Ace/actn3 genetic polymorphisms and athletic performance of female soccer players` / Polimorfismos genéticos em ace/actn3 e desempenho atlético de atletas de futebol feminino / Polimorfismos genéticos en ace/actn3 y desempeño atlético de atletas de fútbol femenino

ABSTRACT Objective: Previous studies have shown controversial relationships between ACE and ACTN3 gene polymorphisms and sports performance. Thus, the aim of our study was to assess anaerobic and aerobic performance indicators of young female soccer players with different ACE/ACTN3 gene profiles. Methods: Twenty-seven female soccer players aged 16-18 underwent acceleration, speed, strength, anaerobic power and aerobic endurance tests and had their ACE and ACTN3 polymorphisms determined. Results: Based on genetic analysis, they were divided into the following groups: ACE II (n=2), ACE ID (n=11), ACE DD (n=14), ACTN3 XX (n=5), ACTN3 RR (n=7) and ACTN3 RX (n=15). ACE DD and ACE ID groups differed significantly in terms of results achieved on the 5 m sprint test (1.15±0.05 s vs 1.10±0.05 s, P=0.42). ACTN3 RR and RX achieved better results than the ACTN3 XX group in seven continuous vertical jumps (26.57±1.59 cm vs 25.77±2.51 cm vs 22.86±1.16 cm, respectively; P=0.007 for RR vs XX and P=0.021 for RX vs XX). Conclusion: High prevalence of ACE DD and ACTN3 RX genotypes in our subjects may suggest that faster and more powerful young females tend to perform better in soccer. Nevertheless, the absence of differences in most of the physical test results indicates that different genotypes are compatible with high-level soccer performance, meaning that it is the phenotype-genotype interaction that makes a successful female soccer player. Level of Evidence I, Prognostic studies — Investigating the effect of a patient characteristic on disease outcome.

RESUMO Objetivo: Estudos anteriores mostraram relações controvertidas entre os polimorfismos dos genes ACE e ACTN3 e desempenho esportivo. Assim sendo, o objetivo deste estudo foi avaliar os indicadores de desempenho anaeróbico e aeróbico de jovens futebolistas do sexo feminino com diferentes perfis dos genes ACE/ACTN3. Métodos: Vinte e sete jogadoras com idade entre 16 e 18 anos realizaram testes de aceleração, velocidade, força, potência anaeróbica e resistência aeróbica e os polimorfismos de seus genes ACE e ACTN3 foram determinados. Resultados: Com base na análise genética, elas foram divididas nos seguintes grupos: ACE II (n = 2), ACE ID (n = 11), ACE DD (n = 14), ACTN3 XX (n = 5), ACTN3 RR (n = 7) e ACTN3 RX (n = 15). Os grupos ACE DD e ACE ID diferiram significativamente quanto aos resultados obtidos no sprint test de 5 metros (1,15 ± 0,05 s vs. 1,10 ± 0,05 s, P = 0,42). Os grupos ACTN3 RR e RX atingiram resultados melhores do que o grupo ACTN3 XX em sete saltos verticais contínuos (26,57 ± 1,59 cm vs. 25,77 ± 2,51 cm vs. 22,86 ± 1,16 cm, respectivamente; P = 0,007 para RR vs. XX e P = 0,021 para RX vs. XX). Conclusão: A alta prevalência de genótipos RX em ACE DD e ACTN3 em nossa amostra pode sugerir que as jovens atletas mais rápidas e com maior potência tendem a ter melhor desempenho no futebol. No entanto, a ausência de diferença na maioria dos resultados dos testes físicos indica que genótipos distintos são compatíveis com o desempenho futebolístico de alto nível, o que significa que é a interação fenótipo-genótipo que faz uma jogadora de futebol ser bem-sucedida. Nível de Evidência I, Estudos prognósticos - Investigação do efeito de característica de um paciente sobre o desfecho da doença.

