Biomedical subjects

P Obert

Publications and source records attributed to P Obert.

At least 37 records · Page 2Linked to original sources

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↗

PubMed1998

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.

Bone Density↗

PubMed1998

Effect of long-term intensive endurance training on left ventricular structure and diastolic function in prepubertal children.

In children, the fact that cardiac anatomy and function, particularly during the diastolic phase, can adapt to endurance training is still uncertain. Therefore, this study was undertaken to evaluate the effect of a long-term intensive endurance swimming program on the cardiac structure and function of 10-11 year old children. The population consisted of 9 children who belonged to a local youth swimming team (S) and 11 recruited from a primary school to serve as a control group (C). The swimmers had been training on average 10 to 12 h x wk(-1) for at least 2 years. All the subjects were examined by M-mode, 2-dimensional and pulsed-wave Doppler analyses according to standard procedures recommended by the American Society of Echocardiography. Investigations were carried out at rest with the subjects in a supine position. The results showed that highly trained children exhibited significantly higher left ventricular (LV) internal diameter (S: 41.6+/-1.6, C: 39.0+/-2.2 mm/m(1/3) surface area, p<0.01) and LV mass (S: 68+/-7, C: 59+/-5 g/m2 SA, p<0.01). There were, however, no differences between S and C for chamber wall thickness (posterior wall S: 5.2+/-0.6, C: 5.3+/-0.6 mm/m(1/3) SA; septum S: 5.8+/-0.3, C: 5.8+/-0.4 mm/m(1/3) SA), LV systolic function parameters (ejection fraction S: 77.1+/-0.3, C: 77.7+/-0.4%; shortening fraction S: 38.9+/-3.0, C: 39.7+/-4.1%) and the diastolic function parameters, estimated from LV inflow velocitometry (E wave S: 1.04+/-0.12, C: 1.07+/-0.16 m/s; A wave S: 0.45+/-0.10, C: 0.55+/-0.11 m/s). Finally, transaortic Doppler examinations demonstrated similar resting cardiac output (Qc) between both groups (S: 3.76+/-0.81, C: 3.90+/-0.67 l x min(-1)). However, Qc were obtained with significantly lower heart rates (S: 69+/-7, C: 83+/-14 beat x min(-1), P<0.01) and higher stroke volumes (S: 55.2+/-8.0, C: 47.5+/-8.5 ml, P<0.05) in S when compared to C. Thus, these findings strongly suggest that, as has been shown before in adults, several cardiac adaptations (including resting bradycardia, increased stroke volume and enlarged left ventricular internal dimensions) can occur in prepubertal children as a result of intensive endurance training. However, our results did not demonstrate any effects of such training during prepuberty on both diastolic and systolic functions parameters.

Adaptation, Physiological↗

PubMed1998

Lean tissue mass is a better predictor of bone mineral content and density than body weight in prepubertal girls.

PURPOSE AND METHODS: Body weight is the most extensively studied correlate of bone mass and is widely used as a covariate in statistical evaluations of bone mineral parameters. Lean tissue mass (LTM) also correlates with bone mass. We evaluated the correlations linking each of these two parameters with bone mineral content and bone mineral density in 41 prepubertal girls, including ten swimmers, 18 gymnasts and 13 nonathletes. Lean tissue mass, bone mineral content and bone mineral density were measured using dual-energy X-ray absorptiometry (Hologic QDR-1000/W; Hologic Inc., Waltham, MA, USA). Forward stepwise multiple regression was used to evaluate correlations linking bone mineral content or density (the dependent variables) to body weight or lean tissue mass (the independent variables). RESULTS: Body weight and lean tissue mass showed strong correlations with all bone mineral content and density measurements in the simple linear regression analysis, with lean tissue mass yielding the highest Pearson's correlation coefficients. In the multiple regression model, lean tissue mass consistently explained the largest proportion of the variance, whereas body weight had little influence or was eliminated from the model. The slopes of the regression lines of bone mineral content or density on body weight were significantly steeper in the subgroup of gymnasts (P < 0.001), whereas the slopes of the regression lines of bone mineral content or density on lean tissue mass were significantly less steep in the swimmers (P < 0.05). CONCLUSION: Our data indicate that lean tissue mass is a significant predictor of bone mass in prepubertal girls and explains a larger part of the variance of bone mineral content and density than body weight. Use of body weight as a covariate in studies of bone mineral density may lead to erroneous results in prepubertal girls.

