Biomedical subjects

P Obert

Publications and source records attributed to P Obert.

At least 19 recordsLinked to original sources

PubMed2005

Chronic hypoxia exposure depresses aortic endothelium-dependent vasorelaxation in both sedentary and trained rats: involvement of L-arginine.

This study was designed to test the hypothesis that the previously demonstrated training-induced improvement of the endothelium vasodilator function would be blunted under conditions of chronic hypoxia exposure as a result of deleterious effects of hypoxia per se on the nitric oxide pathway. Sea-level-native rats were randomly assigned to N (living in normoxia), NT (living and training 5 days/wk for 5 wk in normoxia), CH (living in hypoxia, 2,800 m), and CHT (living and training 5 days/wk for 5 wk in hypoxia, 2,800 m) groups. Concentration-response curves to acetylcholine (ACh; 10(-9) to 10(-4) M) with or without L-arginine (10(-3) to 10(-5) M) and/or nitro-L-arginine methyl ester (10(-5) M) were assessed on aortic isolated rings. The main finding was that chronic hypoxia severely depressed maximal ACh-responses of aortic rings in both sedentary and trained groups. However, chronic hypoxia did not interfere with training-induced increases in maximal ACh responses, considering that maximal ACh vasorelaxation was improved in CHT rats to the same extent as in NT rats when both groups were directly compared with their sedentary counterparts. It should be pointed out that the vasodilator response to ACh was restored in CH and CHT rats to the level obtained in N and NT rats, respectively, by an in vitro L-arginine addition. A hypoxia-induced decrease in L-arginine bioavailability resulting from acclimatization at altitude may be involved in this limitation of the NO pathway in CH and CHT rats. These results are of importance for aerobic performance as the specific vascular adaptations to training at altitude could contribute to limit peripheral vasodilatation and subsequently blood flow during exercise.

Adaptation, Physiological↗

PubMed2005

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.

Anthropometry↗

PubMed2005

Oxygen uptake kinetics during moderate and heavy intensity exercise in humans: the influence of hypoxia and training status.

This study examined the influence of moderate hypoxia on the oxygen uptake (V.O(2)) kinetic response (primary time constant and slow component amplitude) during moderate and heavy cycle exercise in twenty-seven male subjects with various training status. Nine endurance trained (21.5 +/- 2.6 yr), nine sprint trained (22.9 +/- 5.7 yr), and nine untrained controls (24.0 +/- 4.4 yr) completed incremental tests to exhaustion in normoxia (inspired gas concentration or FIO (2) = 21 % O(2)) and hypoxia (FIO (2) = 13 % O(2)) to establish the FIO (2)-specific ventilatory threshold (VT) and maximal VO(2). Subsequently, the subjects performed repeated constant work rate cycling exercises during 7 min at moderate intensity (80 % of FIO (2)-specific VT) and heavy intensity (midway between the FIO (2) specific VT and maximal VO(2)). Pulmonary gas exchange was measured breath-by-breath during all exercise sessions. For both moderate and heavy intensities, the time constant of the primary VO(2) component was significantly (p < 0.05) slowed by approximately 25 to 30 % in hypoxia compared to normoxia to the same extent in the three groups. Hypoxia produced a more important decrease in the amplitude of the slow component in endurance athletes (- 36 %) than in sprinters (- 30 %) and controls (- 12 %). These results suggest that both primary and slow components of VO(2) kinetics during the adjustment to moderate- and heavy-intensity exercise are sensitive to hypoxia while training status tended to modulate partly the slow component amplitude.

Adult↗

PubMed2004

Cardiac remodeling and functional adaptations consecutive to altitude training in rats: implications for sea level aerobic performance.

This study questioned the effect of living and training at moderate altitude on cardiac morphological and functional adaptations and tested the incidences of potential specific adaptations compared with aerobic sea level training on maximal left ventricular performance. Sea level-native rats were randomly assigned to N (living in normoxia), NT (living and training 5 days/wk for 5 wk in normoxia), CH (living in hypoxia, 2,800 m), and CHT (living and training 5 days/wk for 5 wk in hypoxia, 2,800 m) groups. Cardiac adaptations were evaluated throughout the study period by Doppler echocardiography. Maximal stroke volume (LV(SVmax)) was measured during volume overloading before and after the study period. Finally, at the end of the study period, passive pressure-volume relationships on isolated heart and cardiac weighing were obtained. Altitude training resulted in a specific left ventricular (LV) remodeling compared with NT, characterized by an increase in wall thicknesses without any alteration in internal dimensions. These morphological adaptations associated with hypoxia-induced alterations in pulmonary outflow and preload conditions led to a decrease in LV filling and subsequently no improvement in LV performance during resting physiological conditions in CHT compared with NT. Such a lack of improvement was confirmed during volume overloading that simulated maximal effort (LV(SVmax) pretest: NT = 0.58 +/- 0.05, CHT = 0.57 +/- 0.08 ml; posttest: NT = 0.72 +/- 0.06, CHT = 0.58 +/- 0.07 ml; NT vs. CHT in posttest session, P < 0.05). Maximal aerobic velocities increased to the same extent in NT and CHT rats despite marked polycythemia in the latter. The lack of LV(SVmax) improvement resulting from altitude training-induced cardiac morphological and functional adaptations could be responsible for this phenomenon.

