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(1) Background: Physical activity may cause an imbalance in the major functions of the human body. This study aimed to investigate the effects of endurance running training on the parameters of the antioxidant defense system (SOD, CAT, GPx, GR, GSH), LPO (malondialdehyde, MDA), and stress hormones (A, NA) in young healthy, previously untrained men. (2) Methods: The training program was as follows: 8 weeks of running, three times per week; the duration of a single session was 30-70 min, the intensity was twice a week in the so-called extensive endurance zone, and once a week in the anaerobic threshold zone. Blood samples were collected from the subjects, before and after the running program. (3) Results: The training program resulted in a significant increase in maximal oxygen consumption (p < 0.001). The activities of SOD, GPx, and GR also increased significantly (p < 0.05, p < 0.01, and p < 0.05, respectively), while CAT activity and GSH and MDA concentrations remained unchanged. The concentration of A decreased (p < 0.05), while the NA concentration increased significantly (p < 0.05). SOD, GPx, GR, and NA positively correlated with VO2max (p < 0.05, p < 0.001, p < 0.01, p < 0.05, respectively), while a negative correlation was detected between A and VO2max (p < 0.05). (4) Conclusions: These results indicate that there is no persistent oxidative stress in response to the applied 8-week running program, probably due to exercise-induced protective alterations in the antioxidant defense system. Furthermore, adaptations occurred at the hormonal level, making the organism more ready for a new challenge.

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Introduction: Many studies indicate a considerable impact of optimal pacing on long-distance running performance. Given that the amount of carbohydrates in metabolic processes increases supralinearly with the running intensity, we may observe differences between the pacing strategies of two long-distance races and different performance levels of runners. Accordingly, the present study aimed to examine the differences in pacing strategies between marathon and half-marathon races regarding the performance levels of runners. Methods: The official results and split times from a total of 208,760 (marathon, N = 75,492; half-marathon, N = 133,268) finishers in the "Vienna City Marathon" between 2006 and 2018 were analyzed. The percentage of the average change of speed for each of the five segments (CS 1-5), as well as the absolute change of speed (ACS) were calculated. The CS 1-5 for the marathon are as follows: up to the 10th km, 10th - 20th km, 20th - 30th km, 30th - 40th km, and from the 40th km to the 42.195 km. For the half-marathon, the CS 1-5 are half of the marathon values. Four performance groups were created as quartiles of placement separately for sexes and races: high-level (HL), moderate to high-level (MHL), moderate to low-level (MLL), and low-level (LL). Results: Positive pacing strategies (i.e., decrease of speed) were observed in all performance groups of both sex and race. Across CS 1-5, significant main effects (p < 0.001) were observed for the segment, performance level, and their interaction in both sex and race groups. All LL groups demonstrated higher ACS (men 7.9 and 6.05%, as well as women 5.83 and 5.49%, in marathon and half-marathon, respectively), while the HL performance group showed significantly lower ACS (men 4.14 and 2.97%, as well as women 3.16 and 2.77%, in marathon and half-marathon, respectively). Significant main effects (p < 0.001) for the race were observed but with a low effect size in women (ŋ2 = 0.001). Discussion: Better runners showed more even pacing than slower runners. The half-marathoners showed more even pacing than the marathoners across all performance groups but with a trivial practical significance in women.

