Changes in ventricular twist and untwisting with orthostatic stress: endurance athletes versus normally active individuals

Endurance-trained individuals exhibit larger reductions in left ventricular (LV) end-diastolic volume in response to lower body negative pressure (LBNP) compared with normally active individuals. However, the relationship between LV torsion and untwisting and the LV volume response to LBNP in endurance athletes is unknown. Eight endurance-trained athletes [maximal oxygen consumption (Vo2max): 66.4 ± 7.2 ml·kg−1·min−1] and eight normally active individuals (Vo2max: 41.9 ± 9.0 ml·kg−1·min−1) (all men) underwent two cardiac magnetic resonance imaging (MRI) assessments, the first during supine rest and the second during −30 mmHg LBNP. Right ventricular (RV) and LV volumes were assessed, myocardial tagging was applied in order to quantify LV peak torsion and peak untwisting rate, and filling rates were measured with phase-contrast MRI. In response to LBNP, endurance-trained individuals had greater reductions in RV and LV end-diastolic volume and stroke volume (P < 0.05). Endurance athletes had reduced untwis...