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Open access

Evdokia Varamenti, Zoran Nikolovski, Mohamed I. Elgingo, Athanasios Z. Jamurtas and Marco Cardinale

Abstract

The purpose of this study was to observe and report variations in several haematological and biochemical markers throughout an entire athletic season in a large cohort of adolescent athletes of Arab origin. Blood samples were collected from 72 adolescent male athletes at 4 selected time points during their training season. Results expressed in relation to plasma volume were corrected accordingly and significant variations in several variables emerged. Initial uncorrected haematological results revealed that haematocrit (Hct) and mean cell volume (MCV) concentrations noticeably increased at the competitive period (T3) and before the start of the following preseason (T4), whereas reticulocytes equivalent (Ret-He) only rose at T4 phase (p < 0.01). Conversely, corrected red blood cells (RBC), haemoglobin (Hb) and mean cell haemoglobin concentration (MCHC) progressively decreased over the year (p < 0.001). From the electrolytes panel, sodium and chloride considerably reduced at the peak of the training period (T2) to the start of the next preseason (T4), while a significant fall in potassium was mainly observed during the competitive period (T3) (p < 0.001). Coaches and sport scientists could use the results of this study to evaluate typical variations of each age group in order to diagnose potential adverse effects of high training loads, assist in the design of training programs and/or clinical interventions that will safeguard athletes’ health, and consider the important role of plasma volume for the interpretation of results.

Open access

Bianca Miarka, Ciro José Brito, John Amtmann, Cláudio Córdova, Fabio dal Bello and Suzi Camey

Abstract

The present study aimed to compare pacing and decision making of athletes competing in judo, with particular attention paid to effort-pause ratios occurring in the championship phases of the Olympic Games and non-Olympic Games. The sample was composed of 53,403 sequential actions analyzed during 611 performances of the non-Olympic Games (eliminatory n = 330, quarterfinals n = 60, semi-final n = 88, repechage n = 21, third place playoff n = 26, and final n = 79) and 163 from the Olympic Games (eliminatory n = 71, quarterfinals n = 13, semi-final n = 26, repechage n = 20, third place playoff n = 24, and final n = 14). The analysis of effort-pause ratios included separating bouts into states of approach, gripping, attack, groundwork and pause, according to frequency and time. A Markov multi-state model and analysis of variance were applied (p ≤ 0.05). Approach time presented differences of the eliminatory Olympic Games (7.3 ± 3.2 s) versus final non-Olympic Games (6.0 ± 2.2s), and the third place playoff Olympic Games (8.1 ± 2.3 s) versus semi-final (6.2 ± 2.4 s) and third place playoff (5.9 ± 2.1 s) of the non-Olympic Games, and the semi-final Olympic Games (8.6 ± 2.3 s) versus eliminatory (6.5 ± 2.3 s), quarter-finals (6.5 ± 1.7 s), semi-final (6.2 ± 2.4 s), repechage (6.2 ± 2.2 s), third place playoff (5.9 ± 2.1 s), and final (6.0 ± 2.0 s) of the non-Olympic Games. Pause time presented differences of the semi-final Olympic Games (6.8 ± 2.1 s) versus eliminatory (5.1 ± 3.1 s). The present data suggest a focus on pacing strategy during championship phases, which mimic the requirements of judo combats.

Open access

Roberto Alsasua, Daniel Lapresa, Javier Arana, M. Teresa Anguera and Belén Garzón

Abstract

Following observational methodology, we analyzed successful and unsuccessful offensive attacks by professional and elite under-16 (U16) basketball players in Spain using an adapted ad hoc observation instrument designed to study efficiency in basketball. We identified both similarities and differences between how players from both categories built their attacks. The synchronic statistical analysis based on frequency counts showed that shots were more efficient in professional basketball and that U16 basketball was less static and had a higher frequency of fast breaks. Diachronic analysis, which consisted of T-pattern detection using Theme software, allowed us to identify characteristic successful and unsuccessful offensive sequences in professional and elite U16 basketball. These results have practical implications as they can be used to design training drills and prepare for competitions in U16 and professional basketball.

Open access

Jorge Vargas, Manuel Loureiro, Pantelis T. Nikolaidis, Beat Knechtle, Lorenzo Laporta, Rui Marcelino and Jose Afonso

Abstract

The aim of the present study was to analyse the Japanese National Women’s Volleyball Team and to identify items differentiating it from other teams. All fifteen matches between the six National Teams (i.e., Japan, Brazil, China, Belgium, Turkey and Russia) competing at the Women’s Volleyball World Grand Prix Finals of 2014 were analyzed, in a total of 56 sets and 7,176 situations of ball possession. Data suggested the existence of differences between Japan’s and the other five teams’ gameplay, namely the likelihood of more gameplay with utilization of the float jump serve (20.42; ± 3.79%, very large magnitude) and attack tempo 2 (61.89; ± 29.67%, large magnitude), while exhibiting less gameplay with zero blockers opposing the attack (-42.06; ± 21.28%, large magnitude). Based on these findings, it was concluded that sports success could be achieved even when a core feature of mainstream performance models (e.g., height in volleyball) was lacking.

