Holger Gabriel

BLOOD HORMONES AS MARKERS OF TRAINING STRESS AND OVERTRAINING

SummaryAn 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. This disturbed stress-response corresponds to findings with insulin-induced hypoglycaemia in overtraining suggesting an impaired hypothalamic regulation.However, the role of hormones in the recovery phase and their effect on the receptor and intracellular level remain to be better established. Reference values indicating a ‘normal’ exercise tolerance as well as easier and less expensive laboratory methods are still lacking. External factors influencing the hormonal blood levels require well-standardised sampling conditions which are often difficult to realise in the training environment. The impaired exercise-induced maximal increase of selected hormones and the potential consideration of the psychological stress component by hormonal measurements, however, represent interesting basic findings which encourage future investigations.

Impaired pituitary hormonal response to exhaustive exercise in overtrained endurance athletes.

The aim of the present prospective longitudinal study was to investigate the hormonal response in overtrained athletes at rest and during exercise consisting of a short-term exhaustive endurance test on a cycle ergometer at an intensity 10% above the individual anaerobic threshold. Over a period of 19+/-1 months, 17 male endurance athletes (cyclists and triathletes; age 23.4+/-1.6 yr; VO2max. 61.2+/-1.8 mL x min(-1) x kg(-1); means+/-SEM) were examined five times on two separate days under standardized conditions. Short-term overtraining states (OT, N=15) were primarily induced by an increase of frequency of high-intensive bouts of exercise or competitions without increase of the total amount of training. OT was compared with normal training states intraindividually (NS, N=62). During OT, the time to exhaustion of the exercise test was significantly decreased by 27% on average. At rest and during exercise, the concentrations in plasma and the nocturnal excretion in urine of free epinephrine and norepinephrine were not significantly changed during OT. At physical rest, the concentrations of (free) testosterone, cortisol, luteinizing hormone, follicle-stimulating hormone, adrenocorticotropic hormone, growth hormone, and insulin during OT were comparable with those during NS. A significantly (P < 0.025) lower maximal exercise-induced increase of the adrenocorticotropic hormone and growth hormone, as well as a trend for a decrease of cortisol (P=0.060) and insulin (P=0.036), was measured. The response of free catecholamines as well as the ergometric performance of an all-out 30-s test was unchanged. Serum urea, uric acid, ferritin, and activity of creatine kinase showed no differences between conditions. In conclusion, the results confirm the hypothesis of a hypothalamo-pituitary dysregulation during OT expressed by an impaired response of pituitary hormones to exhaustive short-endurance exercise.

Is determination of exercise intensities as percentages of VO2max or HRmax adequate

UNLABELLED Often exercise intensities are defined as percentages of maximal oxygen uptake (VO2max) or heart rate (HRmax). PURPOSE The purpose of this investigation was to test the applicability of these criteria in comparison with the individual anaerobic threshold. METHODS One progressive cycling test to exhaustion (initial stage 100 W, increment 50 W every 3 min) was analyzed in a group of 36 male cyclists and triathletes (24.9 +/- 5.5 yr; 71.6 +/- 5.7 kg; VO2max: 62.2 +/- 5.0 mL x min(-1) x kg(-1); individual anaerobic threshold = IAT: 3.64 +/- 0.41 W x kg(-1); HRmax: 188 +/- 8 min). Power output and lactate concentrations for 60 and 75% of VO2max as well as for 70 and 85% of HRmax were related to the IAT. RESULTS There was no significant difference between the mean value of IAT (261 +/- 34 W, 2.92 +/- 0.65 mmol x L(-1)), 75% of VO2max (257 +/- 24 W, 2.84 +/-0.92 mmol x L(-1)), and 85% of HRmax (259 +/- 30 W, 2.98 +/- 0.87 mmol L(-1)). However, the percentages of the IAT ranged between 86 and 118% for 75% VO2max and 87 and 116% for 85% HRmax (corresponding lactate concentrations: 1.41-4.57 mmol x L(-1) and 1.25-4.93 mmol x L(-1), respectively). The mean values at 60% of VO2max (198 +/- 19 W, 1.55 +/- 0.67 mmol x L(-1)) and 70% of HRmax (180 +/- 27 W, 1.45 +/- 0.57 mmol x L(-1)) differed significantly (P < 0.0001) from the IAT and represented a wide range of intensities (66-91% and 53-85% of the IAT, 0.70-3.16 and 0.70-2.91 mmol x L(-1), respectively). CONCLUSIONS In a moderately to highly endurance-trained group, the percentages of VO2max and HRmax vary considerably in relation to the IAT. As most physiological responses to exercise are intensity dependent, reliance on these parameters alone without considering the IAT is not sufficient.

Physical training increases isometric muscular strength and proprioceptive performance in haemophilic subjects.

