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Journal Details
Format
Journal
eISSN
1899-7562
First Published
13 Jan 2009
Publication timeframe
5 times per year
Languages
English

Search

Volume 62 (2018): Issue 1 (June 2018)

Journal Details
Format
Journal
eISSN
1899-7562
First Published
13 Jan 2009
Publication timeframe
5 times per year
Languages
English

Search

24 Articles

Section I – Kinesiology

Open Access

Comparison of Core Muscle Activation Between a Prone Bridge and 6-RM Back Squats

Published Online: 13 Jun 2018
Page range: 43 - 53

Abstract

Abstract

The purpose of this study was to compare core muscle activation during a prone bridge (plank) until failure and 6-RM back squats. Twelve resistance-trained males (age 23.5 ± 2.6 years, body mass 87.8 ± 21.3 kg, body height 1.81 ± 0.08 m) participated in this study. Total exercise time and EMG activity of the rectus abdominis, external abdominal oblique and erector spinae were measured during 6-RM back squats and a prone bridge with a weight of 20% of participants’ body mass on their lower back. The main findings showed non-significant differences between the exercises in the rectus abdominis or external oblique, but greater erector spinae activation in squatting. Furthermore, in contrast to the prone bridge, the erector spinae and rectus abdominis demonstrated increasing muscle activation throughout the repetitions while squatting, whereas the prone bride demonstrated increasing external oblique activation between the beginning and the middle of the set. It was concluded that since squatting resulted in greater erector spine activation, but similar rectus abdominis and oblique external activation as the prone bridge, high-intensity squats rather than isometric low intensity core exercises for athletes would be recommended.

Key words

  • EMG
  • core stability
  • core strength
  • performance
Open Access

Changes in Injury Risk Mechanisms After Soccer-Specific Fatigue in Male Youth Soccer Players

Published Online: 13 Jun 2018
Page range: 33 - 42

Abstract

Abstract

The aim of this study was to examine the acute effects of soccer specific fatigue on muscular and neuromuscular function in male youth soccer players. Elite soccer players (n = 20; age 15.7 ± 0.5 y; body height 177.75 ± 6.61 cm; body mass 67.28 ± 8.29 kg) were measured before and after soccer specific exercise (SAFT90). The reactive strength index (RSI) was determined by a drop jump test, leg stiffness (LS) by a 20 sub-maximal two-legged hopping test, and a functional hamstring to quadriceps strength ratio from isokinetic concentric and eccentric strength of the dominant and non-dominant leg (measured at angular velocities of 1.05 rad · s−1 and 3.14 rad · s−1). Metabolic response to the SAFT90 was determined by blood lactate and perceived exertion was assessed by the Borg scale. After simulated match play, a significant decrease in absolute LS (t = 4.411; p < 0.001; ω2 = 0.48) and relative LS (t = 4.326; p < 0.001; ω2 = 0.49) was observed and the RSI increased significantly (t = 3.806; p = 0.001; ω2 = 0.40). A reduction in LS found after the SAFT90 indicates possible reduction in dynamic knee stabilization. However, if we consider the changes in other observed variables, the present study did not clearly confirm that fatigue induced by a soccer specific protocol increased the risk of ACL and hamstring injury. This may be attributed to the simulated rather than actual match play used in the present study.

Key words

  • leg stiffness
  • reactive strength
  • neuromuscular function
  • isokinetic
  • ACL
Open Access

How To Maintain Maximal Straight Path Running Speed on a Curved Path in Sprint Events

Published Online: 13 Jun 2018
Page range: 23 - 31

Abstract

Abstract

This study aims to clarify the ideal technique for running on a curved path during sprinting events. Participants were twelve male track and field athletes including long jumpers and sprinters. The participants performed a 60-m sprint with maximal effort on straight and curved paths. Participants were divided into “good curve runners” and “poor curve runners” according to the curved path running speed relative to that of the straight path. Kinematic variables and ground reaction forces (GRFs) were registered and compared between the groups and paths. The running speed, step length, and flight distance of the outside leg on the curved path were lower than on the straight path only in poor curve runners. The medial-lateral GRF and impulse showed an increase during curved path running for both groups. However, the maximum posterior GRF and impulse decreased only in poor curve runners. The ideal technique for running on a curved path is to maintain the same kinematics and kinetics in the sagittal plane as on a straight path.

