Comparison of seismocardiography and cardiopulmonary exercise testing for assessing peak oxygen uptake in athletes: first experiences in middle-distance runners

Background Peak oxygen consumption (pVO2) is one of the most important parameters for assessing cardiorespiratory fitness (CRF). Therefore, it is of considerable importance in the field of athletes. The gold standard method for measuring pVO2 is the cardiopulmonary exercise test (CPET). However, integrating performance tests involving maximal exhaustion into the daily training routines of athletes is not always feasible. Recently, Seismocardiography (SCG) has emerged as new, non-invasive, non-exercise-based method for estimating pVO2, showing promising results. However, the validity of SCG in endurance-athletes remains unclear. Purpose Comparison between CPET and SCG for estimating pVO2 in middle-distance runners. Methods At the beginning and at the end of a four-month training period, SCG and CPET were conducted in exactly the same manner. After a resting phase of 5 minutes in a relaxing supine position, SCG was performed. Subsequently, CPET was performed on a treadmill using a flat ramp with a starting velocity of 4 m/s, an acceleration of 0.5 m/s per minute, and 1% of elevation. Continuous gas exchange measurements were used to determine pVO2. PVO2 was defined as the highest mean value obtained over a 20-second averaging interval. To compare both methods, statistical analyses included calculating the Standard Error of the Estimate (SEE), the Mean Absolute Percentage Error (MAPE) along with Bland-Altman plots to assess agreement. Results 7 middle-distance runners (male: 100%; age: 17.7±2 yrs; BMI: 19.72±1.7) were investigated. One athlete was lost to follow-up. At initial measurement, mean CPET values during maximal effort were: pVO2 of 62.88±3.95 ml/min/kg; RER of 1.25±0,03. Mean values for pVO2 estimation using SCG were: 63.4±4.7 ml/min/kg (100.82% of CPET, SEE=4.9ml/min/kg, MAPE=5.9%). At second measurement, mean CPET values during maximal effort were: pVO2 of 63.93±3.97 ml/ min/kg; RER of 1.17±0,05. Mean values for pVO2 estimation using SCG were: 64.2 ml/min/kg (99.2% of CPET, SEE=4.5ml/kg/min, MAPE=4.69%). The aggregated results across all 13 test sessions were: CPET measured pVO2 of 63.10±3.85 ml/min/kg and a SCG estimated pVO2 of 63.76±4.24 ml/min/kg (101.05% of CPET, SEE=4.3 ml/kg/min, MAPE=5.34%). There was no significant change in either the CPET-measured or SCG-estimated pVO2 between the measurements. Conclusion The applicability of SCG-based pVO2 estimation was simple and reliable. The results showed a good agreement with CPET-derived mean values. With a MAPE of 5.34%, the estimated pVO2 value is well within the acceptable range for non-athletes. The diagnostic requirements for athletes are considerably stricter. Therefore, individual deviations are currently too high to accurately evaluate CRF in athletes compared to non-athletes. If future studies demonstrate further improvements in accuracy, SCG could establish itself as a reliable and promising tool not just for use with non-athlete populations, but in sports too.SCG estimated pVO2 vs CPET measured pVO2For image description, please refer to the figure legend and surrounding text. SCG Curve of a middle-distance runnerFor image description, please refer to the figure legend and surrounding text.