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Pericardial-mediated diastolic ventricular interactions in endurance-trained athletes during orthostatic stress Esch, Ben Thomas Alexander.


Purpose: To assess diastolic ventricular interaction (DVI) and its consequences in endurance athletes and normally active individuals during lower body positive (LBPP) and negative pressure (LBNP). Methods: Eight male endurance athletes (VO₂ max 65.4 ± 5.7 mL•kg⁻¹•min⁻¹) and eight normally active individuals (VO₂ max 45.1 ± 6.0 mL•kg⁻¹•min⁻¹) underwent three experimental days: 1) assessment of VO₂ max 2) a negative orthostatic tolerance test, and 3) LBPP (0 to 60 mmHg) and LBNP (0 to -80 mmHg) during which time ventricular volumes were examined via echocardiography. Results: All normally active individuals completed the tolerance test on experimental day two, but seven out of eight athletes did not complete this test due to signs of presyncope. There were no statistically significant differences between groups in resting left ventricular end-diastolic volume (LVEDV), stroke volume, or cardiac output. In response to LBNP on experimental day three there was a similar decrease in right ventricular (RV) end-diastolic area in both groups. However, there was a differential group response to LBNP (a greater decrease in the endurance athletes) during day three with respect to LVEDV (p<0.05). The endurance athletes also had significantly greater decreases in stroke volume and cardiac output during LBNP compared to the normally active group (p<0.05). During LBPP on day three, the endurance athletes showed greater increases in LVEDV and stroke volume, despite similar responses in RV end diastolic area (p<0.05). Conclusion: Endurance athletes likely had a relatively slack pericardium causing minimized DVI during conditions of orthostatic stress, whereas the normally active individuals appear to have more marked DVI during orthostatic stress which allows for a paradoxically greater maintenance of LV filling in response to LBNP.

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