Biomedical subjects

M Bedu

Publications and source records attributed to M Bedu.

At least 37 records · Page 2Linked to original sources

PubMed2000

Testing peak cycling performance: effects of braking force during growth.

The purpose of this study was to investigate the relationship between cycling peak power (CPP; flywheel inertia included) and the applied braking force (F(B)) on a friction-loaded cycle ergometer in male children, adolescents, and adults. A total of 520 male subjects aged 8-20 yr performed three brief maximal sprints against three F(B): 0.245, 0.491, and 0.736 N x kg(-1) body mass (BM) (corresponding applied loads: 25 [F(B)25], 50 [F(B)50], and 75 [F(B)75] g x kg(-1) BM). For each F(B), peak power (PP) was measured (PP25, PP50 and PP75). For each subject, the highest PP was defined as CPP. Results showed that PP was dependent on F(B). In young adults PP25 underestimated CPP by more than 10%, and consequently, F(B)25 seemed to be too low for this population. However, in children, PP75 underestimated CPP by about 20%. A F(B) of 0.736 N x kg(-1) BM was definitively too high for the pediatric population. Therefore, the optimal F(B), even corrected for BM, was lower in children than in adults. The influence of growth and maturation on the force-generating capacity of the leg muscles may explain this difference. In this study, however, it was shown that the difference between PP50 and CPP was independent of age for the whole population investigated. Consequently, when flywheel inertia is included, one cycling sprint with a F(B) of 0.495 N x kg(-1) BM (corresponding applied load: 50 g x kg(-1) BM) is a feasible method for testing both children, adolescents, or young adults.

Adolescent↗

PubMed1999

Prediction of hypoxemia and mechanical ventilation after lung resection for cancer.

BACKGROUND: Hypoxemia usually occurs after thoracotomy, and respiratory failure represents a major complication. METHODS: To define predictive factors of postoperative hypoxemia and mechanical ventilation (MV), we prospectively studied 48 patients who had undergone lung resection. Preoperative data included, age, lung volume, force expiratory volume in one second (FEV1), predictive postoperative FEV1 (FEV1ppo), blood gases, diffusing capacity, and number of resected subsegments. RESULTS: On postoperative day 1 or 2, hypoxemia was assessed by measurement of PaO2 and alveolar-arterial oxygen tension difference (A-aDO2) in 35 nonventilated patients breathing room air. The other patients (5 lobectomies, 9 pneumonectomies) required MV for pulmonary or nonpulmonary complications. Using simple and multiple regression analysis, the best predictors of postoperative hypoxemia were FEV1ppo (r = 0.74, p < 0.001) in lobectomy and tidal volume (r = 0.67, p < 0.01) in pneumonectomy. Using discriminant analysis, FEV1ppo in lobectomy and tidal volume in pneumonectomy were also considered as the best predictive factors of MV for pulmonary complications. CONCLUSIONS: These results suggest that the degree of chronic obstructive pulmonary disease in lobectomy and impairment of preoperative breathing pattern in pneumonectomy are the main factors of respiratory failure after lung resection.

Adult↗

PubMed1999

Increased resting energy expenditure is related to plasma TNF-alpha concentration in stable COPD patients.

UNLABELLED: The objective of this study was to test whether increased resting energy expenditure (REE) in chronic obstructive pulmonary disease (COPD) patients is related to increased cost of breathing and/or to increased cytokine production. In 36 non-inflammatory (CRP: 17.6 +/- 13.1 mg.l(-1), mean +/- SD; orosomucoid: 0.71 +/- 0.18 g.l(-1)), non-malnourished (BMI: 23.6 +/- 4.3 kg.m(-2)), clinically stable, non severely hypoxic COPD patients (60.5 +/- 8.9 years) we measured REE, pulmonary function and plasma cytokine concentrations (TNF-alpha, IL1 and IL6). REE was increased by 10 +/- 11% (P< 0.001) above predicted values. Plasma TNF-alpha concentration was increased in all patients (mean value 26.3 +/- 14.3 pg.ml(-1)). Excess REE (with respect to values predicted by Harris-Benedict equations) was correlated with plasma TNF-alpha concentration (P< 0.005), but not with the degree of airway obstruction, lung overinflation, or with oxygen cost of breathing. Theophylline treatment resulted in a significant increase in REE by 15%. IN CONCLUSION: non-malnourished, clinically stable, non-severely hypoxic COPD patients display an increased REE that is related with plasma TNF-alpha concentration (without apparent systemic inflammation) and to theophylline treatment, but that is independent of parameters of respiratory function.

