Skeletal muscle enzymes and fiber composition in male and female track athletes.

Muscle samples were obtained from the gastrocnemius of 17 female and 23 male track athletes, 10 untrained women, and 11 untrained men. Portions of the specimen were analyzed for total phosphorylase, lactic dehydrogenase (LDH), and succinate dehydrogenase (SDH) activities. Sections of the muscle were stained for myosin adenosine triphosphatase, NADH2 tetrazolium reductase, and alpha-glycerophosphate dehydrogenase. Maximal oxygen uptake (VO2max) was measured on a treadmill for 23 of the volunteers (6 female athletes, 11 male athletes, 10 untrained women, and 6 untrained men). These measurements confirm earlier reports which suggest that the athlete's preference for strength, speed, and/or endurance events is in part a matter of genetic endowment. Aside from differences in fiber composition and enzymes among middle-distance runners, the only distinction between the sexes was the larger fiber areas of the male athletes. SDH activity was found to correlate 0.79 with VO2max, while muscle LDH appeared to be a function of muscle fiber composition. While sprint- and endurance-trained athletes are characterized by distinct fiber compositions and enzyme activities, participants in strength events (e.g., shot-put) have relatively low muscle enzyme activities and a variety of fiber compositions.     

蹲跳、反向跳和下落跳的膝关节屈伸肌群肌电信号分析

目的：通过观察肌电图（EMG）的变化,了解运动员与普通中学生在纵跳过程中,膝关节屈伸肌群工作特点,为运动员科学选材提供依据。方法：30名男女青少年运动员和30名男女普通中学生进行各种形式纵跳（蹲跳、反向跳、下落跳）,测试膝关节屈伸肌群的EMG变化情况。结果：主动肌（股外肌）EMG的变化存在性别差异,随着下肢工作强度的增加,男运动员积分肌电图（iEMG)和平均功率频率（Fmean)均没有显著变化,女运动员iEMG增加,Fmean没有显著变化,对抗肌（股二头肌）,随着下肢工作强度的增加。青少年运动员EMG活动变化较小,而普通中学生的EMG活动明显增加。结论：在增加工作负荷的过程中,男运动员膝关节伸肌群以提高效率为主,女运动员以提高肌肉的募集数量为主;运动员的对抗肌协调水平高于普通中学生。     

Athletes'' pseudoanaemia

To characterize the so-called pseudoanaemia of endurance-trained athletes, the plasma volume (PV), red cell volume (RCV) and total blood volume (TBV) of 12 male and 12 female athletes and 5 male and 5 female nonexercising controls were measured using 125I-labelled human serum albumin and 51Cr-labelled erythrocytes. The mean PV of the male athletes (52.8 ml.kg-1) was 37.5% higher than that of the controls (38.4 ml.kg-1), while the 18.1% increase measured in the female runners (51.5 ml.kg-1) over the controls (43.6 ml.kg-1) was a novel observation. Although the RCV was significantly greater (34.7%) in male athletes (32.6 ml.kg-1 vs 24.2 ml.kg-1 in the controls), a similar elevation (3.6%) was not found in the female athletes (25.9 ml.kg-1) compared to the sedentary women (22.8 ml.kg-1). This could have been due to iron-limited erythropoiesis because the RCV of the female athletes defined as clinically anaemic was markedly lower that of the nonanaemic women (P less than 0.05). The elevated plasma protein mass and concentration measured in the athletes partly accounted for their expanded PV. It was concluded that the decreased blood haemoglobin levels reported in the endurance athletes was largely a dilutional effect.     

