Improvement of tissue oxygenation during a 20 days-stay at moderate altitude in connection with mild exercise

Summary The influence of a prolonged exposure to medium altitude (1740 m) on the oxygen affinity of hemoglobin was studied in eight male subjects. Moderate altitude is of special interest for several reasons. Many people live or spend their vacations at this elevation, and various studies have indicated that a prolonged stay at such altitudes can have a protective effect angainst some cardiovascular diseases. Further, a shift of the oxygen dissociation curve to the right- as described in many high altitude studies - is beneficial for the tissue oxygen supply only if the arterial oxygen saturation is nearly normal which is the case at this altitude. During the first few days at medium altitude an increase in the oxygen affinity was found when using the non-pH correctedP ₅₀-value (Bohr effect). The continuous increase in the 2,3-DPG concentration was so marked that not only was the Bohr effect counteracted but the curve was also shifted to the right. No significant variation could be found neither in the red blood count nor in the concentrations of potassium or chloride. The inorganic phosphorus increased significantly after ascent. The DPG-induced decrease of oxygen affinity indicates an enhancement of the tissue oxygenation. It is emphasized that this increase of oxygen delivery to the tissue takes place without increase of cardiac output or other energy requiring processes.This study was supported by the Government of the Land Salzburg     

Effects of protein supplementation during prolonged exercise at moderate altitude on performance and plasma amino acid pattern

Summary The effects of two levels of protein intake on muscle performance and energy metabolism were studied in humans submitted to repeated daily sessions of prolonged exercise at moderate altitude. For this purpose, 29 healthy males, were exposed to seven successive stages of ski-mountaineering at altitudes between 2500 and 3 800 m, and to an isocaloric diet (4000 kcal·day^–1, 16760 kJ·day^–1) with either 1.5g·kg^–1·day^–1 (C group,n =14), or 2.5 g·kg^–1·day^–1 (PR group,n =15) protein intake. Measurements made after the ski-mountaineering programme did not show any change in body mass. The peak torque during maximal isometric voluntary contraction (MVC) of the quadriceps muscle was unaffected by the repeated exercises, whereas the endurance time at 50% MVC was decreased in PR subjects (–26.8%,P<0.001). Increased levels of both free fatty acids (+147%,P<0.001) and glycerol (+170%,P<0.001) observed in C subjects would suggest that lipolysis was enhanced after the repeated exercise. The plasma amino acid pattern was altered after completion of the ski-mountaineering programme; the plasma concentration of the three branched-chain amino acids (BCAA) was significantly decreased in C subjects, whereas the higher level of protein intake (PR group) greatly minimized the exercise-induced decrease in serum BCAA.     

Acid-base balance and O2 transport at high altitude

Ear lobe blood pH_a, P_aCO ₂, P_aO ₂, and O₂ saturation (S_aO₂) were measured in healthy Caucasians and Sherpas at 3400 m (Namche Bazaar, Nepal, n=4/5), 5050 m (Pyramid Laboratory, Lobuche, Nepal, n=20/5) and 6450 m (Camp II of Mt Everest, n=11/7). In the investigated altitude range, pH_a increased progressively with altitude from 7.463±0.005 (mean±SE) to 7.496±0.006 in Caucasians whereas it remained essentially constant (7.45–7.46) in Sherpas. At all altitudes, P_aCO ₂ was higher in Sherpas than in Caucasians (P<0.02). By contrast, P_aO ₂ and S_aO₂ were the same in Caucasians and Sherpas at all investigated altitudes. Moreover, in Caucasians sojourning for 3 weeks at 5050 m, P_aCO ₂ kept decreasing whereas pH_a, P_aO ₂ and S_aO₂ remained constant. These data suggest that: (1) respiratory alkalosis was a common finding both in Caucasians and Sherpas; (2) at 6450 m, Sherpas were less alkalotic due to higher P_aCO ₂ than Caucasians, possibly a consequence of a blunted ventilatory response; (3) at 6450 m, S_aO₂ and P_aO ₂ were the same in Caucasians and Sherpas despite different P_aCO ₂ values. The latter finding could be the consequence of one or more of the following adjustments in Sherpas: (1), an increased efficiency of alveolar O₂ transfer, i.e. smaller alveolar-arterial O₂ gradient; (2) a decreased (arterial – mixed venous) O₂ difference, possibly due to increased cardiac output; (3) a reduced increase of the [2,3-DPG]/[Hb] ratio; but not (4) an elevated gas exchange ratio (R). It is concluded that both physiological and biochemical variables contribute to optimize the O₂ transport at altitude. Apparently a more efficient adaptation to hypoxia allows Sherpas to limit alkalosis through a lower ventilatory drive and to maintain S_aO₂ at the same P_aO ₂ by decreasing the [2,3-DPG]/[Hb] ratio.     