Key words

  • curved path
  • running technique
  • maximal running speed
  • sprinting
Open Access

Balance and Lower Limb Muscle Activation Between in-Line and Traditional Lunge Exercises

Published Online: 13 Jun 2018
Page range: 15 - 22

Abstract

Abstract

In-line and traditional lunge exercises present differences in technique as lower limb positioning (anterioposterior), and medio-lateral (ML) balance may differentially affect primary and stabilizer muscles. The purposes of this study were to examine ML balance and muscle activation in anterior and posterior leg positions between in-line and traditional lunge exercises. Fifteen young, healthy, resistance-trained men (25 ± 5 years) performed 2 different lunge exercises (in-line and traditional) at their 10 repetition maximum in a randomized, counterbalanced fashion. Surface electromyography measured muscle activation of the vastus lateralis, biceps femoris, gluteus maximus, and gluteus medius. ML balance was measured with a Wii Fit Balance Board. The vastus lateralis activity was not significantly different between exercises or leg positions. The biceps femoris activity was not significantly different between exercises, however, it was significantly greater in the anterior compared to the posterior position for the in-line (p = 0.003), and traditional lunge (p < 0.001). The gluteus maximus activity was not significantly different between exercises, however, it was significantly greater in the anterior compared to posterior position for the in-line (p < 0.001) and traditional lunge (p < 0.001). ML balance was significantly greater in the in-line exercise in the anterior limb (p = 0.001). Thus, both in-line and traditional lunge exercises presented similar overall levels of muscle activation, yet the anterior limb generated the highest biceps femoral and gluteus maximus muscle activation when compared to the posterior limb. The in-line lunge presents greater ML balance when compared to the traditional lunge exercise.

Key words

  • electromyography
  • strength
  • performance
Open Access

The Effects of Repeated Sprints on the Kinematics of 3-Point Shooting in Basketball

Published Online: 13 Jun 2018
Page range: 5 - 14

Abstract

Abstract

Fatigue modifies the kinematics of various sports-related movements. Basketball induces fatigue, however, the effects of fatigue on the kinematics of shooting have never been studied. This study analysed the effects of fatigue induced by repeated sprints on the kinematics of 3-point shooting (3PS) in young, elite basketball players (U18 level). 3D joint angles were calculated at the maximum and minimum heights of the centre of mass during 3PS, using inertial measurement units (Biomech system, Xsens Technologies BV, Enschede, The Netherlands). Height, velocity and the angle of the ball at the time of release were extrapolated from the wrist joint angles. All players performed four 3PS actions in dynamic conditions before and after a fatigue protocol at 70% of their maximal exercise capacity. The fatigue protocol consisted of a shuttle test with repeated 20-m sprints interspersed with sets of 5 jumps. There was no change in the kinematics of 3PS (p > 0.05), or the ball release variables (p > 0.05) following the fatigue protocol. This suggests that elite basketball players are able to cope with physical fatigue while performing coordinated movements such as 3PS.

Key words

  • biomechanics
  • team sport
  • kinematics
  • elite players
  • fatigue

Section II – Exercise Physiology & Sports Medicine

Open Access

Skeletal Muscle Cell Damage Indicators in Volleyball Players after the Competitive Phase of the Annual Training Cycle