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Anticipation of stress induces physiological, behavioral and cognitive adjustments that are required for an appropriate response to the upcoming situation. Additional research examining the response of cardiopulmonary parameters and stress hormones during anticipation of stress in different chronic stress adaptive models is needed. As an addition to our previous research, a total of 57 subjects (16 elite male wrestlers, 21 water polo player and 20 sedentary subjects matched for age) were analyzed. Cardiopulmonary exercise testing (CPET) on a treadmill was used as the laboratory stress model; peak oxygen consumption (VO2) was obtained during CPET. Plasma levels of adrenocorticotropic hormone (ACTH), cortisol, alpha-melanocyte stimulating hormone (alpha-MSH) and N-terminal-pro-B type natriuretic peptide (NT-pro-BNP) were measured by radioimmunometric, radioimmunoassay and immunoassay sandwich technique, respectively, together with cardiopulmonary measurements, 10 minutes pre-CPET and at the initiation of CPET. The response of diastolic blood pressure and heart rate was different between groups during stress anticipation (p = 0.019, 0.049, respectively), while systolic blood pressure, peak VO2 and carbon-dioxide production responses were similar. ACTH and cortisol increased during the experimental condition, NT-pro-BNP decreased and alpha-MSH remained unchanged. All groups had similar hormonal responses during stress anticipation with the exception of the ACTH/cortisol ratio. In all three groups, ΔNT-pro-BNP during stress anticipation was the best independent predictor of peak VO2 (B = 36.01, r = 0.37, p = 0.001). In conclusion, the type of chronic stress exposure influences the hemodynamic response during anticipation of physical stress and the path of hormonal stress axis activation. Stress hormones released during stress anticipation may hold predictive value for overall cardiopulmonary performance during the stress condition.

LAY SUMMARYThe study revealed differences in hormonal and hemodynamic responses during anticipation of stress between athletes and sedentary participants. Stress hormones released during stress anticipation may hold predictive value for overall cardiopulmonary performance during the stress condition.

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BACKGROUND: The aim was to determine the relationship between the cross-sectional area of the quadriceps femoris and strength performance in the deep and parallel barbell squat. METHODS: The sample included 16 university students (seven female, 24.1 ± 1.7 years). Muscle strength was expressed as external load, including the one-repetition maximum and the body mass segments involved (calculated according to Dempster's method). The cross-sectional area of the quadriceps femoris muscles was determined using ultrasound, while leg muscle mass was measured using the Bioelectrical Impedance method. RESULTS: The cross-sectional areas of the three vastii muscles and leg muscle mass showed moderate to strong correlation with external load in both squat types (r = 0.509-0.873). However, partial correlation (cross-sectional area of quadriceps femoris muscles were controlled) showed significant association only between leg muscle mass and deep squat (r = 0.64, p < 0.05). The cross-sectional area of the vastus lateralis showed a slightly higher correlation with external load in the parallel than in the deep squat (r = 0.67, p < 0.01 vs. r = 0.59, p < 0.05). The regression analysis extracted the vastus medialis cross-sectional area as the most important factor in manifesting strength (parallel squat: R 2 = 0.569; deep squat: R 2 = 0.499, both p < 0.01). The obtained results suggest that parallel squat strength depends mainly on the cross-sectional area of the vastii muscles, while it seems that the performance in the deep squat requires an additional engagement of the hip and back extensor muscle groups.

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The aim of the study was to compare the effects of two different training protocols, which differ in the duration of the eccentric phase, on the one-repetition maximum (1RM), thickness and contractile properties of elbow flexors. Twenty untrained college students were randomly divided into two experimental groups, based on the training tempo: FEG (Faster Eccentric Group: 1/0/1/0) and SEG (Slower Eccentric Group: 4/0/1/0). Training intervention was a biceps bending exercise, conducted twice a week for 7 weeks. The intensity (60-70% RM), sets (3-4) and rest intervals (120 s) were held constant, while repetitions were performed until it was not possible to maintain a set duration. In the initial and final measurements, 1RM, muscle thickness and tensiomyography parameters - contraction time (Tc) and radial deformation (Dm) - were evaluated. An ANCOVA model (using baseline outcomes as covariates) was applied to determine between-group differences at post-test, while Pearson's product-moment correlation coefficient was used to investigate the relationship between absolute changes in muscle thickness and Dm. Muscle strength increase was greater for SEG than for FEG (6.0 ± 1.76 vs. 3.30 ± 2.26 kg, p < 0.01). In both groups muscle thickness increased equally (FEG: 3.24 ± 2.01 vs. SEG: 3.57 ± 1.17 mm, p < 0.01), while an overall reduction in Dm was observed (FEG: 1.99 ± 1.20 vs. SEG: 2.26 ± 1.03 mm, p < 0.01). Values of Tc remained unchanged. A significant negative relationship was observed between changes in muscle thickness and Dm (r = -0.763, Adj.R² = 0.560, p < 0.01). These results indicate that the duration of the eccentric phase has no effect on muscle hypertrophy in untrained subjects, but that slower eccentric movement significantly increases 1RM.

