Validity and reliability of seismocardiography for the estimation of cardiorespiratory fitness

Background Low cardiorespiratory fitness (ie, peak oxygen consumption [V.O(2)peak]) 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 V.O(2)peak 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 V.O(2)peak at rest using seismocardiography.Objective The purpose of this study was to investigate the validity and reliability of Seismofit V.O(2)peak estimation in a healthy population.Methods On 3 separate days, 20 participants (10 women) underwent estimations of V.O(2)peak with Seismofit (x2) 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 V.O(2)peak showed a significant bias of -3.1 +/- 2.4 mLmin(-1)kg(-1) (mean +/- 95% confidence interval) and 95% limits of agreement (LoA) of +/- 10.8 mLmin(-1)kg(-1) compared to CPET. The mean absolute percentage error (MAPE) was 12.0%. Seismofit V.O(2)peak 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 mLmin(-1)kg(-1) with 95% LoA of +/- 1.6 mLmin(-1)kg(-1) in test-retest. In addition, Seismofit showed a 2.4 mLmin(-1)kg(-1) smaller difference in 95% LoA than PFT compared to CPET.Conclusion The Seismofit is highly reliable in its estimation of V.O(2)peak. However, based on the measurement error and MAPE >10%, the Seismofit V.O(2)peak estimation model needs further improvement to be considered for use in clinical settings.

Automated summary

This study investigated the validity and reliability of Seismofit in estimating V.O(2)peak in a healthy population. The results showed that Seismofit had a high level of consistency in its estimation, but further improvement is needed in the clinical application due to measurement errors and a MAPE value exceeding 10%.