Regulation of red cell 2,3-DPG and Hb-O2-affinity during acute exercise

Summary Reports from the literature and our own data on red cell 2,3-DPG and its importance for unloading O₂ from Hb to the tissues during exhaustive exercise are contradictory. We investigated red cell metabolism during incremental bicycle ergometry of various durations. Furthermore changes in blood composition occurring during exercise were simulated under in vitro conditions. The effect of a moderate (11.2 mmol · l^–1 lactate, pH=7.127) and severe (18 mmol · l^–1 lactate, pH=6.943) lactacidosis on red cell 2,3-DPG concentration was compared with the effect of similar acidosis induced by HCl. Our data indicate that the concentration of 2,3-DPG in red cells depends on the degree of lactacidosis, but not on the duration of exercise. During moderate lactacidosis red cell 2,3-DPG remains unchanged. This can be explained by an interruption of red cell glycolysis on the PK and GAP-DH step caused by a lactate and pyruvate influx into the erythrocyte, as well as an intraerythrocytic acidosis and a drop in the NAD/NADH ratio. During severe lactacidosis and HCL-induced acidosis a decrease in 2,3-DPG due to an inhibition of 2,3-DPGmutase and other glycolytic enzymes can be found. Mathematical correction of the observed P-50 value for the decrease in 2,3-DPG occurring during severe lactacidosis showed that a decrease in Hb-O₂-affinity during strenuous exercise depends on the degree of lactacidosis and temperature elevation.     

Changes in ventilation at the start and end of moderate and heavy exercise of short and long duration

Summary These experiments examined the effect of exercise intensity and duration on the magnitude of the abrupt change in ventilation at the start ( ) and end ( ) of exercise. Five subjects performed constant load treadmill exercise at 50% and 80% of their maximum oxygen consumption ( ) for 6 and 10 min while inspiring atmospheric air. The subjects also completed additional exercise tests at 80% for 10 min while inspiring an oxygen-enriched gas mixture. During each exercise trial ventilation was measured breath-by-breath. The and were determined by using non-linear curve-fitting techniques. The results showed that was greater at the start of the 80-% exercise tests compared to the 50-% tests and that at each level of exercise was greater than . The results also demonstrated that was inversely related to the intensity and duration of exercise. Furthermore, the was not altered subsequent to the inspiration of oxygen-enriched air. These findings have led us to postulate that the stimulus responsible for is reduced during exercise and that the degree of reduction is related to the intensity and duration of exercise. In addition, it was concluded that these changes might occur independently of peripheral chemoreceptor activity.     

Metabolic consequences of reduced frequency breathing during submaximal exercise at moderate altitude

Summary The intention of this study was to determine the metabolic consequences of reduced frequency breathing (RFB) at total lung capacity (TLC) in competitive cyclists during submaximal exercise at moderate altitude (1520 m; barometric pressure, P _B=84.6 kPa; 635 mm Hg). Nine trained males performed an RFB exercise test (10 breaths · min ^–1) and a normal breathing exercise test at 75–85% of the ventilatory threshold intensity for 6 min on separate days. RFB exercise induced significant (P<0.05) decreases in ventilation (V _E), carbon dioxide production (VCO₂), respiratory exchange ratio. (RER), ventilatory equivalent for O₂ consumption (V _E/VO₂), arterial O₂ saturation and increases in heart rate and venous lactate concentration, while maintaining a similar OZ consumption (VO₂). During recovery from RFB exercise (spontaneous breathing) a significant (P< 0.05) decrease in blood pH was detected along with increases in V _E, VO₂, VCO₂, RER, and venous partial pressure of carbon dioxide. The results indicate that voluntary hypoventilation at TLC, during submaximal cycling exercise at moderate altitude, elicits systemic hypercapnia, arterial hypoxemia, tissue hypoxia and acidosis. These data suggest that RFB exercise at moderate altitude causes an increase in energy production from glycolytic pathways above that which occurs with normal breathing.     

