Validity and reliability of seismocardiography for the estimation of cardiorespiratory fitness.

Background: Low cardiorespiratory fitness (ie, peak oxygen consumption [Opeak]) is associated with cardiovascular disease and all-cause mortality and is recognized as an important clinical tool in the assessment of patients. Cardiopulmonary exercise test (CPET) is the gold standard procedure for determination of Opeak but has methodological challenges as it is time-consuming and requires specialized equipment and trained professionals. Seismofit is a chest-mounted medical device for estimating Opeak at rest using seismocardiography.

Objective: The purpose of this study was to investigate the validity and reliability of Seismofit Opeak estimation in a healthy population.

Methods: On 3 separate days, 20 participants (10 women) underwent estimations of Opeak with Seismofit (×2) and Polar Fitness Test (PFT) in randomized order and performed a graded CPET on a cycle ergometer with continuous pulmonary gas exchange measurements.

Results: Seismofit Opeak showed a significant bias of -3.1 ± 2.4 mL·min·kg (mean ± 95% confidence interval) and 95% limits of agreement (LoA) of ±10.8 mL·min·kg compared to CPET. The mean absolute percentage error (MAPE) was 12.0%. Seismofit Opeak had a coefficient of variation of 4.5% ± 1.3% and an intraclass correlation coefficient of 0.95 between test days and a bias of 0.0 ± 0.4 mL·min·kg with 95% LoA of ±1.6 mL·min·kg in test-retest. In addition, Seismofit showed a 2.4 mL·min·kg smaller difference in 95% LoA than PFT compared to CPET.

Conclusion: The Seismofit is highly reliable in its estimation of Opeak. However, based on the measurement error and MAPE >10%, the Seismofit Opeak estimation model needs further improvement to be considered for use in clinical settings.