Absorptiometry, Photon↗

PubMed1997

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

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 12 h 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 (R(aw)) 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. R(aw) 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.

Airway Resistance↗

PubMed1996

Effect of long-term intense swimming training on the upper body peak oxygen uptake of prepubertal girls.

The purpose of the present investigation was to determine the effect of a long-term intense swimming programme on the aerobic potential of prepubertal girls. Five girls [GS, aged 9.3 (SD 0.5) years] participated in a 40-month intense training period. The girls trained on average 10-12 h*week(-1), approximately 1 h-1.5 h twice a day, 5 days each week. Nine girls [CG aged 9.3 (SD 0.4) years] who were engaged in various activities (on average 1-4 h*week(-1)), but not in sports involving upper body muscle mass, served as the control group. All the children completed, on a special swim bench, an incremental maximal exercise prior to (pretest) and after (post-test) the swimming programme. Biometric parameters and the peak oxygen uptake (VO(2peak)) were determined using the same procedure at the pre- and post-test sessions. There was no significant difference between the two groups for any of the variables at the beginning of the study. The biometric characteristics remained similar at the post-test session, indicating that intense swimming training early in life has no influence on the physical growth of prepubertal children. The VO(2peak) expressed in absolute values, however, increased over a year in GS and CG by 38 percent and 13 percent, respectively. The improvement in CG VO(2peak) was related to normal growth and development while that of GS was much higher (P<0.01) than would have been expected due to growth factors alone. The reason for such an improvement could be attributed to an increase in the stroke volume and/or in the difference of the arteriovenous concentration of oxygen since the maximal O(2) pulse was different between CG and GS only at the post-test. Moreover, it increased after 10 months only in GS (delta maximal O(2) pulse: GS 1.09, P<0.01; CG 0.27 NS, ml.beat(-1)). Thus, the results of this study show that physiological adaptations can occur in prepubertal children as a consequence of intense physical training.

Child↗

PubMed1996

Effect of altitude and socioeconomic status on VO2max and anaerobic power in prepubertal Bolivian girls.

The aim of this work was to evaluate the effects of high altitude and low socioeconomic status (SES) on aerobic and anaerobic power in 11-yr-old Bolivian girls. At both high (3,600 m) and low (420 m) altitudes, low-SES groups of girls were compared to similarly aged, high-SES girls. At low altitude, low-SES girls were also compared with younger high-SES girls with the same anthropometric characteristics. Anthropometric data were similar between high-SES and low-SES girls at both altitudes, but low-SES girls showed a 9-mo growth delay. Maximal O2 uptake was significantly lower for low-SES girls at both altitudes. Values did not differ when expressed relative to body weight at high altitude for high-SES vs. low-SES girls (37.6 +/- 1.2 vs. 39.3 +/- 1.0 ml.min-1.kg body wt-1), but a difference persisted at low altitude between high- and low-SES girls (37.5 +/- 1.0 vs. 34.7 +/- 0.7 ml.min-1.kg body wt-1). Anaerobic power (Pmax, force-velocity test; Pwing, Wingate test) was reduced for low-SES girls at both altitudes, whatever the mode of expression. For a given SES, the relative anaerobic performances were lower at low altitude. At low altitude, low-SES girls developed lower anaerobic power than did younger high-SES girls with similar anthropometric characteristics. In conclusion, at both altitudes, the reduction of anaerobic performances observed in girls of low SES could not be totally explained by anthropometric factors. Structural and/or functional muscle alterations are suggested. Moreover, at low altitude, tropical and other factors may have contributed to differences in performance between low- and high-SES girls.

Altitude↗

PubMed1994

Evaluation of physical fitness from field tests at high altitude in circumpubertal boys: comparison with laboratory data.

