[Effects of surgical face masks on exercise performance and perceived exertion of exercise in well-trained healthy boys]. / Einfluss einer Mund-Nase-Maske auf die objektive körperliche Leistungsfähigkeit sowie das subjektive Belastungsempfinden bei gut-trainierten, gesunden Jungen.

This study investigated the effects of surgical "everday" face masks on the physical performance and perceived exertion in trained eleven-year-old boys.No decrease in objective performance parameters was found in the aerobic and aerobic-anaerobic transition zones. However, at the maximum performance level with surgical face mask, there was a significant reduction in running time as well as a significant increase in the subjective perception of exertion with otherwise unchanged performance parameters. In summary, the use of surgical face masks in trained children does not affect athletic activities as long as the loads are performed primarily in the aerobic intensity range.

Endurance Exercise in Hypoxia, Hyperoxia and Normoxia: Mitochondrial and Global Adaptations.

We hypothesized short-term endurance exercise (EN) in hypoxia (HY) to exert decreased mitochondrial adaptation, peak oxygen consumption (VO2peak) and peak power output (PPO) compared to EN in normoxia (NOR) and hyperoxia (PER). 11 male subjects performed repeated unipedal cycling EN in HY, PER, and NOR over 4 weeks in a cross-over design. VO2peak, PPO, rate of perceived exertion (RPE) and blood lactate (Bla) were determined pre- and post-intervention to assess physiological demands and adaptation. Skeletal muscle biopsies were collected to determine molecular mitochondrial signaling and adaptation. Despite reduced exercise intensity (P<0.05), increased Bla and RPE levels in HY revealed higher metabolic load compared to PER (P<0.05) and NOR (n.s.). PPO increased in all groups (P<0.05) while VO2peak and mitochondrial signaling were unchanged (P>0.05). Electron transport chain complexes tended to increase in all groups with the highest increase in HY (n.s.). EN-induced mitochondrial adaptability and exercise capacity neither decreased significantly in HY nor increased in PER compared to NOR. Despite decreased exercise intensity, short term EN under HY may not necessarily impair mitochondrial adaptation and exercise capacity while PER does not augment adaptation. HY might strengthen adaptive responses under circumstances when absolute training intensity has to be reduced.

Effects of a Whole-Body Electrostimulation Program on Strength, Sprinting, Jumping, and Kicking Capacity in Elite Soccer Players.

The aim of the present study was to investigate the effect of a 14-week dynamic Whole-Body Electrostimulation (WB-EMS) training program on muscular strength, soccer relevant sprint, jump and kicking velocity performance in elite soccer players during competitive season. Twenty-two field-players were assigned to 2 groups: WB-EMS group (EG, n = 12), jump-training group (TG, n = 10). The training programs were conducted twice a week concurrent to 6-7 soccer training sessions during the 2nd half of the season. Participants were tested before (baseline), during (wk-7) and after (wk-14). Blood serum samples for analyzing IGF-1 and CK were taken before each testing, 15-30min post and 24h post the training program. Our findings of the present study were that a 14-week in-season WB-EMS program significant increased one-leg maximal strength (1RM) at the leg press machine (1.99 vs. 1.66 kg/kg, p = 0.001), and improved linear sprinting (5m: 1.01 vs. 1.04s, p=0.039), sprinting with direction changes (3.07 vs. 3.25s, p = 0.024), and vertical jumping performance (SJ: 38.8 vs. 35.9cm p = 0.021) as well as kicking velocity (1step: 93.8 vs. 83.9 km·h-1, p < 0.001). The TG showed no changes in strength and performance. The EG revealed significantly increased CK levels 24h post training and yielded significantly higher CK levels compared to the TG. IGF-1 serum levels neither changed in the EG nor in the TG. The results give first hints that two sessions of a dynamic WB-EMS training in addition to 6-7 soccer sessions per week can be effective for significantly enhancing soccer relevant performance capacities in professional players during competitive season.

Effects of Cycling Versus Running Training on Sprint and Endurance Capacity in Inline Speed Skating.

