Difference of catecholamine responses to exercise in men with trisomy 21, with or without chronotropic incompetence.

OBJECTIVE: Our purpose was to analyse if catecholamine responses to exercise would be different in Down syndrome (DS) with or without chronotropic incompetence. RESEARCH DESIGN AND METHODS: Twenty five men with DS (mean age 22.2 ± 3.2) and twenty six controls (CONT, mean age 22.5 ± 1.4) participated in the study, and are divided into 3 groups: CONT, DS with chronotropic incompetence (DS+) and DS without chronotropic incompetence (DS-). During two treadmill incremental tests, blood samples were collected for the determination of hormonal and metabolic variables. RESULTS: Ten out of 25 DS had chronotropic incompetence whereas no CONT. At rest, compared to CONT, despite similar physical activity, DS with chronotropic incompetence had significantly higher subcutaneous fat mass (p<0.001), lower epinephrine concentration (p<0.01), and higher leptin (p<0.01) and insulin concentrations (p<0.05). At peak exercise, all DS had lower heart rate, oxygen uptake and blood lactate concentrations than controls (p<0.001). During a 'Submaximal incremental test', DS with chronotropic incompetence had lower HR and lactate values (p<0.001) compared to CONT and DS without chronotropic incompetence (p<0.01). They also had blunted epinephrine and impaired norepinephrine responses to exercise compared to DS without chronotropic incompetence and CONT (p<0.01 and p<0.05 respectively). CONCLUSIONS: Our results indicate that catecholamine adaptations to exercise are not adequate in DS+ and are associated with exercise intolerance. Thus, this endocrine profile at rest and during exercise may limit endurance performance of DS.

Maximal and submaximal treadmill tests in a young adult with fragile-X syndrome.

Fragile X syndrome is associated with expansion of a CGG triplet repeat in the FMR1 gene, which abolishes production of the FMRP protein. This abnormality is expressed as a number of neuro-endocrine disorders (the adrenal axis, macroorchidism) and the emergence of significant behavioural stress. Here, we report on the hormonal status of a young adult with fragile X syndrome, with a focus on catecholamine and cortisol changes during a submaximal treadmill test. The patient showed abnormally high epinephrine and norepinephrine concentrations. During a submaximal incremental test, cortisol levels were higher than the laboratory reference range. Although the submaximal incremental test has a significant "stressful" effect, this young adult was able to complete the entire protocol without any maladaptive behaviour or withdrawal.

Are hormonal responses to exercise in young men with Down's syndrome related to reduced endurance performance?

The aim of the present study was to analyse whether hormonal responses could explain an exercise limitation in Down's syndrome (DS). Fourteen young men with DS (mean age 22.5 +/- 0.7 years) and 15 controls (CONT, mean age 22.5 +/- 0.3 years) participated in the study. During a treadmill submaximal incremental test, blood samples were collected for determination of hormonal and metabolic variables. Compared to CONT, DS individuals showed lower VO(2max) (P < 0.05), and lower duration of submaximal incremental exercise (P < 0.001). At rest, DS individuals showed greater catecholamines, insulin and leptin values (P < 0.05), but lower testosteronemia and cortisolemia (P < 0.05), compared to CONT. During submaximal incremental tests, catecholamines and cortisol were not increased, whereas the insulin concentration of DS individuals was significantly higher (P < 0.01) compared to CONT. Glycaemia increased significantly at the end of submaximal incremental test for CONT but not for DS individuals (P < 0.01). Maximal fat oxidation was lower (P < 0.01), whereas non-esterified fatty acids concentrations rose significantly during submaximal exercise in DS individuals. These results indicate an altered hormonal response to exercise in DS individuals. This endocrine profile at rest and during exercise may limit endurance performance in DS individuals.

A fatigue questionnaire (QFES) for child athletes: a four-year follow-up study in young skiers.

