An imbalance between the overall strain experienced during exercise training and the athlete's tolerance of such effort may induce overreaching or overtraining syndrome. Overtraining syndrome is characterised by diminished sport-specific physical performance, accelerated fatiguability and subjective symptoms of stress. Overtraining is feared by athletes yet there is a lack of objective parameters suitable for its diagnosis and prevention. In addition to the determination of substrates (e.g. lactate, ammonia and urea) and enzymes (e.g. creatine kinase), the possibilities for monitoring of training by measuring hormonal levels in blood are currently being investigated. Endogenous hormones are essential for physiological reactions and adaptations during physical work and influence the recovery phase after exercise by modulating anabolic and catabolic processes. Testosterone and cortisol are playing a significant role in metabolism of protein as well as carbohydrate metabolism. Both are competitive agonists at the receptor level of muscular cells. The testosterone/cortisol ratio is used as an indication of the anabolic/catabolic balance. This ratio decreases in relation to the intensity and duration of physical exercise, as well as during periods of intense training or repetitive competition, and can be reversed by regenerative measures. Correlations have been noted with the training-induced changes of strength. However, it seems more likely that the testosterone/cortisol ratio indicates the actual physiological strain in training, rather than overtraining syndrome. The sympatho-adrenergic system might be involved in the pathogenesis of overtraining. Overtraining appears as a disturbed autonomic regulation, which in its parasympathicotonic form shows a diminished maximal secretion of catecholamines, combined with an impaired full mobilisation of anaerobic lactic reserves. This is supposed to lead to decreased maximal blood lactate levels and maximal performance. Free plasma adrenaline (epinephrine) and noradrenaline (norepinephrine) may provide additional information for the monitoring of endurance training. While prolonged aerobic exercise conducted at intensities below the individual anaerobic threshold lead to a moderate rise of sympathetic activity, workloads exceeding this threshold are characterised by a disproportionate increase in the levels of catecholamines. In addition, psychological stress during competitive events is characterised by a higher catecholamines to lactate ratio in comparison with training exercise sessions. Thus, the frequency of training sessions with higher anaerobic lactic demands or of competition, should be carefully limited in order to prevent overtraining syndrome. In the state of overtraining syndrome and overreaching, respectively, an intraindividually decreased maximum rise of pituitary hormones (corticotrophin, growth hormone), cortisol and insulin has been found after a standardised exhaustive exercise test performed with an intensity of 10% above the individual anaerobic threshold.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Hormones as Markers of Training Stress and Overtraining

levies a financial burden on those who fear and experience bone fractures. Physical activity as a way to prevent osteoporosis is based on evidence that it can regulate bone maintenance and stimulate bone formation including the accumula

Physical activity in the prevention and amelioration of osteoporosis in women : interaction of mechanical, hormonal and dietary factors.

A model for systematic changes in patterns of inter-individual variation in affective responses to physical activity of varying intensities is presented, as a conceptual alternative to the search for a global dose – response curve. It is theorized that trends towards universality will emerge in response to activities that are either generally adaptive, such as moderate walking, or generally maladaptive, such as strenuous running that requires anaerobic metabolism and precludes the maintenance of a physiological steady state. At the former intensity the dominant response will be pleasure, whereas at the latter intensity the dominant response will be displeasure. In contrast, affective responses will be highly variable, involving pleasure or displeasure, when the intensity of physical activity approximates the transition from aerobic to anaerobic metabolism, since activity performed at this intensity entails a trade-off between benefits and risks. Preliminary evidence in support of this model is presented, ...

Variation and homogeneity in affective responses to physical activity of varying intensities: An alternative perspective on dose – response based on evolutionary considerations

A focus on low body weight and body fat content, combined with regulations in some weight-sensitive sports, are considered risk factors for extreme dieting, eating disorders (EDs) and related health consequences among athletes. At present there are, from a health perspective, no generally accepted optimum values for body weight or percentage of fat mass in different sports and there is no ‘gold standard’ method for body composition assessment in athletes. On the basis of health considerations as well as performance, medical support teams should know how to approach elite athletes who seek to achieve an unrealistic body composition and how to prevent restrictive eating practices from developing into an ED. In addition, these teams must know when to raise the alarm and how to advice athletes who are affected by extreme dieting or clinical EDs. However, there is no consensus on when athletes struggling with extreme dieting or EDs should be referred for specialist medical treatment or removed from competition. Based on the present review, we conclude that there is a need for (1) sport-specific and gender-specific preventive programmes, (2) criteria for raising alarm and ‘does not start’ (DNS) for athletes with EDs and (3) modifications to the regulations in some sports. Further, the key areas for research identified include the development of standard methods for body composition assessment in elite athletes; screening measures for EDs among athletes; development and testing of prevention programmes; investigating the short and long-term effects of extreme dieting; and EDs on health and performance.