The purpose of this study was to compare the effects of running versus cycling training on sprint and endurance capacity in inline speed skating. Sixteen elite athletes (8 male, 8 female, 24 ± 8 yrs) were randomly assigned into 2 training groups performing either 2 session per week of treadmill running or ergometer cycling in addition to 3 skating specific sessions (technique, plyometrics, parkour) for 8 weeks. Training intensity was determined within non-specific (cycling or running) and effects on specific endurance capacity within a specific incremental exercise test. Before and after the intervention all athletes performed a specific (300m) and one non-specific (30s cycling or 200m running) all-out sprint test according to the group affiliation. To determine the accumulation of blood lactate (BLa) and glucose (BGL) 20 µl arterialized blood was drawn at rest, as well as in 1 min intervals for 10 min after the sprint test. The sport-specific peak oxygen uptake (VO2 peak) was significantly increased (+17%; p = 0.01) in both groups and highly correlated with the sprint performance (r = -0.71). BLa values decreased significantly (-18%, p = 0.02) after the specific sprint test from pre to post-testing without any group effect. However, BGL values only showed a significant decrease (-2%, p = 0.04) in the running group. The close relationship between aerobic capacity and sprint performance in inline speed skating highlights the positive effects of endurance training. Although both training programs were equally effective in improving endurance and sprint capacities, the metabolic results indicate a faster recovery after high intensity efforts for all athletes, as well as a higher reliance on the fat metabolism for athletes who trained in the running group. Key pointsIn addition to a highly developed aerobic performance inline speed skaters also require a highly trained anaerobic capacity to be effective in the sprint sections such as the mass start, tactical attacks and finish line sprint.An 8-week low-intensity endurance training program of either cycling or running training combined with additional routine training improves classical aerobic characteristics (17% increase of VO2 peak), as well as values for acceleration and speed.Athletes who trained in the running group demonstrated a higher reliance on the fat metabolism in the sport-specific post-testing.The significant reduction in anaerobic ATP turnover during repeated sprints appears to be partially compensated by an increase in VO2 in subsequent sprint. The results revealed a close relationship between the aerobic capacity and sprint performance in inline speed skating.

Cardiorespiratory demands during an inline speed skating marathon race: a case report.

This study was designed to investigate the intensity profile during an inline speed skating marathon road race. A highly-trained male athlete (20 y, 73.4 kg, 178 cm, V̇O2 peak: 60.8 mL·kg-1·min-1) participated in a marathon road race. Oxygen uptake (V̇O2), respiratory exchange ratio (RER), heart rate (HR) and speed were measured using a portable gas analysis system with a HR monitor and GPS-Sensor integrated. The athlete´s peak V̇O2, HR and speed at ventilatory thresholds were assessed during an incremental field test (22 km·h-1, increase 2 km·h-1 every 5 min) one week before the race. During the race, the absolute time spent in the "easy intensity zone" (V̇O2 below VT1) was 1 min, 49 min "moderate intensity zone" (V̇O2 between VT1 and VT2), and 26 min in the "hard intensity zone" (V̇O2 above VT2). The average HR was 171±6 bpm, corresponding to 95% of the maximum. This study shows that inline speed skating road races over a marathon are conducted at moderate to high V̇O2 and heart rate levels. The physiological racing pattern is very intermittent, requiring both a high level of aerobic and anaerobic capacity.

Effects of Cycling vs. Running Training on Endurance Performance in Preparation for Inline Speed Skating.