Published Online: 13 Jun 2018
Page range: 81 - 90

Abstract

Abstract

The aim of the study was to evaluate the impact of the competitive phase on physiological and metabolic indices and selected markers of skeletal muscle damage in male volleyball players. The study group consisted of 24 young male volleyball players. During the study, participants underwent two series of measurements, before and after the competitive phase of the annual training cycle. In both study terms, players performed an incremental treadmill running test to determine their ventilatory threshold and maximal oxygen uptake. Venous and capillary blood samples were taken for biochemical analysis. There was no significant difference in the physical fitness level, values of biochemical variables and the level of antioxidant status in the surveyed athletes between the two study terms. Significant changes within skeletal muscle damage markers were observed between the beginning and the end of the competitive period: an increase in the concentration of cellular DNA damage products (8-hydroxy-2′-deoxyguanosine; p < 0.0001) and a decrease in muscle activity of creatine kinase (p<0.05). In spite of the increment in cell damage markers, the unaffected level of physiological and biochemical markers may indicate that the experienced cell destruction did not negatively affect the level of physical fitness. When designing the annual training plan, coaches and athletes need to take into consideration that temporary physiological states – oxidative stress and inflammation – may be required to attain training adaptation.

Key words

  • training
  • team sports
  • injury
  • prevention
  • biochemical variables
Open Access

Epidemiology of Time-Loss Injuries in Senior and Under-18 Portuguese Male Rugby Players

Published Online: 13 Jun 2018
Page range: 73 - 80

Abstract

Abstract

Rugby union has one of the highest injury incidence rates in team sports, however, most of the available data focus on the epidemiology of injuries in countries where rugby is popular. We aimed to report the incidence rate and relevant epidemiological aspects of injuries occurred in a group of Portuguese male rugby players. A prospective cohort study was conducted with a group of 45 senior and 32 under-18 male players (total of 77 players). Outcome measures included injury incidence, position, type, location and severity of injuries. The match injury incidence for all players was 55.84 per 1000 player match-hours (66.66 for seniors, 42.85 for under-18), while mean time-loss for injury was 20.79 days. No statistical differences were found between groups. Lower limb injuries accounted for 60.5% of all injuries, while joint/ligament injuries were the most prevalent type. Contact events were responsible for 65.1% of injuries. Despite the limitations, the obtained data are consistent with the literature. Time-loss injuries seem highly prevalent in rugby union and the incidence rates found in this Portuguese-based study were lower than the reported for international and senior men’s professional rugby union, but higher than those occurring in community rugby in tier-1 countries. The authors believe these data reinforce the need to develop and implement effective injury surveillance and prevention programs.

Key words

  • athletic injuries
  • injury surveillance
  • rugby union
Open Access

Interactions Between COL5A1 Gene and Risk of the Anterior Cruciate Ligament Rupture

Published Online: 13 Jun 2018
Page range: 65 - 71

Abstract

Abstract

Collagen alpha-1(V) chain, encoded by the COL5A1 gene, plays a crucial role in abundant fibrillar collagens supporting many tissues in the body containing type I collagen and appears to regulate the association between heterotypic fibers composed of both type I and type V collagen occurring among others in muscles, tendons and ligaments. Taking this fact into consideration we decided to examine the association between COL5A1 rs12722 and rs13946 polymorphisms, individually and as inferred haplotypes, with anterior cruciate ligament rupture risk (ACLR) in professional soccer players. A total of 134 male professional soccer players with surgically diagnosed primary anterior cruciate ligament ruptures and 211 apparently healthy male professional soccer players, who were without any self-reported history of ligament or tendon injury, were included in the study. Both the cases and the healthy controls were recruited from the same soccer teams, of a similar age category, and had a comparable level of exposure to anterior cruciate ligament injury. Genomic DNA was extracted from oral epithelial cells using GenElute Mammalian Genomic DNA MiniprepKit. All samples were genotyped for the rs12722 and rs13946 polymorphisms using a Rotor-Gene realtime polymerase chain reaction. Statistically significant differences in the genotype frequencies for the COL5A1 rs13946 polymorphisms in dominant modes of inheritance occurred (p = 0.039). Statistically significant differences were documented only in the dominant model under the representation tendency of the C-C haplotype in the ACLR group compared to controls (p = 0.038). Our results suggest that variation in the COL5A1 gene may be one of the non-modifiable factors associated with the ACL injury in professional soccer players. The C-C rs12722-rs13946 haplotype provides a protective effect against the ACL tear.