The role of hemoglobin oxygen affinity in oxygen transport at high altitude

Hemoglobin is involved in the regulation of O(2) transport in two ways: a long-term adjustment in red cell mass is mediated by erythropoietin (EPO), a response to renal oxgyenation. Short-term, rapid-response adjustments are mediated by ventilation, cardiac output, hemoglobin oxygen affinity (P50), barriers to O(2) diffusion, and the control of local microvascular tissue perfusion. The distribution of O(2) between dissolved (PO2) and hemoglobin-bound (saturation) is the familiar oxygen equilibrium curve, whose position is noted as P50. Human hemoglobin is not genetically adapted for function at high altitude. However, more specialized species native to high altitudes (guinea pig and bar-headed goose, for example) seem to have a lower P50 than their sea level counterparts, an adaptation that presumably promotes O(2) uptake from a hypoxic environment. Humans, native to very high altitude either in the Andes or Himalayan mountains, also can increase O(2) affinity, not because of a fundamental difference in hemoglobin structure or function, but because of extreme hyperventilation and alkalosis.     

Fluid distribution and tissue thickness changes in 29 men during 1 week at moderate altitude (2,315 m)

To quantify fluid distribution at a moderate altitude (2,315 m) 29 male subjects were studied with respect to tissue thickness changes [front (forehead), sternum, tibia], changes of total body water, changes of plasma volume, total protein concentrations (TPC), colloid osmotic pressure (COP), and electrolytes. Tissue thickness at the forehead showed a significant increase from 4.14 mm to 4.41 mm 48 h after ascent to the Rudolfshuette (2,315 m) (P < 0.05). At 96 h after ascent the tissue thickness at the tibia was decreased to 1.33 mm compared to the control value of 1.59 mm (P < 0.01). Body mass increased from 75.5 kg (control) to 76.2 kg on the last day (P < 0.05) and body water from 44.21 to 45.01 during the week (P < 0.01). The accumulation fluid in the upper part of the body was paralleled by a decrease in TPC and COP. At 48 h after the ascent COP dropped from 29.5 mmHg to 27.5 mmHg (P < 0.01). After 96 h at moderate altitude COP was still significantly decreased compared to the control level. At 1.5 h after the return from the Rudolfshuette in Saalfelden (744m) COP was back to the control values. The TPC also showed an initial drop from 7.75 g · dl^–1 to 7.48 g · dl^–1 after 48 h at altitude and remained below the control value during the whole week (P < 0.01). It seems from our study that even with exposure to moderate altitude measurable fluid shifts to the upper part of the body occurred which were detected by our ultrasound method.     

The effects of exercise training and denervation on the morphology of intrafusal muscle fibers

Summary The morphological effects of daily bouts of exercise and denervation on teres minor intrafusal muscle fibers were investigated in male Sprague-Dawley rats. After denervation, nuclear bag and nuclear chain muscle fiber cross-sectional area atrophied only 25 and 33% of the amount experienced by extrafusal fibers. Of the two fiber types, the nuclear chain fibers appeared to be more responsive to the effects of exercise than the nuclear bag fibers; however, this trend for enlargement had no statistical significance. Length measurements did not reveal any marked changes of any fiber type to the experimental conditions of this study. It was concluded that the possible differences in function and innervation of the nuclear bag and nuclear chain fibers could partly account for these findings.Supported in part by funds provided by the Graduate College.     

The delayed effects of prolonged physical exercise and physical training on cholesterol level

Summary The delayed effects of prolonged physical exercise on total and high-density lipoprotein (HDL) cholesterol were studied before and after a training period of 8 weeks. In 15 subjects, 1 and 2 days after a 3 h running test, total cholesterol was significantly lower than 1 day before and 8 days after the end of the exercise. One day post-exercise, HDL-cholesterol was significantly higher compared with 1 day before and 8 days afterwards. In ten subjects participating in the training program, decreased total cholesterol values were again found on the first day after the post-training exercise test. Total and HDL cholesterol levels were not significantly affected by 8 weeks of training.This work was supported by the Bundesinstitut für Sportwissenschaft, Köln     

The effects of different inspiratory muscle training intensities on exercising heart rate and perceived exertion

This study investigated the relationship between the intensity of an inspiratory muscle training programme and its effect on respiratory muscle strength, exercising heart rate, and ratings of perceived exertion. A total of 66 subjects were randomly assigned to one of three groups. One group trained at 100% of maximum inspiratory pressure (MIP) for 6 weeks (MAX, n=22). A second group performed 6 weeks of inspiratory muscle training at 80% of MIP (SUB, n=21) and a third control group received no inspiratory training (CON, n=23). Both the MAX and SUB training groups improved MIP relative to the control group [32 (19) cmH₂O, P=0.01; 37 (25) cmH₂O, P=0.001, respectively]. A significant decrease in heart rate [–6 (9) beats min^–1, P=0.02] and rating of perceived exertion [–0.5 (1.4), P=0.04] was observed for the MAX group only. It is concluded that 6 weeks of both MAX and SUB training were sufficient to improve inspiratory muscle strength. However, exercising heart rate and perceived exertion decreased with MAX training only.     

