Determination of the heart rate recovery (HRR) after the session of a physical activity, represents the valuable parameter for the investigation of autonomic balance and its dynamic in the general population, but also in the population of elite athletes. However, the methodology for its determination and analysis is still not entirely specified. It is necessary to define an adequate protocol of cardiopulmonary exercise test, by choosing an adequate ergometer (treadmill, ergo-bicycle or step bench). Organization of recovery period (active or passive), after the session of exercise is also very important, because its protocol interfered significantly with the value of HRR. Interpretation of obtained HRR values varies a lot, and researcher has freedom to choose the most adequate way, in accordance with the objectives of his study. Following paper represents a short review of determination, interpretation and analysis of HRR, followed by the latest recommendations.Key words: heart rate recovery, cardiopulmonary exercise test, maximal oxygen uptake, autonomic balance SažetakPraćenje oporavka srčane frekvencije nakon sesije fizičke aktivnosti (engl. heart rate recovery, HRR) predstavlja veoma značajan parametar koji možemo koristiti u cilju izučavanja balansa autonomnog nervnog sistema, kako u opštoj populaciji, tako i u populaciji vrhunskih sportista. Metodologija koja se koristi za određivanje i analizu HRR, međutim, još uvek nije adekvatno definisana. Prvenstveno je potrebno definisati adekvatan protokol testa opterećenja koji koristimo u svrhu određivanja HRR, a zatim i odabrati odgovarajući ergometar (tredmil, ergo -bicikl ili step -klupica). Potrebno je definisati i protokol perioda oporavka (da li će oporavak biti aktivan ili pasivan), budući da odabrani protokol značajno utiče na dobijene vrednosti HRR. Interpretacija dobijenih vrednosti HRR veoma varira od studije do studije, tako da istraživači imaju slobodu da izaberu način interpretacije koji najviše odgovara potrebama specifičnog istraživanja. Uzevši u obzir gore navedene činjenice, naš rad predstavlja jedan kratak pregled protokola koje možemo koristiti u određivanju, interpretaciji i analizi vrednosti HRR, prateći najnovije preporuke. Ključne reči: oporavak srčane frekvencije, test fizičkog opterećenja, maksimalna potrošnja kiseonika, balans autonomnog nervnog sistema

SažetakUvod: Kao jedna od prednosti redovne fizičke aktivnosti navodi se niža srčana frekvencija u miru i njen brži oporavak nakon testa maksimalnog opterećenja, kao posledica jačeg parasimpatičkog (vagusnog) tonusa. Oporavak srčane frekvencije se koristi kao pouzdan parametar fizičke utreniranosti, ali i u prognostičke svrhe kao parametar rizika za obolevanje od kardiovaskularnih bolesti. Cilj: Cilj ove studije je da pokaže postojanje statistički značajnih razlika u oporavku srčanih frekvencija nakon maksimalnog opterećenja i razlike frekvencija u mirovanju između različitih grupa vrhunskih sportista. Materijal i metode: Ovom studijom je obuhvaćeno 575 odraslih (23,1 ± 4,3 godina) sportista muškog pola, podeljenih u četiri grupe sportova: sportove veštine, snage, mešovitih disciplina i izdržljivosti. Svi ispitanici su izveli maksimalni, progresivni kardiopulmonalni test fizičkim opterećenjem na traci za trčanje. Oporavak srčane frekvencije u prvom (ΔHRR1) i trećem minutu (ΔHRR3) definisan je razlikom maksimalne srčane frekvencije i frekvencije u prvom, odnosno trećem minutu po okončanju vežbanja. Rezultati: Statistički značajno niže vrednosti srčane frekvencije u mirovanju zabeležene su u grupi izdržljivosti (56,2 ± 10,6 min -1 ) u odnosu na grupe sportova veština, snage i mešovitih disciplina (62,9 ± 11,4; 61,5 ± 10,0; 59,9 ± 10,4 min ) u odnosu na grupe sportova veštine, snage i mešovitih disciplina (24,3 ± 10,9; 25,5 ± 11,2; 27,8 ± 15,6 min -1 ) (p = 0,05). Vrednosti ΔHRR3 su bile značajno više u grupi snage, mešovi-tih disciplina i izdržljivosti (74,8 ± 14,3; 79,5 ± 12,7; 79,4 ± 12,6 min -1 ) u odnosu na grupu veština (67,3 ± 16,1 min -1 ) (p = 0,05). Zaključak: Treniranje sportova iz grupe izdržljivosti najviše doprinosi smanjenju srčane frekvencije u mirovanju i brzini njenog oporavka u prvom minutu nakon vežbanja zbog preovlađujućeg parasimpatičkog tonusa. Ključne reči: srčana frekvencija, oporavak, trening, sportisti Abstract Introduction: One of the benefits of regular physical activity is lower resting heart rate and its faster recovery after maximal exercise test, as a result of a stronger parasympatic (vagal) tone. Heart rate recovery is used as reliable parameter for prescription of the training program and also in prognostic purposes as a parameter of risk for developing cardiovascular diseases. Aim: The purpose of this study is to show significant differences in heart rate recovery after maximal exercise test and resting heart rate among different groups of elite athletes. Material and Methods: This study subjected 575 adult (23.1 ± 4.3 years), male athletes divided into four sport groups: skill, power, mixed and endurance. Every subject performed progressive, maximal cardiopulmonary exercise test on a treadmill. Heart rate recovery in first (ΔHRR1) and third (ΔHRR3) minute was calculated as a difference of maximal heart rate and heart rate in the first and the third minute after cessation of exercise, respectively. Results: Compared to skill, power and mixed group (62.9 ± 11.4; 61.5 ±...

