Introduction
The relationship between resting echocardiographic measures of cardiac
function and exercise capacity is weak 1–4. At peak
exercise, left ventricular (LV) function, especially longitudinal
motion, is better correlated with maximum exercise capacity5. The shape of the relationship, as well as the
relative contribution of various measurable facets of heart function is
not known. Amongst athletes with phenotypically abnormal hearts,
augmentation of left ventricular ejection fraction (LVEF) by more than
10% differentiates those with adaptive rather than cardiomyopathic
hearts 6,7. Understanding the shape to the
relationship between contractile reserve and exercise attainment is
vital to understand the physiology, and to establish target parameters
that might be useful when investigating disease states. We therefore
hypothesized that detailed measures of exercise myocardial recruitment
would explain individual exercise performance, and that longitudinal
function would be the primary adaptive strategy. This was achieved by
recording oxygen uptake (VO2) and echocardiography
simultaneously across an incremental exercise protocol in a cohort of
healthy volunteers.