Consequences of 6 weeks of strength training on red cell O2 transport and iron status

Summary Effects of endurance training on OZ transport and on iron status are well documented in the literature. Only a few data are available concerning the consequences of strenuous anaerobic muscular exercise on red cell function. This study was performed to test the influence of strength training alone on parameters of red cell O₂ transport and iron status. Twelve healthy untrained males participated in a strength-training pro gramme of 2-h sessions four times a week lasting 6 weeks. After 6 weeks a small but significant reduction of haemoglobin (Hb; – 5.4 g·l^–1) was found (p<0.05). Mean red cell volume did not change, but a pronounced decrease of mean cell Hb concentration (from 329.2g·l^–1, SE 2.5 to 309.8g·l^–1, SE 1.2;p<0.001) and mean corpuscular Hb (from 29.6 pg, SE 0.4 to 27.7 pg, SE 0.3;p<0.01) was observed. Serum ferritin decreased significantly by 35% (p<0.01); transferrin, serum iron and iron saturation of transferrin were unaltered. Serum haptoglobin concentration was diminished significantly by 30.5% (p<0.01). The reticulocyte count had already increased after 3 weeks of training (p<0.05) and remained elevated during the following weeks. Strength training had no significant influence on the O₂ partial pressure at which Hb under standard conditions was 50% saturated, red cell 2,3-diphospho glycerate and ATP concentration as well as on erythrocytic glutamate-oxalacetate transaminase activity. The data demonstrate that mechanical stress of red cells due to the activation of large muscle masses led to increased intravascular haemolysis, accompanied by a slightly elevated erythropoiesis, which had no detectable influence on Hb-O₂ affinity. Training caused an initial depletion of body iron stores (prelatent iron deficiency). Although Hb had decreased by the end of the training phase a true sports anaemia could not be detected.     

Influences of exercise and endurance training on the oxygen dissociation curve of blood underin vivo andin vitro conditions

In experiments with graded exercise of 15 men (6 untrained, 3 semitrained, 6 endurance-trained) the trained subjects showed a massive shift to the right of thein vivo O₂ dissociation curve (ODC) of femoral venous blood. At a saturation of 20 to 25% (18 mkp/sec)P _{O 2} was about 9 mm Hg higher for the trained than for the untrained group. The following factors play a role: 1. The 2,3-diphosphoglycerate [2,3-DPG] concentration was increased by 15 to 20% in the trained group which explains about 2 mm Hg of the difference inP _{O 2}. 2. Exercise acidosis in the femoral venous blood depends to a large extent on CO₂ in the trained, but on lactic acid in the untrained group. At low saturations the CO₂-Bohr effect increases sharply thus having a greater importance in the trained subjects. This factor can explain about 2 mm Hg of the difference. However, influence of chloride and 2,3-DPG on the Bohr effect must be taken into consideration. 3. Since the large ODC-shift to the right of the trained group was not reproducible underin vitro conditions, it is suggested that a rapidly decaying unknown substance accounts for the remaining difference inP _{O 2}.A preliminary report was presented at the 39th meeting of the German Physiological Society, Erlangen, 1972.Supported by Deutsche Forschungsgemeinschaft BO 360/2.     

The effects of high-intensity exercise on skeletal muscle neutrophil myeloperoxidase in untrained and trained rats