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COVID-19 disease has been a problem in today's society, which has worldwide effects on different areas, especially on the economy; also, from a health perspective, the disease affects the daily life quality. Physical activity is one major positive factor with regard to enhancing life quality, as it can improve the whole psychological, social, and physical health conditions. Current measures such as social distancing are focused on preventing the viral spread. However, the consequences on other areas are yet to be investigated. Elderly, people with chronic diseases, obese, and others benefit largely from exercise from the perspective of improved health, and preventive measures can drastically improve daily living. In this article, we elaborate the effects of exercise on the immune system and the possible strategies that can be implemented toward greater preventive potential.

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The aim of this study was to develop international standards for evaluating strength endurance with the use of the 3-Minute Burpee Test. The results of 3862 women (Poland - 2502, Great Britain - 500, Hungary - 412, Serbia - 448) and 5971 men (Poland - 4517, Great Britain - 500, Hungary - 451, Serbia - 503) aged 18-25 (mean age of 20.36 ± 0.94 and 20.05 ± 1.25 y, respectively) were collated between 2004 and 2018. The students' strength endurance was evaluated in the 3-Minute Burpee Test. The results were expressed on a uniform scale with the 3-sigma rule which was used to develop the T-score scale for the 3-Minute Burpee Test. Men completed 56.69 cycles/3 min and women - 48.84/3 min on average. The best male participant completed 82 burpees, and the best female participant - 73 burpees. The majority of male and female participants (66.71% and 68.18%, respectively) were characterized by average strength endurance in the 3-Minute Burpee Test (range of scores: 47-66 and 37-60 cycles/3 min, respectively). Very good strength endurance (76-85 and 72-83 cycles/3 min, respectively) was noted in the smallest percentage of male and female participants (0.52% and 0.26%, respectively). Similar studies should be carried out in other countries and in different age groups to develop objective international classification standards for variously-aged individuals.

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The usage of alcohol is widespread, but the effects of acute alcohol ingestion on exercise performance and the stress hormone axis are not fully elucidated.We studied 10 healthy white men, nonhabitual drinkers, by Doppler echocardiography at rest, spirometry, and maximal cardiopulmonary exercise test (CPET) in two visits (2-4 days in between), one after administration of 1.5 g/kg ethanol (whisky) diluted at 15% in water, and the other after administration of an equivalent volume of water. Plasma levels of NT-pro-BNP, cortisol, and adrenocorticotropic hormone (ACTH) were also measured 10 min before the test, at maximal effort and at the third minute of recovery. Ethanol concentration was measured from resting blood samples by gas chromatography and it increased from 0.00 ±â€Š0.00 to 1.25 ±â€Š0.54‰ (P < 0.001). Basal echocardiographic and spirometric parameters were normal and remained so after acute alcohol intake, whereas ACTH, cortisol, and NT-pro-BNP nonsignificantly increased in all phases of the test. CPET data suggested a trend toward a slight reduction of exercise performance (peak VO2 = 3008 ±â€Š638 vs. 2900 ±â€Š543 ml/min, ns; peak workload = 269 ±â€Š53 vs. 249 ±â€Š40 W, ns; test duration 13.7 ±â€Š2.2 vs. 13.3 ±â€Š1.7 min, ns; VE/VCO2 22.1 ±â€Š1.4 vs. 23.3 ±â€Š2.9, ns). Ventilatory equivalent for carbon dioxide at rest was higher after alcohol intake (28 ±â€Š2.5 vs. 30.4 ±â€Š3.2, P = 0.039) and maximal respiratory exchange ratio was lower after alcohol intake (1.17 ±â€Š0.02 vs. 1.14 ±â€Š0.04, P = 0.04). In conclusion, we showed that acute alcohol intake in healthy white men is associated with a nonsignificant exercise performance reduction and stress hormone stimulation, with an unchanged exercise metabolism.

