Left ventricles of aging athletes: better untwisters but not more relaxed during exercise.

OBJECTIVE: With an aging population and the increasing prevalence of heart failure with preserved ejection fraction, developing strategies to prevent diastolic dysfunction is crucial. Regular endurance training has been suggested to be one such strategy. However, the underlying mechanisms of training, including the effect on left ventricular (LV) untwist, which promotes LV filling, are unclear and studies exploring the heart during exercise in the aging heart are lacking. METHODS: Cardiopulmonary exercise testing with speckle tracking echocardiography was realized in male subjects: 16 young athletes (YA), 19 young controls (YC), 22 middle-aged athletes (MA) with a lifelong history of endurance training, and 20 middle-aged controls (MC). RESULTS: During exercise, the early filling was lower in MC compared to YC, whereas it was preserved between YA and MA. At exercise, peak untwisting rate/peak twist ratio and the percentage of untwist during isovolumic relaxation time were decreased in senior groups but higher in YA and MA compared to age-matched controls. Early diastolic filling reserve correlated with untwisting rate/peak twist reserve in YA and MA (R 2 = 0.22, p < 0.05) but not in controls. LV relaxation indices in athletes at rest and during exercise were not improved compared to age-matched controls. CONCLUSION: LV intrinsic relaxation was similarly lower with age, independently of training, while the age-related decrease of untwist during exercise was lower with lifelong exercise training. The preservation of untwist mechanics in MA could thus sustain the early filling during exercise. Further studies are needed to confirm the role of exercise training as a preventive strategy for diastolic dysfunction and heart failure.

Two months of endurance training does not alter diastolic function evaluated by TDI in 9-11-year-old boys and girls.

OBJECTIVE: Superior global cardiac performance (ie stroke volume) is classically reported after training in children. Current knowledge of the impact of exercise training on myocardial relaxation, a major component of left ventricular (LV) filling and subsequently stroke volume, is, however, limited in the paediatric population. This study aimed to investigate the effect of aerobic training on LV wall motion velocities by tissue Doppler imaging (TDI) in healthy children. METHODS: 25 children (11 girls, 14 boys) were enrolled in a 2 month high-intensity aerobic training programme and 25 (12 girls and 13 boys) served as controls. The children (9-11 years old) performed a graded maximal exercise test on a treadmill to evaluate maximal oxygen uptake. Standard Doppler echocardiography and TDI measurements were performed at baseline and end of the study. Tissue Doppler systolic, early and late myocardial velocities were obtained at the mitral annulus in the septal, lateral, inferior and posterior walls. RESULTS: Maximal oxygen uptake increased by 6.5% (before: 51.6 (SD 4.2), after: 55.0 (4.5) ml/min/kg p<0.001) after training. A modest but significant increase in left ventricular end-diastolic diameter was also noticed (before: 46.1 (3.4), after: 48.3 (4.3) mm.BSA(-1/2), p<0.001), whereas left ventricular wall thickness and mass were unchanged. Neither transmitral inflow velocities nor early and late wall motion (Em: before = 18.4 (2.7), after = 18.0 (2.3) cm/s, Am: before = 6.8 (1.2), after = 6.7 (1.3) cm/s) were affected by training. Shortening fraction and regional systolic function (Sm: before = 10.1 (1.6), after = 10.2 (1.4) cm/s) by TDI were also unchanged. CONCLUSION: High-intensity aerobic sessions repeated over a 2 month period failed to improve regional diastolic function assessed by TDI in healthy young children.

Alteration in left ventricular normal and shear strains evaluated by 2D-strain echocardiography in the athlete's heart.

