Aims The extent to which augmentation of heart function mirrors the increased metabolic demands of the peripheral musculature is not well characterised. The details of ventricular augmentation may provide insight into determinants of cardiac efficiency for optimal exercise performance. The aims were to establish how much of the variability in exercise performance could be explained by myocardial recruitment, and which parameter of systolic function was most closely related to exercise performance. Methods and results Untrained volunteers were recruited prior to training for the London Marathon. All performed a cardiopulmonary exercise test combined with stress echocardiography. Systolic and diastolic longitudinal velocities (S’ and E’), ejection fraction (LVEF), stroke volume (SV) and strain were obtained throughout exercise. Continuous S’ showed a strong correlation with absolute VO2 (rho=0.83;p<0.0001). Only SV and S’ were predictive of VO2peak. LVEF and E’ as well as both global longitudinal and circumferential strain showed no correlation. The systolic efficiency slope (SES) was calculated by determining the individual regression lines for VO2 and S’. A moderate relationship between the SES and VO2peak was observed for both septal S’; r=0.57;p<0.001 and lateral S’, r=0.53;p<0.001). Conclusion A detailed description of myocardial function is described; linear for S’ and E’ and a plateau for EF and GLS. S’ during exercise is a better predictor of exercise performance than LVEF, SV or GLS. The SES slope was able to predict VO2peak suggesting the process driving systolic velocity and its augmentation is a key determinant of exercise ability.

But facts are chiels that winna ding An downa be disputed – from _A Dream_ by Robert Burns (1786) (But facts are fellows that will not be overturned, And cannot be disputed) _Wave separation, wave intensity, the reservoir-wave concept, and the instantaneous wave-free ratio (2015) N Westerhof, P Segers and BE Westerhof, Hypertension, DOI: 10.1161/HYPERTENSIONAHA.115.05567_ Hereinafter referred to as [WSW]. This paper by three distinguished workers in the field of cardiovascular mechanics, concludes that both the reservoir pressure and instantaneous wave-free ratio are ’... both physically incorrect, and should be abandoned’. These are very strong conclusions which, if they were opinions could only be debated. Reading the paper in detail, however, reveals that it contains numerous factual errors in their discussion of these two entities. Since facts are different from opinions, we believe that it is essential that these errors be corrected before they gain credence by repetition. False facts are highly injurious to the progress of science, for they often endure long; but false views, if supported by some evidence, do little harm, for every one takes a salutary pleasure in proving their falseness. – Charles Darwin (1871) Because we are naturally prejudiced about the validity of both the reservoir pressure (Pres) and instantaneous wave-free ratio (iFR), having been involved in the conception and development of both ideas, we will try to present our arguments as transparently and fairly as possible. As far as possible we will demonstrate the errors by direct quotations from the paper. The whole paper¹ is available from the Hypertension web site and should be consulted directly if there are any questions about our treatment of the text. Approximately two thirds of the paper is taken up with a discussion of wave separation and wave intensity from the point of view of the more usual Fourier-based methods of analysing cardiovascular mechanics, frequently called the impedance method. This part of the paper is, as far as we can see, both insightful and free of major errors. We found some of the discussion about wave intensity analysis thought-provoking and agree with most of their conclusions. We recommend the first two-thirds of this paper to anyone interested in arterial mechanics. In contrast, the last third of the paper, starting with the final sentence of the section ’Summary of Wave Separation and WIA’ is riddled with errors of interpretation and, more importantly, contains a number of mistakes (or in Darwin’s terms ’false statements of fact’) that need to be corrected. Instead of dealing with these errors chronologically, we will point out the fundamental errors first and then deal with their sequelae.