Exercise-induced hypoxaemia in highly trained athletes

Traditionally, the pulmonary system has not been considered the limiting factor in determining maximal oxygen uptake (VO2max) in healthy individuals since arterial oxygen-haemoglobin saturation is thought to remain high during intense exercise. However, there appears to be a major exception to this rule. Recent evidence suggests that arterial hypoxaemia results during heavy exercise in well trained individuals with a high VO2max. Further, the degree of arterial desaturation is inversely related to VO2max. This exercise-induced hypoxaemia does not appear to be due to hypoventilation although athletes who have limited hyperventilation seem to exhibit the lowest arterial oxygen-haemoglobin saturation. A significant venoarterial shunt has been ruled out as a primary cause of the hypoxaemia based on both experimental and theoretical considerations. Therefore, it appears that the exercise-induced hypoxaemia seen in highly trained athletes during heavy exercise is primarily due to diffusion limitations and ventillation-perfusion inequality. It is postulated that incomplete diffusion in the healthy lung may be due to a rapid red blood cell transit time through the pulmonary capillary. In summary, recent findings suggest that the limits of the human pulmonary system may be reached or even exceeded during intense exercise in some individuals. In light of these findings the role of the pulmonary system as a limiting factor during maximal exercise in the highly trained endurance athlete warrants further investigation.     

Basophil releasability in young highly trained and older athletes

PURPOSE: Exercise-induced hypoxemia in highly trained athletes is associated with an increase in histamine release during exercise. The cells most implicated in blood histamine release are basophils. The aim of this study was to determine whether high-level endurance training induces modifications in histamine releasability from human basophils. METHODS: Seven young highly trained athletes (YA) [aged 26.1+/-1.3 yr (mean +/- SEM)] and seven master athletes (MA) (64.4+/-4.1 yr), all known to develop exercise-induced hypoxemia, were respectively compared with seven young untrained men (YC) (23.0+/-1.5 yr) and seven older untrained men (OC) (61.6+/-1.3 yr). During an incremental exhaustive exercise, blood samples for measurement of anti-IgE-induced histamine release from leukocytes were drawn at rest, VO2max, and recovery. RESULTS: Basophils from "leukocyte-rich" supernatant in YA and MA showed significantly higher histamine release induced by anti-IgE (1 microg x mL(-1) than, respectively, YC (P<0.01) and OC (P<0.05) at rest, VO2ax (P<0.01), and recovery (P<0.01). Basophils in YA and MA also showed a histamine release induced by anti-IgE that was higher at VO2max than at rest (respectively. P<0.01 and P<0.05), but this change was not found in the control groups. CONCLUSION: In conclusion, the basophils in highly trained endurance athletes, both young and older, showed higher anti-IgE-induced histamine release than those of untrained men. This effect of high-level training seemed to be potentiated by exercise.     

Ventilatory threshold in various groups of highly trained athletes

The ventilatory threshold (VT) was determined on a treadmill in highly trained male marathon, male and female long-distance, young male long-distance, adult male and female and young female middle-distance runners, modern pentathlonists, adult canoeists of both sexes, young male canoeists and football players, and on a bicycle ergometer in table tennis players, water slalom paddlers, young female canoeists rowers, and ice hockey players. Young female canoeists were also examined on the paddling ergometer and rowers on the rowing ergometer. VT expressed in %VO2 max was higher the longer the duration of racing performance (in marathoners 86.7%). %VO2 max at the VT level depends on the type of load and is higher the better the organism is adapted to a load. In young female canoeists and rowers examined on the bicycle ergometer, we found the VT level at 74.2% and 74.6% of %VO2 max, respectively. In the case of specific loading, we recorded 84.8% and 85.0% of %VO2 max, respectively, in the same athletes. In the case of nonspecific loading highly trained individuals may have low VT values close to the level characteristic for normal subjects. In relatively equally trained young and adult athletes we did not find significant differences in %VO2 max at the VT level (for long-distance runners, 85.2% and 85.3%, respectively, in female middle-distance runners, 82.8% and 82.7%, respectively, and in canoeists 81.3% and 78.9% of %VO2 max, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Electrocardiographic changes in 1000 highly trained junior elite athletes