Basal Metabolism↗

PubMed1999

Effect of recovery duration on muscular power and blood lactate during the bench press exercise.

In order to assess the effect of recovery on power and blood lactate, 10 males performed 10 sets (S1 to S10) of 6 repetitions of bench press at 70% of their maximal strength, with 1 (Prot1), 3 (Prot3) or 5 (Prot5) min rest between sets. From the measurements of force and displacement of the bar, mean power during each repetition (MPR) and set (MPS), were calculated. Blood lactate was evaluated before and immediately after each set. No significant variations in power or blood lactate occurred during prot3 and prot5. From S4 to S10, significantly lower MPS (27% decrease) and higher blood lactate (7.6 +/- 2.0 mmol/l) were demonstrated in prot1 vs prot3 or prot5. In spite of this, MPR in protl were significantly lower for repetitions 4, 5 and 6 only: MPR of repetitions 1, 2 and 3 were similar in the 3 protocols. During prot1 only, power decrease was related to lactate accumulation for all subjects (0.64 < or = r < or = 0.99, p < or = 0.05). These results indicate that although muscular power and blood lactate were both affected by the recovery interval, acidosis was not the direct cause of fatigue during the 1 min rest condition. The concomitant effects of lactate accumulation and insufficient time for a complete resynthesis may have resulted in a diminution of PCr stores, leading to power decrements.

Acidosis, Lactic↗

PubMed1998

Effect of recovery duration on the force-velocity relationship.

The aim of this study was to investigate the effect of different Recovery Duration (RD) between each sprint (30 s, 1 min, 3 min, 5 min, 10 min and 24 h) during the force-velocity test and to analyse associated anaerobic parameters such as maximal anaerobic power and blood lactate concentrations. Twelve male physical education students aged from 18 to 26 years took part in this study. Maximal anaerobic power (Pmax) was not statistically different whatever the recovery duration (from 885 to 938 watts, for RD 30 s to RD 24 h, respectively). This was associated with a tendency during the longer RD tests for optimal velocity to decrease (p = ns) while optimal force increased (p < 0.05). Blood lactate concentrations were regularly increased from 1.7 to a 9 mmol x l(-1) plateau at sprint 4 for RD tests < 10 min and were quite stable from the second sprint with an associated value from 2.2 to 4.7 mmol x l(-1) for RD 10 min and RD 24 h. In spite of statistically different values for [L]s between the tests, the power developed for each sprint remained unchanged. These data indicate that the attainment of maximal power seems independent from the recovery duration (> 10 s) and the pre-blood lactate values observed between each sprint during the force-velocity test. The way to reach Pmax was different between the tests. Different partition of energetic pathways are suggested. In conclusion, the force-velocity test could be performed with a shorter and the arbitrary five minutes recovery duration.

Adolescent↗

PubMed1997

A 5-min running field test as a measurement of maximal aerobic velocity.

