The left ventricular (LV) volume and ejection fraction (EF) response to upright exercise was assessed on 15 normal subjects during cycle ergometry. Measures of cardiac function and gas exchange were made at rest, at 85% of the ventilatory anaerobic threshold (VAT; WL1), and at peak exercise (WL2). EF increased from rest (58 +/- 12%) during WL1 (66 +/- 10%), reaching significantly higher values at WL2 (69 +/- 8%; p less than .05). End-diastolic volume increased from rest during WL1 (136 +/- 36 ml vs. 118 +/- 32 ml; p less than .05), becoming significantly higher than rest during WL2 (141 +/- 41 ml). End-systolic volume was unchanged from rest (51 +/- 25 ml) during submaximal exercise (50 +/- 20 ml), but it decreased significantly during WL2 (44 +/- 21 ml; p less than .05). The systolic pressure/end-systolic volume ratio increased from 3.0 +/- 1.7 (rest) to 5.8 +/- 3.0 at WL2 (p less than .05). These results suggest that the Frank-Starling mechanism is operative throughout exercise, particularly during exercise below the VAT. LV performance after the VAT is further augmented by increased contractility with continued, yet diminished, utilization of the Frank-Starling mechanism.
"The constant E/E a indicates a constant filling pressure, and thus no indication of Frank–Starling mechanism. E/E a ratio is slightly higher than in previous studies   , as tissue velocity is by colour Doppler  . The lack of evidence of the Frank– Starling effect in this group of young males is in accordance with Gerstenblith et al.  . "
[Show abstract][Hide abstract] ABSTRACT: To study left ventricular mechanics of exercise with Doppler and tissue Doppler.
Twenty-one males (mean age, 26; height, 184 cm; weight, 84 kg), exercised on a bicycle, with increasing workload, with oxygen uptake, Doppler flow and tissue Doppler recordings during exercise. There was correlation between peak systolic LVOT flow and annulus velocity; R=0.72, (p<0.001) and between peak mitral E flow and annulus E(a) velocity; R=0.68(p<0.001). Finally there was correlation between peak LVOT and mitral flow velocity; R=0.83(p<0.001) and peak systolic and early diastolic annulus velocity R=0.69(p<0.001). All intervals of the heart cycle decreased with RR-interval. There was a linear relation between diastolic filling and RR-interval, while ejection period was less increased with RR-intervals above 600 ms, and thus not a linear relationship. There was no change in E/E(a) ratio during exercise.
Mechanism for increased filling as well as ejection during exercise seems to be increased contraction and relaxation velocity, with no evidence of Frank-Starling mechanism. Bazett's formula gives a better heart rate correction of LVET at high heart rates than Weissler's.
[Show abstract][Hide abstract] ABSTRACT: The assessment of cardiac function, particularly cardiac output (Q) during heavy exercise is essential for the evaluation of cardiovascular factors that might limit oxygen transport. A series of invasive and noninvasive techniques has been developed for the assessment and monitoring of Q during resting and submaximal exercise conditions. However, very few techniques have been found to give accurate and reliable determinations of Q during vigorous to maximum exercise. For exercise physiologists and sport cardiologists, maximal exercise data are of primary importance. The 'gold standard' measures of cardiac function are considered to be the direct Fick and dye-dilution methods. These have been widely shown to give accurate and reliable determinations of Q during resting and submaximal exercise conditions; however, their use during maximal exercise conditions is debatable due to the inherent risks involved with each and their increasing inaccuracy during the later stages of vigorous exercise. Thermodilution has also been considered to be a relatively good method for the determination of Q during rest and exercise conditions, but recent authors have questioned its use due to the nature of the measure and its inaccuracy during strenuous exercise. Various noninvasive measures of cardiac function have been developed to overcome the problems associated with the 'gold standard' measures. The first part of this article discusses conventional techniques used in exercise physiology settings. The majority of these provide accurate and reliable determinations of Q during rest and submaximal exercise. However, very few techniques are suitable for maximal exercise conditions. Perhaps only the foreign gas rebreathe using acetylene (C2H2) meets all the criteria of being noninvasive, simple to use, reliable over repeated measurements, accurate and useful during maximal exercise.
Sports Medicine 02/1999; 27(1):23-41. DOI:10.2165/00007256-199927010-00003 · 5.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Training adaptations in patients with coronary artery disease (CAD) have been reported previously, but little is known about central and peripheral adaptations in those recovering from coronary artery bypass graft surgery (CABG). The purpose of this study was to examine the effects of 12 weeks of endurance exercise training on exercise performance and left ventricular and peripheral vascular reserve in a group of uncomplicated CABG patients.
Thirty-one patients were recruited and began training 8 to 10 weeks after uncomplicated CABG. Patients underwent progressive exercise training consisting of walking and jogging, at 75% to 80% maximal oxygen intake (VO2max). Measures of left ventricular function included ejection fraction (EF), ventricular volumes, and the pressure volume ratio, an index of contractility. Peak ischemic exercise calf blood flow and vascular conductance was determined using strain-gauge plethysmography. Maximal oxygen intake and submaximal blood lactate concentration also was determined.
A significant improvement in VO2max (1497 +/- 60 mL/min versus 1691 +/- 71 mL/min) was observed after training. This change was accompanied by an increase in the EF during submaximal exercise (60 +/- 3% versus 63 +/- 2% at 40% VO2max; 61 +/- 3% versus 64 +/- 3% at 70% VO2max) (P < 0.05), and the change in EF from rest to exercise (delta EF). No changes were observed for ventricular volumes during exercise, although there was a trend for a higher stroke volume at 70% VO2max. A significant increase (18%) was observed for peak ischemic exercise calf blood flow and vascular conductance. In addition, submaximal blood lactate concentration was lower after training.
These data indicate that exercise training for 12 weeks in patients recovering from CABG can elicit significant improvements in functional capacity that, for the most part, are secondary to peripheral adaptations, with limited support for improvement in left ventricular function.
Journal of Cardiopulmonary Rehabilitation 05/1999; 19(3):144-50. DOI:10.1097/00008483-199905000-00001
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