BACKGROUND: The use of a fatigue monitoring questionnaire is an increasingly widespread practice in sports medicine. OBJECTIVE: To evaluate variations in the QFES fatigue questionnaire score according to periods of rest, training or competition. METHODS: Sixty-six skiers (either alpine or cross-country skiers, aged between 11 and 14 years and training for between 12 and 18 hours per week) filled out a total of 400 fatigue questionnaires over a four-year follow-up period. RESULTS: Our analysis of the QFES fatigue scores showed that only a small proportion of the skiers (5.25%, on average) exceeded the fatigue alert threshold at some point during the longitudinal follow-up; periods of competition correspond to rising fatigue scores, in comparison with the beginning of season and girls always have higher scores than boys (25.32+/-0.90 versus 20.46+/-0.91, respectively; p<0.0002). In contrast, there was no correlation between fatigue levels and the type of skiing discipline practiced. CONCLUSION: Our main results show that the QFES fatigue questionnaire is a sensitive tool for tracking down particular periods of fatigue (competition, intense training). Even though the mechanism of fatigue is still not fully understood (highlighting the complexity of this syndrome), the systematic use of a fatigue questionnaire when monitoring children performing competitive sport and high volumes of training confirms the possible preventive role of this type of tool.

Use of the fatigue questionnaire (QFES) in child athletes for individual follow-up: two cases.

BACKGROUND: Fatigue is one of the multiple components of the life of an athlete. It may have adverse consequences on the health of child athletes in particular in the short or long term. For the trainer or medical staff, detecting fatigue as fast as possible is therefore advisable. OBSERVATIONS: Two young skiers beginning a sports class at age 11 were followed for 3 years within the framework of their practice for sport competition (1 alpine and 1 cross-country skier). At the same time as medical follow-up organized within the sports classes of the school they attended, the children completed at six times a questionnaire about fatigue, the QFES, (in French: Questionnaire de fatigue de l'enfant sportif). At one precise time during this follow-up, the QFES score for each child, both at age 12, clearly increased, by 175% and 133.3%, respectively, from previous scores. A thorough analysis of data gathered by the QFES allowed for revealing particular parameters of the fatigue: decreased sports performance, difficulties in relations and sleep disorders. CONCLUSIONS: Systematic use of the QFES in parallel with medical consultations for children participating in sport may be an efficient tool to detect the early appearance of fatigue and may therefore be integrated in preventive guidance to protect children in sports practice.

[Utilisation of a questionnaire of fatigue in sport children: effect of sport, age and gender]. / Utilisation du questionnaire de fatigue chez de jeunes enfants sportifs: effets de l'activité sportive, de l'âge et du sexe.

In children, fatigue induced by regular sport activity with important training sessions and competitions is still difficult to objective. The purpose of this study was to evaluate the fatigue induced by intensive training, with an auto-questionnaire of fatigue specially elaborated for sport children aged in 8 to 16 year-old, and the incidence of age, sex and the type of sport practiced. A study was conducted on 780 auto-questionnaires (QFES) distributed to 581 children, during 24 months in France (Rhône-Alpes-Auvergne). Results to the QFES are equivalent between sedentary and sport children. For 84.1% of them, no significant sign of fatigue was detected. No age effect has be seen, but girls presented a greater score of fatigue (+5.5%) compared to boys. When considering the specificity of sport, sex difference disappeared. On the contrary, in children with elevated score of fatigue, three domains were principally affected: physical signs, symptoms and motivation. The results obtained in this study assess the relevance of this questionnaire in evaluating sport induced fatigue. Prevention should mainly focus in sport children, in order to reduce potential risks of a sport activity practiced in exhausting conditions.

[Creation and validation of a questionnaire for diagnosing sport fatigue in children]. / Elaboration et validation d'un questionnaire de fatigue chez l'enfant sportif.

Fatigue induced by regular sport activity in children with important training sessions and competitions has not received an important attention from researchers. In this context, we developed an auto-questionnaire of fatigue, especially for athletic children of 8 to 15 years old. We tested this questionnaire for the following psychometric properties: comprehension, construct validity, sensibility and reproducibility. These criteria were evaluated by specific and reliable statistic analysis. Results of this validation were sterling (compliance=98.48%, confidence interval superior to 95%, homogeneity of the analysis by principal components and Cronbach coefficient superior 95%). These first analyses of sport child's fatigue enables us to confirm its feasibility, on the condition of using specific tools, for the clinician or for the professionals involved in sport medicine, and its relevance as an element for evaluating the needs linked with the health of the young sport population.

Clenbuterol treatment affects myosin heavy chain isoforms and MyoD content similarly in intact and regenerated soleus muscles.

