Validity and Reliability of a Clinical Method for Assessment of Cardiorespiratory Fitness Using Seismocardiography

Measurement of cardiorespiratory fitness (here VO2max) is considered a valuable tool for improving the risk prediction of cardiovascular disease and overall patient management. However, the gold standard method for determining VO2max requires both maximal exercise until exhaustion and expensive equipment, why it is not always feasible. A new method for estimating VO2max using a non-exercise prediction model with seismocardiography (SCG) information has been proposed. SCG is recording and interpretations of vibrations originating from the beating heart measured on the chest wall with an accelerometer. SCG has previously been shown to correlate to physiologic events in the cardiac cycle and thus a measure of cardiac performance. VO2max is generally believed to be limited by the rate of oxygen delivery to the muscles, where maximal cardiac output and oxygen carrying capacity of the blood are considered the main limiting factors. The theoretical basis for incorporating SCG to a VO2max prediction model is therefore evident. The previous studies assessed the prediction model in a cross-sectional study design to compare validity of the method. A requirement of further validation of the prediction model with reliability assessment is therefore needed. Biological age is a concept trying to relate the age to the health status rather than the date of birth. Biological age assesses the heterogeneity in functional metabolic status and vulnerability to disease. A Biological age model has previously been designed for health promotion interventions. However, reliability assessment of the model is needed. The purpose of the current study was therefore to: 1. investigate the validity and reliability of a new clinical method for estimation of maximal oxygen consumption (VO2max) using seismocardiography. 2. investigate the reliability of the biological age model.