OBJECTIVES: To evaluate the spectrum of electrocardiographic (ECG) changes in 1000 junior (18 or under) elite athletes. METHODS: A total of 1000 (73% male) junior elite athletes (mean (SD) age 15.7 (1.4) years (range 14-18); mean (SD) body surface area 1.73 (0.17) m2 (range 1.09-2.25)) and 300 non-athletic controls matched for gender, age, and body surface area had a 12 lead ECG examination. RESULTS: Athletes had a significantly higher prevalence of sinus bradycardia (80% v 19%; p<0.0001) and sinus arrhythmia (52% v 9%; p<0.0001) than non-athletes. The PR interval, QRS, and QT duration were more prolonged in athletes than non-athletes (153 (20) v 140 (18) milliseconds (p<0.0001), 92 (12) v 89 (7) milliseconds (p<0.0001), and 391 (27) v 379 (29) milliseconds (p = 0.002) respectively). The Sokolow voltage criterion for left ventricular hypertrophy (LVH) and the Romhilt-Estes points score for LVH was more common in athletes (45% v 23% (p<0.0001) and 10% v 0% (p<0.0001) respectively), as were criteria for left and right atrial enlargement (14% v 1.2% and 16% v 2% respectively). None of the athletes with voltage criteria for LVH had left axis deviation, ST segment depression, deep T wave inversion, or pathological Q waves. ST segment elevation was more common in athletes than non-athletes (43% v 24%; p<0.0001). Minor T wave inversion (less than -0.2 mV) in V2 and V3 was present in 4% of athletes and non-athletes. Minor T wave inversion elsewhere was absent in non-athletes and present in 0.4% of athletes. CONCLUSIONS: ECG changes in junior elite athletes are not dissimilar to those in senior athletes. Isolated Sokolow voltage criterion for LVH is common; however, associated abnormalities that indicate pathological hypertrophy are absent. Minor T wave inversions in leads other than V2 and V3 may be present in athletes and non-athletes less than 16 but should be an indication for further investigation in older athletes.     

Hemoglobin desaturation in highly trained athletes during heavy exercise

It has been generally accepted that during exercise at sea level, the pulmonary system of normal, healthy individuals is capable of maintaining arterial oxygen tension at near resting levels. However, recent evidence questions whether this generalization applies to the highly trained endurance athlete who is capable of achieving very high levels of metabolic demand. Hence, the purpose of these experiments was to examine the relationship between maximal oxygen consumption (VO2max) and arterial oxygen-hemoglobin saturation (%SaO2) during short-term heavy exercise in trained athletes and untrained individuals. Ten trained distance runners and 7 untrained males exercised at 95% of VO2max for 3 min. Minute-by-minute measurement of %SaO2 was obtained via ear oximetry. The correlation coefficients between %SaO2 and VO2max during exercise were r = -0.68, r = -0.74, and r = -0.72 (P less than 0.05) for minutes 1 through 3, respectively. In general those individuals with the highest VO2max showed the greatest decrease in %SaO2. By comparison there was no difference (P greater than 0.05) in resting %SaO2 between the trained (96.3 +/- 0.2% [SE]) and the untrained (96.3 +/- 0.4%) subjects. However, at minute 3 of exercise, %SaO2 was significantly lower (P less than 0.05) in the trained subjects (87.0 +/- 0.7%) than in the untrained subjects (92.6 +/- 0.7%). These data demonstrate that arterial desaturation occurs in healthy, highly trained endurance athletes during heavy exercise and that the level of the arterial desaturation is inversely related to VO2max.     

Influence of sports participation and menarche on bone mineral density of female high school athletes

Weight-bearing exercise during adolescence may enhance peak bone mineral density (BMD) and reduce osteoporosis risk. The association of sports participation before and after menarche with areal BMD (by central DXA) was investigated in 99 female high school athletes (age 15.5+/-1.3 year). The frequency and duration of structured sports (school-based or other organized team) were assessed using an interviewer-assisted questionnaire. Overall, the average number of years of weight-bearing sport participation was 7.4+/-3.4 years; 72% of the athletes began sport participation before menarche. Training patterns and BMD were examined by tertiles of yearly weight-bearing sport participation (hours/year) before (WBpre), after (WBpost) menarche, and in total (WBtotal). After adjusting for chronological age, gynecological age, and BMI, compared to athletes in the WBtotal low tertile, athletes in the WBtotal high tertile had significantly greater BMD at the spine (p=0.009), total hip (p=0.03), trochanter (p=0.03), and total body (p=0.009). Similar patterns were found by WBpre or WBpost status, separately, with the exception of spine BMD which was significantly different across tertiles in WBpost only (p<0.01). While the number of years of participation was similar across tertiles of WBtotal, the number of months/year was significantly greater among athletes in the high tertile than athletes in the low tertile (9.2+/-3.4 month/year versus 5.0+/-2.9 month/year, respectively (p<0.001)). These results indicate that near year-round participation in structured weight-bearing sports during early adolescence may help young girls optimize bone mineral accrual during these critical years, and may decrease their risk of osteoporosis with advancing age.     