Sclerostin concentrations in athletes: role of load and gender

Bone mass is the net product of formation and resorption, which are closely regulated by the equilibrium between endogenous/exogenous factors. Sclerostin inhibits the Wnt canonical signaling and is considered an anti-anabolic factor. We compared sclerostin serum concentrations between genders in athletes belonging to different sport disciplines, characterized by a different weight-bearing, and in their sedentary counterparts in order to study the possible link between bone metabolism in athletes and its peripheral concentration. We also compared sclerostin levels with bone alkaline phosphatase activity, a marker of bone formation. Sixty-one elite athletes, belonging to weight-bearing (15 male rugby players, 11 male enduro racers, 8 female basketball players), high-impact (6 male tennis players, 8 female ice skaters), non weight-bearing sports (13 male cyclists) and 16 sedentary controls were enrolled. Higher levels of sclerostin were found in females. Sclerostin was higher in weight-bearing than in non-weight-bearing disciplines in males. Significant inverse age-related correlation was found. Higher bone alkaline phosphatase activity was observed in females. The young adult elite athlete represents a peculiar physiologic model for studying sclerostin behavior: the applied load increased the marker concentrations, testifying a high bone turnover rate; however, a gender effect is evident.     

Serum lactate dehydrogenase fails to predict response to treatment and survival in acute non-lymphocytic leukemia

Total serum lactate dehydrogenase (LDH) activity was measured in 514 adult patients with de novo acute non-lymphocytic leukemia (ANLL) prior to any treatment and was compared with several disease features, with response to induction treatment, and with relapse-free survival. LDH was higher in the M4 and M5 FAB cytological subtypes and was positively correlated with the white blood cell count (WBC). The proportion of remissions, of deaths during induction, and of failure, and the duration of relapse-free survival, were clearly unrelated to LDH activity, in the whole series as well as in different age groups (below 40 years, and 40 to 60 years) and in any FAB cytological subtype. Multivariate analysis showed that only WBC and sex (female better than male) were marginally related with relapse-free survival. These data provide conclusive evidence that LDH does not help in defining the prognosis of adult ANLL, either because enzyme activity fails to reflect the number and proliferation rate of leukemic cells efficiently, or because with current standard treatment these features are of borderline importance, in contrast with acute lymphocytic leukemia and malignant lymphomas.     

不同日龄和吊飞过程中桔小实蝇成虫飞行肌能量代谢相关酶活性的变化

【目的】明确桔小实蝇Bactrocera dorsalis(Hendel)飞行肌对能源物质的利用。【方法】通过生化方法测定了能源物质代谢相关5种酶[3-磷酸甘油醛脱氢酶(GAPDH)、3-磷酸甘油脱氢酶(GDH)、乳酸脱氢酶(LDH)、柠檬酸合酶(CS)和3-羟酰辅酶A脱氢酶(HOAD)]活性的变化。【结果】桔小实蝇成虫中所测的5种酶活性随日龄的变化而变化,4日龄GAPDH,GDH,LDH和CS活性最高,20日龄HOAD活性最高。吊飞过程中,GAPDH,GDH和CS的活性变化基本一致,随吊飞时间的延长活性逐渐升高;LDH和HOAD的活性变化雌、雄虫完全不同。雄虫LDH活性除吊飞2 h外其他时间均高于静息状态,雌虫则始终低于静息状态;雄虫HOAD活性只有吊飞24 h低于静息状态水平,而雌虫吊飞后HOAD活性一直在静息状态水平及以下波动。【结论】桔小实蝇飞行所利用的能源物质包括糖类和脂肪,以糖类能源为主。吊飞过程中,雄虫除可以进行高速有氧代谢以外,还具备一定的无氧代谢能力,而雌虫只进行有氧代谢;雄虫能利用脂肪供给能量,雌虫则几乎不动用脂肪。研究结果为进一步阐明桔小实蝇的迁飞行为机制提供了依据。     

Pulmonary blood volume and interventricular circulation time in physically trained and untrained subjects.