AIMS: Pharmacological treatment with the beta2-adrenoceptor agonist clenbuterol is known to induce a slow-to-fast fibre type and myosin heavy chain (MHC) isoform transition in intact muscle. This study examined the sensitivity of regenerated soleus muscle to 4 weeks of clenbuterol treatment (2 mg kg-1 day-1). METHODS: Female Wistar rats were divided into two groups: vehicle treated (n = 8) and clenbuterol treated (n = 8). The clenbuterol effects on MHC and MyoD expression were examined in soleus muscles either intact, or previously degenerated by venom of the Notechis scutatus scutatus snake. RESULTS: Post-treatment body weights and skeletal muscle weights were not affected by clenbuterol treatment. Muscle protein concentration was higher, and body fat lower in clenbuterol-treated rats than in vehicle-treated animals (P < 0.05). Polyacrylamide gel electrophoresis of soleus myofibrillar protein indicated a clenbuterol-induced decrease in the relative percentage of type I MHC with a concomitant increase in type IIa MHC (31%, P < 0.001). No degeneration effect was observed after 28 days of recovery on the MHC isoform content, and regenerated soleus muscles exhibited the same phenotypical profile as intact soleus muscles, whether or not they were treated with clenbuterol. In intact and in regenerated soleus muscles, MyoD protein levels were significantly increased by clenbuterol treatment (90 and 77%, respectively, P < 0.001). CONCLUSION: These results show that regenerated soleus muscles, comprising a homogeneous population of fibres deriving from satellite cells, have a similar response to clenbuterol as intact muscle arising from at least two discrete populations of myotubes; it is suggested that the activity of signalling pathways involved in the effects of clenbuterol on MHC transitions is not related to the developmental history of myofibres.

Urinary profile of androgen metabolites in a population of sportswomen during the menstrual cycle.

The aim of this investigation was to evaluate the urinary profile of androgen metabolites during menstrual cycle in both young-trained female athletes, and young sedentary women, not presenting any pathological signs. Urines were collected for 24 hours (08 : 00 a. m. the first day to 08 : 00 a. m. the second day) from all sportive and sedentary subjects. All steroids were measured by specific radioimmunological analysis, and the implications of these results in terms of concentrations and modifications by exercise will be discussed. During follicular phase, control values were respectively, testosterone glucuronide (TG): 1.67 +/- 0.70 nmol x mmol C -1; epitestosterone glucuronide (ETG): 2.51 +/- 0.88 nmol x mmol C -1; TG/ETG ratio: 0.72 +/- 0.26 and cortisol (FLU): 10.02 +/- 0.79 nmol x mmol C -1. No significant modifications were observed during luteal phase (respectively: TG: 1.48 +/- 0.50 nmol x mmol C -1; ETG: 2.65 +/- 0.93 nmol x mmol C -1; TG/ETG ratio: 0.67 +/- 0.31 and FLU: 9.29 +/- 3.37 nmol x mmol C -1. Similarly, no significant effect of physical training was observed on studied parameters between these two groups during either follicular phase (TG: 1.96 +/- 1.00 nmol x mmol C -1; ETG: 1.97 +/- 0.70 nmol x mmol C -1; TG/ETG ratio: 0.66 +/- 0.05 and FLU: 11.31 +/- 3.73 nmol x mmol C -1) or luteal phase (TG: 1.93 +/- 0.86 nmol x mmol C -1; ETG: 3.19 +/- 1.23 nmol x mmol C -1; TG/ETG ratio: 0.69 +/- 0.33 and FLU: 9.52 +/- 3.86 nmol x mmol C -1). It is concluded that although physical training could play a role in androgen metabolism, it has no significant incidence on urinary TG/ETG ratio. This study thus confirms that sportswomen can also be considered as normal subjects when they do not present any obvious endocrine disorder induced by physical activity.

Effects of hindlimb suspension and androgen treatment on testosterone receptors in rat skeletal muscles.

