Validation Of A New Portable Metabolic Unit While Riding A Mechanical Galloping Simulator

PURPOSE: Measuring oxygen consumption (VO2) while equestrian athletes (EqA) ride horses has previously been challenging due to the cost, noise, and wires and hoses associated with portable metabolic units (METUnit). Innovation leading to new portable METUnits that addresses these concerns provides potential for capturing EqA's VO2 data. The purpose is to validate a new portable METUnit (U1) to a non-portable gold standard MetUnit (U2) while EqA ride a mechanical galloping simulator. We hypothesized that 1) VO2 data between U1 and U2 would have strong positive correlations and 2) the U1 metabolic unit VO2 data would fall within 5% of U2 values during all conditions. METHODS: Participants were healthy equestrians who galloped regularly. Researchers collected VO2 and heart rate (HR) during all conditions. All conditions included five minutes of resting and two minutes of galloping at three simulated speeds (S1:20-25mph; S2:28-32mph; S3:36-40mph). Participants rested for 15 minutes between each speed and for 20 minutes before repeating the same protocol with the second METUnit. The order of the METUnit was random. Data analysis included Pearson correlations and equivalence testing. RESULTS: Twenty EqA (19 females) with an average age of 29.0 ± 7.9 years completed the study. The different simulated galloping speeds had moderate to strong positive correlations, with S1 r2 = 0.52, S2 r2 = 0.52, and S3 r2 = 0.65. Equivalence testing demonstrated significant differences (p > 0.05) in all conditions between U1 and U2. The average difference in VO2 data between U1 and U2 readings was 8.3% at rest, 11.8% at S1, 13.9% at S2, and 11.7% at S3. The average HR for all conditions between the two units had significant positive correlations of r2 = 0.78-0.87 with average differences of 2.5-3.2%. CONCLUSIONS: The new portable METUnit does not provide equivalent VO2 data compared to a non-portable gold standard METUnit at a similar heart range during resting and simulated galloping conditions. These results suggest that considerations should be made when using this new METUnit, as the equivalence testing indicated the average difference was significantly greater than the 5% threshold commonly used for METUnit validation.