Winter weather conditions restrict regular sport-specific endurance training in inline speed skating. As a result, this study was designed to compare the effects of cycling and running training programs on inline speed skaters' endurance performance. Sixteen (8 men, 8 women) high-level athletes (mean ± SD 24 ± 8 years) were randomly assigned to 1 of 2 groups (running and cycling). Both groups trained twice a week for 8 weeks, one group on a treadmill and the other on a cycle ergometer. Training intensity and duration was individually calculated (maximal fat oxidation: ∼52% of V[Combining Dot Above]O2peak: 500 kcal per session). Before and after the training intervention, all athletes performed an incremental specific (inline speed skating) and 1 nonspecific (cycling or running) step test according to the group affiliation. In addition to blood lactate concentration, oxygen uptake (V[Combining Dot Above]O2), ventilatory equivalent (VE/V[Combining Dot Above]O2), respiratory exchange ratio (RER), and heart rate were measured. The specific posttest revealed significantly increased absolute V[Combining Dot Above]O2peak values (2.9 ± 0.4, 3.4 ± 0.7, p = 0.01) and submaximal V[Combining Dot Above]O2 values (p ≤ 0.01). VE/V[Combining Dot Above]O2 and RER significantly decreased at maximal (46.6 ± 6.6, 38.5 ± 3.4, p = 0.005; 1.1 ± 0.03, 1.0 ± 0.04, p = 0.001) and submaximal intensities (p ≤ 0.04). None of the analysis revealed a significant group effect (p ≥ 0.15). The results indicate that both cycling vs. running exercise at ∼52% of V[Combining Dot Above]O2peak had a positive effect on the athletes' endurance performance. The increased submaximal V[Combining Dot Above]O2 values indicate a reduction in athletes' inline speed skating technique. Therefore, athletes would benefit from a focus on technique training in the subsequent period.

Comparison of sport-specific and non-specific exercise testing in inline speed skating.

BACKGROUND: The most effective way to measure exercise performance in inline speed skating (ISS) has yet to be established. Generally most athletes are examined by means of traditional but unspecific cycling (CYC) or running (RUN) testing. The present study investigates whether a sport-specific incremental test in ISS reveals different results. METHODS: Eight male top level inline speed skaters (age: 30±4 years; 65.4±6.3 mL∙kg-1∙min-1, training: 12-14 h/week) performed three incremental exhaustive tests in a randomized order (ergometer CYC, field RUN, field ISS). During the tests, heart rate (HR), oxygen uptake (V̇O2, energy expenditure (EE) and blood lactate concentration (BLC) were measured. RESULTS: Analysis of variance revealed no significant differences for peak HR (187±9, 191±9, 190±9; P=0.75), BLC (10.9±2.3, 10.8±2.4, 8.5±3.2; P=0.25), V̇O2 (65.4±6.3, 66.8±3.5, 66.4±6.5; P=0.91) and EE (1371±165, 1335±93, 1439±196; P=0.51) between ISS and CYC or RUN test. Similar results appeared for HR and V̇O2 at submaximal intensities (2 and 4 mmol·L-1 BLC; P≥0.05). Small to moderate effect sizes 0.3-0.87 and considerable variability of differences between the exercise modes (mean bias range between 1% and 17% with 95% limits of agreement between 3% and 33%) among submaximal and maximal results limit the comparability of the three tests. CONCLUSIONS: Consequently, CYC and RUN tests may be considered as qualified alternatives for a challenging ISS test. However a sport-specific test should be conducted in cases of doubt, or when precision is required (e.g. for elite athletes or scientific studies).

Influence of Whole-Body Electrostimulation on Human Red Blood Cell Deformability.

Red blood cell-nitric oxide synthase (RBC-NOS)-dependent NO production is essential for the maintenance of RBC deformability, which is known to improve oxygen supply to the working tissue. Electrostimulation of the whole body (WB-EMS) has been shown to improve maximal strength, springiness, and jumping power of trained and untrained athletes. To examine whether these 2 parameters are associated, this study, for the first time, aimed to investigate the effects of an 18-week dynamic WB-EMS program on RBC deformability in addition to maximal strength performance (1 repetition maximum [1RM]) in elite soccer players. Fifteen test persons were assigned in either WB-EMS group (EG, n = 10) or training group (TG, n = 5). Next to their weekly training sessions, EG performed 3 × 10 squat jumps under the influence of WB-EMS twice per week between weeks 1 and 14 and once per week between weeks 14 and 18. Training group only performed 3 × 10 squat jumps. Performance was assessed by a maximal strength test on the leg press machine (1RM). Subjects were tested at baseline and after weeks 7, 14, and 18 with blood sampling before (Pre), 15-30 minutes after (Post), and 24 hours after (24-hour Post) the training. The results showed that maximal strength was significantly improved in EG (p < 0.01). Maximum RBC deformability (EImax) increased on EMS stimulus in EG while it remained unaffected in the TG. Acute increase in EImax at baseline was explained by an increase in RBC-NOS activation while chronic increase of deformability must be caused by different, yet unknown, mechanisms. EImax decreased between weeks 14 and 18 suggesting that 1 WB-EMS session per week is not sufficient to alter deformability (EImax). In contrast, the deformability at low shear stress (EI 3 Pa), comparable with conditions found in the microcirculation, significantly increased in EG until week 14, whereas in TG deformability only, increased until week 7 due to increasing training volume after the winter break. The results indicate that WB-EMS represents a useful and time-saving addition to conventional training sessions to improve RBC deformability and possibly oxygen supply to the working tissue and thus promoting general force components in high performance sport.