Key words

  • COL5A1
  • ACLR
  • soccer players
  • injuries
Open Access

Thermal Sensations During a Partial-Body Cryostimulation Exposure in Elite Basketball Players

Published Online: 13 Jun 2018
Page range: 55 - 63

Abstract

Abstract

Partial-body cryostimulation is used to improve recovery after exercise, especially during competitions or heavy training; however, a limited number of studies have been conducted with international-level athletes in situ during competitions. This study was undertaken to assess the thermal sensation ratings during 3 min of cold exposure (at –130°C) in 24 international-level athletes during the European Basketball Championship. The mean thermal sensation score, measured using a perceptive scale, increased significantly (p < 0.05) during partial-body cryostimulation exposure in athletes from 3.0 ± 1.7 at 30 s to 5.7 ± 2.3 at 3 min (maximal observed value = 10.0). The mean value of 5.7 is considered a “cold” sensation on the scale (ranging from 0 = neutral sensation to 10 = very cold). However, we observed a large inter-individual variation in the perceived thermal sensations. The body mass index was significantly and negatively correlated with the thermal sensation value after 2 min 30 s and 3 min of exposure in females (r = –0.61, n = 13, p < 0.05; r = –0.56, n = 13, p = 0.054, respectively). Three participants reported high perceived thermal sensation after 30 s of exposure and their cold-induced discomfort worsened as the exposure continued. In conclusion, a 3-min exposure is globally well tolerated by athletes and can be used during a heavy competition period and/or during a training period. However, special attention should be given to female athletes with a low body mass index as they seem to be much more sensitive to cold.

Key words

  • competition
  • cryotherapy
  • international-level athletes
  • perceived cold sensation
  • recovery

Section III – Sports Training

Open Access

Does Tempo of Resistance Exercise Impact Training Volume?

Published Online: 13 Jun 2018
Page range: 241 - 250

Abstract

Abstract

Volume and intensity of exercise are the basic components of training loads, having a direct impact on adaptive patterns. Exercise volume during resistance training has been conventionally evaluated as a total number of repetitions performed in each set, regardless of the time and speed of performing individual exercises. The aim of this study was to evaluate the effect of varied tempos i.e. regular (REG) 2/0/2/0, medium (MED) 5/0/3/0 and slow (SLO) 6/0/4/0 during resistance exercise on training volume, based on the total number of performed repetitions (REPsum1-5) and time under tension (TUTsum1-5). Significant differences in TUT (s) were found in particular sets for each tempo of 2/0/2/0, 5/0/3/0 and 6/0/4/0 (p < 0.001). The ANOVA also revealed substantial differences in the REP for individual sets (p < 0.001). Post-hoc analyses showed that TUT for each set and total TUTsum1-5 were significantly higher in the 5/0/3/0 and 6/0/4/0 tempos compared to 2/0/2/0 (p < 0.001). REP was significantly higher for the 2/0/2/0 tempo compared to 5/0/3/0 and 6/0/4/0 tempo in each set. Total REPsum1-5, TUTsum1-5 between 5/0/3/0 and 6/0/4/0 tempos were not significantly different. The main finding of this study is that the movement tempo in strength training impacts training volume, both in terms of repetitions and total time under tension.

Key words

  • resistance training
  • tempo
  • volume
  • time under tension
Open Access

Effects of Single versus Multiple Bouts of Resistance Training on Maximal Strength and Anaerobic Performance

Published Online: 13 Jun 2018
Page range: 231 - 240

Abstract

Abstract

This study examined the effects of one single bout daily versus triple bouts of resistance exercise for 12 weeks on muscular strength and anaerobic performance of the upper body. Twenty young male adults (age: 22.0 ± 1.0 years, bench press: 44.0 ± 10.3 kg) were randomly assigned to a single bout (SB) or triple bouts (TB) of resistance exercise group. Maximal strength and anaerobic performance of the upper body using the bench press (one-repetition maximum) and the modified 30 s Wingate test were determined before and after the intervention. Additionally, changes in lactate levels before and after the Wingate test were measured. Although the SB and TB groups showed a significant increase in maximal strength (post-intervention, SB: 67.2 ± 9.2 and TB: 67.6 ± 7.6 kg, respectively) compared with the values at pre-intervention (SB: 44.6 ± 11.4 and TB: 43.9 ± 8.7 kg, respectively), there was no significant difference for this variable between the two groups post-intervention (p > 0.05). The anaerobic performance of the upper body in the SB and TB groups also displayed improvements without significant difference between the two groups after the completion of different training regimes. On the basis of the same training volume, multiple bouts of resistance training showed similar improvements in maximal strength and anaerobic performance to one bout of resistance training in young adult men without prior experience in resistance training