RESUMEN Objetivo: Estudios anteriores mostraron relaciones controvertidas entre los polimorfismos de los genes ACE y ACTN3 y desempeño deportivo. Siendo así, el objetivo de este estudio fue evaluar los indicadores de desempeño anaeróbico y aeróbico de jóvenes futbolistas del sexo femenino con diferentes perfiles de los genes ACE/ACTN3. Métodos: Veintisiete jugadoras con edad entre 16 y 18 años realizaron tests de aceleración, velocidad, fuerza, potencia anaeróbica y resistencia aeróbica y fueron determinados los polimorfismos de sus genes ACE e ACTN3. Resultados: Con base en el análisis genético, ellas fueron divididas en los siguientes grupos: ACE II (n = 2), ACE ID (n = 11), ACE DD (n = 14), ACTN3 XX (n = 5), ACTN3 RR (n = 7) y ACTN3 RX (n = 15). Los grupos ACE DD y ACE ID difirieron significativamente cuanto a los resultados obtenidos en el sprint test de 5 metros (1,15 ± 0,05 s vs. 1,10 ± 0,05 s, P = 0,42). Los grupos ACTN3 RR y RX alcanzaron resultados mejores que el grupo ACTN3 XX en siete saltos verticales continuos (26,57 ± 1,59 cm vs. 25,77 ± 2,51 cm vs. 22,86 ± 1,16 cm, respectivamente; P = 0,007 para RR vs. XX y P = 0,021 para RX vs. XX). Conclusión: La alta prevalencia de genotipos RX en ACE DD y ACTN3 en nuestra muestra puede sugerir que las jóvenes atletas más rápidas y con mayor potencia tienden a tener mejor desempeño en el fútbol. Sin embargo, la ausencia de diferencia en la mayoría de los resultados de los tests físicos indica que genotipos distintos son compatibles con el desempeño futbolístico de alto nivel, lo que significa que es la interacción fenotipo-genotipo que hace que una jugadora de fútbol sea exitosa. Nivel de Evidencia I, Estudios pronósticos - Investigación del efecto de característica de un paciente sobre el desenlace de la enfermedad.

Methodological considerations in the calculation of the rate of force development scaling factor.

OBJECTIVE: Within this methodological study, we aimed to explore the effects of seven different commonly applied routines for rate of force development (RFD) calculation on the calculation of rate of force development scaling factor (RFD-SF) and r 2 and the between session reliability of RFD-SF in three different muscle groups. APPROACH: We tested grip force muscles, elbow extensors and knee extensors of 13 healthy subjects asking them to produce around 120 rapid isometric force pulses per muscle to varying submaximal amplitudes. Then, we applied different filtering and analysis procedures, such as different filtering cut-off frequencies (no filter, 5 Hz cut-off, 10 Hz cut-off) and time windows during which RFD was calculated (0-50 ms, 0-75 ms, 0-100 ms and time from onset of contraction to peak force (PF) value). RFD-SF and r 2 were obtained from the relationship between the PF and the corresponding RFD. RESULTS: Our results showed that the magnitude of the calculated RFD-SF and r 2 values significantly differed among different RFD calculation methods (p < 0.0005), but that r 2 was high in most applied methods (RFD-SF ranged between 4.6 and 17.7, while r 2 ranged between 0.63 and 0.98). Regardless of the tested muscle group and applied method to calculate RFD, the reliability of the calculated RFD-SF was moderate (0.5 < ICC3,1 < 0.75) to good (ICC3,1 > 0.75). The highest r 2, highest ICC, lowest SEM% and MDD% were observed in case of RFD calculated during first 100 ms and when cut-off filter at 5 Hz was applied, indicating those two methods as the most appropriate ones. SIGNIFICANCE: Our study contributes to the establishment of methodological suggestions that will help in maximizing the reliability of RFD-SF measurements, collecting normative data, and comparing results among different populations and lab settings.

Biphasic response of cardiodynamic adaptations to swimming exercise in rats.

The aim of research was to assess exercise-induced changes in mechanics of hearts isolated from rats, as well as time-course of those changes. Wistar rats (n = 42) were divided into control, moderately trained (swimming 1 hour, 5 days a week for 9 or 12 weeks) and strenuously trained (swimming 2, 3 and 4 times a day for an hour in weeks 10, 11 and 12, respectively) groups. After sacrificing, hearts (weight: 1480.82 ± 145.38 mg) were isolated and perfused on a Langendorff apparatus. Coronary perfusion pressure (CPP) was gradually increased (from 40 to 120 cm H(2)O) in order to establish coronary autoregulation. Parameters of cardiac contractility were recorded: maximum and minimum rate of change of pressure in the left ventricle (dp/dt max and dp/dt min), systolic and diastolic left ventricular pressure (SLVP and DLVP), heart rate (HR) and coronary flow (CF). Nine weeks of moderate exercise induced slight depression of coronary function (decrease of dp/dt max, dp/dt min, SLVP and DLVP), while 3 additional weeks of moderate training improved hearts function, but not to the extent that the strenuous training program did. The results of our study add evidence about beneficial effects of regular moderate exercise on heart, and furthermore, show that exercising frequently, if the intensity stays within moderate range, may not have detrimental effects on cardiodynamics.