Effects of physical exercise on individual resting state EEG alpha peak frequency.

Previous research has shown that both acute and chronic physical exercises can induce positive effects on brain function and this is associated with improvements in cognitive performance. However, the neurophysiological mechanisms underlying the beneficial effects of exercise on cognitive processing are not well understood. This study examined the effects of an acute bout of physical exercise as well as four weeks of exercise training on the individual resting state electroencephalographic (EEG) alpha peak frequency (iAPF), a neurophysiological marker of the individual's state of arousal and attention, in healthy young adults. The subjects completed a steady state exercise (SSE) protocol or an exhaustive exercise (EE) protocol, respectively, on two separate days. EEG activity was recorded for 2 min before exercise, immediately after exercise, and after 10 min of rest. All assessments were repeated following four weeks of exercise training to investigate whether an improvement in physical fitness modulates the resting state iAPF and/or the iAPF response to an acute bout of SSE and EE. The iAPF was significantly increased following EE (P = 0.012) but not following SSE. It is concluded that the iAPF is increased following intense exercise, indicating a higher level of arousal and preparedness for external input.

Monitoring drug residues in donor blood/plasma samples using LC-(MS)/MS--a pilot study.

Quality assurance of pharmaceutical products is of particular importance and thoroughly controlled. Among these, the preparation of human plasma follows strict guidelines from the point of donor selection to product processing. While various precautions particularly concerning antiviral treatment as well as quality assessment are standard procedure, tests for drug residues are rarely, if at all, conducted with fresh frozen plasma products. With the constantly increasing sensitivity and specificity of modern analytical instruments, the detection of trace amounts of therapeutics in plasma is feasible and can be applied to blood products where considered appropriate. To estimate the prevalence of a selection of commonly prescribed and over-the-counter drugs (including diuretics, beta-receptor blocking agents, contraceptives, ß2 -agonists, antibiotics, antidepressants, analgesics, opioids, glucocorticosteroids, benzodiazepines, stimulants, and oral anti-diabetics) as well as cannabinoids in human donor plasma, a total of 100 specimens (61 female, 39 male) collected at the German Red Cross Organization in 2012 was subjected to an established analytical approach. The methodology was based on protein precipitation followed by liquid chromatographic-high resolution/high accuracy mass spectrometric analysis. Following initial test results, confirmatory analyses were conducted with respective reference substances employing a conventional liquid chromatography-triple-quadrupole mass spectrometer (LC-MS/MS) apparatus. Out of one hundred samples, five were found to contain diuretics (four hydrochlorothiazide and one torasemide), five contained beta-receptor blocking agents (four bisoprolol and one metoprolol), one was found with residues of pseudoephedrine (stimulant) and one with drosperinone (contraceptive). Overall, 12% of samples yielded detectable amounts of drug residues at concentrations estimated to levels common to individuals under therapeutic treatment. In addition, six aliquots of different lots of commercially available plasma preparations with solvent-detergent processing were tested. Here, no drug residues of the targeted therapeutics were detected.

Responses of serum neurotrophic factors to exercise in pregnant and postpartum women.

