Effect of eight weeks of endurance exercise training on right and left ventricular volume and mass in untrained obese subjects: a longitudinal MRI study.

The aim of the present investigation was to examine how 8 weeks of intense endurance training influenced right and left ventricular volumes and mass in obese untrained subjects. Ten overweight subjects (19-47 years; body mass index of 34+/-5 kg/m(2)) underwent intensive endurance training (rowing) three times 30 min/week for 8 weeks at a relative intensity of 72+/-8% of their maximal heart rate response (mean+/-SD). Before and after 8 weeks of endurance training, the left and the right end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), stroke volume (SV) and ventricular mass (VM) were measured by Magnetic resonance imaging (MRI). Submaximal heart rate decreased from 126+/-5 to 113+/-3 b.p.m. (10%; P<0.01), and from 155+/-5 to 141+/-4 b.p.m. (9%; P<0.001) at submaximal workloads of 70 and 140 W (110 W for women), respectively (mean+/-SEM). Resting ventricular parameters increased significantly: left ventricular SV, EDV and VM increased by 6%, 7% and 13%, respectively (P<0.01). The right side of the heart showed significant changes in SV, EDV and VM with increase of 4%, 4% and 12%, respectively (P<0.05). Eight weeks of endurance training significantly increased left ventricular SV and right ventricular SV, due to an increase in left ventricular EDV and right ventricular EDV. Furthermore, left VM and right VM increased. We conclude that using MRI and a longitudinal design it was possible to demonstrate similar and balanced changes in the right and left ventricle in response to training.

Effects of passive heating on central blood volume and ventricular dimensions in humans.

Mixed findings regarding the effects of whole-body heat stress on central blood volume have been reported. This study evaluated the hypothesis that heat stress reduces central blood volume and alters blood volume distribution. Ten healthy experimental and seven healthy time control (i.e. non-heat stressed) subjects participated in this protocol. Changes in regional blood volume during heat stress and time control were estimated using technetium-99m labelled autologous red blood cells and gamma camera imaging. Whole-body heating increased internal temperature (> 1.0 degrees C), cutaneous vascular conductance (approximately fivefold), and heart rate (52 +/- 2 to 93 +/- 4 beats min(-1)), while reducing central venous pressure (5.5 +/- 07 to 0.2 +/- 0.6 mmHg) accompanied by minor decreases in mean arterial pressure (all P < 0.05). The heat stress reduced the blood volume of the heart (18 +/- 2%), heart plus central vasculature (17 +/- 2%), thorax (14 +/- 2%), inferior vena cava (23 +/- 2%) and liver (23 +/- 2%) (all P

The plasma atrial natriuretic peptide response to arm and leg exercise in humans: effect of posture.

During arm exercise (A), mean arterial pressure (MAP) is higher than during leg exercise (L). We evaluated the effect of central blood volume on the MAP response to exercise by determining plasma atrial natriuretic peptide (ANP) during moderate upright and supine A, L and combined arm and leg exercise (A + L) in 11 male subjects. In the upright position, MAP was higher during A than at rest (102 +/- 6 versus 89 +/- 6 mmHg; mean +/- s.d.) and during L (95 +/- 7 mmHg; P < 0.05), but similar to that during A + L (100 +/- 6 mmHg). There was no significant change in plasma ANP during A, while plasma ANP was higher during L and A + L (42.7 +/- 12.2 and 43.3 +/- 17.1 pg ml(-1), respectively) than at rest (34.6 +/- 14.3 pg ml(-1), P < 0.001). In the supine position, MAP was also higher during A than at rest (100 +/- 7 versus 86 +/- 5 mmHg) and during L (92 +/- 5 mmHg; P < 0.01) but similar to that during A + L (102 +/- 6 mmHg). During supine A, plasma ANP was higher than at rest and during L but lower than during A + L (73.1 +/- 22.5 versus 47.2 +/- 15.9, 67.4 +/- 18.3 and 78.1 +/- 25.0 pg ml(-1), respectively; P < 0.05). Thus, upright A was the exercise mode that did not enhance plasma ANP, suggesting that central blood volume did not increase. The results suggest that the similar blood pressure response to A and to A + L may relate to the enhanced central blood volume following the addition of leg to arm exercise.