Adaptation, Physiological↗

PubMed2004

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.

Adult↗

PubMed2003

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.

Blood Pressure↗

PubMed2002

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.

Adaptation, Physiological↗

PubMed2002

Physical training increases heart rate variability in healthy prepubertal children.

BACKGROUND: The aim of the present study was to evaluate the effect of an endurance training program on heart rate variability (HRV) in prepubertal healthy children and to determine the relationships between HRV components and training-induced cardiac adaptations. METHODS: Nineteen prepubertal children (aged 10-11 years old) took part in this study: 12 children were assigned to participate in a 13-week endurance training program (3 x 1 h week-1; intensity, > 80% HRmax) and 7 children served as a control group. Before and after the 13-week study period, all the children were tested for maximal oxygen uptake (V O(2max)), HRV was measured by spectral and time domain analysis of 5 h night ECG recordings, and left ventricular (LV) cardiac morphology and function were assessed by means of Doppler-Echocardiography. RESULTS: V O(2max) increased significantly (+15.5% +/- 12.1; P < 0.01) after the training program. All the frequency domain components (absolute values) increased after training except the low (LF) to high (HF) frequency ratio. Also, LF and HF did not change when expressed relative to total power. For the time domain components, only N-N intervals, the standard deviation of all N-N and the average of all 5 min standard deviations of N-N increased after training. Our training program induced also an increase in LV internal diameter and mass as well as an enhancement in early diastolic passive LV filling with a concomitant reduction in late diastolic active LV filling. These cardiac morphological and functional adaptations did not correlate however, with the autonomous nervous system modifications due to training. CONCLUSION: Our study shows that an endurance training program had a positive effect on aerobic potential, morphological and functional cardiac parameters and on nocturnal global HRV in healthy prepubertal children without inducing sympathetic and parasympathetic modifications.

Case-Control Studies↗

PubMed2002

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.

Adaptation, Physiological↗

PubMed2002

Effect of two aerobic training regimens on the cardiorespiratory response of prepubertal boys and girls.

UNLABELLED: The aim of this study was to examine the effect of two endurance training regimens of varying duration and frequency on maximal oxygen uptake (VO2max) of prepubertal boys and girls. The subjects consisted of 84 prepubertal children, aged 10-11 y. Two groups, EG1 (n = 36) and EG2 (n = 20), were involved in a 13 wk endurance training programme (intensity: higher than 80% of maximal heart rate for both groups; frequency: 3 and 2 sessions per week: duration: 25-35 min and 15-20 min per session in the target zone, for EG1 and EG2, respectively). Another group of 28 children served as a control group. Each subject performed a continuous and progressive exercise test to exhaustion on a cycle ergometer to evaluate VO2max before and after the 13 wk study period. The main findings of this study were: (i) there was no improvement in VO2max after a training programme with the following characteristics: 2 sessions per week with 15-20 min of exercise performed at an intensity higher than 80% of maximal heart rate; (ii) a VO2max enhancement (on average +7%) was seen only in children who participated in a training programme organized on the basis of three sessions per week during which exercise intensities higher than 80% of maximal heart rate were sustained for at least 25 min per session; and (iii) there was no gender difference in the training response. CONCLUSION: It appeared from this longitudinal study that only a programme with continuous activity, organized on the basis of three sessions per week, with 25-35 min at an intensity higher than 80% of maximal heart rate at each session, enhanced VO2max in prepubertal boys and girls.

Child↗

PubMed2001

Effect of aerobic training and detraining on left ventricular dimensions and diastolic function in prepubertal boys and girls.