The contraction of cardiomyocytes induces a systolic increase in left ventricular (LV) normal (radial, circumferential and longitudinal) and shear strains, whose functional consequences have not been evaluated, so far, in athletes. We used 2D ultrasound speckle tracking imaging (STI) to evaluate LV regional strain in high-level cyclists compared to sedentary controls. Sixteen male elite cyclists and 23 sedentary controls underwent conventional, tissue Doppler, and STI echocardiography at rest. We assessed LV long and short axis normal strains and shear strains. We evaluated circumferential-longitudinal shear strain from LV torsion, and circumferential-radial shear strain from the difference between subendocardial and subepicardial torsion. Apical radial strain (42.7 +/- 10.5% versus 52.2 +/- 14.3%, P < 0.05) and LV torsion (6.0 +/- 1.8 deg versus 9.2 +/- 3.2 deg, P < 0.01) were lower in cyclists than in controls, respectively. Rotations and torsion were higher in the subendocardial than in the subepicardial region in sedentary controls, but not in cyclists. Haemodynamic and tissue Doppler based indexes of global LV diastolic and systolic functions were not different between cyclists and controls. Athlete's heart is associated with specific LV adaptation including lower apical strain and lower myocardial shear strains, with no change in global LV diastolic and systolic function. These mechanical alterations could improve the cardiovascular adjustments to exercise by increasing the radial strain and torsional (and thus untwisting) response to exercise, a key element of diastolic filling and thus of cardiac performance in athletes.

Flow-mediated dilation and exercise-induced hyperaemia in highly trained athletes: comparison of the upper and lower limb vasculature.

AIM: The main purpose of the present study was to assess whether similar vascular adaptive changes could be obtained by long-term intensive training involving predominantly either the lower or the upper limb musculature. METHODS: In 11 cyclists (C), 10 swimmers (S) and 10 sedentary controls (Sed), duplex Doppler ultrasonography was used to measure post-occlusion endothelium-dependent flow-mediated dilation (FMD), endothelium-independent, glycerine trinitrate-induced dilation (GTND) and exercise-induced blood flow changes in the arm (axillary artery) and leg (superficial femoral artery). Limb-specific exercise was achieved by one elbow-flexion or one leg-extension maximal exercise test, thereby allowing assessment of upper and lower limb muscle perfusion, vascular conductance and vasodilatory capacity of resistance vessels during effort. RESULTS: C and S exhibited vascular remodelling associated with improved FMD and GTND in the predominantly trained limbs compared to Sed. Both showed greater muscle perfusion and vascular conductance than Sed during isolated exercise involving the predominantly trained musculature. C showed also higher FMD in the brachial artery and greater peak muscle perfusion and conductance in the non-exercising muscles, whereas S presented only enhanced FMD in the superficial femoral artery. CONCLUSION: Therefore, in the upper as well as in the lower limb vasculature, repetitive exposure to increased shear stress over a long-term period results in improved FMD of large conduit arteries as well as greater vasodilatory capacity during isolated exercise in the predominantly trained muscles. Long-term training involving predominantly the lower limbs also results in enhanced vascular reactivity in upper limb conduit and resistance vessels.

Tissue Doppler imaging reproducibility during exercise.

Tissue Doppler imaging (TDI) is an echocardiographic technique used during exercising to improve the accuracy of a cardiovascular diagnostic. The validity of TDI requires its reproducibility, which has never been challenged during moderate to maximal intensity exercising. The present study was specifically designed to assess the transmitral Doppler and pulsed TDI reproducibility in 19 healthy men, who had undergone two identical semi-supine maximal exercise tests on a cycle ergometer. Systolic (S') and diastolic (E') tissue velocities at the septal and lateral walls as well as early transmitral velocities (E) were assessed during exercise up to maximal effort. The data were compared between the two tests at 40 %, 60 %, 80 % and 100 % of maximal aerobic power. Despite upper body movements and hyperventilation, good quality echocardiographic images were obtained in each case. Regardless of exercise intensity, no differences were noticed between the two tests for all measurements. The variation coefficients for Doppler variables ranged from 3 % to 9 % over the transition from rest to maximal exercise. The random measurement error was, on average, 5.8 cm/s for E' and 4.4 cm/s for S'. Overall, the reproducibility of TDI was acceptable. Tissue Doppler imaging can be used to accurately evaluate LV diastolic and/or systolic function for this range of exercise intensity.

Reproducibility of automated pulse wave velocity measurement during exercise. Running head: pulse wave velocity during exercise.