Based on a theoretical approach from world record running data, we have previously calculated that the most suitable duration for measuring maximal aerobic velocity (Vamax) by a field test was 5 min (Vamax(5)). The aim of this study was, therefore, to check this hypothesis on 48 men of various levels of physical fitness by comparing (Vmax(5)) with (Vamax) determined at the last step of a progressive treadmill exercise test when the subject felt exhausted (Vamax(t)) and during a test on a running track, behind a cyclist (following an established protocol) (Vamax(c)). For each test, (VO2max) was also measured by a direct method on a treadmill (VO2max(1)) and calculated by an equation for field tests (VO2max(5) and VO2max(c)). The Vamax(5) [17.1 (SD 2.2) km.h-1] and (Vamax(c)) [(18.2 (SD 2.4) km.h-1] were significantly higher than (Vamax(t)) [16.9 (SD 2.6) km.h-1; P < 0.001]. The (Vamax(t)) was strongly correlated with (Vamax(5)) (r = 0.94) and (Vamax(c)) (r = 0.95) (P < 0.001). The best identity and correlation between (Vamax(5)) and track performances were found in the runners (n = 9) with experience over a distance of 3,000 m. The VO2max(5) and (VO2max(c)) were higher than VO2max(t) (+ 5.0% and + 13.7%, respectively; P < 0.001) and VO2max(t) was highly correlated with Vamax(5) (r = 0.90; P < 0.001). These results suggest that the 5-min field test, easy to apply, provided precise information on Vamax and to a lesser degree on VO2max.

Adolescent↗

PubMed1997

Serum insulin-like growth factor I and physical performance in prepubertal Bolivian girls of a high and low socio-economic status.

The aim of the study was to determine if a decrease in serum insulin-like growth factor I (Igf-I) levels under marginal malnutrition is responsible for the lower physical performance of girls of a low socio-economic status (LSES). Girls were selected after physical examination (Tanner's stage 1) and anthropometric measurements (height, body mass or mb, body mass index or BMI = mb height2). Lean body mass mb,1 was measured after skinfold thickness determination; serum IGE-I, by radioimmunoassay; maximal O2 consumption, (VO2max), directly during incremental exercise up to exhaustion; and maximal aerobic power (Wmax), using the force-velocity test. LSES girls (n = 31) had been malnourished in the past and, currently, were suffering from marginal malnutrition: they were smaller (135.2 +/- 5.5 vs 146.1 +/- 4.3 cm), lighter (31.7 +/- 3.9 vs 37.6 +/- 5.0 kg), exhibited a lower mb,1 (24.2 +/- 2.5 vs 27.5 +/- 3.0 kg) but same BMI compared with HSES (high socio-economic status) girls (n = 32). Igf-I levels (27.7 +/- 7.9 vs 34.1 +/- 6.5 nmol.1(-1), VO2max (45.26 +/- 4.72 vs 50.74 +/- 6.02 ml. min-1.kg-1 LBM) and Wmax (6.00 +/- 1.15 vs 8.70 +/- 1.53 W.kg-1 mb,1 were lower in LSES girls. Moreover, the differences in every parameter were not the consequence of the younger age (10.8 +/- 0.9 vs 11.2 +/- 0.6 years) of the LSES girls. Our results provide evidence that the lower Wmax of undernourished prepubertal girls was partly the consequence of alterations in muscle function at the qualitative level, as a result of a decrease in Igf-I levels. Conversely, under normal nutritional conditions, anthropometric characteristics only are explicatory factors for physical performances.

Bolivia↗

PubMed1997

Maximal aerobic velocity measured by the 5-min running field test on two different fitness level groups.

The aim of the study was to verify the validity and the accuracy of the 5-min running field test (5RFT) relatively to the classical treadmill test. Two groups of subjects were tested, the first one being made of sub-elite runners (G1, n = 18) and the second one of athletes of other individual or collective disciplines (G2, n = 23). To check the field technique, maximal aerobic velocity (vamax) and an approached VO2max calculated from vamax during the 5RFT were compared with the corresponding values directly determined during a treadmill test. vamax obtained on treadmill (vamax(t)) or during a 5RFT (vamax(5)) were significantly higher in G1 than in G2 (+3.7 km.h-1 and +3.6 km.h-1 among the test). In each group, the difference between vamax(t) and vamax(5) was not significant (19.4 +/- 1.0 vs 19.5 +/- 0.9 km.h-1 in G1; 15.7 +/- 2.2 vs 15.9 +/- 1.2 km.h-1 in G2). A significant correlation was found between vamax(t) and vamax(5) (slope = 0.92; r = 0.86 in G1; slope = 0.71; r = 0.84 in G2). In each group, the approached VO2max(5) was significantly higher than VO2max(t) (respectively 67.8 +/- 2.9 vs 63.7 +/- 3.5 in G1; 54.8 +/- 3.9 vs 52.0 +/- 3.2 ml.min-1.kg-1 in G2. Weak but significant correlations were found between VO2(t) and vamax(5) (r = 0.69 and r = 0.56 respectively in G1 and G2). In conclusion, the 5RFT allows to measure vamax accurately whatever the physical fitness of the subjects but more closely in runners than in non-runners. The low correlation between VO2max(t) and vamax(5) for both groups indicates that a vamax running field test is specific and cannot evaluate VO2max with reasonable accuracy whatever the group, runners or non-runners.