Resting pulmonary plasma and blood volumes (PPV and PBV), interventricular circulation time (IVCT), cardiac and stroke index (CI and SI), heart rate (HR), total plasma and blood volumes (PV and BV) were determined in athletes (two male groups representing different types of sport activities, and one female group) and compared with those of non-athletes (one male and one female group). In addition to high maximal aerobic power, the athletes were characterized by greater SI, BV and PV and lower resting HR than non-athletes, PPV and PBV were significantly larger and IVCT significantly longer in the trained than in the untrained groups, probably reflecting an improved capacity of the pulmonary circulation. PPV as per cent of PV was almost equal in all the groups, indicating the same distribution of plasma between the pulmonary and systemic circulation. The data also indicate that total blood volume is an important determinant of the magnitude of the pulmonary vascular bed. The increased volume of flowing blood and increased stroke volume in athletes probably allows for a reduction in flow velocity and thereby a reduction in kinetic energy.     

The development of lactate and malate dehydrogenases in the C57BL-6 mouse kidney

The development of lactate dehydrogenase (LDH; EC 1.1.1.27) and malate dehydrogenase (MDH; EC 1.1.1.37) was measured in the kidney of male and female $\text{C57BL}\text{6}$ mice from ages prenatal 16 days to 80 days. Maximum reactions rates of the enzymes were measured in vitro by following the reduction of the nicotinamide-adenine dinucleotide spectrophotometrically.Analysis of variance showed no significant sex difference for LDH and MDH. There was a significant sex difference for the ratio LDH:MDH and a significant age difference for LDH, MDH, and the ratio LDH:MDH. In the male and female, LDH activity increased from prenatal 16 days to 30 days. Malate dehydrogenase activity reached adult values at 22 days in the male and at 30 days in the female. The ratio LDH:MDH in the male decreased from prenatal 16 days to 3 days, after which the ratio continued to decline to 20 days at a less rapid rate. This general pattern was also found in the female followed by a further decline in the ratio at 50 days.The development of LDH and MDH in the $\text{C57BL}\text{6}$ mouse is tissue specific and probably parallels the development of the tissue's function. In the case of the kidney, LDH and MDH development may reflect maturation of mitochondrial function and the kidney's ability to concentrate urine.     

Gender differences in changes of motor cortex excitability during elevated blood lactate levels

Gender differences in cortical excitability have been detected by using transcranial magnetic stimulation (TMS). The present study was carried out to compare the effects of high blood lactate levels, induced by performing a maximal exhausting exercise, on the excitability of the primary motor cortex in young male and female athletes. The study was carried out on 21 young males and 20 females from the Middle Distance Track Team of our university. Before the exercise, at the end, as well as 5 and 10 min after the conclusion, venous blood lactate and glucose were measured and excitability of the motor cortex was evaluated by using TMS. We observed a similar enhancement of excitability of primary motor cortex, concomitantly with an increase of blood lactate, in both young male and female athletes. However, the improvement was significantly higher (p < 0.05) in women (37.4% ± 3.97) than in men (42.0% ± 6.43), suggesting a greater sensitiveness of female cerebral cortex to blood lactate.     

Erythropoietic adaptations to endurance training

Erythropoietic adaptations involving the oxygen dissociation curve (ODC) and erythropoietin production have been implicated in the etiology of reduced blood haemoglobin concentrations in sportspersons (known as sports anaemia). A significant increase in the half-saturation pressure indicating a right-shift in the ODC was measured in 34 male [25.8-27.4 mmHg (3.44-3.65 kPa)] and 16 female (25.8-27.7 mmHg (3.44-3.69 kPa)] trained distance runners (P less than 0.01 for both genders) after completing a standard 42-km marathon. Erythrocyte 2,3-diphosphoglycerate concentrations measured concurrently were unaltered by exercise, although consistently higher in the female compared to the male athletes (P less than 0.05). The serum erythropoietin (EPO) concentrations of 15 male triathletes (26.3 U.ml-1) were significantly lower than those of 45 male distance runners (31.6 U.ml-1; P less than 0.05). However, the mean serum EPO concentrations of male and female athletes engaged in a variety of sports were not different from those of sedentary control subjects of both sexes (26.5-35.3 U.ml-1). Furthermore, the serum EPO concentrations were unaltered after prolonged strenuous exercise in 20 male marathon runners. These data suggest that the haematological status of these endurance athletes is in fact normal and that the observed shift in the ODC, while providing a physiological advantage during exercise, has no measurable effect on the erythropoietic drive.     

