E. Van Praagh

Effect of individualized weight‐loss programmes on adiponectin, leptin and resistin levels in obese adolescent boys

Aim:  We investigate the effects of a 2‐month weight‐loss programme on plasma levels of adiponectin, leptin and resistin in obese adolescent boys.

Preserved Bone Health in Adolescent Elite Rhythmic Gymnasts despite Hypoleptinemia

Background/ Aims: Leptin is linked to hormonal disturbances occurring in anorexia and positively linked with bone mineral density. The aim of this study was to determine whether hypoleptinemia occurring in rhythmic gymnasts may affect bone health. Method: Leptin, insulin, cortisol, IGF1 levels and bone markers were determined in 36 rhythmic gymnasts (EG) and 20 controls (C). Body composition, BMD at the whole body (WBBMD), lumbar spine (LSBMD) and bone ultrasound properties (SOS, BUA) were measured. Results: The rhythmic gymnasts had lower fat mass and leptin level than the controls. There was no difference for IGF1, cortisol and insulin levels. Bone turnover rate was higher in elite gymnasts. The uncoupling index showed that remodeling favored the bone formation. LSBMD, WBBMD, SOS and BUA were higher in elite gymnasts after adjustment for fat mass. Leptin correlated positively with fat mass and negatively with physical activity. Conclusion: High impact training is able to counterbalance bone effects usually encountered in hormonally disturbed subjects. Our results suggest that hypoleptinaemia might be related to direct osteogenic effects and indirect hormonal mechanisms including preservation of IGF and cortisol levels.

Enzymatic and hormonal responses following a 24 h endurance run and a 10 h triathlon race

SummaryMuscle cell leakage and hormonal changes were compared immediately after and during the 3 days following a 24 h endurance run (R24 h) in 8 subjects, and a 10 h triathlon non-competitive race (T10 h) in 6 subjects. The study showed three main differences: 1) plasma enzyme increases were considerably more significant in R24 h than in T10 h: compared with resting levels, creatine kinase increased ×120 after R24 h but only ×2 after T10 h; lactic dehydrogenase ×4, as opposed to ×1.5; and transaminases only showed an increase after R24 h. The plasma myoglobin increase after R24 h was double that found after T10 h; 2) for the same magnitude of plasma aldosterone and cortisol after R24 h and T10 h (3 times the resting levels), a highly significant decrease in urinary Na+ (p<0.001) and an increase in urinary K+ (p<0.01) were found only after R24 h; and 3) the plasma free noradrenaline level increased significantly after R24 h (×2.6) whereas it was unchanged after T10 h. In contrast, the plasma level of conjugated dopamine increased only after T10 h (×3.7, p<0.05). These results suggest that long-distance running causes more muscular lesions than the triathlon, and that important factors other than aldosterone are probably involved in the regulation of urinary electrolyte excretions during T10 h.

Two-month effects of individualized exercise training with or without caloric restriction on plasma adipocytokine levels in obese female adolescents

OBJECTIVES To examine if, in young obese patients, an individualized training programme in association with a caloric restriction programme which had an effect on whole-body lipid oxidation, was able to induce changes on plasma adipocytokine concentrations. MATERIALS AND METHODS Twenty-seven obese female adolescents participated in the study. Whole-body lipid oxidation during exercise was assessed by indirect calorimetry during a graded cycle ergometer test. Body mass (BM), body mass index (BMI), percentage of body fat (%BF), insulin homeostasis model assessment (HOMA-IR) and fasting levels of circulating adipocytokines were assessed prior and after a two-month diet programme, individualized training programme targeted at Lipox(max) corresponded to the power at which the highest rate of lipids was oxidized and combined diet/training programme. RESULTS The diet/training programme induced both a shift to a higher-power intensity of Lipox(max) (+27.8 + or - 5.1 W; p<0.01) and an increase of lipid oxidation at Lipox(max) (+96.8 + or - 16.2mg/min; p<0.01). The enhancement in lipid oxidation was significantly (p<0.01) correlated with the diet/training-induced improvement in %BF (r = -0.47), HOMA-IR (r = -0.66), leptin (r = -0.41), TNF-alpha (r = -0.48), IL-6 (r = -0.38), adiponectin (r = 0.43) and resistin (r = 0.51). CONCLUSION This study showed that in obese female adolescents a moderate training protocol targeted at Lipox(max) and combined with a diet programme improved their ability to oxidize lipids during exercise, and that this improvement was associated with changes in plasma adipocytokine concentrations.

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

AbstractField 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 (v3os) and a progressive shuttle run test until their maximal aerobic velocity (vmaxsRT). Maximal oxygen consumption was extrapolated from the last test.

Leg cycling tracking by dynamic vision

\left( {\dot VO_{2maxSRT} } \right)

Anaerobic cycling performance characteristics in prepubescent, adolescent and young adult females.

. In the laboratory, the boys performed a force-velocity test (Pmax), a Wingate test (PWing) and a graded test to measure maximal oxygen consumption