Παράγοντες κόπωσης στην υδατοσφαίριση και εξέταση δύο προπονητικών προγραμμάτων για την αναχαίτισή της

Η παρούσα Διατριβή διερεύνησε την επίδραση: α) του αγώνα υδατοσφαίρισης σε βασικές φυσικοτεχνικές ικανότητες των παικτών, β) των αμυντικών συστημάτων στις φυσιολογικές αποκρίσεις αμυνόμενων και επιτιθέμενων παικτών και γ) της προπόνησης στην αναχαίτιση της ασκσιογενούς κόπωσης. Μια σειρά δοκιμασιών απόδοσης εκτελέστηκαν στην αρχή, στο ημίχρονο και στο τέλος του αγώνα: επαναλαμβανόμενα σπριντ (ΕΣ), χειροδυναμομέτρηση (ΧΔΜ), «πόδια ποδήλατο» με εξωτερική επιβάρυνση. Πριν και στο τέλος του αγώνα πραγματοποιήθηκαν 400μ ελεύθερο και αξιολόγηση της ευστοχίας και ταχύτητας ρίψης της μπάλας με σουτ σε προκαθορισμένο στόχο (Ν=16). Επίσης, προσδιορίστηκαν οι φυσιολογικές αποκρίσεις μετά την εφαρμογή διαφορετικών αμυντικών συστημάτων (πιεστική άμυνα, στατική ζώνη, κινητική ζώνη) σε κανονικά παιχνίδια (Ν=18) και σε αγώνες που παίχτηκαν σε μία εστία (Ν=14). Επιπλέον, 8 υδατοσφαιριστές εκτέλεσαν ΕΣ,ΧΔΜ, 400μ, και ευστοχία σε αγώνες που πραγματοποιήθηκαν στα τέλη της μεταβατικής περιόδου (ΤΜΠ), στο τέλος της προ-αγωνιστικής (ΠΡΟ-Π) και στο τέλος της αγωνιστικής περιόδου (ΑΠ). Η επίδοση στα ΕΣ, στη ΧΔΜ, στα 400μ και στην ευστοχία μειώθηκε στο τέλος του παιχνιδιού (ΕΣ: 14,03±0,6 έναντι 15,2±1,0 s, ΧΔΜ: 59,3±6,4 έναντι 53,8±6,6 kg, 400μ: 300,8±11,1 έναντι 320,4±20,6 s, ευστοχία: 2,7±0,5 έναντι 2,1±0,7 πόντοι, p<0,01), ενώ δεν παρατηρήθηκαν αλλαγές μεταξύ ημιχρόνου και τέλους του αγώνα. Η απόδοση στα «πόδια ποδήλατο» με εξωτερική επιβάρυνση και στην ταχύτητα ρίψης της μπάλας παρέμεινε αμετάβλητη (p>0,05). Στα παιχνίδια σε μια εστία, η αγωνιστική ένταση είναι μεγαλύτερη με την πιεστική άμυνα ενώ σε κανονικά παιχνίδια η ένταση δεν διαφοροποιείται μεταξύ των αμυντικών συστημάτων. Μετά την ΠΡΟ-Π η απόδοση βελτιώθηκε στα ΕΣ (4±3%), ΧΔΜ (3±3%) και 400μ (4±1%) στην αρχή του παιχνιδιού συγκριτικά με την ΤΜΠ αλλά παρέμεινε αμετάβλητη μετά την ΑΠ. Επιπρόσθετα, στο ημίχρονο και στο τέλος του αγώνα, η απόδοση στα ΕΣ και 400μ ήταν καλύτερη μετά την ΠΡΟ-Π (ΕΣ:5±3%, 4±2%, αντίστοιχα, 400μ:3±3%), ενώ δεν παρατηρήθηκαν αλλαγές μετά την AΠ. Συμπερασματικά, η απόδοση των παικτών μειώνεται καθώς εξελίσσεται ο αγώνας. Το αμυντικό σύστημα δεν επηρεάζει την ένταση του παιχνιδιού. Η προπόνηση μπορεί να αναχαιτίσει την ασκησιογενή κόπωση

