Analyzing the impact of increased physical loads on the microcirculation and mechanical-acoustic properties of human limb skin

The conclusion about a higher reserve potential of capillary bloodstream and variability of the acoustic properties of integumentary limb tissues in athletes is made based on studying the microcirculatory and anisotropic mechanical—acoustic properties of the limb skin in male athletes of high qualification (track-and-field athletes and wrestlers of the Greco-Roman style) at the age of 19–25 years and nonathletes at the age of 17–25 years. The revealed phenomena are based on the adaptive responses of the support-motor system to regular increased physical loads. A growth in capillary blood flow in the shank skin during a functional ischemic test is revealed to be higher in track-and-field athletes in comparison with the indicators in nonathletes. The reserve index of the capillary blood flow is 66.2% exceeded. The speed of propagation of a surface acoustic wave (SSAW) in the shank skin surpassed the corresponding SSAW parameters in the femoral integumentary tissue in the group of athletes and in the subjects of the control group. A similar excess of the SSAW index is observed in the forearm skin with respect to the shoulder parameters. The plastic reserves of the skin during change in the spatial position of a limb are revealed, which indicates the dynamic character of its viscoelastic properties during making movements. The mechanisms of the observed phenomena are supposed to be based on the structural distinctions of the skin and intensity of the capillary blood flow.     

Reaction of the gastric glands in wrestlers aged 7–32 years to threshold-power bicycle ergometer exercise

Problems of quick adaptation of the gastric glands of wrestlers to threshold-power bicycle ergometer exercise during sports and postsports ontogeny are discussed. It has been established that threshold-power bicycle ergometer exercise may suppress, stimulate, or not affect the secretion of H₂O, HCl, and pepsinogen. The pattern of these shifts is aimed at optimizing the actual level of protein hydrolysis; it depends on the age, sports experience, and qualification and is correlated with the body weight.     

Postural stability during static strain before and after submaximal aerobic bycycle test in athletes

The aim of study was to investigate static balance control in wrestlers (n = 31) and effects of fatigue on postural regulation in two position: bipedal stance and squat position with open eyes prior to and 2 min after bicycle PWC(170) test. A force platform ("Ritm". Russia) was used to determine static balance control. We found a minimum difference in postural control between wrestlers and controls prior to exercise in bipedal stance. In squat position linear and angular (all p < 0.001) sway velocity of centre of pressure were lower in wrestlers and were negatively correlated to PWC(170) index (r = 0.454 and r = 455, p < 0.001 with linear and angular sway velocities respectively) indicating that 20% dispersion of sway velocities in static strain position may be determined to physical working capacity. After PWC(170) test all parameters of sway were increased in both groups both in bipedal stance (p < 0.01) and squat position (p < 0.001) indicating an important role of muscular fatigue in the decrease of postural stability in both groups. Linear velocity after PWC(170) in bipedal stance increased to an equal extent in both groups but the increases of velocities of sway of centre of pressure in squat position were lower in athletes (ANOVA, p = 0.037 for linear and p = 0.008 for angular sway velocities respectively) and were negatively correlated to an extent of recovery of heart rate after PWC(170) indicating some contribution (6.5-14.2% of dispersion of linear and angular sway velocities) of an recovery rate to maintenance of a high level of postural stability in an static strain position in wrestlers during physical fatigue.     

Variations in circulating levels of prolactin and growth hormone during physical exercise in man: influence of the intensity of the workout

In trained subjects, circulating PRL and GH increase significantly after a 20 minutes exercise on ergometer bicycle performed either at submaximal or maximal intensity. The magnitude of PRL response appeared to be similar for both kinds of exercise, but the increase in GH level is higher after maximal exercise than after submaximal one.     