Adult↗

PubMed1996

Effect of anthropometric characteristics and socio-economic status on physical performances of pre-pubertal children living in Bolivia at low altitude.

We have previously observed that 11-year-old children of low socio-economic status (LSES) showed a delayed physical growth of approximately 2 years and developed lower normalized short-term power output than children of high socio-economic status (HSES) of the same age. In contrast, maximal oxygen uptake (VO2max) per unit of fat free mass was no different in either group. The aim of this study was to evaluate the effect of anthropometric characteristics between HSES and LSES prepubertal children in aerobic and anaerobic performance. To compare children of the same body dimensions, 11-year-old boys (n = 30) and girls (n = 31) of LSES and 9-year-old boys (n = 21) and girls (n = 27) of HSES were studied. Anthropometric measurements, VO2max (direct test), maximal anaerobic power (Pmax, force-velocity test) and mean anaerobic power (P, Wingate test) were determined. In these children having the same body dimensions: mean VO2max were the same in LSES and HSES children [1.2 (SD 0.2) l.min-1]; Pmax and P were lower in LSES subjects [154.0 (SD 33.2) vs 174.6 (SD 38.4) W and 116.3 (SD 23.3) vs 128.2 (SD 28.0) W, respectively]; the linear relationships between VO2max and fat free mass were the same in LSES and HSES boys but, in the girls, the LSES group had lower values. For anaerobic performance, the relationships were significantly different: the slopes were the same but LSES values for the both sexes were lower. These results would suggest that factors other than differences in body dimensions alone were responsible for the lower performance of LSES girls and boys. Cultural factors and motor learning, structural and functional alterations of muscle induced by marginal malnutrition have been discussed.

Altitude↗

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↗

PubMed1996

Heart rate recording method validated by whole body indirect calorimetry in 10-yr-old children.

The aim of the study was to validate the heart rate (HR) recording method against whole body indirect calorimetry in prepubertal children. Nineteen 10.5-yr-old healthy children (10 boys, 9 girls) participated in this study. HR and energy expenditure (EE) were recorded through laboratory tests. Individual relationships between HR and EE were computed (equation established in laboratory). Several models were tested and validated from 24-h measurements of EE and HR by whole body indirect calorimetry. The best fit was obtained with individual polynomial relationships. Mean differences between predicted (equation established in laboratory) and measured total daily EE averaged 7.6 +/- 20.1%. The causes of the differences and the means of improving the accuracy of the prediction equation are discussed.

Calorimetry, Indirect↗

PubMed1996

Interaction between cold and hypoxia on pulmonary circulation in COPD.

This study was designed to investigate the interaction of mild and localized cold exposure and hypoxia on pulmonary hemodynamics in chronic obstructive pulmonary disease (COPD). Nineteen patients with COPD were studied at sea level and seven at an altitude of 2,640 m. For all patients, pulmonary hemodynamic measurements were performed 10 min after insertion of a catheter in a femoral vein and following 10 min of cold exposure. Cold exposure was restricted to the forehead, and subjects breathed air at ambient temperature. Flow and temperature of air (1.5 L.s(-1), 5 degrees C) to the forehead were chosen to cool down the forehead skin to approximately 20 degrees C without discomfort for the subject. For the seven patients studied at high altitude, the same measurements were also performed after 5 min of oxygen supplementation with and without cold exposure. At sea level, an increase in pulmonary vascular resistance (PVR) during cold exposure was inversely related to the initial PaO2. In six severe hypoxic subjects (PaO2 < 50 mm Hg), PVR increased by 24%. At high altitude, PVR was significantly increased by 15%. After O2 supplementation, cold exposure did not induce an increase in PVR. We concluded that mild and localized cold exposure to the forehead only induced an increase in PVR in COPD patients with severe hypoxia. Moreover, in cold exposure responders, O2 supplementation negated the effect of cold exposure on pulmonary hemodynamics.

