P. Obert

Effect of physical training on bone mineral density in prepubertal girls: A comparative study between impact-loading and non-impact-loading sports

Physical activity is known to have an anabolic effect on bone tissue. It has been shown to increase the bone mineral density (BMD) in young adults, as well as in teenagers. But there is little information about the effect of intensive physical activity in childhood, particularly at the prepubertal stage. To examine the influence of an early intensive physical training on BMD, we have studied a group of elite prepubertal girls, at the starting phase of their peak bone mass acquisition. Subjects were engaged either in sport requiring significant impact loading on the skeleton, or in sport without impact loading. Forty-one healthy prepubertal girls took part in this study. The sport group consisted of 10 swimmers (10.5±1.4 years old) and 18 gymnasts (10.4±1.3 years old), who had performed 3 years of high-level sport training (8–12 h per week for swimmers, 10–15 h per week for gymnasts). Thirteen girls (10.7±1 years old) doing less than 3 h per week of physical activity served as a control group. BMD measurements were done using dual-energy X-ray absorptiometry. There was no statistical significant difference between groups as regards age, body height and weight, and body composition. There was no statistical significant difference between swimmers and controls for all the BMD measurements. Mean BMD in gymnasts was statistically higher than in the control group for mid-radius (+15.5%,p<0.001), distal radius (+33%,p<0.001), L2–4 vertebrae (+11%,p<0.05), femoral neck (+15%,p<0.001) and Ward’s triangle (+15%,p<0.01). Moreover, in gymnasts, BMD at radius, trochanter and femoral neck was above normative values. We conclude that physical activity in childhood could be an important factor in bone mineral acquisition in prepubertal girls, but only if the sport can induce bone strains during a long-term program: gymnastics has such characteristics, unlike swimming. Such acquisition could provide protection against risks of osteoporosis in later life, but this remains debatable.

Effect of intensive swimming training on lung volumes, airway resistances and on the maximal expiratory flow-volume relationship in prepubertal girls

Abstract The aim of the present study was to analyse the effect of 1 year of intensive swimming training on lung volumes, airway resistance and on the flow-volume relationship in prepubertal girls. Five girls [9.3 (0.5) years old] performing vigorous swimming training for 12u2009h a week were compared with a control group of 11 girls [9.3 (0.5) years old] who participated in various sport activities for 2 h per week. Static lung volumes, maximal expiratory flows (MEF) at 75, 50 and 25% of vital capacity, 1-s forced expiratory volume (FEV1.0) and airway resistance (Raw) were measured by means of conventional body plethysmograph techniques. Prior to the training period there were no significant differences between the two groups for any of the parameters studied. Moreover, for both groups, all parameters were within the normal range for children of the corresponding age. After 1 year of training, vital capacity (VC), total lung capacity (TLC) and functional residual capacity (FRC) were larger (P<0.05) in the girl swimmers than in the control group, while physical development in terms of height and weight was similar. FEV1.0 (P<0.01), MEF25, MEF50 (P<0.05) and MEF75 as well as the ratio MEF50 / TLC (P<0.05) had increased in the girl swimmers but were unchanged in the control group. Raw tended to be lower in the girl swimmers and higher in the control group. The results indicate that intensive swimming training prepuberty enhances static and dynamic lung volumes and improves the conductive properties of both the large and the small airways. As to the causative mechanism, it can be speculated that at prepuberty intensive swimming training promotes isotropic lung growth by harmonizing the development of the airways and of alveolar lung spaces.

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.

Bone mineral 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. □Bone mass, growth, gymnasts, prepubertal training, somatic development

Different modalities of exercise to reduce visceral fat mass and cardiovascular risk in metabolic syndrome: the RESOLVE* randomized trial

BACKGROUNDnOpinions differ over the exercise modalities that best limit cardiovascular risk (CVR) resulting from visceral obesity in individuals with metabolic syndrome (MetS). As little is known about the combined effects of resistance and endurance training at high volumes under sound nutritional conditions, we aimed to analyze the impact of various intensities of physical activity on visceral fat and CVR in individuals with MetS.nnnMETHODSn100 participants, aged 50-70 years, underwent a diet restriction (protein intake 1.2g/kg/day) with a high exercise volume (15-20 h/week). They were randomized to three training groups: moderate-resistance-moderate-endurance (re), high-resistance-moderate-endurance (Re), or moderate-resistance-high-endurance (rE). A one-year at-home follow-up (M12) commenced with a three-week residential program (Day 0 to Day 21). We measured the change in visceral fat and body composition by DXA, MetS parameters, fitness, the Framingham score and carotid-intima-media-thickness.nnnRESULTSn78 participants completed the program. At D21, visceral fat loss was highest in Re (-18%, p<.0001) and higher in rE than re (-12% vs. -7%, p<.0001). Similarly, from M3, visceral fat decreased more in high-intensity-groups to reach a visceral fat loss of -21.5% (Re) and -21.1% (rE)>-13.0% (re) at M12 (p<.001). CVR, MetS parameters and fitness improved in all groups. Visceral fat loss correlated with changes in MetS parameters.nnnCONCLUSIONnIncreased intensity in high volume training is efficient in improving visceral fat loss and carotid-intima-media-thickness, and is realistic in community dwelling, moderately obese individuals. High-intensity-resistance training induced a faster visceral fat loss, and thus the potential of resistance training should not be undervalued (ClinicalTrials.gov number: NCT00917917).