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Brain natriuretic peptide (NT-pro-BNP) was implicated in the regulation of hypothalamic-pituitary-adrenocortical (HPA) responses to psychological stressors. However, HPA axis activation in different physical stress models and its interface with NT-pro-BNP in the prediction of cardiopulmonary performance is unclear. Cardiopulmonary test on a treadmill was used to assess cardiopulmonary parameters in 16 elite male wrestlers (W), 21 water polo player (WP) and 20 sedentary age-matched subjects (C). Plasma levels of NT-pro-BNP, cortisol and adrenocorticotropic hormone (ACTH) were measured using immunoassay sandwich technique, radioimmunoassay and radioimmunometric techniques, respectively, 10min before test (1), at beginning (2), at maximal effort (3), at 3rdmin of recovery (4). In all groups, NT-pro-BNP decreased between 1 and 2; increased from 2 to 3; and remained unchanged until 4. ACTH increased from 1 to 4, whereas cortisol increased from 1 to 3 and stayed elevated at 4. In all groups together, ΔNT-pro-BNP2/1 predicted peak oxygen consumption (B=37.40, r=0.38, p=0.007); cortisol at 3 predicted heart rate increase between 2 and 3 (r=-0.38,B=-0.06, p=0.005); cortisol at 2 predicted peak carbon-dioxide output (B=2.27, r=0.35, p<0.001); ΔACTH3/2 predicted peak ventilatory equivalent for carbon-dioxide (B=0.03, r=0.33, p=0.003). The relation of cortisol at 1 with NT-pro-BNP at 1 and 3 was demonstrated using logistic function in all the participants together (for 1/cortisol at 1 B=63.40, 58.52; r=0.41, 0.34; p=0.003, 0.013, respectively). ΔNT-pro-BNP2/1 linearly correlated with ΔACTH4/3 in WP and W (r=-0.45, -0.48; p=0.04, 0.04, respectively). These results demonstrate for the first time that HPA axis and NT-pro-BNP interface in physical stress probably contribute to integrative regulation of cardiopulmonary performance.

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Brain natriuretic peptide (NT-pro-BNP) is used as marker of cardiac and pulmonary diseases. However, the predictive value of circulating NT-pro-BNP for cardiac and pulmonary performance is unclear in physiological conditions. Standard echocardiography, tissue Doppler and forced spirometry at rest were used to assess cardiac parameters and forced vital capacity (FVC) in two groups of athletes (16 elite male wrestlers (W), 21 water polo player (WP)), as different stress adaptation models, and 20 sedentary subjects (C) matched for age. Cardiopulmonary test on treadmill (CPET), as acute stress model, was used to measure peak oxygen consumption (peak VO2), maximal heart rate (HRmax) and peak oxygen pulse (peak VO2/HR). NT-pro-BNP was measured by immunoassey sandwich technique 10min before the test - at rest, at the beginning of the test, at maximal effort, at third minute of recovery. FVC was higher in athletes and the highest in W (WP 5.60±0.29 l; W 6.57±1.00 l; C 5.41±0.29 l; p<0.01). Peak VO2 and peak VO2/HR were higher in athletes and the highest in WP. HRmax was not different among groups. In all groups, NT-pro-BNP decreased from rest to the beginning phase, increased in maximal effort and stayed unchanged in recovery. NT-pro-BNP was higher in C than W in all phases; WP had similar values as W and C. On multiple regression analysis, in all three groups together, ΔNT-pro-BNP from rest to the beginning phase independently predicted both peak VO2 and peak VO2/HR (r=0.38, 0.35; B=37.40, 0.19; p=0.007, 0.000, respectively). NT-pro-BNP at rest predicted HRmax (r=-0.32, B=-0.22, p=0.02). Maximal NT-pro-BNP predicted FVC (r=-0.22, B=-0.07, p=0.02). These results show noticeable predictive value of NT-pro-BNP for both cardiac and pulmonary performance in physiological conditions suggesting that NT-pro-BNP could be a common regulatory factor coordinating adaptation of heart and lungs to stress condition.

