Role of left ventricular untwisting in diastolic dysfunction after long duration exercise.

Numerous studies have reported that long duration exercise induces transient left ventricular (LV) dysfunction. Using 2D-strain echocardiography, we aimed to describe cardiac mechanics following 2 h of exercise. We focused especially on LV twist since untwisting is crucial in the development of intraventricular pressure gradient, a key element of LV early filling. Twenty healthy males (20-41 years) underwent a resting echocardiography including a 2D-strain evaluation based on velocity vector imaging before and after 2-h of cycling at a moderate intensity. Measurements included LV longitudinal, radial and circumferential strains, and LV rotations and twist. After the prolonged exercise, the depressed diastolic function (peak E: 77.5 ± 11.4 vs. 71.9 ± 10.9, P < 0.01) was associated with a delay in peak untwisting velocity (110 ± 14 vs. 119 ± 14% of systolic duration, P < 0.05), whereas LV peak diastolic strain rates, indexes of LV relaxation, were unchanged. LV global systolic function and LV peak systolic strain rates remained normal after the exercise (fractional shortening: 36.8 ± 2.8 vs. 36.9 ± 5.7, NS). In conclusion, the present study gives new insight into cardiac dysfunction following long duration exercise. It demonstrates that depressed diastolic function is associated with delayed untwisting velocity, but depressed LV relaxation and contractility following exercise remains controversial.

Maximalist vs. minimalist shoes: dose-effect response of elastic compression on muscular oscillations.

BACKGROUND: The aim of this study was to establish whether maximalist shoes engender fewer muscular oscillations than minimalist shoes and determine to what extent these shoes, when combined with elastic compression (EC), help reduce muscle oscillations. For that purpose, we tested the effects of various levels of compression on the muscular oscillations in maximalist and minimalist footwear. METHODS: Eleven volunteers executed 16 one-minute passages on a flat treadmill in a randomized order: maximalists or minimalists, walking (6 km/h) or running (10 km/h), without EC (control condition [CON]) or with EC applying different pressures (9.6 mmHg, 14.5 mmHg and 20.4 mmHg). The muscular oscillations were measured on both thighs, on the rectus femoris and on the vastus medialis with tri-axial accelerometers. RESULTS: Muscular oscillations are lower in maximalist shoes than in minimalist shoes, for both walking to 6 km/h and running to 10 km/h (P<0.05). Oscillations are also reduced with EC (P<0.05). This decrease is most marked when the pressure exercised by the EC is increased. CONCLUSIONS: Increased compression with minimalist shoes reduces muscular oscillations as much as maximalist shoes, when combined with lower compression.

Depressed systolic function after a prolonged and strenuous exercise.

INTRODUCTION: Prolonged and strenuous exercise (PSE) induces transient left ventricular (LV) dysfunction. Although a consensus exists regarding the decrease in diastolic function, the existence of a decrease in systolic function by a PSE remains controversial, probably due to the transient tachycardia and changes in loading conditions observed upon the completion of exercise. Therefore, the objective was to evaluate LV systolic function before and after a PSE using two-dimensional speckle tracking echocardiography not only at rest but also during incremental tests to adjust heart rates (HR). METHODS AND RESULTS: Sixteen healthy young men (23 ± 3 yr old) performed a 3-h period of intensity-controlled upright cycling. LV strain (S), systolic strain rate (SR), rotation, and systolic rotational rate were evaluated by two-dimensional speckle tracking echocardiography before and after a 3-h period of PSE at rest and during incremental tests. Posttest evaluation was performed once the HR had returned to the pretest value. Under resting conditions, parameters of systolic function were either unchanged or increased after the PSE. However, during the incremental test, all LV systolic SR and apical rotational rates were decreased after PSE (radial SR at workload 3 (W3): 2.21 ± 0.12.s(-1) vs 1.87 ± 0.10.s(-1), P < 0.01 and apical rotational rate at W3: 128 ± 28 deg.s(-1) vs 105 ± 26 deg.s(-1), P < 0.05). Regression analyses between LV systolic SR and HR showed lower y-intercepts without differences in slopes, suggesting a decrease of both global and regional systolic functions irrespective of HR after the PSE. CONCLUSION: Our findings based on LV S and SR data during incremental tests demonstrate that the 3-h period of PSE induces LV systolic dysfunction.