The effects of hydrogen peroxide promoted by homocysteine and inherited catalase deficiency on human hypocatalasemic patients

Elevated plasma homocysteine can generate oxygen free radicals and hydrogen peroxide. The enzyme catalase is involved in the protection against hydrogen peroxide. We examined the effect of oxidative stress promoted by homocysteine on erythrocyte metabolism (blood hemoglobin, MCV, folate, B12, serum LDH, LDH isoenzymes, haptoglobin) in the oxidative stress sensitive Hungarian patients with inherited catalase deficiency. The plasma homocysteine (HPLC method, Bio-Rad), folate, B12 (capture binding assay, Abbott), blood hemoglobin concentrations, blood catalase activity (spectrophotometric assay of hydrogen peroxide), and MCV values were determined in 7 hypocatalasemic families including hypocatalasemic (male:12, female:18) patients and their results were compared to those of the normocatalasemic (male:17 female: 12) family members. We found decreased (p <.036) folate (ng/ml) concentrations (male hypocatalasemic 5.44 +/- 2.81 vs. normocatalasemic 7.56 +/- 1.97, female 5.01 +/- 1.93 vs. 6.61 +/- 1.91), blood hemoglobin (p <.010, male:140.2 +/- 11.0 vs. 153.6 +/- 11.6 g/l, female: 128.4 +/- 10.9 vs. 139.6 +/- 9.2 g/l). Increased levels of MCV (p <.001) were detected in hypocatalasemic patients (male: 98.6 +/- 3.4 vs. 90.1 +/- 7.5 fl, female: 95.9 +/- 3.9 vs. 90.1 +/- 2.5 fl), plasma homocysteine (p <.049, male: 9.72 +/- 3.61 vs. 7.36 +/- 2.10 umol/l, female: 9.06 +/- 3.10 vs. 6.84 +/- 2.50 umol/l) and not significant (p >.401) plasma B12 (male: 336 +/- 108 vs. 307 +/- 76 pg/ml, female: 373 +/- 180 vs. 342 +/- 75 pg/ml). The serum markers of hemolysis (LDH, LDH isoenzymes, haptoglobin) did not show significant (p >.228) signs of oxidative erythrocyte damage. We report firstly on increased plasma homocysteine concentrations in inherited catalase deficiency. The increased plasma homocysteine and inherited catalase deficiency together could promote oxidative stress via hydrogen peroxide. The patients with inherited catalase deficiency are more sensitive to oxidative stress of hydrogen peroxide than the normocatalasemic family members. This oxidative stress might be responsible for the decreased concentration of the blood hemoglobin via the oxidation sensitive folate and may contribute to the early development of arteriosclerosis and diabetes in these patients.     

Effects of cadmium on lactate dehydrogenase activities in mouse pre-embryos at various stages

A decline in LDH activity from four-cell to late blastocyst was demonstrated in pre-embryos from F1 (C57 female X A2G male) female mice. An exposure to 0.5 or 1 microgram/ml cadmium did not affect the in vitro development of the four-cell pre-embryos and morulae or their LDH activities. At 5 or 10 micrograms/ml cadmium, the in vitro development of the treated pre-embryos was affected. Although most of the treated four-cell pre-embryos had proceeded to compaction, they became degenerated 24 h after treatment. The LDH activity of these degenerated pre-embryos was higher than that in the control blastocysts. We propose that cadmium may interfere with the general energy metabolism of the cells. This causes a reduced rate of LDH degradation, leading to a slower decline in LDH activity in cadmium-treated pre-embryos. Failure of some critical biochemical processes after cadmium treatment may ultimately lead to the subsequent degeneration of the treated pre-embryos.     