Field tests of running and laboratory tests were performed in La Paz [high altitude (HA), 3700 m] and in Clermont-Ferrand [low altitude (LA), 300 m] to investigate their validity at HA. Prepubertal boys of mean ages 10.6 years (HA1, n = 16; LA1, n = 28) and pubertal boys of 13.7 years (HA2, n = 12; LA2, n = 41) took part in the study. All the boys performed a 30-m sprint (V30m), a 30-s shuttle run (V30s) and a progressive shuttle run test until their maximal aerobic velocity (VmaxSRT). Maximal oxygen consumption was extrapolated from the last test (VO2maxSRT). In the laboratory, the boys performed a force-velocity test (Pmax), a Wingate test (PWing) and a graded test to measure maximal oxygen consumption (VO2maxB; direct method) on a cycle ergometer. At similar ages, there was no significant difference between HA and LA boys for V30m and Pmax. The V30s of HA boys was 3%-4% lower than those of LA boys (P < 0.05); there was no significant difference for PWing. Significant relationships were observed at both altitudes between Pmax (watts per kilogram) and V30m (HA: r = 0.76; LA: r = 0.84) and between PWing and V30s (HA: r = 0.67; LA: r = 0.77); the slopes and the origins were the same at HA and LA. The VO2max, VmasSRT and VO2maxB were lower by 9%, 12% and 20%, respectively, at HA than at LA (P < 0.05). However, the relationships between VO2maxB and VO2maxSRT (litres per minute) at HA (r = 0.88) and at LA (r = 0.93) were identical.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

Anthropometry and lung function of 10- to 12-year-old Bolivian boys.

Anthropometric measurements of 23 HAHSES, 44 HALSES, 43 LAHSES, and 28 LALSES boys (see Introduction to this Supplement) are presented here. They include body height (H), body weight (BW), upper arm circumference (UAC), and skinfold thickness taken at four locations. From these measurements, body fat, lean body mass, and body mass index (BMI = BW/H2) were calculated. The degree of maturation was assessed according to Tanner, orchidometry, and by quantification of testosterone in saliva. Lung function data include: vital capacity (VC), forced expired volume per 1 s (FEV1), functional residual capacity (FRC), residual volume (RV), and total lung capacity (TLC). The results show enhanced lung volumes in both HA groups in comparison to LA groups, with HALSES boys having the greatest increase, even though the LSES boys were significantly smaller compared to the HSES boys at both altitudes and their growth was delayed by approximately 2 years. From the anthropometric data it appears that physical growth of prepubertal boys is dependent on SES but not on high-altitude exposure. We tentatively conclude that chronic hypoxia per se does not affect physical growth in prepubertal boys in an Andean environment and that development of lung function is accelerated in relation to linear growth as has been suggested by other authors (15).

Altitude↗

PubMed1994

Effect of chronic hypoxia and socioeconomic status on the maximal oxygen uptake of 10- to 12-year-old Bolivian boys.

The aim of this study was to analyze the effect of altitude and socioeconomic status on the maximal oxygen uptake (VO2max) of prepubertal Bolivian boys. The subjects were 143 prepubertal boys (10 to 11.5 years old) living in La Paz (altitude 3600 m, n = 67) and Santa Cruz de la Sierra (altitude 420m, n = 76). At high altitude, 23 boys were from a high socioeconomic status (HAHSES) and 44 from a low socioeconomic background (HALSES). At low altitude, 29 boys were from a high socioeconomic level (LAHSES) and 47 from a low socioeconomic background (LALSES). Anthropometric characteristics were determined in order to assess the physical growth of the boys. The VO2max was determined from a progressive maximal exercise (direct method). The subjects performed this test using the same cycle ergometer at both high and low altitudes. For the overall anthropometric parameters, there was no significant difference between highland and lowland boys of the same socioeconomic status. However, regardless of altitude, boys from a low socioeconomic background were 2 years behind those from a high socioeconomic background. There was no significant difference for VO2max between boys from high and low socioeconomic backgrounds at HA (HAHSES: 37.2 +/- 5.6; HALSES: 38.9 +/- 6.4 ml.min-1.kg-1 body weight) and at LA (LAHSES: 42.6 +/- 5.4; LALSES: 43.1 +/- 4.9 ml.min-1.kg-1 body weight). The VO2max of highland boys was, on average, 11% lower than that of lowland boys. It appears, therefore, that a difference in socioeconomic status has no effect on the VO2max (ml.min-1.kg-1) of prepubertal children at low altitude as well as the altitude of 3600m.

Altitude↗

PubMed1993

Effect of chronic hypoxia and socioeconomic status on VO2max and anaerobic power of Bolivian boys.