Short-term sleep deprivation and human thermoregulatory function during thermal challenges

bstractRelatively short periods of inadequate sleep provoke physiological and psychological perturbations, typically leading to functional impairments and degradation in performance. It is commonly accepted that sleep deprivation also disturbs thermal homeostasis, plausibly enhancing susceptibility to cold- and heat-related illnesses. Herein, we summarize the current state of human-based evidence on the impact of short-term (i.e., ≤4 nights) sleep deprivation on autonomic and behavioural thermoeffectors during acute exposure to low and high ambient temperatures. The purpose of this brief narrative review is to highlight knowledge gaps in the area and stimulate future research to investigate whether sleep deprivation constitutes a predisposing factor for the development of thermal injuries.QCR 20210317</p

ODNOS ANTROPOMETRIJE I FREKVENCIJE ROTACIONIH POKRETA NOGU POD USLOVIMA SPOLJAŠNJEG PRITISKA U VATERPOLU

We intend to investigate whether specific anthropometric characteristics and/or frequency of leg movement are related to the water-polo players’ ability to resist external pressure during the eggbeater kick. Twenty-four male water-polo players participated in this study. Preliminarily, the participants’ anthropometric characteristics were measured. Thereafter, a 20-sec eggbeater kick test was conducted in order to determine the minimum load the participants could resist. On the day of the experiment, each participant performed the 20-sec eggbeater kick test, starting from 10 kg and thereafter with a progressive increase of 1 kg external load until peak external load (PEL) was reached. The external load the players could effectively resist before the failed effort was considered the PEL. Significant correlations between the majority of anthropometric characteristics and PEL were observed (r=0.38 to 0.62, P<0.05). Multiple regression analyses revealed that stature and body mass explained the total variance of PEL by 67% and 58% respectively (P<0.05), while frequency of leg movements were also significant predictors explaining more than 45% of PEL variance (P<0.05). The factor analysis showed that anthropometric characteristics and leg frequency movements totally explained 80.42% of the PEL variance. However, the multiple regression analysis based on scores from the factor analysis revealed that only anthropometric characteristics were significant predictors of PEL during the eggbeater kick, explaining more than 37% of the total variance (P<0.05). The present study indicates that anthropometric characteristics are more important predictors of the performance of the eggbeater kick.Nameravamo da istražimo da li su specifične antropometrijske karakteristike i/ili učestalost pokreta nogu povezani sa sposobnošću vaterpolista da se odupru spoljašnjem pritisku tokom rotacionih pokreta nogu. U ovom istraživanju učestvovalo je dvadeset četiri vaterpolista. Preliminarno su izmerene antropometrijske karakteristike učesnika. Nakon toga, sproveden je 20-sekundni eggbeater kick test kako bi se utvrdilo minimalno opterećenje kome učesnici mogu da izdrže. Na dan eksperimenta, svaki učesnik je izvršio 20-sekundni eggbeater kick test, počevši od 10 kg i nakon toga sa progresivnim povećanjem spoljašnjeg opterećenja od 1 kg dok se ne postigne vršno spoljno opterećenje (PEL). Spoljašnje opterećenje kome su igrači mogli efikasno da se odupru pre nego što se neuspeli pokušaj smatra PEL. Uočene su značajne korelacije između većine antropometrijskih karakteristika i PEL (r=0,38 do 0,62, P<0,05). Višestruke regresione analize su otkrile da stas i telesna masa objašnjavaju ukupnu varijansu PEL za 67% i 58% respektivno (P<0,05), dok su učestalost pokreta nogu takođe bili značajni prediktori koji objašnjavaju više od 45% varijanse PEL (P<0,05). Faktorska analiza pokazala je da antropometrijske karakteristike i frekventni rotacioni pokreti nogu u potpunosti objašnjavaju 80,42% varijanse PEL. Međutim, analiza višestruke regresije zasnovana na rezultatima faktorske analize otkrila je da su samo antropometrijske karakteristike bile značajni prediktori PEL tokom rotacionih pokreta nogu, objašnjavajući više od 37% ukupne varijanse (P<0,05). Ova studija ukazuje na to da su antropometrijske karakteristike važniji prediktori performansi rotacionih pokreta nogu

Diet and exercise effects on aerobic fitness and body composition in seriously mentally ill adults