Effects of three-day bed rest on metabolic, hormonal and circulatory responses to an oral glucose load in endurance or strength trained athletes and untrained subjects.

The study was designed to find out (1) whether the effect of 3-day bed rest on blood glucose (BG) and plasma insulin (IRI) responses to glucose ingestion depends on preceding physical activity and (2) whether plasma adrenaline (A), noradrenaline (NA) and cardiovascular changes following a glucose load are modified by bed rest. Eleven sedentary students (22.5+/-0.3 yrs), 8 long distance runners (18.6+/-0.3 yrs) and 10 strength trained athletes (21.2+/-2.1 yrs) were examined before and after bed rest. Plasma IRI, BG, NA, A, heart rate (HR), and blood pressure (BP) were measured during 2 hrs following glucose (75 g) ingestion. The responses of BG and IRI to glucose load were calculated as incremental areas under the curves (auc). Both in athletes and untrained subjects bed rest markedly increased IRIauc, while BGauc was elevated only in sedentary subjects (p<0.05). The greatest increases in IRIauc and IRI/BG ratios were found in the endurance athletes. The data from all subjects (n = 29) revealed that the initial plasma NA and glucose-induced increases in NA and A were lowered after bed rest (p < 0.01). These effects were most pronounced in the endurance athletes. Bed rest did not influence HR or BP in any group. It is concluded that (1) the athletes have more adequate compensation for the bed-rest-induced decrement in insulin sensitivity than sedentary men; (2) three-day bed rest diminishes basal sympathetic activity and attenuates sympathoadrenal response to oral glucose; (3) endurance athletes have greater sympathetic inhibition than strength athletes or sedentary men.     

Altered Blood Biomarker Profiles in Athletes with a History of Repetitive Head Impacts

The long-term health effects of concussion and sub-concussive impacts in sport are unknown. Growing evidence suggests both inflammation and neurodegeneration are pivotal to secondary injury processes and the etiology of neurodegenerative diseases. In the present study we characterized circulating brain injury and inflammatory mediators in healthy male and female athletes according to concussion history and collision sport participation. Eighty-seven university level athletes (male, n = 60; female, n = 27) were recruited before the start of the competitive season. Athletes were healthy at the time of the study (no medications, illness, concussion or musculoskeletal injuries). Dependent variables included 29 inflammatory and 10 neurological injury analytes assessed in the peripheral blood by immunoassay. Biomarkers were statistically evaluated using partial least squares multivariate analysis to identify possible relationships to self-reported previous concussion history, number of previous concussions and collision sport participation in male and female athletes. Multiple concussions were associated with increases in peripheral MCP-1 in females, and MCP-4 in males. Collision sport participation was associated with increases in tau levels in males. These results are consistent with previous experimental and clinical findings that suggest ongoing inflammatory and cerebral injury processes after repetitive mild head trauma. However, further validation is needed to correlate systemic biomarkers to repetitive brain impacts, as opposed to the extracranial effects common to an athletic population such as exercise and muscle damage.     

Sexual differences and steroid-induced changes in metabolic activity in toadfish sonic muscle

Since the male oyster toadfish (Opsanus tau) is more active in sound production than the female, we hypothesized that sonic muscles of the male are biochemically specialized to perform more work. In order to categorize the muscle biochemically and test for sexual differences, we measured the activity of two anaerobic enzymes, 3-phosphoglyceraldehyde dehydrogenase (3PG) and lactic dehydrogenase (LDH), and two aerobic enzymes, malate dehydrogenase (MDH) and glutamic oxaloacetic transaminase (GOT). Males exhibited greater 3PG and GOT activity than females (p less than 0.05). Both MDH and LDH showed little activity in either sex. High 3PG and low LDH levels indicate a sustained level of glycolysis, with pyruvate shuttled into aerobic metabolism, and high GOT activity indicates a high level of aerobic metabolism. From this and other data, we conclude that toadfish sonic muscle can be classified as fast-twitch oxidative glycolytic or fast-twitch fatigue resistant. The endocrine basis for these sexual differences was examined by implanting steroid pellets into ovariectomized females. Testosterone induced a doubling of 3PG activity (p less than 0.02), and dihydrotestosterone induced an eight-fold increase (p less than 0.0005) in GOT concentration over controls. The steroids had no effect on LDH and MDH activities. Hormones, therefore, trigger one of the fundamental sexual differences underlying toadfish communication, namely a difference in metabolism, providing the male with the capacity for increased sound production.     