Open access

Géraldine Martens, Dorian Deflandre, Cédric Schwartz, Nadia Dardenne and Thierry Bury

Abstract

Running biomechanics and its evolution that occurs over intensive trials are widely studied, but few studies have focused on the reproducibility of stride evolution in these runs. The purpose of this investigation was to assess the reproducibility of changes in eight biomechanical variables during exhaustive runs, using three-dimensional analysis. Ten male athletes (age: 23 ± 4 years; maximal oxygen uptake: 57.5 ± 4.4 ml02·min-1·kg-1; maximal aerobic speed: 19.3 ± 0.8 km·h-1) performed a maximal treadmill test. Between 3 to 10 days later, they started a series of three time-to-exhaustion trials at 90% of the individual maximal aerobic speed, seven days apart. During these trials eight biomechanical variables were recorded over a 20-s period every 4 min until exhaustion. The evolution of a variable over a trial was represented as the slope of the linear regression of these variables over time. Reproducibility was assessed with intraclass correlation coefficients and variability was quantified as standard error of measurement. Changes in five variables (swing duration, stride frequency, step length, centre of gravity vertical and lateral amplitude) showed moderate to good reproducibility (0.48 ≤ ICC ≤ 0.72), while changes in stance duration, reactivity and foot orientation showed poor reproducibility (-0.71 ≤ ICC ≤ 0.04). Fatigue-induced changes in stride biomechanics do not follow a reproducible course across the board; however, several variables do show satisfactory stability: swing duration, stride frequency, step length and centre of gravity shift.

Open access

Krystian Rubajczyk and Andrzej Rokita

Abstract

The relative age effect (RAE) is related to discrimination against youth athletes born in the last quarter of the calendar year. The current study presents research on the RAE in elite youth soccer players in Poland. Players in the Central Junior League (CLJ) finals represent 0.59% of the 25,756 players under 20 years old (U20). This study analyzed the post-game protocols of the CLJ knockout stage from the 2013/2014 and 2014/2015 seasons as well as the U17-U21 teams during 2015, including only players who played on the field for at least one minute (n = 395). The results revealed the existence of RAE in the examined groups ( CLJ 2013/2014, χ23 = 15.441, p < 0.01, CLJ 2014/2015, χ23 = 20.891, p < 0.001 U17-U21, χ23 = 25.110, p < 0.001). In addition, the results differed by monthly birth distribution in the Polish population (PP) between 1995 and 1999. This study is the first to examine the RAE in youth soccer in Poland. The occurrence of the RAE with regard to the most promising youth and national team players suggests that a similar effect exists among younger age categories. To reduce the RAE related to identifying soccer talent, tools should be implemented to optimize the player-selection process, such as those that consider the biological development of a player.

Open access

Nicolas Olivier and Frédéric N. Daussin

Abstract

Swimming and throwing are involved in water-polo player performance. These movements have a common biomechanical basis in the use of the internal shoulder rotation and adductor muscles. The aim of the study was to evaluate the relationship between shoulder isokinetic evaluation and throwing velocity as well as swimming performance in female water-polo players. Fifteen high level water-polo players completed two isokinetic shoulder evaluations to determine peak torque of shoulder rotators of the dominant shoulder (concentric and eccentric movements at an angular velocity of 60°·s-1 and concentric movements at an angular velocity of 240°·s-1) and shoulder extensors of both arms (concentric movements at an angular velocity of 60°·s-1 and 240°·s-1). Throwing velocity was measured using a radar gun placed 5 m behind the goal post. Front crawl swimming velocity was determined at 25 m, 100 m and 400 m distances. Concentric peak torque at 60°·s-1 and 240°·s-1 of internal rotators and eccentric peak torque at 60°·s-1 of external rotators were predictors of throwing velocity. The best model to explain the relationship between isokinetic evaluations and throwing velocity was obtained with concentric IR peak torque at 60°·s-1 and eccentric ER peak torque at 60°·s-1 (r2 = 0.52, p = 0.012). Relative total work done and peak torque of shoulder extensors were predictors of 25 m swimming velocity. Shoulder isokinetic evaluations correlate significantly with swimming performance and throwing velocity of female water-polo players. The results may help coaches to develop new strategies such as eccentric dry land training programs to increase both shoulder external rotators strength and throwing velocity.