It was recently shown in humans that exercise affects the neurotrophic factors known to function as neurogenesis regulators. No data related to exercise and pregnancy, however, is yet available. Thus, we investigated the effects of acute exercise on pregnant women during late pregnancy and women postpartum, on the serum concentration of the brain-derived neurotrophic factor (BDNF), the insulin-like growth factor 1 (IGF-1), the vascular endothelial growth factor (VEGF), prolactin (PRL) and cortisol (COR). Twenty women with uncomplicated pregnancies underwent a graded submaximal exercise test during pregnancy (weeks 32-36 of gestation; T(1)) and postpartum (10-12 weeks after childbirth; T(2)). On two of these test days the women carried out an intensifying exercise test (25 W steps) on a cycle ergometer until a heart rate of 150 bpm was reached. Blood samples were taken in the rest period before beginning the exercise, immediately at the end of the exercise and after recovery periods of 5 and 10 min, respectively. Basal maternal IGF-1, PRL and COR were found to be higher during T(1) (p<.01), while the BDNF was higher during T(2) (p=.00). VEGF was not detectable in the serum of the pregnant women. During T(2), VEGF, which was found to be within the normal range before exercise, was at a higher level after exercise (p<.01). Exercise increased the BDNF and IGF-1 during T(1) and T(2) (p<.01). This study also shows that exercise increases the serum concentrations of IGF-1 and BDNF during pregnancy and postpartum as well as VEGF postpartum. Thus, exercise might be a beneficial lifestyle factor with therapeutic/public health implications i.e. with regard to maternal mood and cognitive performance.

Increased slow wave sleep and reduced stage 2 sleep in children depending on exercise intensity.

BACKGROUND: There is controversy about the consequences of physical exercise on human sleeping behaviors. Evidence suggests that voluntary physical exercise affects brain structures and functions. However, there are inconsistent data regarding the effects of exercise on sleep architecture and sleep continuity, especially the amounts of slow wave sleep (SWS) and rapid eye movement (REM) sleep. OBJECTIVE: The aim of the present study was to investigate the effects of moderate and high intense physical exercise on vigilance state and sleep patterns in school-aged children. METHODS: Eleven healthy children (12.6+/-0.8 years old) were recruited for this polysomnographic study and underwent two exercise sessions. The two exercise sessions on a bicycle ergometer were performed 3-4h prior to bedtime, lasted 30min and varied in intensity. The moderate-intensity exercise was at 65-70% of maximal heart rate (HR(max)) while the high-intensity exercise was at 85-90% HR(max) to exhaustion. Polysomnographic and physiological measurements, including oximetry, were made on three nights in random order and separated by 1 week. Vigilance tests were carried out before and after the three sleep periods. RESULTS: Only high-intensity exercise resulted in a significantly elevated SWS proportion and less sleep in stage 2 as well as a higher sleep efficiency and shorter sleep onset latency. No significant effects on REM sleep were found. CONCLUSION: The results suggest that exercise intensity is responsible for the effects on stage 2 sleep and SWS in children and support the hypothesis of homeostatic sleep regulation.

Physical activity and the elderly.

Functional ageing processes are characterized by a loss of performance capabilities regarding coordination, flexibility, strength, speed, and endurance. The effects of ageing processes on the cardiovascular system and skeletal muscle are the foci of attention. After age 30, the maximum aerobic dynamic performance capacity decreases by an average of 8% per decade. The causes are mainly a reduction in the maximum cardiac output and decreases in capillarization and in the skeletal muscle mass. An improvement in the maximum oxygen uptake by 18% and in the aerobic-anaerobic threshold by 22% was achieved in untrained men aged 55-70 years, in a 12-week-long bicycle ergometer-training programme. The strength of the skeletal muscle decreases particularly after 50-60 years of age. The main cause is the reduction in the number of motor units and muscle fibres. Further, modifications of the endothelial function and the development of sarcopenia are of particular importance in ageing processes. General aerobic dynamic training can improve the endothelial function in old age and thus help prevent cardiovascular diseases. Strength training is most appropriate for the prevention of sarcopenia. Imaging techniques over the last 20 years have provided new findings on the influence and the significance of physical activity on the brain. We call this new interdisciplinary area 'Exercise Neuroscience'. Demands on coordination and aerobic dynamic endurance are suitable in counteracting age-related neuronal cellular loss, synapsis hypotrophy, and in improving neurogenesis and capillarization. Adjusted physical activity is thus capable of counteracting age-related changes and performance loss not only in the cardiovascular system but also in the brain.