Effects of beta-hydroxy-beta-methylbutyrate and creatine monohydrate supplementation on the aerobic and anaerobic capacity of highly trained athletes

AIM: The aim of this study was to investigate the effects of 6 wks oral supplementation of beta-hydroxy-beta-methylbutyrate (HMB) and a mixture of HMB and creatine monohydrate (HMBCr) on aerobic and anaerobic capacity in highly trained athletes. It was hypothesised that HMB and HMBCr would have positive effects on aerobic and anaerobic power. METHODS: A prospective study involving a repeated measures design was utilised where subjects underwent testing prior to, and immediately after, a 6 wks supplementation period. Elite, male rugby league players (n=27) were divided into 3 groups, a control group (n=6), a HMB group (3 g/d; n=10) and a HMBCr group (3 g/d HMB + 3 g/d Cr; n=11). Testing involved a multistage fitness test to determine aerobic power and a 60 sec maximal cycle test to determine anaerobic capacity. Peak power, total work and peak lactate levels were measured in the anaerobic cycle test. RESULTS: Two-way repeated measures ANOVA revealed no effect of HMB or HMBCr on any of the measured parameters in comparison to the control group. CONCLUSION: Aerobic and anaerobic ability of highly trained male athletes is unaffected by 6 wks oral supplementation with HMB or a combination of HMB and creatine monohydrate.     

Induction and decay of short-term heat acclimation in moderately and highly trained athletes

A rethinking of current heat-acclimation strategies is required as most research and advice for improving physiological strain in the heat includes maintaining hydration using long-term acclimation protocols (>10 days). Furthermore, these strategies have tended to use untrained and moderately trained participants. Therefore, the aims of this review were to (i) investigate the effectiveness of short-term heat acclimation (STHA) with moderately and highly trained athletes; (ii) determine the importance of fluid regulatory strain, which has a thermally independent role in heat adaptation; (iii) assess the impact of STHA on a marker of thermotolerance (inducible heat-shock protein 70 [HSP70]); and (iv) provide further information on the decay of acclimation to heat. The review suggests that 5-day STHA is effective, and adaptations may be more pronounced after fluid regulatory strain from a dehydration-acclimation regimen. Furthermore, highly trained athletes may have similar physiological gains to those who are less trained using STHA. However, research has tended to focus on untrained or moderately trained participants and more information is required for highly trained populations. HSP70 response is upregulated across STHA. This indicates increased thermotolerance and protective adaptive change that may indicate HSP70 response as a useful marker of heat acclimation. Physiological adaptations after heat acclimation are relatively short term and may vanish only a few days or weeks after removal from heat exposure. From a practical perspective 5-day STHA may be the preferred acclimation regimen for moderately and highly trained athletes as it has been shown to be effective, less expensive and less likely to disrupt the tapering for competition in elite performers. Furthermore, updated information on the time course of acclimation decay may allow a reliable estimate of how long individuals can be free from heat exposure before reacclimation is required. This is particularly pertinent in present times as many athletes, civilians and military personnel increasingly have to relocate to different climates of the world, often within a short period of time.     

Sex, sport, and body-size dependency of hematology in highly trained athletes

Blood hemoglobin concentration, hematocrit, red cell count, white cell count (WBC), and plasma ferritin concentration were measured on 1604 occasions from 706 nationally ranked athletes in 12 sports. The blood samples were taken from a forearm vein amidst periods of moderate to intense training but at least 6 h after a training session. A multiple regression model, accounting for correlations between variables and incorporating the categorical variables of sex and sport revealed the following. Each blood variable was found to be dependent on body mass index, (mass/height2, BMI), with the exception of WBC in the males. As BMI increased so did the magnitude of these blood variables (P less than 0.01). Each blood variable was also dependent on the sport (P less than 0.01), significant differences being observed between several sports in each case. Furthermore, as has been previously reported, the magnitude of the blood variables was dependent on the sex of the athlete, each being significantly greater in males (P less than 0.01), with the exception of the WBC, which was greater in females (P less than 0.01). These data indicate that the rationality of interpreting the hematology in highly trained athletes may be increased by taking BMI and sport into account, as well as gender.     