The effects of endurance training and thiamine supplementation on anti-fatigue during exercise

The purpose of this study was to find the effect of endurance training and thiamine supplementation on anti-fatigue during the exercise. Each nine students from K Women’s University went through three cross-over treatments: placebo treatment, training treatment and thiamine treatment. Training treatment was performed with bicycle ergometer exercise for four weeks (five days per week). Each exercise was performed for an hour with intensity set at 70% (50rpm) of maximal oxygen uptake. Thiamine treatment group was given 10mg of thiamine tetrahydrofurfuryl disulfide per one kilogram for four weeks. The bicycle ergometer exercise was performed at 70% of maximal oxygen uptake in exercise intensity which 60 minutes of exercise was performed at 50rpm . Lactate concentration was significantly decreased during 15 to 30 minutes of exercise for those with training treatment and 15 to 60 minutes of exercise for those with thiamine treatment compared to placebo treatment group. Ammonia concentration was significantly decreased during 15 to 60 minutes of exercise and 15 to 30 minutes of recovery for those with training and thiamine treatment compared to placebo treatment. Resting blood thiamine concentrations of placebo treatment were significantly lower than training treatment. 60 minutes after the exercise, plasma thiamine concentration was significantly increased in all treatment group. To sum up the previous, thiamine intake during exercise positively benefits carbohydrate metabolism in a way that will decrease lactate concentration, ammonia concentration, and anti- fatigue by reducing the RPE. Therefore, we can consider thiamine intake to be utilized as similar benefits as endurance training.     

Cerebral hemodynamics response to low intensity physical exercise

The aim of this research was to study the cerebral hemodynamics reaction to step increase of physical exercises intensity during bicycle ergometer test in young healthy male subjects. Hemodynamics parameters were registered with the transcranial Doppler ultrasonography of middle cerebral artery (MCA) prior to the study and during the last seconds of every step of physical exercise. Cerebral hemodynamics response to physical exercise was characterized by a significant increase of peak systolic blood velocity in the MCA up to 0.25 W/kg of the body weight (90 rpm with regard to 0 W/kg) without further increase of blood velocity in the same physical exercise becoming more intensive up to 0.5 W/kg of the body weight. The stabilization mechanism of blood velocity in cerebral arteries in case of physical exercise increase and, hence, the autoregulation mechanism of cerebral circulation means that the increase of regional cerebral vascular resistance depends on the value of arterial pressure. The autoregulation mechanism of cerebral circulation starts working with he exercise intensity of 0.25 W/kg and the value of systolic blood pressure about 140-145 mm Hg.     

Cerebral hemodynamic reaction to physical exercise of moderate intensity

The aim of this research was to study the cerebral hemodynamic reaction to stepped increase of physical exercises during the bicycle ergometer test in 12 young healthy male patients. The starting value of exercise was 0.25 W/kg of the body weight, with the 0.25 W/kg increase at every subsequent step up to the value of 1.75 W/kg of the body weight. Hemodynamic parameters were registered with the Doppler ultrasonography of middle cerebral artery before the study, during the last 10 seconds of every step, and during the 3 minutes of restorative period with a 1-minute interval. The peak systolic blood flow increase in the middle cerebral artery was observed only as the result of low intensity exercises (0.25 W/kg of the body weight). The blood pressure (BP) restoration occurred by the end of the third minute of the rest, while the cerebral hemodynamic indices became normal during the first minute. The research revealed a correlation between increases of vascular resistance caused by physical exercises and the BP, and no correlation between increases of peak systolic blood flow and BP, which displays the phenomenon of cerebral circulation autoregulation.     

Effect of Fenfluramine on Human Growth Hormone Release

In order to investigate the effect of fenfluramine on hormonal and metabolic changes with exercise, five normal volunteers have been studied during and after 20 minutes of steady exercise on a bicycle ergometer after injection of fenfluramine (20 mg intravenously). Fenfluramine abolished the rise of plasma human growth hormone (HGH) which occurred in control investigations. Fenfluramine also affected plasma insulin, blood glucose, and ketone body levels.The acute effect of fenfluramine on the release of growth hormone was examined further by studying its effect in patients with acromegaly. A marked depression of growth hormone occurred both at rest and with exercise. These observations indicate that fenfluramine has a direct effect on pathways controlling growth hormone release. We also suggest that this action may have practical use in the medical treatment of acromegaly.     