Werner Forssmann, Eberswalde, the 1956 Nobel Prize for medicine.

Since October 1949 Werner Forssmann was a regular guest of Prof. Dr. Hugo Wilhelm Knipping in the Medical University Clinic of Cologne. Established himself as urologist in Bad Kreuznach, Werner Forssmann had read about the American further development of heart catherization, which was invented by himself. Prof. Wilhelm Bolt, who was one of the medical station doctors of the Cologne Clinic, had already learned the technique of heart catherization in 1947. Thus, it was routinely performed in patients at the Cologne University Hospital. A close collaboration between Werner Forssmann and our research group (Hugo Wilhelm Knipping, Wilhelm Bolt, Helmut Valentin, Helmut Venrath, Hans Rink, Wildor Hollmann) was established. After the notification that Werner Forssmann had been awarded the Nobel Prize for Medicine in 1956, Hugo Wilhelm Knipping instructed me to help Werner Forssmann with the preparation of his lecture. Details of events in the year 1956 are illustrated. One of the important developments in which Werner Forssmann participated with the Medical University Clinic of Cologne was the selective pulmonary angiography.

Acute BDNF and cortisol response to low intensity exercise and following ramp incremental exercise to exhaustion in humans.

The effect of short-term aerobic exercise and a following ramp incremental cycle ergometry to exhaustion on the acute response of the serum concentrations of brain derived neurotrophic factor (BDNF) and cortisol (COR) was examined in 8 healthy male athletes. Venous and capillary blood samples were drawn at rest, immediately after a 10 min warm-up period with aerobic exercise and after a ramp test to exhaustion, as well as 3, 6, 10 and 15 min post exercise. Capillary blood lactate (LA) concentration and blood gases as well as serum BDNF and COR concentrations did not change during the warm-up period. LA was increased (p<0.05) at the end of the ramp test and during recovery period while bicarbonate concentration, carbon dioxide pressure, pH and base excess were decreased (p<0.05) during this period. Serum BDNF was increased at the point of exhaustion (p<0.05) while no significant differences were found between values at rest and those during recovery period. At 10 and 15 min post incremental exercise, COR concentrations were increased (p<0.05) compared to rest. The present study is the first to demonstrate in humans that in contrast to short duration aerobic exercise immediately after a following short duration high-intensity exercise to exhaustion, there is a transient augmentation of serum BDNF concentration. Short-term response of serum BDNF and COR concentrations differs as BDNF returns to baseline level faster than COR.

[Heart and sports medicine-history and perspectives]. / Herz und Sportmedizin-historische Entwicklungen und Perspektiven.

The origin of sports medicine in the 19th and 20th century is listed. The same applies to the development of devices in the course of performance diagnostics. The required parameters for evaluation of the cardiopulmonary performance ability are mentioned in their historical context.The athlete's heart is described from its beginnings until today in its differently characterized clinical concepts. The secured facts are provided in detail in combination with modern investigation techniques.A particular sports medical merit in the area of cardiology is the investigation of the significance of the body periphery regarding the heart activity. The performance-limiting factors for the local aerobic dynamic endurance are specified in addition to the training methods for performance enhancement and the consequences for heart activity. The paper closes with a short description of the significance of sports medicine for today's rehabilitative cardiology.

Physiological responses to nordic walking, walking and jogging.