Continuous physical activity leads to a series of adaptive changes to athletes' cardiovascular system, collectively called Athlete's heart. Recognizing such physiological ECG changes and distinguishing them from the pathological myocardium-related findings, play an important role in sudden cardiac death prevention among athletes. The aim of our study was to examine the effect of the type of sport on the frequency of electrocardiographic changes between two groups of subjects, football and volleyball players. The study included 47 subjects, students of the Faculty of Medicine, University of Belgrade, divided into two groups depending on type of sport they play. The first group consisted of 29 volleyball players, while the second group consisted of 18 football players. Anthropometric parameters: body height (BH), body weight (BW), body mass index (BMI), body fat percentage (%BF) were measured first. Resting electrocardiographic test was performed in supine position, using twelve-lead electrocardiograph. From obtained electrocardiograms (ECG), using the Seattle criteria for interpretation of ECG findings in athletes, following parameters were analyzed: heart rate, heart rhythm, rhythmicity, respiratory arrhythmia, cardiac axis, duration and amplitude of individual waves, segments and intervals, QTc, right and left atrial enlargement, isolated voltage criteria for left and right ventricular hypertrophy, incomplete right bundle-branch block, first degree AV block, second degree AV block-Mobitz type I (Wenckebach), and T wave inversion. Statistical analysis was performed using paired T-test and Chi square test, within the SPSS package. Results of the study showed higher values of amplitude of P wave in the V1 lead among football players (p=0.015), alongside significant difference in frequency of T wave inversion in leads V1-V3 (p=0.048). Volleyball players demonstrated significantly higher frequency of left atrial enlargement (p=0.019). Based on presented results, we can conclude that observed ECG changes indicate that different types of sports may lead both to changes in electrical activity of cardiac conduction system and myocardium.

