The morphology and stability of the oxygen pulse curve during cardiopulmonary exercise testing

Objectives This study aimed to assess the relative and absolute reliability (agreement) of various parameters derived from the oxygen pulse (   O ˙ 2 P u l s e ) curve during cardiopulmonary exercise testing (CPET), a tool critical for evaluating cardiopulmonary function and fitness. Design Retrospective test-retest reliability study. Equipment and methods Twelve recreationally active male participants underwent two CPETs within a test-retest interval of≤72hours. The study analysed different components of the   O ˙ 2 P u l s e curve, including the area under the curve (AUC) and its slope in relation to the work-rate. Statistical analysis was then undertaken to determine the associated intraclass correlation coefficient (reliability), standard error of measure and minimal detectable change (agreement – SEM and MDC) values. Results Statistical analysis indicated a range in the reliability of   O ˙ 2 P u l s e curve parameters, from poor (intraclass correlation coefficient, ICC=0.49) for slope values to excellent (ICC=1.00) for the filtered   O ˙ 2 P u l s e AUC. The mean percentage minimal detectable change (%MDC) for filtered AUC was calculated at 15±0.8, signifying the threshold for confidently determining true change. Conclusion The findings suggest that the   O ˙ 2 P u l s e curve is a stable and robust variable in CPET, offering significant insights into cardiovascular health. These results have implications for exercise prescription, risk stratification, and rehabilitation in clinical settings. The study highlights the importance of adopting consistent reporting criteria like %MDC in future studies for better comparison across research and clinical practices.