Key words

  • muscular performance
  • Wingate test
  • training frequency
Open Access

Discriminatory Power of Women’s Handball Game-Related Statistics at the Olympic Games (2004-2016)

Published Online: 13 Jun 2018
Page range: 221 - 229

Abstract

Abstract

Sports performance analysis has been a growing field of study in the last decade. However, the number of studies in handball is small. The aims of this present study were (i) to compare handball game-related statistics by the match outcome (winning and losing teams) and (ii) to identify characteristics that discriminated performance in elite women’s handball. The game-related statistics of the 236 matches played in the last four Olympic Games (Athens, Greece, 2004; Beijing, China, 2008; London, United Kingdom, 2012; and Rio de Janeiro, Brazil, 2016) were analysed. Differences between match outcomes (winning or losing teams) were determined using the chi-squared statistic, also calculating the effect sizes of the differences. A discriminant analysis was then performed applying the sample-splitting method according to match outcomes. The results showed the differences between winning and losing teams were red cards and assists. Also, the discriminant analysis selected five variables (shots, goalkeeper-blocked shots, technical fouls, steals, and goalkeeper-blocked fast-break shots) that classified correctly 83% of matches. The selected variables included offensive and defensive predictors. Coaches and players can use these results as a reference against which to assess their performance and plan training.

Key words

  • performance analysis
  • notational analysis
  • discriminant analysis
  • match analysis
  • goalkeeper
Open Access

Correlation Between Match Performance and Field Tests in Professional Soccer Players

Published Online: 13 Jun 2018
Page range: 213 - 219

Abstract

Abstract

The aim of this study was to investigate possible correlations between aerobic and anaerobic fitness (in field tests) with performance during a 90 min friendly match, through the following variables: total distance covered, maximal running speed, number of high-intensity actions and number of sprints. Eighteen professional soccer players from a Brazilian elite team (age 23 ± 3 years, body mass 77.5 ± 8.9 kg) participated in the study. The athletes performed a Yo-Yo Endurance Test (aerobic fitness) and a Running Anaerobic Sprint Test (six maximal 35 m efforts separated by 10 s of passive recovery, anaerobic fitness). Data were collected during friendly matches using a GPS with 5 Hz technology. To establish the correlation between the variables determined during the matches, the Pearson correlation coefficient was used (significance level of p ≤ 0.05). A high correlation was found between distance covered in the Yo-Yo endurance test and total distance covered (r = 0.72; p < 0.05), number of high-intensity actions (r = 0.78; p < 0.05) and number of sprints (r = 0.88; p < 0.01) in the soccer matches. The RAST variables did not relate to the standards set during the matches (p < 0.05). From the results of the present study, it may be concluded that there is no correlation between RAST and friendly match data variables. However, better results in the Yo-Yo endurance test correlate with total distance, number of high-intensity actions and sprints during matches.

Key words

  • Yo-Yo Endurance Test
  • RAST
  • soccer evaluation
  • GPS
Open Access

An Accurate and Rapid System to Identify Play Patterns in Tennis Using Video Recording Material: Break Point Situations as a Case Study

Published Online: 13 Jun 2018
Page range: 199 - 212

Abstract

Abstract

The goal of this study was to present an accurate and rapid detection system to identify patterns in tennis, based on t-pattern analysis. As a case study, the break point situations in the final matches of the clay court tournaments played during the seasons 2011 and 2012 between the tennis players Novak Djokovic and Rafael Nadal were chosen. The results show that Nadal achieves a higher conversion rate with respect to Djokovic in the break point situations, independent of the outcome of the match. Some repetitive patterns of both players were revealed in break point circumstances. In long rally sequences (higher than seven hits), the Spanish player won more break points, both serving and receiving, as a result of unforced errors of his opponent’s backhand. In medium rally sequences (between four and seven hits), other factors such as the type, direction or serve location have shown to play an important role in the outcome of the point. The study also reveals that Djokovic frequently commits double faults in these critical situations of the match. This is the first time that t-patterns have been used to analyze the sport of tennis. The technique is based on computer vision algorithms and video recording material to detect particular relationships between events and helps to discover the hidden mechanistic sequences of tennis players.