The primary purpose of this study was to examine the effects of high-intensity acute exercise on neutrophil infiltration in different muscle fiber types of untrained rats and to compare postexercise neutrophil accumulation in muscles of untrained and trained animals. The effect of high-intensity acute exercise on blood neutrophil degranulation reaction in trained animals was also elucidated. Neutrophil enzyme myeloperoxidase (MPO) was determined as a measure of neutrophil migration into muscles and blood neutrophil degranulation. Male albino rats were subjected to acute exercise and 5 weeks of training. The used model of intensive acute exercise consisted of 5, 15, and 25 intermittent swimming bouts with the addition of weight (8% of total body mass) for 1-min each, followed by 1.5-min rest intervals. MPO was analyzed in quadriceps muscle (white and red portion) and in soleus muscle 24 h after acute exercise. MPO content in resting blood plasma and neutrophils was determined 48-h following the completion of a training process. In addition, MPO content in the trained rats was measured immediately (in blood plasma and neutrophils) after and 24 h (in muscles) following a single-bout of exercise to exhaustion. The remaining two-third of the trained animals were exposed to a single-bout of nonstop swimming with the addition of 6% body mass until exhaustion. These animals were sacrificed immediately and 24 h after loaded swimming to analyze leukocyte count, MPO content in blood plasma and neutrophils and in muscles, respectively. About 24 h after exercise MPO concentrations in the red portion of quadriceps muscle and in soleus muscle were 4–7-fold higher as compared to the white portion of m. quadriceps. There was an association between the quantity of repetitive bouts of swimming and MPO content in the muscles. The duration of swimming to exhaustion of trained rats was 3.8-fold longer than untrained sedentary control. At rest, plasma MPO concentration was found to be 40% higher in trained rats compared to untrained controls (P < 0.05). Postexercise plasma MPO concentrations were significantly higher both in untrained (+137%; P < 0.05) and trained (+81%; P < 0.05) rats compared to resting values. At rest neutrophil MPO concentration was found to be 33% lower in trained rats compared to untrained controls (P < 0.05). There were no significant differences in muscle MPO concentrations between untrained and trained rats at rest. A single-bout of exercise to exhaustion produced a greater increase in MPO content in untrained compared to trained rats. The data suggest that postexercise neutrophil infiltration is more intensive in red fibers types compared to white fiber types. A smaller neutrophil infiltration in muscles of trained animals after exhaustive exercise suggests a protective effect of previous training to muscle injury.Portions of this paper were presented by V. Morozov in 2003 at the 6th ISEI Symposium on Exercise Muscle Metabolism and Immune Function, Copenhagen.     

高原肺水肿患者血流动力学变化及对吸氧反应的测定

目的:探讨高原肺水肿的发病机理。方法:采用右心漂浮导管检测法, 对9例高原肺水肿患者及9例同海拔高原健康人的血流动力学指标进行了检测, 同时也观察了吸入纯氧对高原肺水肿患者血流动力学的影响。结果:高原肺水肿患者发病时, 肺动脉平均压、肺血管阻力、心脏指数均明显高于同海拔高度健康人, 而患者肺动脉楔压, 右心房压力同对照组相比, 未见显著差异;吸氧后, 高原肺水肿患者心率、肺动脉平均压力, 肺血管阻力及心脏指数均较吸氧前明显下降, 特别是肺动脉平均压及肺血管阻力下降尤为明显, 肺动脉平均压力在吸氧1min后即明显下降, 吸氧5min后, 下降至最低值, 但吸氧20min后仍未达对照组水平。结论:高原肺水肿是非心源性肺水肿, 肺动脉高压在其发病中起重要作用。     

Beneficial effects of regular exercise on sleep in old F344 rats

With aging there is a significant decline in the normal architecture of sleep and a reduction in the diurnal amplitude of core body temperature. Regular moderate exercise has been shown to have a positive impact in the elderly and here we investigate whether sleep–wake patterning can also be improved. Young (3 months) and old (22 months) F344 rats were exercised once a day for 50 min at night onset over an 8-week period. Thereafter, polysomnographic recordings were obtained immediately after exercise. To determine the lasting consequences of exercise, sleep was also recorded 2 days and 2 weeks after exercise had ended. Old rats that were exercised had a significant weight loss, were awake more during the last third of their active period, had less sleep fragmentation and the amplitude of the diurnal rhythm of core body temperature was significantly increased. Old exercised rats also had an overall increase in the amplitude of EEG power (0.5–16 Hz) during wake and theta EEG power during REM sleep. In young rats regular exercise increased EEG delta power (0.5–4 Hz) during NREM sleep. Our data indicate regular exercise in old rats improves sleep architecture, EEG power and diurnal rhythm of temperature.     