Age and sex dependence of hemodynamic parameters of human internal carotid arteries

The study of the ultrasound diameter, linear velocity, and resistance of the internal carotid arteries in 647 subjects of both sexes aged from 1 to 74 years has been performed. Additionally, shear stress and the Reynolds number have been calculated. During the period from early childhood to adolescence and from the first mature to younger elderly ages, there is an increase in the diameter of the internal carotid arteries. Phases of an increase in the vascular resistance by the first period of childhood, adolescence, and younger elderly age are observed. The space flow velocity has relatively stable parameters till youth, and then it declines by younger elderly age. The average linear velocity, shear stress, and the Reynolds number progressively diminish twice by younger elderly age. Laminar blood flow with local twists in the early stages of postnatal ontogenesis is characteristic of the internal carotid arteries. The diameter of the internal carotid arteries, vascular resistance index, and blood flow velocity are higher in men than in women during most age periods. Shear stress in both internal carotid arteries during all the age periods studied is symmetrical and has no sex differences.     

The durations of the phases and periods of the cardiac cycle in athletes as dependent on the specific type of training

Polycardiography was used to analyze cardiac cycle phases in young track athletes during a two-year training cycle. The subjects were examined in the state of relative muscular rest and during moderate bicycle ergometer exercise. It was found that track training leads to a decrease in the heart rate and regulatory myocardial hypodynamic syndrome. Adaptive rearrangements in myocardial contractility were observed; they depended on the age of athletes and the type of training during the training macrocycle. The performance of the test with a moderate intensity was accompanied by a hyperdynamic syndrome, the degree of its manifestation depending on the age of the subject and the exercise intensity.     

A comparison of the oxygen consumption/body weight relationship obtained during submaximal exercise on a bicycle ergometer and on a treadmill.

It is widely accepted that the relationship between oxygen consumption and body weight obtained during exercise on a bicycle ergometer differs from that obtained during treadmill walking. Experimental evidence to support this claim is lacking. To examine this difference a group of subjects (body weight 41--81 kg) undertook a predetermined level of submaximal exercise on a bicycle ergometer and a treadmill. Oxygen consumption was measured in a steady state at rest (i.e. sitting on the bicycle ergometer and standing on the treadmill) and during the two modes of exercise. A significant positive correlation between oxygen consumption and body weight was obtained under all four conditions of measurement. At rest the two regression lines did not differ in slope or elevation. During exercise the slope and the elevation of the line obtain from treadmill walking were significantly greater than from bicycle ergometer exercise. The 'metabolic cost' of bicycle ergometer exercise, (Vo2 during exercise--V02 at rest), showed no significant correlation with body weight. In contrast, there was a significant positive correlation during walking. It is suggested that these differences have arisen due to a different proportion of the total body weight supported by the subject in the two forms of exercise.     

Leg exercise conditioning increases peak forearm blood flow.

To examine whether forearm vascular adaptations could occur after upright-leg exercise training, the reactive hyperemic blood flow after 10 min of forearm circulatory arrest (RHBF10) was studied. RHBF10 was examined in seven subjects before, at 2 wk, and after the completion of 4 wk of bicycle ergometer training. Maximal O2 consumption (VO2max) for leg ergometer work increased 13% (P less than 0.05) over 4 wk. Over that period of time RHBF10 in the forearm increased 50% (P less than 0.05), with a reciprocal drop in minimum vascular resistance. Resting heart rate decreased 15% (P less than 0.05) during the same period. Changes in RHBF10 and VO2max were noted after 2 wk of training. Mean arterial pressure did not change. We conclude that vascular adaptations can occur in the forearm muscle beds, even though the training regimen is designed to condition the lower extremities.     