This study tested the specific and combined effects of testosterone treatment and hindlimb suspension (HS) on the properties of steroid receptors in skeletal muscle. Male rats were either administered weekly high doses of testosterone heptylate (10 mg x kg(-1)) or olive oil placebo, and were either tail-suspended or acted as controls. After 3 weeks of treatment, three muscles were excised from each animal, soleus (SOL), extensor digitorum longus (EDL), and plantaris. The results showed that the testosterone treatment was unable to minimise the HS-induced atrophy of skeletal muscle. As expected, HS altered the fibre-type composition of SOL muscles (-33% of type I, +188% and +161% of type IIa and intermediate fibres respectively, P < 0.01). No overall effect of treatment was detected on the fibre-type composition of either slow or fast-twitch muscles. Binding capacity determined by a radiocompetition technique was increased by HS, especially in SOL and EDL muscles (P < 0.01), while HS or steroid treatment decreased the affinity of the steroid receptors. The combination of HS and testosterone administration resulted in a decrease in binding capacity and affinity of steroid receptors in skeletal muscles. Steroid receptors in fast-twitch muscles exhibited a higher affinity than those in slow-twitch muscles, and it is suggested that it is likely that testosterone treatment is more effective in fast-twitch than in slow-twitch muscles. It was concluded that the lack of preventive effect of testosterone treatment on HS-induced SOL muscle atrophy could be explained by both a decrease in steroid sensitivity and the removal of mechanical factors.

Effect of competition stress on tests used to assess testosterone administration in athletes.

The drug test for exogenous administration of testosterone is based on the testosterone/epitestosterone ratio (T/E) in urine. Physiological and psychological stresses may alter plasma testosterone concentrations. The question is to know how much the psychological conditions of competition can modify the T/E ratio. In order to study this issue, 20 athletes practising modern pentathlon participated in a study designed to determine the effects of a pistol shooting trial on their hormonal response. Pistol shooting induces a high psychological stress without increasing energy expenditure. Venous blood samples were drawn before and after the trial according to the usual drug testing procedure. Athletes were separated into two groups: a group of young athletes (n = 10; mean age 19 +/- 0.3 years) and another group of aged subjects (n = 10; mean age 45 +/- 1.5 years). The rise in plasma testosterone concentrations reached 75% in older subjects versus 55% in younger ones. The plasma luteinizing hormone (LH) concentrations were not influenced by the trial. After shooting trial the elevation in cortisol concentrations was greater for older subjects than for younger ones (273 +/- 30 ng.ml-1 vs 173 +/- 7 ng.ml-1). The catecholamine response was identical in both groups. The urinary T/E ratio remained unchanged after the shooting trial and always remained lower than the International Olympic Committee limit of 6. These results indicate that the psychological stress associated with competition increases the production of steroid hormones (testosterone, cortisol), and that this phenomenon is more pronounced in older athletes. These hormonal changes do not influence the urinary excretion of steroid metabolites used as criterion for drug testing.

Changes in testosterone muscle receptors: effects of an androgen treatment on physically trained rats.

From results obtained in physiological investigations carried out on various tissues sensitive to androgens, it seems that the hormonal receptivity can reflect changes in the endocrine status and specific response of a tissue. The purpose of the present investigation was to test whether an androgen treatment could modify the receptivity to testosterone of the skeletal muscle and myocardium of endurance trained rats. The experiment extended over 8 weeks, and animals received injections of delayed testosterone heptylate every seven days. The myocardium and two skeletal muscles with opposed functions and typology were examined: the extensorum digitorum longus (EDL), and the soleus (SOL). Results obtained using techniques based upon the radio-competition principles provided information on the testosterone-receptor binding. The binding curves were plotted up to the saturating concentration of tritiated mibolerone, a synthetic androgen specific of androgen receptors. The quantity of receptors, calculated at the specific saturation plateau is expressed in fmol/mg protein. Results show that contractile muscular activity always increased the quantity of receptors whereas the steroid treatment decreased it. Thus for EDL and SOL of control trained rats the quantity of receptors was 0.78 and 0.82 fmol/mg protein, respectively, compared to 0.23 and 0.43 fmol/mg protein for sedentary testosterone-treated rats. The same "contractile activity" effect was observed on the myocardium but enhanced with values of 1.63 fmol/mg protein for control trained rats versus 0.30 fmol/mg protein for sedentary testosterone-treated rats. The receptivity to testosterone of the skeletal muscle and myocardium changes under the effect of an androgen treatment.(ABSTRACT TRUNCATED AT 250 WORDS)