Pulse wave velocity measurement is used as an index of arterial stiffness. The purpose was to evaluate the reproducibility of pulse wave velocity measurement at rest, during exercise and recovery from exercise, using an automated device. Twelve healthy young adults (mean age 22.0 +/- 3.1 yrs) underwent an upright submaximal cycle test on two separate occasions, one week apart. Pulse wave velocity, systolic and diastolic blood pressures and heart rate were assessed at rest, during the last 2 min of exercise and 10 min later. Pulse wave velocity was measured on the upper limb and the forearm by the cross-correlation function of photoplethysmography and Doppler signals. Brachial artery pulse wave velocity was calculated from upper limb and forearm pulse wave velocities. No significant difference was found on duplicate measurements of heart rate, systolic and diastolic blood pressures at rest, during exercise and recovery, showing that pulse wave velocity was measured under similar conditions. Coefficient of variation for upper limb and forearm pulse wave velocities ranged from 2.9 to 5.9% at rest and during recovery, and were respectively 2.9% and 8.3% during exercise. However, coefficient of variation for brachial pulse wave velocity was 7.7 and 10.3% at rest, 15.7% during exercise, and 5.8% during recovery. During exercise, pulse wave velocity measurements were satisfying, but indirect assessment of brachial artery pulse wave velocity showed poor reproducibility. Thus, upper limb and forearm pulse wave velocities may be used during exercise to assess the effect of training or drugs on arterial wall mechanical properties.

Effect of intensive training on heart rate variability in prepubertal swimmers.

BACKGROUND: In children, there is very limited evidence focusing on the beneficial effect of exercise training on heart rate variability (HRV) during childhood. Despite the fact that more and more children are engaged in intensive training programs, the question arises if such intensive training involves deleterious effects on the cardiac autonomic nervous system during childhood. Thus the aim of the present study was to compare HRV parameters in highly trained swimmer boys and untrained counterparts. METHODS: Twenty prepubertal boys, aged 11-12 years old, took part in the study. The children were divided into 11 highly trained prepubertal swimmers (training sessions of 8-10 h weekly for at least 4 years) and 9 age-matched active boys. HRV analysis was performed on diurnal recordings in the frequency (short-term recordings 6 min the most 'vagal') and time (long-term recordings 4 h centred on the 6 min most 'vagal') domains. RESULTS: No significant differences were obtained between groups for all frequency variables whatever the mode of expression (absolute in ms2, relative in Ln or %). All time-domain components were not significantly different in swimmers and untrained boys. CONCLUSIONS: The results of the present study demonstrate that participating intensively in swimming training does not induce in children changes in HRV indices. Neither time nor domain HRV variables were significantly different between untrained and highly trained prepubertal boys. Thus, intensive training in healthy children does not involve deleterious effects on HRV.

Relationships between left ventricular morphology, diastolic function and oxygen carrying capacity and maximal oxygen uptake in children.

Little attention has been paid to children with respect to factors controlling maximal oxygen uptake (V.O (2max)). This study was therefore specifically designed to examine the potential relationships between cardiac size, diastolic function and O (2) carrying capacity with maximal aerobic capacity. Specifically, body size indices (body surface area, lean body mass), resting left ventricular dimensions and filling characteristics, blood haemoglobin concentration as well as V.O (2max) established during a maximal cycle exercise test were assessed in a large cohort (n = 142) of healthy 10 - 11 year old boys and girls. Results were compared between groups of low (< 50, L), moderate (50 - 60, M) and high (> 60, H) V.O (2max) (ml . min (-1) . kg (-1) of lean body mass). Moreover, potential contributors to V.O (2max) variance were investigated using univariate and multivariate regression analyses over the overall population. The major results show no differences between the 3 groups for all diastolic and systolic function indices as well as blood haemoglobin and systemic vascular resistances (used as an index of afterload). None of these variables emerged from regression analyses as potential predictors of V.O (2max.) After accounting for body size variation, heart dimensions, and especially left ventricular internal dimensions, differed between H and M and L and were associated with higher cardiac filling and subsequently stroke volume. Strong relationships between V.O (2max) and heart dimensions were noticed, due primarily but not exclusively to the influence of body size. After adjusting for lean body mass, end-diastolic diameter contributed modestly (8 %) but significantly to V.O (2max) variance, which is biologically meaningful.

