Hormonal secretion during nighttime sleep indicating stress of daytime exercise.

We tested the hypothesis that long-duration exercise (LDE) of moderate intensity, but not LDE of low intensity, during the daytime changes the typical temporal patterns of hormone release during subsequent nocturnal sleep. Ten trained healthy men participated in a balanced crossover study including three conditions: 1) no exercise, 2) LDE of low intensity (biking 40 km; 1800-2030), and 3) LDE of moderate intensity (biking 120-150 km; 1600-2030). During the subsequent night (2300-0700), somnopolygraphic sleep recordings were obtained, and concentrations of cortisol, growth hormone (GH), and testosterone were measured every 15 min. During the no exercise nights, the typical secretory patterns were present with peak concentrations of GH but nadir concentrations of cortisol during the first half of sleep but increased cortisol levels and minimum GH levels during the second part of sleep. Testosterone concentrations increased during the second half of sleep. LDE of moderate intensity reduced rapid-eye-movement sleep [13.9 vs. 16.9% (no exercise); P < 0.01]. Levels of testosterone decreased with increasing intensity of daytime exercise (P < 0.05). Moderate-, but not low-intensity, LDE decreased GH levels in the first half (P < 0.05) and increased GH levels in the second half (P < 0.005) of sleep. Also, LDE of moderate intensity but not LDE of low intensity increased cortisol levels during the first half (P < 0.005) and decreased cortisol secretion during the second half (P < 0.05) of sleep. Results suggest that nocturnal profiles of GH and cortisol concentrations may serve to indicate the disturbance of normal anabolic functions of sleep due to daytime exercise.

Examinations on the blood flow dependence of tcPO2 using the model of the "circulatory hyperbola".

The relation of transcutaneous pO2 (tcpO2) and cutaneous blood flow (CBF) was measured on the forearm of 19 healthy volunteers by use of a tcpO2 electrode heated to 45 degrees C. CBF was estimated indirectly from the heating power of the electrode (HP) and with a 8 MHz bidirectional ultrasonic probe by Doppler shift in a fingertip warmed to 45 degrees C (DF). Arterial blood flow was regulated by a cuff on the upper arm. The arterial flow was reduced in 10-15% stages of effective perfusion pressure Peff. There was a decrease in pO2 when CBF was restricted in stages as suggested by the model of the "circulatory hyperbola" according to Lübbers. A linear dependence between Peff, HP and DF was observed. These results indicate, that there is no autoregulation in the hyperemizied capillary bed. During respiration of air mean tcpO2 was 86.0 Torr (+/- 6.2) in normal blood flow conditions and reflects well paO2. Transcutaneous pO2 may also be used as a measure of CBF. To distinguish between these two modes, the determination of paO2 in capillary blood probes is necessary for calculating the transcutaneous index tcpO2/paO2.

Quantitative analysis of reflection spectra of the surface of the guinea pig brain.

For a nearly constant light scattering coefficient a method is presented which allows the quantitative analysis of reflection spectra of the brain using a nonlinear multicomponent analysis ( NLMCA ).

[Chondropathia patellae--study of the femoropatellar joints of healthy, athletic children]. / Chondropathia patellae--Untersuchung der Femoropatellargelenke bei gesunden, sporttreibenden Kindern.

155 children, aged 8 to 13 years, who trained regularly, were examined clinically for signs of chondropathy patellae. As control group, 200 children of the same age were included who did not take part in any sports activities except in school. 32% of the training group children showed signs suggestive of chondropathy. With increasing training age, the part of children with these signs increased from 16% in the first to 45% in the third to fourth training year. Non-training children showed in 17% positive signs of chondropathy.

Sports-specific fitness testing in squash.

Maximum oxygen uptake and the running speed at the anaerobic threshold were determined during treadmill running. Performance in these laboratory tests and performance on a squash-specific field test were compared and examined with respect to subjective ratings of squash fitness. The field test was performed in a squash court. Six light bulbs were connected to a programming device causing individual bulbs to light up in a given sequence. The players were instructed to react to the flashes by running towards and striking balloons mounted in the vicinity of the bulbs. By altering the interval between the lighting of the bulbs the intensity of exercise could be varied. The test consisted of a series of 3 min periods of exercise at increasing intensities (increased number of runs per unit of time). The results showed a low correlation (r = 0.52) between treadmill ergometry data and a rank-order list based on an independent, partly subjective estimate of fitness. A higher correlation (r = 0.90) was found for the results of the field test and the rank-order list. Maximum oxygen uptake values and anaerobic threshold values derived from laboratory measurements were thus not sufficient for a valid estimate of competition fitness in these players. The results show that a valid estimate of fitness can be derived from measurements involving exercise closely resembling that which is specific for the sports activity in question. Improved training advice and guidance may result from such studies.

The examination of multicomponent systems in biological materials by means of a rapid scanning photometer.

Only photometers scanning a large range of wavelengths provide the amount of information which is necessary to analyze multicomponent systems in a general form. After a description of a rapid scanning photometer and a discussion of the recording problems, the mathematical method is described which allows an optimal analysis of the concentrations of the single components of a multicomponent system. The error involved in this procedure is demonstrated by the calculation of the four nucleotides in a mixture. The long range photometry has been successfully applied to other problems such as measurements by reflected light and analyses of inhomogeneously distributed substances in living tissues.

PO2 and microflow histograms of the beating heart in response to changes in arterial pO2.

The influence of different values of arterial oxygen partial pressure (PO2) on local tissue PO2 was investigated. Tissue PO2 was measured on the surface of the beating hearts of rabbit and cat by the multiwire surface electrode as described by Kessler and Lübbers (21). In parallel experiments, local hydrogen clearance applying the H2-PH2 probe (33) was used to determine the mean blood flow per area (microflow) at the capillary level. Mean blood flow per area, v, was calculated from PH2 clearance curves obtained by local application of rectangular hydrogen pulses. The results are presented as histograms. Under steady state conditions (barbiturate narcosis), tissue PO2 ranged from 5 to 65 Torr (0.67 to 8.67 kPA) with a median of 31 Torr (4.13 kPA) in the cat heart. Mean flow per area covered values between 25 and 11 mum/s with a median of 55 mum/s. For rabbit heart muscle, the median was v = 37 mum/s and the range 28 to 46 mum/s. Hyperoxia broadened the range of tissue PO2 and shifted flow per area to lower values. Different degrees of hypoxia shifted the PO2 histogram to the left (median PO2 14 Torr and 4 Torr, respectively; [1.87 kPA and 0.53 kPA]) and the flow histogram to the right.