https://bjsm.bmj.com/content/bjsports/47/16/1012.full.pdf

How to minimise the health risks to athletes who compete in weight-sensitive sports review and position statement on behalf of the Ad Hoc Research Working Group on Body Composition, Health and Performance, under the auspices of the IOC Medical Commission

Professional road cycling is an extreme endurance sport. Approximately 30 000 to 35 000km are cycled each year in training and competition and some races, such as the Tour de France last 21 days (∼100 hours of competition) during which professional cyclists (PC) must cover >3500km. In some phases of such a demanding sport, on the other hand, exercise intensity is surprisingly high, since PC must complete prolonged periods of exercise (i.e. time trials, high mountain ascents) at high percentages (∼90%) of maximal oxygen uptake (VO2max) [above the anaerobic threshold (AT)]. Although numerous studies have analysed the physiological responses of elite, amateur level road cyclists during the last 2 decades, their findings might not be directly extrapolated to professional cycling. Several studies have recently shown that PC exhibit some remarkable physiological responses and adaptations such as: an efficient respiratory system (i.e. lack of ‘tachypnoeic shift’ at high exercise intensities); a considerable reliance on fat metabolism even at high power outputs; or several neuromuscular adaptations (i.e. a great resistance to fatigue of slow motor units). This article extensively reviews the different responses and adaptations (cardiopulmonary system, metabolism, neuromuscular factors or endocrine system) to this sport. A special emphasis is placed on the evaluation of performance both in the laboratory (i.e. the controversial Conconi test, distinction between climbing and time trial ability, etc.) and during actual competitions such as the Tour de France.

Physiology of Professional Road Cycling

Eleven high mileage runners (HR) (108.0 +/- 4.5 km.wk-1), 9 moderate mileage runners (MR) (54.2 +/- 3.7 km.wk-1) and 10 sedentary controls (SC) of similar age (28.3 +/- 1.5 yr) were studied to evaluate the effects of volume of endurance training on reproductive function in male runners. Levels of reproductive, adrenal and thyroid hormones were measured during a 1-hr period of serial blood sampling (q20 min) and urinary excretion of 24-hr luteinizing hormone (uLH) was determined on two separate days. Semen exams and sperm penetration of standard cervical mucus (Penetrak) were performed 2-5 times. Levels of total testosterone (TT) and free testosterone (FT) were significantly lower in HR (15.3 +/- 1.3 nmol.l-1 and 60.2 +/- 5.1 pmol.l-1) compared to MR (21.4 +/- 1.6 nmol.l-1 and 86.0 +/- 6.1 pmol.l-1) and SC (19.5 +/- 0.9 nmol.l-1 and 75.9 +/- 3.6 pmol.l-1). No differences (p > 0.05) were found in uLH, serum LH, follicle-stimulating hormone (FSH), and prolactin (PRL) among the three groups. No other hormonal differences (p > 0.05) were observed among the groups. Total motile sperm count and density were lower (p < 0.05) in HR than SC. Decreased (p < 0.0006) sperm motility and an increased (p < 0.004) population of immature sperm and round cells were observed in HR compared to MR and SC. Sperm penetration of bovine cervical mucus was also decreased (p < 0.024) in HR compared to SC. Volume of training, defined by km.wk-1 run, was significantly correlated to sperm motility, density and number of round cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Gonadal hormones and semen quality in male runners : a volume threshold effect of endurance training

To investigate mechanisms of blunted adrenocortical responsiveness to exercise and mild hypercortisolism in amenorrheic runners, adrenocorticotropic hormone [ACTH-(1–24) 0.25 mg Cortrosyn] stimulat...

Clinical tests explain blunted cortisol responsiveness but not mild hypercortisolism in amenorrheic runners

Study Objective: To investigate the effects of two forms of exercise, endurance training (running) and resistance training (weight lifting), on reproductive function in male athletes. Design: Cross-sectional study. Setting: Reproductive Endocrinology and Exercise Laboratory. Subjects: Twenty-eight healthy male volunteers, 18 to 35 years of age, including 10 endurancetrained runners, 8 resistance-trained weight-lifters, and 10 sedentary controls. Main Outcome Measure(s): Hormonal evaluation included determination of plasma levels of total testosterone (T), serum levels of free T, luteinizing hormone (LH), follicle-stimulating hormone, prolactin, and estradiol, and urinary excretion of LH

M. J. De Souza

Papers

Gonadal hormones and semen quality in male runners : a volume threshold effect of endurance training

Clinical tests explain blunted cortisol responsiveness but not mild hypercortisolism in amenorrheic runners

Subclinical alterations in hormone and semen profile in athletes