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.     

Kinematic and kinetic variability associated with the cable put and seated rotation assessments

ABSTRACT

When new protocols are developed, there is a requirement to investigate test–retest reliability of measures for valid use and interpretation of data in research and practice. Therefore, the aim of this investigation was to determine the inter-day reliability of the cable put and seated rotation assessment protocols. On three occasions, nine resistance-trained men performed cable puts and cable rotations at different loads between 6 and 42 kg on a commercially available cable cross over machine. Load stack movement was recorded using a PT5A linear position transducer from which all kinematic and kinetic variables were calculated. Reliability was excellent for peak velocity and displacement based on intraclass correlation coefficient (ICC) and coefficient of variation (CV) across the majority of loads and movements (cable put: ICC = 0.92 to 0.99, CV = 3.1% to 8.6%; cable seated rotation: ICC = 0.76 to 0.99, CV = ?1.7% to 16.1%). However, kinetic variables demonstrated inadequate reliability across the majority of days, loads and movements (ICC = 0.70, CV >10%). It was concluded that peak velocity is a reliable kinematic measure to assess muscular capability from cable put and seated rotation protocols; however, kinetic measures are too variable to provide reliable outputs across testing occasions.