N. Rieth

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.

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

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.

Effects of acute prednisolone administration on exercise endurance and metabolism

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.

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

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.