did not differ statistically (p < .05) for most speeds, except for 70% of peak treadmill speed (p = .039). Mean absolute differences were small (2 to 3 br.min−1; typical error = 4.4%–8.7%). The typical errors for the test 1 versus the test 2 comparisons for respiratory rate ranged from 1.4 to 2.8 br.min−1 (typical error % = 4.3–7.3) for the BioHarness™. There were no significant differences between devices for the absolute respiratory rate, speed, and percent of respiratory rate maximum at the respiratory breakpoint (p > .05). The BioHarness™ is a valid and reliable device for determining respiratory rate and the respiratory breakpoint during exercise of varying intensity.