Towards a new protocol of scoliosis assessments and monitoring in clinical practice: A pilot study.

BACKGROUND: Although intensively investigated, the procedures for assessment and monitoring of scoliosis are still a subject of controversies. OBJECTIVE: The aim of this study was to assess validity and reliability of a number of physiotherapeutic measurements that could be used for clinical monitoring of scoliosis. METHODS: Fifteen healthy (symmetric) subjects were subjected to a set of measurements two times, by two experienced and two inexperienced physiotherapists. Intra-observer and inter-observer reliability of measurements were determined. Following measurements were performed: body height and weight, chest girth in inspirium and expirium, the length of legs, the spine translation, the lateral pelvic tilt, the equality of the shoulders, position of scapulas, the equality of stature triangles, the rib hump, the existence of m. iliopsoas contracture, Fröhner index, the size of lumbar lordosis and the angle of trunk rotation. RESULTS: Intraclass correlation coefficient was high (> 0.8) for majority of measurements when experienced physiotherapists performed them, while inexperienced physiotherapists performed precisely only basic, easy measurements. CONCLUSIONS: We showed in this pilot study on healthy subjects, that majority of basic physiotherapeutic measurements are valid and reliable when performed by specialized physiotherapist, and it can be expected that this protocol will gain high value when measurements on subjects with scoliosis are performed.

The effects of homocysteine-related compounds on cardiac contractility, coronary flow, and oxidative stress markers in isolated rat heart.

Research on the effects of homocysteine on the vascular wall, especially in endothelial and smooth muscle cells, has indicated that increased homocysteine levels lead to cellular stress and cell damage. Considering the adverse effects of homocysteine on vascular function and the role of oxidative stress in these mechanisms, the aim of this study was to estimate the influence of different homocysteine isoforms on cardiac contractility, coronary flow, and oxidative stress markers in isolated rat heart. The hearts of male Wistar albino rats (n = 36, age 8 weeks, body mass 180-200 g), were excised and retrogradely perfused according to the Langendorff technique at a constant perfusion pressure (70 cmH(2)O) and administered with three isoforms of 10 µM homocysteine [DL-Hcy, DL-Hcy thiolactone-hydrochloride (TLHC) and L-Hcy TLHC). After the insertion and placement of the sensor in the left ventricle, the parameters of heart function: maximum rate of pressure development in the left ventricle (dP/dt max), minimum rate of pressure development in the left ventricle (dP/dt min), systolic left ventricular pressure (SLVP), diastolic left ventricular pressure (DLVP), mean blood pressure (MBP) and heart rate (HR)] were continuously registered. Flowmetry was used to evaluate the coronary flow. Markers of oxidative stress: index of lipid peroxidation measured as TBARS, nitric oxide measured through nitrites (NO(2)(-)), superoxide anion radical (O(2)(-)), and hydrogen peroxide (H(2)O(2)) in the coronary venous effluent were assessed spectrophotometrically. Our results showed that administration of Hcy compounds in concentration of 10 µM induced depression of cardiac contractility, manifested by a decrease in dp/dt max after administration of any Hcy compound, decrease in dp/dt min after administration of L-Hcy TLHC, decrease in SLVP after administration of DL-Hcy TLHC and DL-Hcy, and the drop in CF after administration of any Hcy compound. Regarding the effects of Hcy on oxidative stress parameters, only L-Hcy TLHC significantly affected O(2)(-) release. L-Hcy TLHC showed a cardiotoxic effect by affecting heart contractility, but surprisingly, it decreased the release of O(2)(-).

Comparison of blood pro/antioxidant levels before and after acute exercise in athletes and non-athletes.