Effects of high-intensity exercises on 13C-nandrolone excretion in trained athletes.

OBJECTIVE: Nandrolone is an anabolic steroid widely used in several sports. The numerous nandrolone positive cases in the recent years (International Olympic Committee statistics) led to several studies in the antidoping field. Nevertheless, essential questions pertaining to nandrolone endogenous production, the effects of physical exercise on the excretion of nandrolone metabolites, and contamination from nutritional supplements must still be addressed. The purpose of this study was to evaluate the influence of exhaustive exercises on 19-norandrosterone (19-NA) and 19-noretiocholanolone (19-NE) urinary excretion rates after administration of labeled nandrolone. SETTING AND PARTICIPANTS: A total of 34 healthy male Caucasian volunteers from the Institute of Sports Sciences and Physical Education (University of Lausanne) applied to participate in the study. All subjects were free from any physical drug addiction and were instructed strictly to avoid any nutritional supplement or steroid before and during the study. The participants were randomly dispatched in 2 groups in a double-blind way: a placebo group and a group treated with C-labeled nandrolone. MAIN OUTCOME MEASUREMENTS: The urinary concentrations of the 2 main nandrolone metabolites, 19-NA and 19-NE, were measured using gas chromatography coupled with mass spectrometry. In addition, clinical parameters such as creatinine, total protein, and beta2-microglobuline levels were determined using immunologic assays. RESULTS: After an oral ingestion of a 25 mg 3,4-C2-nandrolone dose, followed by a second identical dose 24 hours later, 19-NA and 19-NE could be detected in the urine for a period of 6 days after the initial intake. Despite several interesting observations, the measurements were very scattered and did not appear to be significantly influenced by exercise sessions in the athlete population. CONCLUSIONS: The results of this study suggest that physical exercise cannot be considered as a reliable parameter that systematically affects nandrolone metabolite concentrations in the urine.     

Red blood cell variables in highly trained pubescent athletes: a comparative analysis

BACKGROUND: A suboptimal haematological status has often been recorded in athletes involved in intensive physical activity. There have even been reports of "sports anaemia" associated with intensive physical exercise. However, studies on the effect of different types of exercise practiced over a long period of time on the red blood cell variables in pubescent athletes are very few. AIM: To assess the basic red blood cell variables in highly trained pubescent athletes from different sports and to compare the results with those for a control untrained group. Sex related differences in these variables were also assessed. METHODS: 876 highly trained athletes (559 boys and 317 girls) were included in the study. Their mean (SEM) age, weight, and duration of training were: 14.01 (0.06) years, 56.24 (0.52) kg, and 3.52 (0.07) years respectively. The control group consisted of 357 untrained subjects (171 boys and 186 girls) with mean (SEM) age and weight of 14.58 (0.09) years and 57.75 (0.67) kg. The group of athletes was divided into seven subgroups according to the sport practiced: athletics (105), swimming (107), rowing (230), wrestling (225), weight lifting (47), various team sports (92), and other sports (67). Venous blood samples were drawn from the cubital vein, and the red blood cell count, packed cell volume, haemoglobin concentration, and mean corpuscular volume were measured. Statistical indices were computed for each group and for each variable, and analysis of variance factorial analysis was performed to evaluate the statistical significance of the differences detected. RESULTS: The highly trained group was found to have lower red blood cell count, packed cell volume, and haemoglobin concentration (p<0.001) than the control untrained group (4.61 (0.01) x 10(12)/l v 4.75 (0.02) x 10(12)/l, 0.389 (0.001) v 0.404 (0.002) l/l, and 133.01 (0.38) v 139.9 (0.62) g/l respectively). These variables were lower for the boys of the trained group than for the boys of the control group (p<0.001), and similarly for the girls (p<0.001). The lowest red blood cell count, packed cell volume, and haemoglobin concentration were measured in blood samples from the boys of the swimming subgroup (4.54 (0.06) x 10(12)/l, 0.386 (0.006) l/l, and 129.38 (1.80) g/l respectively) and the rowing subgroup (4.66 (0.03) x 10(12)/l, 0.400 (0.003) l/l, and 136.21 (0.94) respectively). The same distribution was found for the girls: lowest in the rowing subgroup (4.32 (0.04) x 10(12)/l, 0.314 (0.003) l/l, and 124.27 (0.93) g/l) and the swimming subgroup (4.40 (0.05) x 10(12)/l, 0.375 (0.005) l/l, and 125.90 (1.30) g/l). No differences were found in the mean corpuscular volume. CONCLUSIONS: Continuous (more than one year) high intensity sports training (twice a day/five days a week) results in a decrease in the basic red blood cell variables in pubescent boys and girls, this being most pronounced in the submaximal sports.     