Key words

  • tennis
  • break point
  • observation
  • t-patterns
  • Novak Djokovic and Rafael Nadal
Open Access

The Impact of Nonlinear Pedagogy on Decision-Making and Execution in Youth Soccer Players According to Game Actions

Published Online: 13 Jun 2018
Page range: 185 - 198

Abstract

Abstract

The aim of this study was to analyze the effect of a teaching program, based on Non-Linear Pedagogy, on decision-making and performance in youth soccer players as a function of the type of play action. Our participants were 19 players from the U12 age category. The teaching program, which was based on the application of modified games characterized by a numerical superiority in attack, was used for 14 training sessions. This program was conducted in two phases (preparation-for-intervention and intervention). Decision-making and execution for pass and dribbling actions were evaluated through the Game Performance Evaluation Tool. The results showed significant differences in favour of the experimental group in decision-making (p < .000) and the execution of passes (p = .003) after the intervention. However, such differences were not found for dribbling (decision-making, p = .402 and execution, p = .143). These findings demonstrate the effectiveness of this type of program for teaching actions with a high tactical component, such as the pass, and a different approach must be considered in actions with a high technical component, such as dribbling. It is necessary to continue developing studies in this line to clarify these issues.

Key words

  • non-linear pedagogy
  • modified games
  • training categories
  • youth soccer
Open Access

Seasonal Body Composition Variation Amongst Elite European Professional Soccer Players: An Approach of Talent Identification

Published Online: 13 Jun 2018
Page range: 177 - 184

Abstract

Abstract

The primary aim of the investigation was to study the seasonal changes in body composition in elite European soccer players and identify key playing positional differences. Twenty-two players (age = 24 ± 3.7 years, body height = 180.45 ± 5.12 cm, body mass = 76.66 ± 5.34 kg) were tested. Players’ mass (kg), lean body mass (LBM), fat free mass (FFM), fat mass (FM), muscle girths (MG) and sum of 8 skinfolds (mm) were measured across 5 time points (T0 = Start of pre-season training; T1 = End of pre-season training; T2 = Mid-season; T3 = End of mid-season break; T4 = End of season). Players were divided into their tactical positional roles for analysis. The specific positions they were divided into included defenders (n = 8), midfielders (n = 8) and forwards (n = 6). Assessment of training and matchplay exposure were also recorded. Sites-4, Sites-7, Sites-8 and Fat Mass decreased dramatically from T0 to T1 and T2 in all playing positions (p < 0.01), while no remarkable differences were found between T2, T3 and T4. Except for defenders, calf girth and lean mass were higher in T2, T3 and T4 compared to T0 and T1 (p < 0.01). Midfielders were found to be leaner than forwards and defenders in all data collection time point sessions. Defenders showed higher values in calf girth and lean body mass than midfielders and forwards. It can be concluded from this investigation that there are large variances n positional body composition profiles amongst professional European soccer players. Furthermore, significant changes are prevalent and occur across the season from LBM, FFM, MG and skinfold assessment amongst European elite level soccer players.