Long-term endurance training does not prevent the age-related decrease in left ventricular relaxation properties.

AIM: Diastolic filling dynamics in the long-term endurance trained elderly has previously been examined by transmitral flow velocity, which has been shown to be preload dependent. The aim of this study was to assess the effect of long-term endurance training on left ventricular (LV) relaxation in older individuals by using pulsed tissue Doppler imaging. METHODS: Fourteen master athletes with a history of intensive long-term endurance training, 14 aged-matched sedentary controls and 15 young adult men underwent standard Doppler echocardiography and pulsed Doppler tissue imaging, performed in four-chambers apical view, by placing a sample volume at the level of the mitral annulus. RESULTS: Stroke volume was significantly higher and heart rate lower in master athletes compared with aged-matched sedentary subjects. Transmitral Peak E velocity and ratio E/A were significantly higher in master athletes, but did not reach the values of young men. Peak LV wall motion during the early filling phase, an index of LV relaxation, were significantly higher in young men than in both groups of older individuals. However, similar values were obtained between master athletes and sedentary counterparts. CONCLUSIONS: Our data provide evidence that long-term training does not reduce the age-related decline in LV relaxation properties in humans. This finding implies that other mechanisms, such as increased LV filling pressures due to expanded blood volume, are probably responsible for the higher contribution of early diastolic filling to LV filling in master athletes compared with their sedentary counterparts. However this hypothesis needs to be confirmed.

Cardiovascular responses to endurance training in children: effect of gender.

BACKGROUND: The aim of the present study was to determine in healthy children the effect of a well-controlled endurance training programme on cardiac function at maximal exercise and to define whether gender affects the training-induced cardiovascular response. The contribution of factors potentially involved in those adaptations such as cardiac dimensions and diastolic and systolic function was also investigated. METHODS: Thirty-five l0-11-year-old children took part in this study: 19 children (10 girls and nine boys) were assigned to participate in a 13-week endurance training programme (3 x 1 h week-1, intensity: > 80% HR max), and 16 (seven girls and nine boys) served as a control group. A resting echocardiographic evaluation and a maximal upright cycle test, including measurement of stroke volume (SV), cardiac output (Q) and blood pressure, were performed in all children before and after the study period. RESULTS: The training programme led to a rise in maximal O2 uptake (VO2max), brought about however, only by an increase in SVmax in both genders. Moreover, the boys increased their VO2max to a greater extent than the girls (boys: +15%; girls: +8%) only because of a higher SVmax improvement (boys: +15%; girls: +11%). No alterations were noticed in the SV pattern from rest to maximal exercise, indicating that the increase in SVrest was a key factor in the improvement of SVmax and thus VO2max. Regarding resting echocardiographic data, an increase in the left ventricular end-diastolic diameter, concomitant with an improvement in diastolic function, was observed after training and constituted an essential element in the rise in VO2max after training in these children. Moreover, during maximal exercise, a decrease in systemic vascular resistances, probably indicating peripheral cardiovascular adaptive changes, might also play an important role in the increase in VO2max. CONCLUSION: Whatever gender, aerobic training increases VO2max in children, mediated by an improvement in SVmax only. Similar mechanisms, including loading conditions and cardiac morphology, seem to be involved in both genders in order to explain such an improvement.

Cardiovascular responses to progressive cycle exercise in healthy children and adults.

The aim of this study was to compare resting, relative submaximal (at the same percentage of maximal oxygen uptake) and maximal cardiovascular responses to progressive cycle exercise in pre-pubertal children and young adults with similar aerobic aptitude. Fourteen healthy children (7 girls and 7 boys) with a mean age of 10.8 yr and 16 healthy young adults (8 women and 8 men) with a mean age of 22.4 yr underwent a progressive cycle test until exhaustion with estimation of stroke volume and cardiac output by Doppler echocardiography. Submaximal responses were evaluated at similar exercise intensities (around 40, 60 and 80 % of maximal oxygen uptake). Mean submaximal and maximal oxygen uptake were not significantly different between the children and the adults. As expected, the adults demonstrated larger absolute values of stroke volume and cardiac output at all levels of intensity but when related to body surface area, the differences disappeared. The relationships between cardiac output and oxygen uptake calculated from comparable submaximal intensities were similar (slopes and intercepts) in the children and the adults. According to these results, it seems that the lower cardiovascular responses to exercise in children may be attributed to their smaller heart size.