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We tested the hypotheses that the individual strength properties depend on the applied test and the variable extracted, rather than on the muscle group tested. Flexor and extensor muscles acting in the knee and elbow joint were tested in 58 participants. The standard strength test (SST; based on sustained maximum contraction) and alternating consecutive maximum contractions (ACMCs; alternating contractions of antagonistic muscles) performed under static conditions were separately applied to provide the maximum force (F) and the rate of force development (RFD) of each tested muscle. The principal component analysis applied on all 16 variables revealed three factors that explained 85.5% of the total variance. Contrary to our hypotheses, the individual factors were loaded with the variables recorded from individual muscles, rather than with either the particular variables or tests. The present findings suggest that recording both F and RFD in routine strength testing procedures could be redundant since they may assess the same strength property of the tested muscle. In addition, ACMC may be a feasible alternative to SST since it could assess the same strength properties from two antagonist muscles through a single trial, while being based on relatively low and transient forces.

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The response of the body to vigorous physical activity is a multiorgan system phenomenon. As a result, the body undergoes profound morphologic and functional alterations, but as there are different kinds of physical activities, the degree of these changes is highly variable as well. Considering many sudden cardiac deaths in sport, it is needless to say how important it is to know where the border of normal changes of the body due to physical activity is and when these changes become unhealthy. Also it is very important to distinguish physiological changes of the body due to physical activity and pathological changes due to some cardiac diseases. In order to prevent sudden cardiac deaths in sport, it is very important to distinguish athletes heart syndrome and hypertrophic cardiomiopathy, dilatative cardiomiopathy, aritmogenic cardiomiopathy of the right ventricle and myocarditis. More frequent physical examinations of athletes are recommended.

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INTRODUCTION: Sudden cardiac death in athletes is a growing problem, despite the huge existing knowledge in medicine and sports. EFFECTS OF VIGOROUS PHYSICAL ACTIVITY: In response to vigorous physical activity, the body undergoes profound morphologic and functional changes. These changes are usually healthy, but sometimes may gravitate to some cardiac diseases. But still, most saudden cardiac deaths are due to previous unknown diseases. CAUSES OF SUDDEN CARDIAC DEATH: The most common cause of sudden cardiac death in athletes is hypertrophic cardiomyopathy. Other reasons are congenital coronary artery anomalies, nivocarditis, dilatative cardiomyopathy, arrhythmogenic cardiomyopathy of the right ventricle, sarcoidosis, mitral valve prolapse, aortic valve stenosis, atherosclerosis, long QT syndrome, and blunt impact to the chest. CONCLUSION: Bearing in mind the above mentioned, more frequent physical examinations of athletes are recommended.

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INTRODUCTION: The athletic heart syndrome is characterized by morphological, functional and electrophysiological alterations as an adaptive response to vigorous physical activity. Athletes heart is predominantly associated with a programmed, intensive training. But as there are different kinds of physical activities, the degree of these changes is highly variable. ELECTROPHYSIOLOGICAL CHARACTERISTICS OF THE ATHLETE'S HEART: The response of the body to vigorous physical activity is a multiorgan system phenomenon. The integrated functioning of each of these organ systems is very important, but the cardiovascular system plays a critical role in mediating the activity. Because of that, most changes in the neurohumoral regulation predominantly affect the cardiovascular system. These changes include: depression of sympathetic activity and stimulation of parasympathetic activity, so electrophysiological characteristics of the athlete's heart must differ from the sedentary Although these facts, are well known, the athlete's heart is not a precisely defined concept. It is a gray zone between physiology, and pathology. CONCLUSION: Considering the number of sudden cardiac deaths in athletes, it is needless to say how important it is to distinguish physiological changes of the heart due to physical activity, and pathological changes due to some cardiac diseases.