The goal of this study was to evaluate the physiological responses during incremental field tests (FT) in nordic walking (NW), walking (W) and jogging (J). Fifteen healthy middle-aged women participated in three FT. Heart rate (HR) and oxygen uptake (V(O)(2)) were monitored continuously by portable analyzers. Capillary blood lactate (La) was analyzed at rest and after every stage of the FT. The disciplines showed differences during stage 1.8 and 2.1 m s(-1) for V(O)(2) between NW and W (P < 0.05). The maximum value was measured at 1.8 m s(-1 )(8%). In accordance with La, V(CO)(2) was higher in NW compared with W during all stages (P < 0.05) and even higher in NW compared with J during 2.1 and 2.4 m s(-1). While there were higher HR for NW and W at 2.4 m s(-1) than in J (P < 0.01), there were increases for HR at fixed values of 2 (La2) and 4 (La4) mmol l(-1 )lactate for J compared with NW and W (P < 0.01). Although the speed of NW was slower than that of W at La2 and La4 (P < 0.05), there were no differences for the HR and the V(O)(2) Our results demonstrate that metabolic responses are a helpful instrument to assess the intensity during bipedal exercise. As NW speed at submaximal lactate levels is lower than in W and J, W and J test measures of HR and V(O)(2) are not suitable for NW training recommendations. Additionally, the V(O)(2) formed by performing NW is not as high as previously reported.

Bicarbonate reduces serum prolactin increase induced by exercise to exhaustion.

PURPOSE: The aim of the study was to examine the effect of acid-base status on serum prolactin (PRL) concentration postexercise. METHODS: Seven male recreational athletes participated in two experimental trials separated by 1 wk. In the respective trial, subjects received either a placebo infusion (normal isotonic saline) or an alkali infusion (isotonic sodium bicarbonate) before and during exercise. Venous and capillary blood samples were drawn at rest, immediately after a 10-min warm-up period, and after a maximal ramp test on a cycle ergometer, as well as at 3, 6, 10, and 15 min postexercise. RESULTS: Power output, HR, capillary blood lactate concentration, carbon dioxide pressure (PCO2), and partial oxygen pressure (PO2) did not differ between trials at any point in time. Capillary PO2 did not change from resting values, but a significant increase (P < 0.05) was found from the end of warm-up to 3 min of the recovery period. Exercise induced a significant (P < 0.01) decrease in capillary blood bicarbonate concentration (HCO3-), pH, base excess (BE), and PCO2 at exhaustion and during the recovery period. Significantly higher HCO3-, pH, and BE were found during bicarbonate infusion and postexercise in comparison with the placebo trial. Serum PRL concentration was significantly increased 3 min postexercise until the end of the placebo trial, whereas after bicarbonate infusion, serum PRL concentration did not change from values at rest. Significant (P < 0.01) differences between trials in serum PRL concentration were found 10 and 15 min postexercise. CONCLUSIONS: The present study suggests that acidosis is a stimulus for exercise-induced PRL secretion.

Effects of mild leg exercise in a seated position on haemostatic parameters under normobaric hypoxic conditions.

This study tested the hypothesis that in humans mild leg exercise affects haemostasis in normobaric hypoxia and thus avoids the development of a deep venous thrombosis (DVT). Eight young men breathed in a 15.4% oxygen in nitrogen gas mixture for 2 hrs while seated at rest (R) or seated and performing a 3-min mild leg exercise program (Ex) at 15-min intervals to assess the impact of mild leg exercise on haemostatic parameters related to the risk of developing DVT, as has been discussed for hypobaric hypoxic conditions during commercial airline travel. Capillary blood gases were analysed every 30 min. Heart rate was monitored continuously. Haemostatic parameters were analysed from venous blood at the beginning, after 1 and 2 hrs, and after a 30-min resting period in normoxic conditions. Plasminogen-activator-inhibitor-1 diminished in both tests in hypoxia, but not after the resting period. Antithrombin-III decreased in R in the hypoxic period. Platelet count, international normalized ratio, partial thromboplastin time remained unchanged, as did highly sensitive parameters like tissue-plasminogen-activator, alpha2-antiplasmin, d-dimers, thrombin-antithrombin-III-complexes, and prothrombin-fragments 1 and 2. The haematocrit decreased significantly in R. The mild leg execise prevented the decrease of antithrombin-III and caused an increase in haematocrit after an initial drop in the first hour. The present study revealed that normobaric hypoxia did not have clinically relevant effects on haemostasis in humans. Mild leg exercise carried out under those conditions did not lead, via alterations in haemostasis, to a reduced risk of DVT.