The aims of our study were to assess the redox state of adolescent athletes and non-athletes both at rest and after acute exposure to physical load and to find relations between parameters of redox state and morphofunctional characteristics of subjects. 58 young handball players and 37 non-athletes were subjected to body composition analysis, measuring of maximal oxygen consumption and blood sampling immediately before and after a maximal progressive exercise test. At rest, athletes had significantly higher superoxide dismutase (SOD) and catalase (CAT) activity, higher levels of glutathione (GSH) and nitric oxide (NO) and lower levels of lipid peroxidation (TBARS) compared with non-athletes. A maximal exercise test induced statistically significant rise of superoxide anion radical (O2-), hydrogen peroxide (H2O2) and NO levels in non-athletes, while TBARS levels decreased. Athletes experienced the fall in NO levels and the fall in CAT activity. After exercise, athletes had significantly lower levels of O2- compared with non-athletes. Two way repeated measures ANOVA showed that the response of O2-, NO and TBARS to the exercise test was dependent on the sports engagement (training experience) of subjects. Significant correlations between morphofunctional and redox parameters were found. These results suggest that physical fitness affects redox homeostasis.

Nitroglycerine effects on portal vein mechanics and oxidative stress in portal hypertension.

AIM: Тo examine the effects of nitroglycerine on portal vein haemodynamics and oxidative stress in patients with portal hypertension. METHODS: Thirty healthy controls and 39 patients with clinically verified portal hypertension and increased vascular resistance participated in the study. Liver diameters, portal diameters and portal flow velocities were recorded using color flow imaging/pulsed Doppler detection. Cross-section area, portal flow and index of vascular resistance were calculated. In collected blood samples, superoxide anion radical (O(2) (-)), hydrogen peroxide (H(2)O(2)), index of lipid peroxidation (measured as TBARS) and nitric oxide (NO) as a marker of endothelial response (measured as nitrite-NO(2) (-)) were determined. Time-dependent analysis was performed at basal state and in 10th and 15th min after nitroglycerine (sublingual 0.5 mg) administration. RESULTS: Oxidative stress parameters changed significantly during the study. H(2)O(2) decreased at the end of study, probably via O(2) (-) mediated disassembling in Haber Weiss and Fenton reaction; O(2) (-) increased significantly probably due to increased diameter and tension and decreased shear rate level. Consequently O(2) (-) and H(2)O(2) degradation products, like hydroxyl radical, initiated lipid peroxidation. Increased blood flow was to some extent lower in patients than in controls due to double paradoxes, flow velocity decreased, shear rate decreased significantly indicating non Newtonian characteristics of portal blood flow. CONCLUSION: This pilot study could be a starting point for further investigation and possible implementation of some antioxidants in the treatment of portal hypertension.

Exercise-induced changes in redox status of elite karate athletes.

Regular training has been claimed to increase the activity of antioxidant enzymes and, consequently, augments the resistance to oxidative stress; however, large volumes of training performed by elite sportsmen could lead to a chronic oxidative stress state. The aim of our study was to assess the oxidative status of elite athletes at the beginning of the preparatory and the beginning of the competition training phases, so that the influence of three months of programmed physical activity on redox status could be determined. The chronic effects of exercise on the redox state of the athletes were compared to the effects of a single bout of karate training. Thirty elite karate athletes, 16-30 years old, were subjected to maximal graded exercise test to estimate their aerobic capacity; blood sampling was also performed to measure levels of superoxide anion radical (O2⁻), hydrogen peroxide (H2O2), superoxide dismutase activity (SOD) and catalase activity (CAT). The only significant change after the three-month training process was found in the significantly decreased CAT activity (X ± SE: 7.95 ± 0.13 U/g Hb × 10³ in the preparatory period, 6.65 ± 0.28 U/g Hb × 10³ in the competition stage; P < 0.01). After a single karate training session, there was statistically significant decrease of O2⁻(X ± SE: 32.7 ± 4.9 nmol/ml in the preparatory period, 24.5 ± 2.5 nmol/ml in the competition stage; P < 0.05) and increase of H2O2(X ± SE: 11.8 ± 1.0 nmol/ml in the preparatory period, 14.2 ± 0.9 nmol/ml in the competition stage; P < 0.01), as well as significant CAT increase (X ± SE: 6.6 ± 0.6 U/g Hb × 10³ in the preparatory period, 8.5 ± 0.5 U/g Hb × 10³ in the competition stage; P < 0.05). Although the three-month training process induced, at the first sight, negative changes in the redox state, expressed through the decrease in CAT activity, adequate response of the antioxidant system of our athletes to acute exercise was preserved.