Effect of high intensity interval training on 2,3-diphosphoglycerate at rest and after maximal exercise

Summary The purpose of this study was to examine the effect of intense interval training on erythrocyte 2,3-diphosphoglycerate (2,3-DPG) levels at rest and after maximal exercise. Eight normal men, mean ± SE=24.2±4.3 years, trained 4 days·week^–1 for a period of 8 weeks. Each training session consisted of eight maximal 30-s rides on a cycle ergometer, with 4 min active rest between rides. Prior to and after training the subjects performed a maximal 45-s ride on an isokinetic cycle ergometer at 90 rev·min^–1 and a graded leg exercise test (GLET) to exhaustion on a cycle ergometer. Blood samples were obtained from an antecubital vein before, during and after the GLET only. Training elicited significant increases in the amount of work done during the 45-s ride (P<0.05), and also in maximal oxygen uptake ( max: Pre=4.01±0.13; Post=4.29±0.07 l·min^–1;P<0.05) during exercise and total recovery (Pre=19.14±0.09; Post=21.45±0.10 l·30 min^–1;P<0.05) after the GLET. After training blood lactate was higher, base excess lower and pH lower during and following the GLET (P<0.05 for all variables). Training caused no significant differences in erythrocyte 2,3-DPG levels at rest (Pre=11.8±0.7; Post=12.1±0.7 mol·g^–1 hemoglobin (Hb);P>0.05), at exhaustion (Pre=12.0±0.8; Post=11.2±0.8 mol·g^–1 Hb;P>0.05) or during 30 min of recovery from the GLET. Additionally, acute exercise (pre-training GLET) did not effect any change in 2,3-DPG at exhaustion or during recovery from exercise compared to resting values. The higher max and total recovery values observed after training appear to be unrelated to 2,3-DPG levels. Under the present conditions, the role, if any, of 2,3-DPG in enhancing tissue oxygenation during increased metabolic demand remains obscure.Supported by grants from Miles Laboratories, Elkhart, Indiana, and the Ball State Graduate Student Research Fund     

Effects of acute exercise and prolonged exercise training on blood pressure,vasopressin and plasma renin activity in spontaneously hypertensive rats

Summary The purpose of this study was to investigate the effect of swimming training on systolic blood pressure (BP_s), plasma and brain vasopressin (AVP), and plasma renin activity (PRA) in spontaneously hypertensive rats (SHR) during rest and after exercise. Resting and postexercise heart rate, as well as blood parameters such as packed cell volume (PCV), haemoglobin concentration (Hb), plasma sodium and potassium concentrations ([Na⁺], [K⁺]) osmolality and proteins were also studied. Hypophyseal AVP had reduced significantly after exercise in the SHR, whereas PRA had increased significantly in the Wistar-Kyoto (WKY) strain used as normotensive controls. Plasma AVP concentration increased in both strains. By the end of the experiment, training had reduced body mass and BP_s by only 10% and 6%, respectively. Maximal oxygen uptake was increased 10% and plasma osmolality 2% by training. The postexercise elevation of heart rate was not significantly attenuated by training. A statistically significant reduction in postexercise plasma osmolality (10%) and [Na⁺] (4%) was observed. These results suggested that swimming training reduced BPS. Plasma and brain AVP played a small role in the hypertensive process of SHR in basal conditions because changes in AVP contents did not correlate with those of BP_s. Moreover, there were no differences between SHR and WKY in plasma, hypophyseal and hypothalamic AVP content in these basal conditions. Finally, during moderate exercise a haemodilution probably occurred with an increase of plasma protein content. This was confirmed by the exercise-induced increase of plasma AVP and the reduction of hypophyseal AVP content, suggesting a release of this hormone, which probably contributed to the water retention and haemodilution. This investigation showed that swimming training produced an attenuation of the raised resting blood pressure in this strain and that plasma and brain AVP played a negligible role in the maintenance of hypertension in basal conditions. However, during training, this hormone may have played a role, training having induced simultaneously a decrease in BP_s and plasma AVP.     

Effects of exercise on the serum concentrations of FSH,LH, progesterone,and estradiol

Summary The effects of 30 min of exercise (74.1±3.0% (VO₂), on the responses of progesterone (P), estradiol (E₂), follicle stimulating hormone (FSH), and luteinizing hormone (LH) were investigated in 10 women. With such exercise significant increments occurred in P (37.6±9.5%) and E₂ (13.5±7.5%) (p<0.05), whereas no changes were observed in FSH and LH (p>0.05). Exercise in the luteal phase and during menses provoked similar changes in P, but E₂ concentrations remained unchanged when exercise occurred during menses (p>0.05). With 8–11 weeks of training the menstrual cycles were quite irregular and retesting of subjects in the same phase of the cycle was not possible. Yet, when subjects were retested after training, no changes occurred in P, E₂ or LH (p>0.05) but a decrement did occur in FSH (p<0.10). Thus, heavy exercise in untrained subjects provokes significant increments in ovarian hormones, whereas no such increments are observed in trained subjects exercising at the same absolute workload.