Uticaj tipa treninga na atropometrijske i fUnkcionalne karakteristike U popUlaciji sportista takmičara Sažetak: Uvod: Osnovna mera aerobne sposobnosti organizma je količina utrošenog kiseonika (VO 2 ml/min/kg). Aerobna moć ili maksimalni aerobni kapacitet je određen maksimalnom vrednošću potrošnje kiseonika (VO 2 max). Cilj: Cilj ove studije je da uporedi maksimalnu potrošnju kiseonika između dve grupe sportista koji imaju različite programe treninga. Materijali i metode: U našem istraživanju učestvovalo je 204 sportista takmičara različitih sportskih disciplina, muškog pola, starosti između 18 i 35 godina. Ispitanici su bili podeljeni u 2 grupe, u skladu sa preovlađujućim karakteristikama treninga: grupa sportova veština (n = 86) i grupa sportova izdržljivosti (n = 118). Rezultati: Ispitanici u grupi sportova veština bili su statistički značajno stariji u odnosu na ispitanike iz grupe sportova izdržljivosti (25 ± 5; 23 ± 4, respektivno; p < 0.05). Vrednosti telesne visine bile su statistički značajno veće u populaciji sportova izdržljivosti u odnosu na populaciju sportova veština (185,54 ± 7,24; 183,41 ± 7,79, respektivno; p < 0.05). Vrednosti telesne mase se nisu statistički značajno razlikovale među grupama. Indeks telesne mase bio je visokostatistički značajno niži u grupi sportova izdržljivosti u poređenju sa grupom sportova veština (23,32 ± 1,88 kg/m 2 i 24,80 ± 3,37 kg/m 2 , respektivno; p < 0,001). Testiranje je pokazalo da je procenat telesne masti visokostatistički značajno veći u grupi sportova veština u poređenju sa grupom sportova izdržljivosti (13,52 ± 6,45% i 8,39 ± 3,62%, respektivno; p < 0,001). Pripadnici grupe sportova veština imali su statistički značajno manju potrošnju kiseonika u miru u odnosu na grupu sportova izdržljivosti (5,87 ± 1,20 ml/min/kg i 6,54 ± 1,26 ml/ min/kg, respektivno; p < 0.05). Pripadnici grupe sportova izdržljivosti imali su visokostatistički značajno veću maksimalnu potrošnju kiseonika u odnosu na ispitanike u grupi sportova veština (55,35 ± 8,44 ml/min/kg i 45,50 ± 7,49 ml/min/kg, respektivno; p < 0,001).

Introduction: It is known that music can reduce the sense of fatigue and pain during physical exercise as well as to affect the motivation. Physiological effects of music during submaximal intensity cardiopulmonary exercise tests can be examined using a treadmill. Aim: In this study we examined the impact of asynchronous music on cardiopulmonary parameters of students, while they were running on the treadmill on the moderate to high load. Also we examined the difference between these two conditions. Materials and methods: This study involved 6 students from the Faculty of Medicine in Belgrade, which were tested in the conditions with and without music. In order to determine maximal oxygen consumption, maximal exercise tests were conducted in advance. During the testing phase, cardiopulmonary parameters were measured in two different conditions: on 70% of maximal measured VO 2 values and on 90% of previously measured maximal VO 2 values respectively. Results: The breathing frequency, ventilation, exhaled CO 2 volume, blood pressure were significantly increased (p<0.05) in terms of music on a moderate rate of 70% VO 2 max. On high rate of 90% VO 2 max, there has been no significant changes to the parameters (p>0.05) except a decrease in blood pressure and minimal increase in VO 2 /kg. Conclusion: This study confirmed the influence of music on cardiopulmonary parameters and demonstrated that it can affect respiratory variables only on moderate loads. Results showed that music does not affect respiratory variables on high loads, but there was a significant decrease in blood pressure in both, moderate and high loads.

ZSM-5 zeolites are highly silicate materials that have significant application in catalytic processes in petrochemistry, especially due to their high selectivity. Most reactions in the petrochemical industry are acid-catalyzed. The acidic properties of zeolite depend on the number of acid centers, i.e. the presence of hydrogen ions, and therefore, in this paper the possibility of reducing the sodium content in the pores of high silicate zeolite ZSM-5 with the modulus (SiO2 / Al2O3 = 1000) will be investigated, by applying ion exchange with hydrochloric acid. Chemical analysis of samples before and after ion exchange, and application of instrumental methods of X-Ray diffraction, FT-IR spectroscopy, and SEM analysis monitored the influence of the quantity of hydrogen ions on the chemical composition and the structure of ZSM-5 zeolite at different acid concentrations and at different exchange times. It has been shown that the application of ion exchange with hydrochloric acid can reduce the sodium content in zeolite. Even with the application of 5% HCl for 6 hours, the content of sodium in the zeolite is reduced by over 98%. A similar effect is achieved by applying more concentrated hydrochloric acid solutions for a shorter ion exchange time. By prolonging the ion exchange time, there are no significant changes in terms of the final ion exchange. On the other hand, the application of HCl solutions of higher concentrations leads to a slight decrease in the aluminum content in the zeolite, which may partially affect the structural stability of the zeolite. The results obtained by FT-IR and SEM analysis and X-Ray diffraction confirm the possibility of ion exchange with hydrochloric acid, without significant changes in the crystal structure of the zeolite.