Summary. Sufficient muscular strength and proprioception lessen the risk of joint damage, however, both are impaired in haemophilic subjects. The aim of the study was to investigate proprioceptive performance and isometric muscular strength before and after a specialized training in haemophilic subjects (H) compared with two groups of control subjects (C). Nine subjects with severe haemophilia A, and eight ‘active’ C (AC) without haemophilia took part in a physical training programme over a 6‐month period. Eleven ‘passive’ C (PC) were requested to avoid any additional training during this period. Proprioceptive performance and isometric strength were determined before and after the training programme. The maximal isometric muscular strength in the legs, bilaterally measured by knee extensor (and leg press) was increased (P < 0.05) by 34% (29%) after training in the H and by 20% (28%) in the AC groups while remaining unchanged in the PC group. The performance in one‐leg‐stand tests after training was increased (P < 0.05) in the H and AC groups. An improvement of angle reproduction of 20° and 40° (P < 0.05) in the H compared with the PC groups was seen in the tests. Quantitative sensory testing by the tuning fork showed an increase (P < 0.05) in performance of both H and AC groups. The results of the present study confirm that specific sports therapy focused on proprioceptive function and accompanied by gentle strength training with low resistance and 20–25 repetitions is able to increase proprioceptive performance and muscular strength with a minimal stress to the joints. It is strongly recommended that specialized sports therapy be included as an integral component of the complete treatment regimen of haemophilic subjects.

Anaerobic exercise induces moderate acute phase response.

PURPOSE It was intended to compare the immune reaction after single and repeated short bouts of anaerobic exercise. METHODS Twelve unspecifically trained male subjects (27 +/- 2 yr, 75 +/- 2 kg, VO(2peak) 52 +/- 2 mL x min(-1) x kg(-1)) performed one 60-s all-out test (SMT) on a cycling ergometer and the same test followed by eight 10-s all-out tests every 5 min (AN-TS). These tests and one control day (Co-Day) were applied in randomized order. At rest and 15 min, 2 h, and 24 h after cessation of exercise the following venous blood parameters were determined: concentration of neutrophils and (CD16(+ -)) premacrophages (both flow-cytometrically), interleukin 6 and 8 (IL-6, IL-8), C-reactive protein (CRP) and cortisol. RESULTS Two hours after cessation of exercise the neutrophils increased stronger after AN-TS than after SMT (P < 0.01). The peak in the number of premacrophages occurred earlier after SMT (15 min post; P < 0.01 to Co-Day) than after AN-TS (2 h post; P < 0.05 to Co-Day). IL-6 was elevated at 15 min and 2 h after AN-TS (P < 0.01 to SMT and Co-Day) but only slightly 2 h after SMT (P < 0.01 to Co-Day). There were no significant changes in IL-8. CRP was the only elevated parameter 24 h postexercise exclusively after AN-TS (P < 0.05 to Co-Day). CONCLUSIONS Repeated short anaerobic bouts of cycling lead to an acute phase response, which is more pronounced than after a single bout. Athletes should take care in performing such training sessions several times a week because signs of inflammation are detectable even 24 h after cessation of exercise.

Proprioception and isometric muscular strength in haemophilic subjects.

Haemophilia is characterized by intra‐articular bleeding, often requiring immobilization, which may result in muscle atrophy and impaired proprioception. The aim of the study was to investigate differences in proprioceptive performance and isometric muscular strength of the lower limbs in haemophilic subjects compared with control subjects. Twelve subjects with severe haemophilia (11 haemophilia A; one haemophilia B) vs. 12 control subjects were matched for anthropometric data and tested for differences of proprioception (one‐leg‐stand, posturomed, angle‐reproduction, and tuning fork tests) and isometric strength (leg press, knee extensor). The static proprioceptive performance of the haemophilic group, as measured by the one‐leg‐stand test (on hard or soft ground, with open or closed eyes; P < 0.05) was demonstrably impaired (by 41–363%). In contrast, the dynamic proprioceptive perfomance measured by the posturomed test did not show any difference between the groups. The local proprioceptive performance (angle‐reproduction test) of the knee, (the most commonly affected joint in haemophiliacs) showed a trend to impaired function but was not distinctly different from that of controls. The quantitative sensory function (tuning fork) showed significant (P < 0.05) impairment of 9–10% in the haemophilic subjects. Additionally, the isometric muscular strength of the leg extensor was weaker (32–38%) in the haemophilic group when the limbs were tested individually as well as bilaterally (P < 0.05). In conclusion, the results suggest that global proprioceptive performance is impaired and that the isometric strength of the leg extensors is weaker in the haemophilic subjects. Therefore, specialized training for global proprioception would be helpful in order to compensate for proprioceptive deficits. This exercise regimen should also include safe strength‐training for an optimal stabilization of the joints, but must be adapted to the individual needs and situations of the haemophilic subjects.

Circulating leucocyte and lymphocyte subpopulations before and after intensive endurance exercise to exhaustion

SummarySeventeen healthy cyclists [age 20.8 (SD 4.8) years; body mass 68.3 (SD 7.7) kg; body fat, 11.4 (SD 2.6) %; height, 179.1 (SD 5.9) cm;

Differential mobilization of leucocyte and lymphocyte subpopulations into the circulation during endurance exercise

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