Low exercise capacity and high obesity levels are the main characteristics of people with serious mental illness (SMI). We conducted a pilot study on the effects of a 3-month exercise and dietary intervention on the aerobic capacity and body composition of obese adults with SMI taking Olanzapine, a second generation antipsychotic medication known to induce weight increments. Fifty adults with SMI (15 males and 35 females) followed a 3-month weight loss intervention programme based on exercise and diet. Pre- and post-intervention, a submaximal O2 exercise test was performed in order to assess O2max anthropometric and body composition measurements were also performed. All participants were obese (body mass index (BMI): 33.61 ± 0.91 kg/m2). Pre- and post-intervention, a submaximal O2 exercise test on the treadmill was performed in order to assess O2max anthropometric and body composition measurements were also performed. Significant reductions in body weight, BMI, body fat and waist circumference were found from pre to post (p &lt; 0.01). O2max was significantly improved in both genders (males: pre: 30.63 ± 2.06 vs. post: 33.19 ± 1.77 ml.kg-1 min-1, females: pre: 25.93 ± 1.01 vs. post: 29.51 ± 1.06 ml.kg-1 min-1, p &lt; 0.01). A significant correlation was found between the change in O2max and the change in body weight and BMI (p &lt; 0.05). Multiple regression analysis revealed that the relative change in O2max explained approximately 26% of the variance in the changes for both BMI (p = 0.07) and body weight (p = 0.06). A treatment of exercise and diet improves the aerobic capacity and body composition of obese adults with SMI, despite the use of Olanzapine

Evaluation of Physical Fitness in Water Polo Players According to Playing Level and Positional Role

Background: We aimed to investigate whether water polo players of different playing levels and positions differ in fitness parameters (i.e., strength, aerobic endurance, and anaerobic potential). Methods: Twenty-four water polo players were assigned to international- (IL) and national-level (NL) groups or to centers and peripherals. At the beginning of preseason training, maximal bench press strength was measured and a speed&#8315;lactate test (5 &#215; 200m) was performed to determine the speed corresponding to lactate concentrations of 4.0 (V4), 5.0 (V5), and 10.0 (V10) mmol&#183;L&#8722;1. Results: Maximal muscular strength was similar between international- and national-level water polo players, but it was higher in centers than in peripherals (109.2 &#177; 12.2 kg vs. 96.9 &#177; 8.5 kg, p = 0.007). IL players showed higher V4, V5, and V10 compared to NL players (V4, IL: 1.27 &#177; 0.04 m&#183;s&#8722;1 vs. NL: 1.17 &#177; 0.06 m&#183;s&#8722;1), (V5, IL: 1.33 &#177; 0.03 m&#183;s&#8722;1 vs. NL: 1.22 &#177; 0.05 m&#183;s&#8722;1), and V10 (IL: 1.50 &#177; 0.31 vs. NL: 1.35 &#177; 0.06 m&#183;s&#8722;1) (p &lt; 0.01)). However, no significant differences were detected between centers and peripherals inV4, V5, and V10. Conclusions: We suggest that V4, V5, and V10 distinguish playing level in water polo, whereas they are comparable between playing positions. Although maximal strength is similar between playing levels, it is different between playing positions

Physiological Responses of Water-Polo Players Under Different Tactical Strategie

The aim of this study was to investigate the effect of defense tactical strategy on physiological responses characterizing playing intensity in water-polo game. In the first part of the study, fourteen players were assigned to defending (n = 7) and offending (n = 7) groups and participated in nine 4-min plays applying three different defending systems: press, static-zone and zone-press, in front of the defense court of one goalpost. In the second part, 18 players participated in nine different real full court water-polo games consisting of 3X15min of live-time playing periods. Both in defense court plays and real games, the three defense systems were played in a counterbalanced order and heart rate (HR) was continuously recorded. Additionally, in defense court plays, blood lactate concentration (La) was measured at the end of each 4-min period. Mean HR within defense court plays was higher in press (153 ± 10 beats.min-1) than in static-zone (140 ± 11 beats.min-1) and zone-press (143 ± 16 beats.min-1, p 0.05). Defenders and offenders showed similar HR and La responses across the tactical modes. In conclusion, defense tactical strategies affect physiological responses within a part of the game but do not affect the overall playing intensity of a real water-polo game. Tactical strategies similarly affect offenders and defenders