Body composition measurement in highly trained male athletes. A comparison of three methods

BACKGROUND: The purpose of the present study was to evaluate the differences in the body composition estimate of highly trained male athletes by three different methods: dual-energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA) and skinfold thickness measurement (SFT). METHODS: The study occurred during a non-intensive training period. The measurements were performed at the Human Physiology laboratory. Participants: forty-three male athletes (19 waterpolo, 9 judo, 15 karate) who exercised regularly at least three hours per day, six days per week. Measurements: DXA, BIA and SFT measurements of percentage fat mass (%FM) and the amount of fat-free mass (FFM) were performed. Statistical analyses: the different %FM estimates by the three methods were compared using a one-way ANOVA, with posthoc Bonferroni test when values were significantly different. The same test was used to compare FFM values. The coefficient of variation (CV%=100xSD/mean) was calculated for each methods. Methodological differences among the various methods were analysed with the method of Bland-Altman. RESULTS: ANOVA test showed significant differences among the three methods. In particular, DXA significantly (p<0.001) overestimated %FM (12.4+/-4.1%) and underestimate FFM (67.0+/-6.9 kg) respect to SFT (7.8+/-0.9 % and 71.0+/-8.2 kg) and BIA (9.9+/-1.4% and 69.4+/-7.9 kg). Also Bland-Altman comparison among the estimates indicated wide differences between methods. CONCLUSIONS: DXA provides different body composition estimates than those derived from skinfold thickness measurement and BIA, so that the methods should not be used interchangeably.     

Effect of maturational timing on bone health in male adolescent athletes engaged in different sports: The PRO-BONE study

Objectives

To describe differences in bone outcomes according to biological age in male athletes participating in osteogenic (OS) or non-osteogenic (NOS) sports.

Energy system contribution during 200- to 1500-m running in highly trained athletes

PURPOSE: The purpose of the present study was to profile the aerobic and anaerobic energy system contribution during high-speed treadmill exercise that simulated 200-, 400-, 800-, and 1500-m track running events. METHODS: Twenty highly trained athletes (Australian National Standard) participated in the study, specializing in either the 200-m (N = 3), 400-m (N = 6), 800-m (N = 5), or 1500-m (N = 6) event (mean VO2 peak [mL x kg(-1)-min(-1)] +/- SD = 56+/-2, 59+/-1, 67+/-1, and 72+/-2, respectively). The relative aerobic and anaerobic energy system contribution was calculated using the accumulated oxygen deficit (AOD) method. RESULTS: The relative contribution of the aerobic energy system to the 200-, 400-, 800-, and 1500-m events was 29+/-4, 43+/-1, 66+/-2, and 84+/-1%+/-SD, respectively. The size of the AOD increased with event duration during the 200-, 400-, and 800-m events (30.4+/-2.3, 41.3+/-1.0, and 48.1+/-4.5 mL x kg(-1), respectively), but no further increase was seen in the 1500-m event (47.1+/-3.8 mL x kg(-1)). The crossover to predominantly aerobic energy system supply occurred between 15 and 30 s for the 400-, 800-, and 1500-m events. CONCLUSIONS: These results suggest that the relative contribution of the aerobic energy system during track running events is considerable and greater than traditionally thought.     

Failure to repeatedly supercompensate muscle glycogen stores in highly trained men