Timing of neuromuscular activation of the quadriceps and hamstrings prior to landing in high school male athletes, female athletes, and female non-athletes.

There is a discrepancy between males and females in regards to lower extremity injury rates, particularly at the knee [Agel, J., Arendt, E.A., Bershadsky, B., 2005. Anterior cruciate ligament injury in National Collegiate Athletic Association basketball and soccer: a 13-year review. American Journal of Sports Medicine 33, (4) 524-530]. Gender differences in neuromuscular recruitment characteristics of the muscles that stabilize the knee are often implicated as a factor in this discrepancy. There is considerable research in the area of gender differences in regards to neuromuscular characteristics of the lower extremity in response to perturbation; however, most studies have been performed on the adult population only. Additionally, there is no consensus as to the gender differences that have been demonstrated. The purpose of this study was to compare muscular preactivation of selected lower extremity muscles (vastus medialis, rectus femoris, and medial/lateral hamstrings) in adolescent female basketball athletes, male basketball athletes, and female non-athletes in response to a drop landing. Subjects in the female non-athlete group recruited rectus femoris significantly slower than both the female athlete and male athlete groups (619.9=588.5>200.1ms prior to ground contact). The female non-athlete group also demonstrated a significantly slower vastus medialis compared to the female athlete group (127.1 vs 408.1ms), but not significantly slower than the male athlete group (127.1 vs 275.7ms). There were no differences between female athletes and male athletes for time to initial contraction of any muscle groups. No differences were found among the groups for medial or lateral hamstring activation. This study demonstrates that physical conditioning due to basketball participation appears to affect neuromuscular recruitment in adolescents and reveals a necessity to find alternate methods of training the hamstrings for improved neuromuscular capabilities to prevent injury.     

Quadriceps and hamstrings prelanding myoelectric activity during landing from different heights among male and female athletes

ACL tear is a major concern among athletes, coaches and sports scientists. More than taking the athlete away from training and competition, ACL tear is a risk factor for early-onset of knee osteoarthritis, and, therefore addressing strategies to avoid such injury is pertinent not only for competitive athletes, but for all physically active subjects. Imbalances in the prelanding myoelectric activity of the hamstrings and quadriceps muscles have been linked to ACL injuries. We investigated the effect of landing from different heights on prelanding myoelectric activity of the hamstrings and quadriceps muscles in recreational athletes. Thirty recreational athletes (15 male and 15 female) performed three bilateral drop jumps from two different heights; 20 cm and 40 cm while myoelectric activity of the vastus medialis, rectus femoris, biceps femoris and medial hamstrings were collected. When increasing the height of drop landing tasks prelanding normalized myoelectric activity of the quadriceps was increased by 15–20% but no significant changes were found for the hamstrings. Female athletes exhibited higher activity of the medial hamstrings compared to their male counterparts. We concluded that increasing the height of drop landing tasks is associated with increased myoelectric activity of the quadriceps but not the hamstrings in recreational athletes. These differences in muscle activity may be related to increased risk for ACL injury when the height is increased. Female athletes demonstrated higher recruitment of the medial hamstrings.     