Changes in prolactin and testosterone levels induced by acute physical exertion in young female athletes

In order to establish the influence of acute atypical exercise on prolactin and testosterone levels in young female athletes the authors selected a group of 13 short distance runners who were subjected to exercise on a cycle ergometer. Hormone levels were measured before the test, just after the end of test, 30 and 90 minutes thereafter. Significant increase in testosterone concentration appeared immediately after the exercise and 90 minutes after completion of a test testosterone level returned to preexercise levels. Unlike the results of other authors statistically significant decrease in plasma prolactin concentration was found 90 minutes after the end of test.     

Plasma levels of renin, angiotensin II, and 6-ketoprostaglandin F1 alpha in endurance athletes

Twelve male runners and 12 matched nonathletes performed a prolonged uninterrupted graded exercise test on the bicycle ergometer up to exhaustion to study blood pressure and plasma levels of renin (PRA), vasoconstrictor angiotensin II (ANG II), and 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha), a metabolite of the vasodilator prostacyclin. In the athletes work load was increased by 30 W/4 min, and in the control subjects the increments of work load were adjusted to their lower exercise capacity to equalize total exercise duration. Blood was drawn, and blood pressure and O2 uptake (VO2) were measured at rest and at the fourth, eighth, and last steps of exercise. Peak VO2 averaged 60 +/- 1.6 ml . min-1 . kg-1 in the runners and 46.8 +/- 1.5 in the nonathletes. To evaluate differences between athletes and controls, PRA, ANG II, and 6-keto-PGF1 alpha were first adjusted for significant confounding factors, such as age, weight, hematocrit, 24-h urinary sodium excretion, and O2 uptake. PRA was significantly lower in the athletes (F = 11.2; P less than 0.01); ANG II was not different at rest, but its rise with exercise was less steep in the runners (F = 8.2; P less than 0.01), whereas 6-keto-PGF1 alpha was not different between the groups (F = 1.3; NS). Despite the differences in PRA and ANG II, however, blood pressure was similar in athletes and nonathletes (F = 0.0; NS).     

The effect of one-legged sprint training on intramuscular pH and nonbicarbonate buffering capacity

To determine the effect of one-legged sprint training on muscle pH and nonbicarbonate buffering capacity (BC), 9 subjects completed 15 to 20 intervals at 90 RPM, 4 days a week for 7 weeks on a bicycle ergometer adapted for one-legged pedaling. Needle biopsies from the vastus lateralis and blood samples from an antecubital vein were taken at rest and twice during recovery (1 and 4 minutes) from a 60 s one-legged maximal power test on a cycle ergometer. pH one minute after exercise in both the trained and untrained legs following the training period was not different but both were higher than before training. BC increased from 49.9 to 57.8 mumol HCl x g-1 x pH-1 after training (p less than 0.05). Blood lactate levels after exercise were significantly higher for the trained leg when compared to the untrained leg after spring training. Peak and average power output on the 60 s power test increased significantly after training. One-legged aerobic power (VO2max) was significantly increased in the untrained and trained legs. Two-legged VO2max also improved significantly after training. These data suggest that nonbicarbonate buffering capacity and power output can be enhanced with one-legged sprint training. Also, small but significant improvements in VO2max were also observed.     

Comparison of pituitary responses to physical exercise in athletes and sedentary subjects

Serum growth hormone (GH), prolactin (PRL), cortisol, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and thyroid-stimulating hormone (TSH) levels were evaluated before and after a bicycle ergometer exercise test in 8 male competitive volleyball players and in 8 sedentary healthy males of the same age. Increased serum GH and cortisol values after exercise in both groups were found, whereas an exercise-induced PRL release was observed in athletes only. Serum levels of LH, FSH and TSH were unaffected by the test in all subjects. A possible role of training in conditioning the hypothalamopituitary exercise-induced secretion is suggested.     