PURPOSE: The purpose of this study was to determine the effect of an aerobic training program on the left ventricular (LV) cardiac morphology and function of prepubertal children. METHODS: Twenty-nine 10-11 year old boys and girls (TG) participated in a 13-week running program (3 x 1 h/week, intensity: > 80% HRmax), 26, of the same age, served as a control group (CG). M-mode, 2-dimensional and pulsed-wave Doppler analyses were performed, during resting conditions, before and after the training period (T) as well as, for TG only, after 2 months of detraining (D). RESULTS: LV internal chamber dimension increased (+ 4.6 %, p < 0.01) while wall thicknesses concomitantly decreased (-10.7%, p < 0.05) as a result of T. All cardiac morphological parameters returned to pretraining values after D. Doppler-derived measurements of LV diastolic filling performance were also significantly altered by Tand D. A significant enhancement in the early diastolic passive LV filling with a concomitant reduction in the late diastolic active LV filling were in fact obtained after T. The training-induced bradycardia (-7 beats x min(-1), p < 0.01) was probably responsible for the changes in the late characteristics of the diastolic active filling. All diastolic filling indexes returned to pretraining values after D. Systolic function indexes were not modified after either T or D. No changes were obtained for the overall LV morphological and functional variables after 13 weeks of normal life for CG. CONCLUSION: These findings indicate that cardiac morphological adaptations can occur in prepubertal children after several months of aerobic training. These alterations differ however, in some areas, to those classically reported in adults following endurance training programs where both an increase in LV size and mass exist. Our data likewise demonstrate that endurance training is able to induce favourable LV diastolic filling modifications, directed principally towards an enhancement in the early rapid filling inflow and a corresponding reduction in the atrial contribution to the total diastolic inflow.

Adaptation, Physiological↗

PubMed2001

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.

Adolescent↗

PubMed2001

Effect of a 13-week aerobic training programme on the maximal power developed during a force-velocity test in prepubertal boys and girls.

The present study was undertaken in order to evaluate the effect of an aerobic training programme on the maximal power (Pmax) developed during a short-term exercise test in prepubertal children. Thirty-three 10-11 year old boys and girls were investigated: 17 (TG) participated twice a week (1 h per session) in a 13-week running programme and 16 (CG) served as a control group. Pmax was measured during a force-velocity test conducted on a friction-loaded cycle ergometer. The force (Fopt) and velocity (Vopt) at which Pmax was obtained were determined. Lower limb muscle mass (LMM) was evaluated by means of dual X-ray absorptiometry. Following training, Pmax increased even when muscle mass change due to the growth process was taken into account (Pmax W: + 23 %, W x kg(-1) LMM: + 18%, p < 0.001). The increase in Fopt was principally responsible for such an improvement since no alteration was noticed for Vopt after training. As for Pmax, Fopt was still greater following training when LMM was taken into account (p < 0.01). Furthermore, no changes were noticed for CG for all variables evaluated during the anaerobic test after the study period. Differences between TG and CG regarding Pmax and Fopt were obtained after training only. In conclusion this study highlights the effectiveness of an aerobic training programme to improve the maximal power during short-term exercise in prepubertal children.

Adaptation, Physiological↗

PubMed2001

Effect of gender in response to an aerobic training programme in prepubertal children.

The aim of the present study was to investigate the gender effect of an endurance training programme on the maximal oxygen uptake (VO2max) of prepubertal children. The subjects comprised eighty-five 10-11-y-old prepubertal children: 35 (17 girls, 18 boys; EG) were involved in a 13-wk running training programme and 50 (22 girls, 28 boys; CG) served as a control group. Each subject carried out a continuous and progressive cycle ergometer test before and after the 13-wk study period under the same conditions and procedures. Oxygen consumption, carbon dioxide, ventilation and heart rate (HR) were continuously monitored during the test. The training programme consisted of interval and continuous long-distance running (frequency: 3 times a week, duration: 1 h per session, intensity: higher than 80% of maximal HR). V02max significantly increased after the training programme for EG (before = 42.3 +/- 7.7, after = 45.3 +/- 7.5 ml x min(-1) x kg(-1), p < 0.01), while no alterations were noticed for CG (before = 43.1 +/- 6.7, after = 42.6 +/- 7.6 ml x min(-1) x kg(-1), p < 0.01). Such an increase was higher in the girls (+9.1%) than the boys (+4.6%). The lower initial fitness of the girls could explain this, however, because a significant relationship was found between the percentage of VO2max increase after training and the initial VO2max. The present longitudinal study shows that maximal oxygen uptake can increase in prepubertal children after an aerobic training programme and that such an increase is of the same order in boys and girls when the initial aerobic fitness is taken into account.

Anthropometry↗

PubMed2000

The slow component of O2 uptake kinetics during high-intensity exercise in trained and untrained prepubertal children.