Changes in athlete's redox state induced by habitual and unaccustomed exercise.

The purpose of this study was to assess the influence of sport-specific and nonspecific bouts of exercise on athletes' redox state. Blood samples were collected from 14 handball players immediately before and after graded exercise test on the cycle ergometer and handball training. Levels of superoxide anion radical (O(2) (-)), hydrogen peroxide (H(2)O(2)), nitrites (NO(2) (-)) as markers of nitric oxide, index of lipid peroxidation (TBARs), glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) activity were determined. Exercise intensity was assessed by a system for heart rate (HR) monitoring. Average athletes' HR was not significantly different between protocols, but protocols differed in total time and time and percentage of time that athletes spent in every HR zone. The laboratory exercise test induced a significant increase of H(2)O(2) and TBARs as well as the decrease of the SOD and CAT activity, while after specific handball training, levels of NO(2) (-) were increased and SOD activity decreased. It seems that unaccustomed short intensive physical activity may induce oxidative stress in trained athletes, while sport-specific activity of longer duration and proper warm-up period may not. Further research should show whether the change of protocol testing and the implementation of various supplementations and manual methods can affect the redox equilibrium.

Von Willebrand factor and oxidative stress parameters in acute coronary syndromes.

Considering the role of von Willebrand factor (vWf) in hemostasis, and the role of oxidative stress in the development of endothelial dysfunction and atherosclerotic disease, the aim of our study was to investigate the relationship between vWf, parameters of oxidative stress and different types of acute coronary syndromes (ACS). Levels of vWf activity (vWfAct), vWf antigen (vWfAg), nitric oxide (estimated through nitrites-NO(2)-), superoxide anion radical (O(2)-), hydrogen peroxide (H2O2), index of lipid peroxidation (estimated through thiobarbituric acid reactive substances-TBARS), superoxide dismutase (SOD) and catalase (CAT) activity of 115 patients were compared with those of 40 healthy controls. ACS patients had significantly higher vWfAct and vWfAg levels, as well as TBARS levels, while their levels of NO(2)-, H2O2, SOD and CAT activities were lower than controls'. vWfAg showed high specificity and sensitivity as a test to reveal healthy or diseased subjects. Multivariant logistic regression marked only vWfAg and TBARS as parameters that were under independent effect of ACS type. The results of our study support the implementation of vWf in clinical rutine and into therapeutic targets, and suggest that ACS patients are in need of antioxidant supplementation to improve their impaired antioxidant defence.

The effects of vitamin C and nitric oxide synthase inhibition on coronary flow and oxidative stress markers in isolated rat heart.

The aim of this study was to assess the effects of vitamin C (ascorbic acid) on coronary flow and oxidative stress markers with or without non-specific inhibition of nitric oxide synthase by N(ω)-nitro-L-arginine monomethyl ester (L-NAME) in isolated rat hearts. The hearts of male Wistar albino rats (n = 12, age 8 weeks, body mass 180-200 g) were retrograde perfused according to the Langendorff technique at gradually increased constant perfusion pressure (40-120 cm H2O). Coronary flow, nitrite outflow, superoxide anion production, and index of lipid peroxidation (by measuring thiobarbituric acid reactive substances) in coronary effluent were determined. The experiments were performed during control conditions and in presence of vitamin C (100 µM) alone or vitamin C (100 µM) + L-NAME (30 µM). Administration of vitamin C induced only increase of nitrite levels, while vitamin C + L-NAME induced significant decrease of coronary flow above autoregulatory range, i.e. especially at higher coronary perfusion pressure (CPP) values, accompanied with similar dynamic in nitrite outflow. Vitamin C + L-NAME also induced significant decrease in TBARS production. The results of our study show no significant effects of vitamin C administration either on ROS levels or on coronary flow in isolated rat heart.

Oxidative stress and nitrite dynamics under maximal load in elite athletes: relation to sport type.