Changes in Prolactin and Testosterone Levels Induced by Acute Physical Exertion in Young Female Athletes

In order to establish the influence of acute untypical exercise on prolactin and testosterone levels in young female athletes, the authors selected a group of 13 short distance runners who were subjected to exercise on a cycle ergometer. Hormone levels were measured before the test, just after the end of the test, and 30 and 90 minutes thereafter. A significant increase in the testosterone concentration appeared immediately after the exercise, and 90 minutes after the completion of a test, the testosterone level had returned to the preexercise levels. Unlike the results of other authors, a statistically significant decrease in the plasma prolactin concentration was found 90 minutes after the end of the test.     

Mechanism of exercise-induced hyperuricemia

This study was designed to make clear why increases and decreases in serum uric acid levels after vigorous exercise were delayed. Eight healthy male subjects who were given allopurinol before exercise participated in this study. We performed exhaustive exercise test on bicycle ergometer, and investigated the changes in purine metabolites levels in blood and urine. Results were summarized as follow; 1) Serum uric acid concentrations did not change significantly. Urinary excretions of uric acid decreased from 30 minutes to 1 hour after exercise, and recovered thereafter. 2) Plasma oxypurines concentrations exhibited the maximum level at 1 hour after exercise, and maintained the higher levels until 7 hours after exercise. Urinary oxypurines excretions exhibited the maximum level at 1 hour after exercise, and maintained the higher levels until 24 hours after exercise. 3) Plasma inosine concentrations increased only in one subject. Plasma hypoxanthine concentrations increased significantly in all subjects. Plasma xanthine concentrations did not change. 4) Blood ammonia concentrations exhibited the maximum level at 5 minutes after exercise, and returned to basal levels at 2 hours after exercise. These observations suggest that the delays of increases and decreases in serum uric acid levels are due to that the prolonged release of hypoxanthine from skeletal muscle lead to the prolonged production of uric acid in liver.     

The role of behavioral conditioning in the cardiovascular adjustment to exercise

The purpose of this study was to determine if normal subjects could be trained to attenuate their cardiovascular responses while exercising on a bicycle ergometer. Ten young, untrained subjects exercised on a bicycle ergometer for five sessions. Half of the group was asked to slow their heart rate while exercising with heart rate feedback during exercise. Their average heart rate increase was 20% less than that of the control subjects, who exercised without feedback. The control subjects subsequently also received feedback during exercise and they were able to attenuate their heart rate responses comparably. Systolic blood pressure was not affected by feedback training. Changes in rate-pressure product paralleled changes in heart rate. These data show that autonomically mediated adjustments to exercise can be brought under experimental control through the use of appropriate behavioral techniques.     

Cardiovascular resistance to orthostatic load in athletes after aerobic exercise

Cardiovascular resistance to orthostatic load in the athletes in the 2-h recovery period after a prolonged aerobic exercise was studied. The response of the central (stroke volume and cardiac output) and peripheral blood volumes in the lower and upper extremities and abdominal and cervical regions in response to the tilt test before and during 2 h after exercise (30 min; heart rate, 156 ± 8 beats/min) was determined by the impedance method. It is found that (1) in the initial state before exercise, the blood flow distribution in favor of the cervical region in response to the tilt test was more efficient in the athletes, despite the decreased cardiac output, which was due to a large decrease in the blood flow in the lower extremities and an increased blood flow in the cervical region; (2) after exercise, the symptoms of potential orthostatic intolerance develop, such as postural hypotension, tachycardia, and reduced peripheral pulse blood volume, which were expressed in the standing position, and a reduced effectiveness of the blood flow distribution to the cervical region in the tilt test; and (3) the ability to effectively distribute the blood flow in favor of the cervical region in the athletes after exercise remained elevated, which was due to a large decrease in the blood flow in the abdominal region and in the lower extremities at the end of the recovery period.