The aim of the present study was to investigate the O2 uptake slow component in prepubertal children of different aerobic capacity during high intensity exercise. Twenty-three (12 well-trained, T and 11 untrained, U subjects) 10-13 year old prepubertal children took part in 3 tests: one incremental test to determine the maximal aerobic power (PMA) and anaerobic threshold (LAT); two constant-power tests performed at intensities corresponding to 80%LAT and 90%PMA. Oxygen uptake (VO2), heart rate, ventilation (VE) and lactate ([L]s) were evaluated during each test. A monoexponential + linear term model (starting after phase 1) was used to assess VO2 kinetics during both constant-power tests. Our results showed that a slow component, represented by the linear coefficient (S) of the mathematical model, was present during the 90%PMA test only (S = 0.86 +/- 0.48 ml x min(-2) x kg(-1) for the whole population). No relationships were found between either S and VE or [L]s, showing that, at least in prepubertal children, these factors play a minor role in the explanation for the VO2 slow component. The slow component contributed approximately to the same amount of the total VO2 response in both groups (T: 21.4 +/- 8.0, U: 19.3 +/- 3.9%, ns). In conclusion, as previously described in adults, our data demonstrated the existence of a slow component in prepubertal children during high-intensity exercise. Moreover, this slow component was similar in trained and untrained children, exercising at the same relative intensity.

Adolescent↗

PubMed2000

[Study of the reproducibility of cardiac output measurement during exercise in pre-pubertal children by doppler echocardiography and CO2 inhalation].

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.

Carbon Dioxide↗

PubMed1999

Skull bone mass deficit in prepubertal highly-trained gymnast girls.

It is known that impact loading sport can increase the bone mineral density in the stressed sites of the skeleton in athletes. However, non weight-bearing sites are seldom studied in healthy young girl athletes. In order to study the effects of a long term intensive training on the non-stressed region of the skeleton (skull), we investigated both highly-trained girl athletes, involved in sports requiring or not significant impact loading on the skeleton and a girl control group. Bone mineral content (BMC) and density (BMD) were measured in the whole body, at lumbar spine, femoral neck, trochanter, Ward's triangle, radius, head and ribs, in 60 prepubertal girls including 12 swimmers, 32 gymnasts and 16 controls. Measurements were made by DXA. There were no statistical differences between the groups as regards age, height, body weight, body mass index, lean tissue mass and dietary calcium intake. Mean BMD in gymnasts was statistically higher than in other groups for radius (p < 0.001), femoral neck (p < 0.05) and Ward's triangle (p < 0.05) while there was no difference between swimmers and controls. Head BMC was significantly lower in gymnasts compared to other groups (241.9+/-41 g vs. 285.8+/-34.7 g and 291.1+/-50.2 g respectively in swimmers and controls, p < 0.001). The same observation was made for head BMD (p < 0.01). When body weight was used as a covariant, the contribution of the head BMC to the whole body was significantly lower (p < 0.001) in gymnasts (24.97%) than in swimmers (27.88%) and controls (27.77%). When compared between groups, the slopes of the regressions for head/whole body BMC or BMD were significantly lower in gymnasts (p < 0.05) than in other groups. These data suggest that in prepubertal children the increased bone density induced by gymnastic training in the stressed sites of the body could be related to a decreased skull bone mass.

Bone Density↗

PubMed1999

Bone material acquisition and somatic development in highly trained girl gymnasts.

The present study was conducted to investigate both skeletal and somatic developments in a group of highly trained prepubertal girl gymnasts at the beginning of their peak bone mass acquisition. The experimental group included 14 gymnasts who had trained 12-15 h per wk for 3 y before starting the study. The control group consisted of 15 non-exerciser children and 6 swimmers training for 5-6 h/wk. Body composition and bone mineral density (BMD) of the total body, lumbar spine, non-dominant hip and radius were measured using dual-energy X-ray absorptiometry. Calculation of bone age and measurement of body height and weight were done. All measurements and analyses were carried out twice with a 1-y interval by the same technician. There were no differences between groups in age, bone age, body height and weight and lean tissue mass at the start of the study and 1 y later. The somatic changes observed between the first and second years tended to be greater in gymnasts compared to controls, except for body height. At the first and second investigations, BMD values in the gymnasts were statistically higher than in the controls at all skeletal sites, but not for the whole body (from p < 0.05 to p < 0.001, depending on the site). Percentage changes in BMD pre-investigation compared with post-investigation tended to be greater in gymnasts. Variations in lean mass, bone age and fat mass were found to be the best independent predictors of annual changes in BMD for total body, lumbar spine, trochanter and femoral neck sites. These results suggested that high-volume impact loading training could promote a higher annual gain in bone mineral acquisition at the strained body sites in prepubertal girls without affecting somatic growth dimensions.

Body Height↗