Maximal workload in elite athletes induces increased generation of reactive oxygen/nitrogen species (RONS) and oxidative stress, but the dynamics of RONS production are not fully explored. The aim of our study was to examine the effects of long-term engagement in sports with different energy requirements (aerobic, anaerobic, and aerobic/anaerobic) on oxidative stress parameters during progressive exercise test. Concentrations of lactates, nitric oxide (NO) measured through stabile end product-nitrites (NO(2) (-)), superoxide anion radical (O(2) (•-)), and thiobarbituric reactive substances (TBARS) as index of lipid peroxidation were determined in rest, after maximal workload, and at 4 and 10th min of recovery in blood plasma of top level competitors in rowing, cycling, and taekwondo. Results showed that sportmen had similar concentrations of lactates and O(2) (•-) in rest. Nitrite concentrations in rest were the lowest in taekwondo fighters, while rowers had the highest levels among examined groups. The order of magnitude for TBARS level in the rest was bicycling > taekwondo > rowing. During exercise at maximal intensity, the concentration of lactate significantly elevated to similar levels in all tested sportsmen and they were persistently elevated during recovery period of 4 and 10 min. There were no significant changes in O(2) (•-), nitrite, and TBARS levels neither at the maximum intensity of exercise nor during the recovery period comparing to the rest period in examined individuals. Our results showed that long term different training strategies establish different basal nitrites and lipid peroxidation levels in sportmen. However, progressive exercise does not influence basal nitrite and oxidative stress parameters level neither at maximal load nor during the first 10 min of recovery in sportmen studied.

The influence of training status on oxidative stress in young male handball players.

Although exercise-induced oxidative stress receives considerable scientific attention, there is still little information available regarding exercise-induced adaptations of the antioxidant defence system in adolescent and child athletes. The aim of our study was to establish the effects of long-term exercise training on the redox state of adolescents, and to find correlations between elements of redox homeostasis and aerobic power. Thirty-three handball players and 14 non-athletes, 16-19-years old, were subjected to blood sampling to measure levels of nitric oxide (NO; estimated through nitrites (NO2⁻), superoxide anion radical (O2⁻), hydrogen peroxide (H2O2), lipid peroxidation (estimated through TBARS), superoxide dismutase (SOD) and catalase (CAT). Subjects were also subjected to maximal progressive exercise test to estimate their maximal oxygen consumption (VO2max). Athletes had significantly (P < 0.05) higher SOD activity and lower CAT activity compared with non-athletes (SOD: 2175.52 ± 362.07 compared with 1172.16 ± 747.40 U/g of hemoglobin x 10³, and CAT: 2.19 ± 0.31 compared with 3.08 ± 0.47 U/g of hemoglobin x 10³). These differences were the most obvious when comparing non-athletes and athletes with poor/average aerobic power. H2O2 and TBARS levels differed among subjects with poor, average or good aerobic power (P < 0.01, and P < 0.05, respectively). Sports engagement and aerobic capacity are important factors in inducing changes in redox status.

Coordination between nitric oxide and superoxide anion radical during progressive exercise in elite soccer players.

BACKGROUND: Exercise increases production of reactive oxygen and nitrogen species (RONS) via several mechanisms. Inter alia, increased blood flow during exercise exposes endothelial cells to shear stress, resulting in increased nitric oxide (NO) production. Increased oxygen consumption or hypoxia during exercise induces increased production of superoxide anion radical (O(2) (-)). OBJECTIVE: This study investigates the effects of maximal progressive treadmill exercise test on time-course of peripheral blood NO and O(2) (-) production, as well as the effect of long-term training on NO bioavailability. METHODS: Blood samples of 19 elite soccer players were gathered immediately before the test, during last 10 sec of every test stage, and during active recovery phases. RESULTS: Significant increase (p<0.05) in NO production (estimated through nitrites (NO(2) (-))), found between stage I (5.69 ± 1.32 nmol/ml) and basal values (5.36 ± 1.25 nmol/ml), was followed by the decrease in stage II (4.21 ± 0.42 nmol/ml) and production lower than basal to the end of the test. Significant increase (p<0.05) in O(2) (-) values was found between stage I (4.18 ± 0.77 nmol/ml) and resting values (4.01 ± 0.69 nmol/ml), and at stages V (4.24 ± 0.85 nmol/ml) and 1st phase of recovery (4.39 ± 0.92 nmol/ml). CONCLUSION: The regression lines of NO(2) (-) and O(2) (-) crossed at the level of anaerobic threshold, suggesting that anaerobic threshold could be of a crucial importance not only in the anaerobic and aerobic metabolism but in mechanisms of signal transductions as well. Long-term exercise increases NO bioavailability, and there is positive correlation between NO bioavailability and maximal oxygen uptake (VO(2max)).