Estimation of Cardiorespiratory Fitness in Military Applicants Using Seismocardiography

Abstract

Introduction: A run test is used in the assessment of physical fitness in military applicants. Seismocardiography is a fast, non-invasive method for estimation of cardiorespiratory fitness which could replace conventional run tests. We aimed to assess the association between distance covered at a 12-minute run test and estimated maximum oxygen uptake using seismocardiography. We hypothesized was that there was a significant correlation between the distance measured at a 12-minute run test and the estimated maximum oxygen uptake determined by seismocardiography.

Materials and methods: We included healthy military applicants aged between 18 and 49 years. A 12-minute run test was conducted and we measured the covered distance. Maximum oxygen uptake was estimated by seismocardiography with the Seismofit device at rest in connection with the medical examination. We analyzed the association between the covered run test distance and the estimated maximum oxygen uptake by a correlation analysis. We also calculated an expected run distance in meters by Cooper's formula based on the estimated maximum oxygen uptake. The expected and measured run distances were compared with Bland-Altman analysis. The study was presented for the Regional Research Ethics Committee who decided that the study could be conducted without formal approval because it was entirely observational.

Results: We included 219 individuals and complete data were obtained in 204 participants in whom there was a significant correlation between estimated maximum oxygen uptake and the measured 12-minute run distance R = 0.40, P < 0.001. The bias (mean difference) in run distance (expected minus measured) was 155 m, SD 298 m, limits of agreement -429 to 739 m. In women, the mean difference in run distance (expected minus measured) was -49 m, SD 226 m while in men, mean difference (expected minus measured) in run distance was 204 m, SD 294 m. There was a significant negative correlation between BMI and the difference (expected minus measured) in run distance.

Conclusions: A significant association was found between distance measured at a 12-minute run test and the estimated maximum oxygen uptake determined by seismocardiography. There was, however, a low precision as we found too high variability in the difference between expected and measured run distance to allow prediction of run distance.