Open access

Yasuhiro Yuasa, Toshiyuki Kurihara and Tadao Isaka

Abstract

This study aimed to investigate the relationship between toe muscular strength and the ability to change direction in athletes. Seventeen collegiate American-football players participated in the study (age 19.9 ± 0.9 years, competition experience 7.3 ± 1.7 years). Two types of measurements were performed to evaluate toe muscular strength: toe flexor strength with the metatarsophalangeal joint in the planter flexed position and toe-pushing force with the metatarsophalangeal joint in the dorsiflexed position. The ability to change direction was evaluated using the pro-agility and 3-cone tests and change of direction deficits, calculated by subtracting the sprint times from the pro-agility and 3-cone times. There were significant correlations between toe-pushing force and the results of the pro-agility and 3-cone tests, but no significant correlations between toe flexor strength and the pro-agility and 3-cone tests. Neither toe-pushing force nor toe flexor strength was significantly correlated with the sprint test results. Furthermore, toe-pushing force was significantly correlated with the 3-cone test deficit, but toe flexor strength was not. The ability to change direction is more strongly affected by toe muscular strength (measured as toe-pushing force) with the metatarsophalangeal joint in the dorsiflexed angle than by toe muscular strength (measured as toe flexor strength) with the metatarsophalangeal joint in the plantar flexed angle. Our results suggest that athletes can improve their ability to change direction with toe muscular strength training with the metatarsophalangeal joint in the dorsiflexed position.

Open access

Paulo Henrique Borges, Sean Cumming, Enio R.V. Ronque, Felippe Cardoso, Ademar Avelar, Leandro Rechenchosky, Israel Teoldo da Costa and Wilson Rinaldi

Abstract

The aim of the study was to investigate the relationship between tactical performance, somatic maturity, and functional capabilities in young soccer players. Study participants were 48 soccer players (14.80 ± 1.5 years) belonging to an extension project at the State University of Maringa - Brazil. Anthropometric measurements of body mass, body height, and sitting height were carried out. The number of years to peak height velocity (PHV) was used as an index of maturation. Evaluations of functional fitness included the following tests: sit-and-reach, Yo-Yo Intermittent Recovery Test Level 1, handgrip test, modified abdominal test, and vertical jumps (Counter Movement Jump and Jump Squat). Tactical performance was assessed through the System of Tactical Assessment in Soccer (FUT-SAT). Multiple Linear Regression models were used to estimate the relative contributions of functional and maturational capacities to tactical performance. The results indicated weak associations between the tactical performance indices and somatic maturity, functional capacity, and anthropometric attributes (r < 0.40). The Yo-Yo Test contributed to 36% of the defensive tactic performance variation in the under 13 category. These results suggest that the level of maturity, growth status, and functional fitness have limited impact on tactical performance of young soccer players.

Open access

Piotr Gronek, Joanna Gronek, Ewelina Lulińska-Kuklik, Michał Spieszny, Marta Niewczas, Mariusz Kaczmarczyk, Miroslav Petr, Patricia Fischerova, Ildus I. Ahmetov and Piotr Żmijewski

Abstract

The purpose of this study was to investigate individually and in combination the association between the ACE (I/D), NOS3 (Glu298Asp), BDKRB2 (-9/+9), UCP2 (Ala55Val) and AMPD1 (Gln45Ter) variants with endurance performance in a large, performance-homogenous cohort of elite Polish half marathoners. The study group consisted of 180 elite half marathoners: 76 with time < 100 minutes and 104 with time > 100 minutes. DNA of the subjects was extracted from buccal cells donated by the runners and genotyping was carried out using an allelic discrimination assay with a C1000 Touch Thermal Cycler (Bio-Rad, Germany) instrument with TaqMan® probes (NOS3, UCP2, and AMPD1) and a T100™ Thermal Cycler (Bio-Rad, Germany) instrument (ACE and BDKRB2). We found that the UCP2 Ala55Val polymorphism was associated with running performance, with the subjects carrying the Val allele being overrepresented in the group of most successful runners (<100 min) compared to the >100 min group (84.2 vs. 55.8%; OR = 4.23, p < 0.0001). Next, to assess the combined impact of 4 gene polymorphisms, all athletes were classified according to the number of 'endurance' alleles (ACE I, NOS3 Glu, BDKRB2 -9, UCP2 Val) they possessed. The proportion of subjects with a high (4-7) number of 'endurance' alleles was greater in the better half marathoners group compared with the >100 min group (73.7 vs. 51.9%; OR = 2.6, p = 0.0034). These data suggest that the likelihood of becoming an elite half marathoner partly depends on the carriage of a high number of endurance-related alleles.