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.

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). VO2max significantly increased after the training programme for EG (before = 42.3 ± 7.7, after = 45.3 ± 7.5 ml.min‐1. kg‐1, p < 0.01), while no alterations were noticed for CG (before = 43.1 ± 6.7, after = 42.6 ±7.6ml.min‐1.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.

Effect of intensive training on heart rate variability in prepubertal swimmers

Backgroundu2002 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.

Impact of a Lifestyle Program on Vascular Insulin Resistance in Metabolic Syndrome Subjects: The RESOLVE Study

CONTEXT AND OBJECTIVEnImpaired insulin-dependent vasodilation might contribute to microvascular dysfunction of metabolic syndrome (MetS). The aims of this study were to assess the insulin vasoreactivity in MetS, and to evaluate the effects of a lifestyle program. DESIGN, SETTING, PARTICIPANTS, AND OUTCOME MEASURES: Laser Doppler measurements were used to assess cutaneous blood flux (CBF) and flowmotion in response to iontophoresis of insulin and acetylcholine (ACh) in 38 MetS and 18 controls. Anthropometric, plasma insulin, glycemia, and inflammatory markers were measured. MetS subjects (n = 24) underwent a 6-month lifestyle intervention (M6) with a 3-week residential program (D21).nnnRESULTSnThe absolute and relative peak insulin and ACh CBF were significantly higher in controls than in MetS subjects. Significant inverse correlations were found between peak insulin CBF and glycemia, insulin and glycated hemoglobin, active plasminogen activator inhibitor-1 (PAI-1), C-reactive protein (CRP), and IL-6. With respect to flowmotion, MetS subjects showed lower values in total spectrum CBF and in all its components (except respiratory one). At D21 and M6, peak insulin CBF increased and was no longer different from control values whereas peak ACh CBF did not change. From D21, all the different components and the total CBF spectrum became similar to the control values. The changes in peak insulin CBF and in endothelial component between M6 and baseline were inversely correlated with the change in CRP and PAI-1.nnnCONCLUSIONSnThe local vasodilatory effects to insulin and its overall flowmotion are impaired in MetS subjects in relation to inflammation. The lifestyle intervention reversed this insulin-induced vascular dysfunction in parallel to decreased inflammation level.

Increased myocardial dysfunction, dyssynchrony, and epicardial fat across the lifespan in healthy males

BackgroundEvaluation of sensitive myocardial mechanics with speckle tracking echocardiography (STE) across the lifespan may reveal early indicators of cardiovascular disease (CVD) risk. Epicardial adipose tissue (EAT) and left ventricular (LV) myocardial dyssynchrony; subclinical risk-factors of CVD, are of particular clinical interest. However, the evolution of EAT and LV-dyssynchrony across the lifespan, and their influence on myocardial dysfunction remains unclear. We aimed to establish a profile of the healthy aging-heart using conventional, tissue-Doppler imaging (TDI) and speckle-tracking echocardiography (STE), while also exploring underlying contributions from EAT and LV-dyssynchrony towards LV myocardial mechanics, independent of blood biology.MethodsHealthy males aged 19–94 years were recruited through University-wide advertisements in Victoria and New-South Wales, Australia. Following strict exclusion criteria, basic clinical and comprehensive echocardiographic profiles (conventional, TDI and STE) were established. LV-dyssynchrony was calculated from the maximum-delay of time-to-peak velocity/strain in the four LV-annulus sites (TDI), and six LV-segments (STE longitudinal and circumferential axes). Epicardial fat diameter was obtained from two-dimensional grey-scale images in the parasternal long-axis. Blood biological measures included glycemia, hsCRP, triglycerides, total cholesterol, high-density and low-density lipoprotein levels.ResultsThree groups of 15 were assigned to young (<40xa0years), middle (40–65 years), and older (>65) aged categories. Five participants were excluded from STE analyses due to inadequate image quality. Decreased longitudinal strain, increased circumferential apical strain and LV twist were age-related. Moreover, independent of blood biology, significant increases were observed across age categories for EAT (young: 2.5 ± 0.9xa0mm, middle: 3.9 ± 1.0xa0mm, older 5.7 ± 2.4xa0mm; p < 0.01), longitudinal STE-dyssynchrony (young: 42 ± 7.7xa0ms, middle: 58.8 ± 18.9xa0ms, older 88.6 ± 18.2xa0ms; p < 0.05), and circumferential-basal STE-dyssynchrony (young: 50.2 ± 20.5xa0ms, middle: 75.9 ± 20.6xa0ms, older 97.9 ± 20.2xa0ms; p < 0.05). These variables collectively explained 37% and 31% (p < 0.01) of longitudinal strain and LV twist, respectively.ConclusionsThis study enabled comprehensive profiling of LV mechanics at different stages of aging using sensitive echocardiographic technology. Novel findings included increased epicardial fat, and both longitudinal and circumferential LV-dyssynchrony across the healthy age groups. These factors may be key underlying contributors to myocardial dysfunction during aging, and their recognition may promote an advanced understanding of early signs of cardiovascular disease.