The aim of this work was to analyze the effects of altitude and socioeconomic and nutritional status on maximal oxygen uptake (VO2max) and anaerobic power (P) in 11-yr-old Bolivian boys. At both high (HA) (3,600 m) and low (LA) (420 m) altitudes, the boys were divided into high (HA1, n = 23, LA1, n = 48) and low (HA2, n = 44, LA2, n = 30) socioeconomic levels. Anthropometric characteristics, VO2max, and P [maximal P (Pmax) during a force-velocity test and mean P (P) during a 30-s Wingate test] were measured. Results showed that 1) anthropometric parameters were not different between HA1 and LA1 and HA2 and LA2 boys, but HA2 and LA2 boys were two years behind HA1 and LA1 boys in development; 2) VO2max was not different in boys from the same altitude, but at HA VO2max was 10% lower than at LA (HA1 = 37.2 +/- 5.6, HA2 = 38.9 +/- 6.4, LA1 = 42.5 +/- 5.8, LA2 = 42.5 +/- 5.3 ml.min-1 x kg-1 body wt); and 3) Pmax and P were higher in well-nourished than in undernourished boys, but there was no difference in Pmax and P between HA1 and LA1 and HA2 and LA2 boys (HA1 = 6.8 +/- 1.0, HA2 = 5.5 +/- 0.8, LA1 = 7.1 +/- 1.0, LA2 = 5.3 +/- 0.9 W/kg for Pmax; HA1 = 5.2 +/- 0.8, HA2 = 4.5 +/- 0.9, LA1 = 5.2 +/- 0.7, LA2 = 4.0 +/- 0.6 W/kg for P).(ABSTRACT TRUNCATED AT 250 WORDS)

Altitude↗

PubMed1992

Bioenergetic characteristics of swimmers determined during an arm-ergometer test and during swimming.

The maximal oxygen uptake (VO2max) of 13 swimmers was determined by an arm-ergometer test (direct method) and estimated from a maximal multistage swimming test (indirect method) (23). A test-retest of the progressive swimming exercise showed that there were no significant differences from one test to the other and that there were significant correlations between the principal parameters: arm stroke index: 0.73, maximal aerobic swimming velocity: 0.94, VO2max: 0.95, p less than 0.01. Therefore, for swimmers of average ability, the reproducibility of this test has been proved. A significant difference (p less than 0.001) was observed between the two tests for VO2max: arm-ergometer test (VO2max arms): 2.4 +/- 0.5 l.min-1, swimming test (VO2max ST): 3.2 +/- 0.7 l.min-1, p less than 0.01. This difference appeared to be linked to the use of a greater muscle mass (arms and legs) during swimming. A significant correlation (r = 0.73, p less than 0.01) was obtained between VO2max (l.min-1) by using both the direct and indirect exercises as methods of measurement. However, the level of r did not permit the prediction of one parameter from the other. Significant correlations were obtained between VO2max and performances over 200 and 400 m free style regardless of the methodology used (VO2max arm, VO2max ST). Moreover, only VO2max (arm, ST) emerged as a variable accounting for swimming performance from a step-wise multiple regression analysis, in which biometric and bioenergetic parameters were taken into account.

Adolescent↗

PubMed1992

Physical fitness of children resident at high altitude in Bolivia.

In 7-15-yr-old children living in La Paz (Bolivia, altitude 3,700 m) (HA): 1) Maximal oxygen consumption (VO2max) varies from 35 to 45 ml.min-1.kg-1 and maximal heart rate from 188 to 194 beats.min-1. These values are lower than those of their counterparts at low altitude (LA) by 10-20% and 10-15 b.min-1, respectively. 2) The anaerobic metabolism is not affected by chronic hypoxia if the nutritional conditions and pubertal development of HA and LA boys are the same. When related to percent of VO2max, submaximal O2 debts are similar at HA and LA. After supramaximal exercise, maximal O2 debts (45.7 +/- 2.7 vs 45.9 +/- 3.8 ml.kg-1) and blood lactate concentrations (7.6 +/- 0.6 vs 6.5 +/- 0.6 mmol.l-1) are also the same at HA and LA. No differences are observed between the 2 altitudes in ventilatory (60 vs 56% VO2max) and lactate (60 vs 65% VO2max) thresholds. The altitude of La Paz does not alter the anaerobic performance of a force-velocity test (from 6 to 10 W.kg-1) between the ages of 7 to 15 years but reduces by 14-17% the mean anaerobic power developed during a 30-s Wingate test. This decrease could be linked to a lower participation of glycolysis and aerobic metabolism at HA during this test. 3) Poor socio-economic and nutritional conditions do not modify the aerobic performance of boys living in La Paz but lead to lower maximal anaerobic power (from -17% to -25%) when compared with HA boys from a high socio-economic background.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