Cold Temperature↗

PubMed1995

Vasomotor effects of transcutaneous CO2 in stage II peripheral occlusive arterial disease.

Vasomotor effects of skin exposure to carbon dioxide (CO2) have been described in normal subjects. It was of interest, therefore, to determine whether percutaneous CO2 is of therapeutic benefit. In a randomized, double-blind study, 10 patients with lower limb arteriopathy (stage II) were investigated before and after local exposure for twenty minutes to CO2-rich spa gas or to water-vapor-saturated air at the same temperature as that CO2-rich spa gas. Brachial and femoral blood flows, brachial and posterior tibial artery pressures, heart rate, and chest and foot transcutaneous oxygen tensions (tcPO2) were determined. Femoral blood flow, tibial pressure, and foot tcPO2 were significantly increased after exposure of the skin to CO2-rich spa gas. This effect was not accompanied with systemic hemodynamic modifications. Water-vapor-saturated air had no effect. These results suggest that transfer of CO2 across the skin can have beneficial local vasomotor effects in patients with lower limb stage II arteriopathy.

Administration, Cutaneous↗

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

The effect of acute hypoxia at low altitude and acute normoxia at high altitude on performance during a 30-s Wingate test in children.

The effect of acute hypoxia (FIO2 = 0.137 +/- 0.001) at Low Altitude (LA: Clermont-Ferrand, 330 m) and acute normoxia (FIO2 = 0.306 +/- 0.006) at High Altitude (HA: La Paz, 3600 m) on performance during a 30-s Wingate test has been investigated in prepubertal children (Tanner stage 1). Twenty five boys (LA, n = 10; HA, n = 15) aged from 10.6 to 12.7 years performed two Wingate tests at random: at LA, one in normoxia (ambient air) and one in acute hypoxia and at HA, one in chronic hypoxia (ambient air) and one in acute normoxia. The subjects performed the two tests using the same calibrated cycle ergometer. Peak Power (PP), Mean Power (MP), O2 uptake during the 30 s (VO2) and blood lactate accumulation (delta [L]s) were measured. Compared to normoxia, acute hypoxia at LA did not alter PP (8.0 +/- 1.1 vs 7.9 +/- 1.3 W.kg-1 BW) and MP (6.1 +/- 0.7 vs 6.1 +/- 1.1 W.kg-1 BW). Similarly, compared to chronic hypoxia, acute normoxia at HA did not modify these parameters (PP: 7.4 +/- 1.5 vs 7.3 +/- 1.8; MP: 5.4 +/- 1.2 vs 5.5 +/- 1.1; W.kg-1 BW). VO2 and delta [L]s were neither significantly changed by acute hypoxia at LA (520 +/- 50 vs 550 +/- 60 ml O2; 5.3 +/- 1.7 vs 4.8 +/- 1.7 mmol.l-1) nor by acute normoxia at HA (530 +/- 110 vs 500 +/- 90 ml O2; 3.4 +/- 1.3 vs 3.3 +/- 1.0 mmol.l-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMed1994

Effect of chronic hypoxia and socioeconomic status on anaerobic power of 10- to 12-year-old Bolivian boys.