Central and peripheral cardiovascular adaptations to exercise in endurance-trained children.

Stroke volume (SV) response to exercise depends on changes in cardiac filling, intrinsic myocardial contractility and left ventricular afterload. The aim of the present study was to identify whether these variables are influenced by endurance training in pre-pubertal children during a maximal cycle test. SV, cardiac output (Doppler echocardiography), left ventricular dimensions (time-movement echocardiography) as well as arterial pressure and systemic vascular resistances were assessed in 10 child cyclists (VO2max: 58.5 +/- 4.4 mL min-1 kg-1) and 13 untrained children (UTC) (VO2max: 45.9 +/- 6.7 mL min-1 kg-1). All variables were measured at the end of the resting period, during the final minute of each workload and during the last minute of the progressive maximal aerobic test. At rest and during exercise, stroke index was significantly higher in the child cyclists than in UTC. However, the SV patterns were strictly similar for both groups. Moreover, the patterns of diastolic and systolic left ventricular dimensions, and the pattern of systemic vascular resistance of the child cyclists mimicked those of the UTC. SV patterns, as well as their underlying mechanisms, were not altered by endurance training in children. This result implied that the higher maximal SV obtained in child cyclists depended on factors influencing resting SV, such as cardiac hypertrophy, augmented myocardium relaxation properties or expanded blood volume.

Reproducibility of cardiac output measurements by Doppler echocardiography in prepubertal children and adults.

The aim of this study was to examine reproducibility of stroke volume and cardiac output measurements by Doppler echocardiography during submaximal and maximal exercise in adults and children. Fourteen healthy children (8 girls and 6 boys aged 10.9 +/- 0.9yr) and eleven healthy young adults (1 female and 10 males aged 22.3 +/- 3.8 yr) underwent a progressive maximal upright cycle test until exhaustion with estimation of stroke volume and cardiac output by Doppler echocardiography on two separate occasions (one week apart). Maximal oxygen uptake and maximal heart rate were not significantly different between both tests in the children and adults indicating that similar exhaustive efforts were achieved at each test. No significant differences for mean values of stroke volume and cardiac output were observed at rest in the children and whatever the exercise intensity in the children and adults. No significant differences were observed between values of root mean square (precision and precision of error) in both groups. Thus we demonstrated that stroke volume and cardiac output values obtained by Doppler echocardiography at rest and during submaximal and maximal exercise were reproducible on test-retest measurements in children and adults.

[Study of the reproducibility of cardiac output measurement during exercise in pre-pubertal children by doppler echocardiography and CO2 inhalation]. / Etude de la reproductibilité de la mesure du débit cardiaque à l'exercice chez l'enfant prépubère par échocardiographie doppler et par réinhalation de CO2.

Non-invasive measurement of the cardiac output is essential in investigations of healthy children. However, the data concerning the reproducibility of the measurements are very limited. The aim of this study was to assess the reproducibility of the measurement of cardiac output during exercise by Doppler echocardiography and reinhalation of CO2 (extrapolation method). Fourteen pre-pubertal children underwent two similar tests at increasingly intense levels of exercise. The cardiac output was measured at rest and during the last minute of each stepwise increment of exercise. The results show no difference between the cardiac outputs of the two tests, whichever method was used and at all levels of exercise. They also demonstrate a better reproducibility of cardiac output measurement by Doppler echocardiography (coefficient of variation: 7.5% at rest and 5.2% at maximal effort) compared with reinhalation of CO2 (coefficient of variation: 16.8% at rest and 11.7% at maximal effort). Both methods showed better reproducibility on exercise, resulting from smaller variations in heart rate and stroke volume on effort than at rest. The authors conclude that Doppler echocardiography is very accurate and its simplicity makes it the method of choice in pre-pubertal children for measuring cardiac output during exercise.