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Dive into the research topics where N. Rieth is active.

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Featured researches published by N. Rieth.


Hormone Research in Paediatrics | 2007

Preserved Bone Health in Adolescent Elite Rhythmic Gymnasts despite Hypoleptinemia

Daniel Courteix; N. Rieth; Thierry Thomas; E. Van Praagh; Claude-Laurent Benhamou; K. Collomp; Eric Lespessailles; C. Jaffré

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.


British Journal of Sports Medicine | 2007

Short-term glucocorticoid intake combined with intense training on performance and hormonal responses

K. Collomp; A. Arlettaz; Hugues Portier; A.-M. Lecoq; B. Le Panse; N. Rieth; J. De Ceaurriz

Objective: To investigate the effects of short-term prednisolone ingestion combined with intense training on exercise performance, hormonal (adrenocorticotrophic hormone (ACTH), prolactin, luteinising hormone (LH), growth hormone (GH), thyroid-stimulating hormone (TSH), dehydroepiandrosterone (DHEA), testosterone, insulin) and metabolic parameters (blood glucose, lactate, bicarbonate, pH). Methods: Eight male recreational athletes completed four cycling trials at 70–75% peak O2 consumption until exhaustion just before (1) and after (2) either oral placebo or prednisolone (60 mg/day for 1 week) treatment coupled with standardised physical training (2 hours/day), according to a double-blind and randomised protocol. Blood samples were collected at rest, during exercise and passive recovery for the hormonal and metabolic determinations. Results: Time of cycling was not significantly changed after placebo but significantly increased (p<0.05) after prednisolone administration (50.4 (6.2) min for placebo 1, 64.0 (9.1) min for placebo 2, 56.1 (9.1) min for prednisolone 1 and 107.0 (20.7) min for prednisolone 2). There was no significant difference in any measured parameters after the week of training with placebo but a decrease in ACTH, DHEA, PRL, GH, TSH and testosterone was seen with prednisolone treatment during the experiment (p<0.05). No significant change in basal, exercise or recovery LH, insulin, lactate, pH or bicarbonate was found between the two treatment, but blood glucose was significantly higher under prednisolone (p<0.05) at all time points. Conclusion: Short-term glucocorticoid administration induced a marked improvement in endurance performance. Further studies are needed to determine whether these results obtained in recreational male athletes maintaining a rigorous training schedule are gender-dependent and applicable to elite athletes.


British Journal of Sports Medicine | 2008

Effects of acute prednisolone administration on exercise endurance and metabolism

A. Arlettaz; K. Collomp; Hugues Portier; A-M Lecoq; N. Rieth; B. Le Panse; J. De Ceaurriz

Objective: To examine whether acute glucocorticoid (GC) intake alters performance and selected hormonal and metabolic variables during submaximal exercise. Methods: In total, 14 recreational male athletes completed two cycling trials at 70–75% maximum O2 uptake starting 3 h after an ingestion of either a lactose placebo or oral GC (20 mg of prednisolone) and continuing until exhaustion, according to a double-blind randomised protocol. Blood samples were collected at rest, after 10, 20, 30 minutes, and at exhaustion and recovery for measurement of growth hormone (GH), adrenocorticotropic hormone (ACTH), dehydroepiandrosterone (DHEA), prolactin, insulin, blood glucose, lactate and interleukin (IL)-6 determination. Results: Cycling duration was not significantly changed after GC or placebo administration (55.9 (5.2) v 48.8 (2.9) minutes, respectively). A decrease in ACTH and DHEA (p<0.01) was observed with GC during all of the experiments and in IL-6 after exhaustion (p<0.05). No change in basal, exercise or recovery GH, prolactin, insulin or lactate was found between the two treatments but blood glucose was significantly higher with GC (p<0.05) at any time point. Conclusion: From these data, acute systemic GC administration does seem to alter some metabolic markers but did not influence performance during submaximal exercise.


Hormone and Metabolic Research | 2011

Short-term Glucocorticoid Intake and Metabolic Responses During Long-lasting Exercise

R. Thomasson; N. Rieth; L. Jollin; Virgile Amiot; F. Lasne; K. Collomp

The aim of the study was to evaluate the effects of short-term glucocorticoid treatment on plasma amino acids, free fatty acids, blood glucose, and several hormones in healthy volunteers performing long-lasting exercise. 9 young female subjects exercised 2 h at 50-55% VO₂ max twice, once after placebo (Pla) ingestion and once after prednisone (Cor, 50 mg/day/7 days) ingestion, according to a double-blind and randomized protocol. Blood samples were tat rest and during exercise for measurement of amino acids, free fatty acids, blood glucose, adrenocorticotrophic hormone (ACTH), growth hormone, dehydroepiandrosterone (DHEA), insulin, and glucagon. Both ACTH and DHEA values were significantly decreased by Cor vs. Pla (p < 0.01) throughout exercise, and Cor intake also induced lower growth hormone concentrations vs. Pla (p < 0.05) from 60 min to the end of exercise. No significant difference in glucagon, insulin or free fatty acid values was found between the treatments. Branched-chain amino acids and other essential amino acids were significantly higher after Cor vs. Pla from 60 min to the end of exercise (p < 0.05), whereas blood glucose was significantly higher from 90 min to the end of exercise (p < 0.05). We conclude that short-term glucocorticoid intake induces marked hormonal and metabolic changes during long-lasting exercise. Proteolysis can increase with glucocorticoid during this type of exercise and the related higher plasma amino acid concentrations may contribute as energy substrates. Further studies will be necessary to explore and accurately quantify the mechanisms of proteolysis and glyconeogenesis induced by short-term glucocorticoid intake during this type of exercise.


Osteoporosis International | 2009

Effect of antioxidants combined to resistance training on BMD in elderly women: a pilot study

A. Chuin; Mélissa Labonté; Daniel Tessier; Abdelouahed Khalil; Florian Bobeuf; C. Y. Doyon; N. Rieth; Isabelle J. Dionne


Medicine and Science in Sports and Exercise | 2007

Effects of Short-Term Prednisolone Intake during Submaximal Exercise

A. Arlettaz; Hugues Portier; A.-M. Lecoq; N. Rieth; Jacques de Ceaurriz; K. Collomp


European Journal of Applied Physiology | 2009

Effects of short-term corticoid ingestion on food intake and adipokines in healthy recreationally trained men.

N. Rieth; L. Jollin; B. Le Panse; A.-M. Lecoq; A. Arlettaz; J. De Ceaurriz; K. Collomp


European Journal of Applied Physiology | 2009

Short-term glucocorticoid intake improves exercise endurance in healthy recreationally trained women

Bénédicte Le Panse; Rémi Thomasson; Laetitia Jollin; A.-M. Lecoq; Virgile Amiot; N. Rieth; Jacques de Ceaurriz; K. Collomp


Science & Sports | 2004

Évaluation des masses musculaires et des densités osseuses régionales chez des kayakistes de haut niveau

A. Arlettaz; N. Rieth; Daniel Courteix


Science & Sports | 2018

Effet d’une activité physique régulière intradialytique sur le rythme circadien du cortisol chez des patients hémodialysés chroniques

N. Rieth; Mélanie Gallot; Alexandre Ganea; K. Collomp; Nancy Vibarel-Rebot

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K. Collomp

University of Orléans

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A. Arlettaz

University of Orléans

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A.-M. Lecoq

University of Orléans

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B. Le Panse

University of Orléans

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Daniel Courteix

Australian Catholic University

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L. Jollin

University of Orléans

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A. Chuin

University of Orléans

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