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Performing vigorous physical activity means a multiorgan system engagement, but the cardiovascular system plays a critical role. In order to provide enough oxygen to activate muscles during repeated physical activity of high intensity, the heart undergoes profound morphologic, functional and electrophysiological alterations, which have been identified as the "athlete's heart syndrome". "The athlete's heart" is a complex, but not precisely defined concept, anatomically and functionally and in relation to health and disease. It means the whole heart enlargement and/or hypertrophy of the cardiac muscle, also increasing economy of cardiac performance at rest and during physical activity with higher maximal functional capacities, all that having an adaptive response to vigorous physical activity. For morphological changes called the "athlete's heart, full-time, programed and intensive physical activity at maximal levels is primarily responsible. But as there are different kinds of physical activities, the degree of those morphological changes is highly variable. Considering many sudden cardiac deaths in sports, it is needless to say how important it is to know where the borderline is between normal changes of the heart due to physical activity and pathological changes due to some cardiac diseases. As sport has a growing socio-economic significance, sudden cardiac death events have to be reduced.

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INTRODUCTION: The purpose of this research was to compare changes in running velocity at ventilatory threshold with the veliocity at VO2max, before and after the eight-week exercise program. MATERIAL AND METHODS: 32 male subjects (age: 22.3 +/- 2.5 years, height: 179.8 +/- 7.6 cm, body mass: 76.8 +/- 9.0 kg) performed a progressive test for ventilatory threshold (VT) measurement and VO2max on treadmill. After 8 weeks of endurance training (3 times per week, 30 to 70 min, in different zones in respect to the ventilatory threshold) the performed the same test. RESULTS: Running velocity at ventilatory threshold increased significantly (p = 0.0001), between initial and final measurements (10.88 +/- 2.09, 12.94 +/- 1.90 km/h, respectively); as well as at VO2max (14.63 +/- 1.86, 16.44 +/- 1.59 km/h, respectively). At the initial test, velocity at ventilatory threshold was 74.11 % of VO2max. At the final test, velocity at ventilatory threshold was 78.43% of VO2max. Running velocity at ventilatory threshold has significantly increased at final test (p = 0.001). DISCUSSION: Running velocity at ventilatory threshold has significantly increased after eight weeks of endurance training (p = 0.001), when expressed in absolute values and percentage of velocity at VO2max. CONCLUSION: Comparison between the initial and final test demonstrated a significant increase of observed variables, under experimental conditions: at final test running velocity has increased at ventilatory threshold, in respect to absolute values and expressed as percentage at VO2max.

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The objective of the study was to test the possibility of using the fixed value (12-13) of the Rating of Perceived scale (RPE scale), as a valid method for determination of ventilatory threshold (VT). The sample of the subjects included 32 physically active males (age: 22.3; TV: 180.5; TM: 75.5 kg; VO2max: 57.1 mL/kg/min). During the continuous test of progressively increasing load on a treadmill, cardiorespiratory and other parameters were monitored using ECG and gas analyzer. Following the test, VT and VO2max were determined. During the test, at each level, at the scale from 6 to 20, the subjects pointed the number that suited best their currently feeling of strain. The RPE threshold was defined as constant value of 12-13. Average values of ventilatory and RPE threshold were expressed by parameters that were monitored and then compared by using t-test for dependent samples. No significant difference was found between mean values of VT and RPE threshold, when they were expressed by relevant parameters: speed, load, heart rate, absolute and relative oxygen consumption. Fixed value (12-13) of RPE scale may be used to detect the exercise intensity that corresponds to ventilatory threshold.

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