The aim of this study was to analyze the effect of chronic high altitude hypoxia and socioeconomic status on the anaerobic power, developed during short-term maximal exercises, of prepubertal Bolivian boys. We studied 67 prepubertal boys (9-12.6 years) at high altitude in La Paz (3600 m, Bolivia); 23 were from a high socioeconomic background (HAHSES) and 44 from a low socioeconomic background (HALSES). The group studied at low altitude in Santa Cruz de la Sierra (420 m, Bolivia) consisted of 78 boys of the same age; 30 were from a high (LAHSES) and 48 from a low (LALSES) socioeconomic background. Maximal anaerobic power (Pmax) was determined by a force-velocity test and mean anaerobic power (P) was measured by a 30-s Wingate test. The tests were realized at high and low altitude on the same calibrated cycle ergometer. At both high and low altitudes, Pmax expressed in absolute terms or relative to body weight were significantly higher in boys of high socioeconomic status (HAHSES: 6.8 +/- 1.0; LAHSES: 7.1 +/- 1.0 W.kg-1 BW) than in boys of low socioeconomic status (HALSES: 5.5 +/- 0.8; LALSES: 5.3 +/- 0.9 W.kg-1 BW). However, there was no significant difference between highland and lowland boys of the same socioeconomic class. The same observations were obtained for P (HAHSES: 5.2 +/- 0.8; HALSES: 4.5 +/- 0.9; LAHSES: 5.2 +/- 0.7; LALSES: 4 +/- 0.6 W.kg-1 BW). To conclude, boys of the same socioeconomic class at high and low altitude had the same anaerobic power. However, regardless of altitude, low socioeconomic status led to lower power developed during short-term maximal exercises.

Altitude↗

PubMed1993

Analysis of performance of prepubertal swimmers assessed from anthropometric and bio-energetic characteristics.

The relationship between anthropometric and bio-energetic data and timed performance over 50 to 400 m was studied in 25 young male swimmers [11.3 (SD 1) years]. Anthropometric measurements included height, body mass, body fat mass, body area, thoracic section area (Ats) thoracic circumferences, lengths of upper limb, bi-acromial and bi-iliac diameters. Maximal oxygen consumption (VO2max; direct method), maximal anaerobic power (W(an),max; force-velocity test) and mean power in 30 s sprint (W30 s; Wingate test) were also measured. Each of these bio-energetic variables was expressed in absolute terms, relating to body mass, body area and Ats. The stepwise regression method was used to determine contribution of the variables (anthropometric and/or bio-energetic) of the time achieved over the distance. The W30 s/Ats accounted for 46% of the time over 50 m (negative correlation). The VO2max/Ats and height were negatively correlated with the times of performances over 100 m, 200 m and 400 m, these two variables accounted for 71% to 77% of the performance. These results would indicate that even in young boys, anthropometric and bio-energetic characteristics are both important in swimming performance, particularly the bio-energetic variables expressed per Ats.

Body Composition↗

PubMed1993

Bioenergetic characteristics in prepubertal swimmers. Comparison with active and non-active boys.

The effects of physical activity (PA) on bioenergetic characteristics were studied in 53 prepubertal boys. Maximal oxygen consumption (VO2max; direct method), maximal anaerobic power (Pmax, force-velocity test), and mean power in 30 s (P30s, Wingate test) were compared (mean +/- SD) in three groups of boys of the same age (11 years): swimmers (Sw, n = 26, PA = 8 +/- 3 hrs/week), active boys (A, n = 16, PA = 7 +/- 2 hrs/week) and non-active boys (C, n = 11, PA = 3 +/- 2 hrs/week). No significant difference appeared between groups for VO2max (Sw, 50.7 +/- 5.4; A, 50.8 +/- 6.0; C, 49.4 +/- 7.0; ml.min-1 x kg-1), Pmax (Sw, 8.1 +/- 1.4; A, 8.4 +/- 1.4; C, 8.1 +/- 1.4; W.kg-1) and P30s (SW, 5.8 +/- 1.0 A, 6.3 +/- 1.7; C, 5.0 +/- 1.1; W.kg-1). Significant relationships (p < 0.01) existed between Pmax, P30s (W.kg-1) and VO2max (ml.min-1 x kg-1): r = 0.37 and r = 0.40, respectively. This indicates that there is neither aerobic nor anaerobic specialization during prepubertal development, and that regular sporting activity induces no great changes in the bioenergetic characteristics of prepubertal boys.

Child↗