PURPOSE: It is not known whether it is possible to repeatedly supercompensate muscle glycogen stores after exhaustive exercise bouts undertaken within several days. METHODS: We evaluated the effect of repeated exercise-diet manipulation on muscle glycogen and triacylglycerol (IMTG) metabolism and exercise capacity in six well-trained subjects who completed an intermittent, exhaustive cycling protocol (EX) on three occasions separated by 48 h (i.e., days 1, 3, and 5) in a 5-d period. Twenty-four hours before day 1, subjects consumed a moderate (6 g.kg)-carbohydrate (CHO) diet, followed by 5 d of a high (12 g.kg.d)-CHO diet. Muscle biopsies were taken at rest, immediately post-EX on days 1, 3, and 5, and after 3 h of recovery on days 1 and 3. RESULTS: Compared with day 1, resting muscle [glycogen] was elevated on day 3 but not day 5 (435+/-57 vs 713+/-60 vs 409+/-40 mmol.kg, P<0.001). [IMTG] was reduced by 28% (P<0.05) after EX on day 1, but post-EX levels on days 3 and 5 were similar to rest. EX was enhanced on days 3 and 5 compared with day 1 (31.9+/-2.5 and 35.4+/-3.8 vs 24.1+/-1.4 kJ.kg, P<0.05). Glycogen synthase activity at rest and immediately post-EX was similar between trials. Additionally, the rates of muscle glycogen accumulation were similar during the 3-h recovery period on days 1 and 3. CONCLUSION: We show that well-trained men cannot repeatedly supercompensate muscle [glycogen] after glycogen-depleting exercise and 2 d of a high-CHO diet, suggesting that the mechanisms responsible for glycogen accumulation are attenuated as a consequence of successive days of glycogen-depleting exercise.     

Effects of inhaled bronchodilators and corticosteroids on exercise induced arterial hypoxaemia in trained male athletes

Objectives: To determine the effect of prophylactic treatment with an inhaled bronchodilator and anti-inflammatory on arterial saturation (SaO₂) in trained non-asthmatic male athletes with exercise induced arterial hypoxaemia (EIAH). Methods: Nine male athletes (mean (SD) age 26.3 (6.7) years, height 182.6 (7.9) cm, weight 79.3 (10.5) kg, VO₂MAX 62.3 (6.3) ml/kg/min, SaO₂MIN 92.5 (1.1)%) with no history of asthma were tested in two experimental conditions. A combination of a therapeutic dose of salbutamol and fluticasone or an inert placebo was administered in a randomised crossover design for seven days before maximal cycling exercise. Oxygen consumption (VO₂), ventilation (VE), heart rate (HR), power output, and SaO₂ were monitored during the exercise tests. Results: There were no significant differences between the drug (D) and placebo (P) conditions for minimal SaO₂ (D = 93.6 (1.4), P = 93.0 (1.1)%; p = 0.93) VO₂MAX (D = 61.5 (7.2), P = 61.9 (6.3) ml/kg/min; p = 0.91), peak power (D = 444.4 (48.3), P = 449.4 (43.9) W; p = 0.90), peak VE (D = 147.8 (19.1), P = 149.2 (15.5) litres/min; p = 0.82), or peak heart rate (D = 182.3 (10.0), P = 180.8 (5.5) beats/min; p = 0.76). Conclusions: A therapeutic dose of salbutamol and fluticasone did not attenuate EIAH during maximal cycling in a group of trained male non-asthmatic athletes.     

Interleukins 1-beta, -8, and histamine increases in highly trained, exercising athletes

PURPOSE: Exercise-induced hypoxemia (EIH) in highly trained athletes is associated with an increase in histamine release (%H) during exercise. Certain cytokines, known as histamine-releasing factors, are capable of interacting with basophils and/or mast cells to cause the release of histamine. The aim of this study was to determine whether the increased histamine release in highly trained athletes is related to a high plasma level in interleukin-1 beta (IL-1beta), IL-3, or IL-8 in arterial blood. METHODS: These parameters were measured in 11 endurance athletes (23.2 +/- 1.2 yr (mean +/- SEM)) known to develop exercise-induced hypoxemia and 11 control subjects (25.0 +/- 1.1 yr) at rest, during an incremental exhaustive exercise test, and at the fifth minute of recovery. RESULTS: Histamine release increased between rest and maximal exercise in the athletes (P < 0.01), showing a strong correlation with EIH (r = 0.76, P < 0.01) and was unchanged in the controls. IL-3 plasma concentration was not altered with training and/or with exercise. Circulating IL-8 levels were not different between trained and untrained subjects at any testing level and increased at maximal exercise in both groups (P < 0.01). IL-1beta plasma levels were higher in athletes than in controls (P < 0.05) at each testing level and increased during exercise only in the athletes (P < 0.05). CONCLUSION: An elevated concentration of IL-1beta in plasma and its association with increased IL-8 levels during exercise may partly explain the increase in %H associated with EIH in highly trained athletes. Histamine, IL-8, and IL-1beta releases during exercise reflect an inflammatory reaction, which is probably involved in EIH.