DIO基因多态性与有氧耐力的相关性研究

目的:研究碘代甲状腺氨酸脱碘酶(DIO)基因多态性与有氧耐力的相关性,寻找与有氧耐力表型相关的分子标记。方法:应用基质辅助激光解吸电离飞行时间质谱检测技术,对123名中国北方汉族优秀长跑运动员(EEA)与127名中国北方汉族普通大学生(CG)DIO1基因C785T位点及DIO2基因的Thr92Ala和Gly3Asp位点进行解析并分析比较,其中优秀运动员又根据运动等级和运动项目分为国际健将与健将组(43vs80),及5/10km和马拉松组(92vs31)。结果:在DIO1的C785T位点及DIO2的Thr92Ala位点,各组间基因型和等位基因频率均无显著性差异(P>0.05);在DIO2的Gly3Asp位点,三种基因型在CG组与国际健将组、CG组与马拉松组间的分布均差异显著(P<0.05),其中TT基因型在CG组中不表达,仅存在于EEA组,但频率很低。DIO2的Thr92Ala及Gly3Asp位点处于强连锁不平衡,CT单体型在男CG组与女CG组、男CG组与男EEA组间分布均差异显著(P<0.05),在男CG组与男健将组、男马拉松组间的分布也均差异显著(P<0.05),TC单体型则在女CG组与女国际健将组、女5000m和10000m组间的分布差异显著(P<0.05)。结论:DIO2基因Thr92Ala及Gly3Asp位点的CT单体型分布具有性别差异,是男子EEA有氧耐力素质的分子标记,可用于男子长跑健将级运动员及马拉松运动员的分子选材,TC单体型则是女子长跑国际健将运动员和5000m、10000m运动员有氧耐力素质的分子标记。     

Blood lactate accumulation during arm exercise in world class kayak paddlers and strength trained athletes

Blood lactate accumulation was studied during progressive arm exercise in male and female world class kayak paddlers (K male, K female, n = 11), weight-/power-lifters (WL/PL, n = 6), bodybuilders (BB, n = 8) and non-athletes (NA, n = 6). The heavy resistance trained athletes exhibited greater upper-body muscle volume than the other subject groups. During low submaximal exercise intensities, blood lactate concentrations were significantly lower both in male and female kayakers compared with WL/PL, BB, and NA. Mean values at 120 W were 1.9 (K male), 2.1 (K female), 4.8 (WL/PL), 4.5 (BB), and 5.1 (NA) mmol X l-1. At higher power outputs the difference between females and non-kayakers diminished, while the difference between K male and all other groups increased. Exercise tolerance was greatest in K male and was equal among the other groups. Our results suggest that factors other than the muscle mass per se involved in exercise are responsible for the blood lactate response during this kind of work. Moreover, the physiological response observed in kayakers probably represents the upper limit of man's ability to perform continuous progressive arm-cranking exercise.     

NO ASSOCIATION BETWEEN tHbmass AND POLYMORPHISMS IN THE HBB GENE IN ENDURANCE ATHLETES

The aim of this study was to examine the association between tHbmass and HBB gene polymorphisms in athletes of endurance disciplines. Eighty-two well-trained athletes (female n=36, male n=46), aged 19.3 ± 2.7 years, representing cross country skiing (n=37) and middle- and long-distance running (n=45), participated in the study. Genotyping for 2 polymorphisms in the HBB gene (- 551C/T and intron 2, +16 C/G) was performed using restriction fragment length polymorphism analysis. Total haemoglobin mass (tHbmass) was determined by the optimized carbon monoxide rebreathing method. Blood morphology, indices of iron status (ferritin, transferrin receptor and total iron binding capacity) and C reactive protein were also determined. No differences were found in the HBB genotype and allele frequencies between male and female athletes. Regardless of the polymorphisms, no relationships were found between HBB genotypes as well as alleles and relative values of tHbmass, expressed per body mass (g · kg^-1 BM), both in female and male athletes. Our results demonstrated that -551 C/T and intron 2, +16 C/G polymorphisms of the HBB gene have no association with total haemoglobin mass in endurance athletes. It cannot be ruled out that several polymorphisms, each with a small but significant contribution, may be responsible for the amount of haemoglobin.