Key words

  • human performance
  • positional analysis
  • anthropometry
Open Access

Soccer Small-Sided Games Activities Vary According to the Interval Regime and their Order of Presentation within the Session

Published Online: 13 Jun 2018
Page range: 167 - 175

Abstract

Abstract

In order to investigate the physical demands of widely used in soccer small-sided games (SSGs), we compared game variations performed under different interval (fixed or variable) and timing regimens (beginning or end of a training session). Twelve male players wore GPS devices during the SSGs to record total distance, relative distance, distance at different speeds, and maximum velocity variables. Four variations of SSGs (4x4) were randomly applied: beginning of a training session with fixed and variable recovery, or end of a training session with fixed and variable recovery. During the beginning or end of a training session settings with fixed recovery duration, 2-min of playing and 2-min of recovery were provided. During the beginning and end of a training session settings with variable recovery, athletes kept playing until a goal was scored, or up to 2-min if no goals were scored. Results were analysed using MANOVA. Total distance and relative distance were higher in the beginning compared to end of training sessions for both fixed and variable recovery duration (small to moderate effect sizes). Distance at various speed ranges (i.e., 13-18 km/h and >18 km/h) was higher (p ≤ 0.01) at the beginning than at the end of training sessions with variable recovery. In addition, distance >18 km/h was higher at the beginning of a training session with variable recovery than fixed recovery and at the end of a training session with variable recovery than fixed recovery. In conclusion, several physical demand characteristics are affected by the moment of SSG application, while others respond to the recovery regime during SSGs, thus providing indications to the coaches to prescribe the intended training intensity by manipulating the context.

Key words

  • youth athletes
  • soccer
  • game-based training
  • movement patterns
Open Access

Effect of Pitch Size on Technical-Tactical Actions of the Goalkeeper in Small-Sided Games

Published Online: 13 Jun 2018
Page range: 157 - 166

Abstract

Abstract

The aim of this paper was to determine how the size of the pitch affected technical and tactical actions of the goalkeeper when playing small-sided games. The participants were 13 male youth players, including 3 goalkeepers. Three different pitch sizes were used (62 x 44 m; 50 x 35 m; 32 x 23 m). On each pitch, the players played three matches of 8 minutes, with 5-minute breaks between matches. Numerous variables were recorded and examined: defensive and offensive technical and tactical actions, opponent’s shooting zone, length and zone of the offensive action, and goal zone where the shoot was directed. An ad hoc observational tool was used. A descriptive analysis was described. The Fisher’s exact test was used when the expected distribution was below 5 or included values below 1%. Statistical significance was set at p < 0.05. The results showed that the technical-tactical actions of the goalkeeper differed among pitch sizes. In defensive actions, when the pitch was larger, the 1-on-1 situations took precedence, whereas when the pitch was smaller, the proportion of blocks increased. In offensive actions, the goalkeepers did not show a wide variety of actions when the pitch was larger, but when the pitch was smaller, passes with a hand or foot increased. These results show that the size should be taken into account when planning and designing tasks.

Key words

  • performance analysis
  • soccer
  • tasks
Open Access

Changes in Effective Playing Space When Considering Sub-Groups of 3 to 10 Players in Professional Soccer Matches

Published Online: 13 Jun 2018
Page range: 145 - 155

Abstract

Abstract

Success in soccer is much dependent on how players and teams create and restrict space and time. In match situations, players constitute small sub-groups to improve their collective synchronization and achievement of specific goals. This study aimed to identify changes in the effective playing space (EPS, defined as the smallest polygonal area delimited by the peripheral outfield players) when considering sub-groups of 3 to 10 players. Twenty outfield professional players participated in this study. The EPS, its regularity pattern (measured by the approximate entropy), coefficient of variation and players’ mean speed were calculated for sub-groups of 3, 4, 5, 6, 7, 8, 9 and 10 players, considering the smallest inter-player distance as the criterion. The EPS presented a most likely increase with a higher number of players, especially considering the transition from 3 to 4 players (~440% of variation, very large). As the EPS increased with the number of players, the correspondent regularity presented a trend of a most likely increase (from EPS3 vs. EPS4: ~25%, very large; to EPS9 vs. EPS10: ~11%, moderate). The mean speed results suggest that players may achieve different states of collective coordination, mainly between ~6 to 8 km.h-1. Overall, three different match scenarios should require additional attention when aiming to design more match transferable tasks: i) transition from EPS3 to EPS4; ii) transition from EPS4 up to EPS8; and iii) transition from EPS8 to EPS9. These results help to understand match self-organized behaviours and, consequently, allow to optimize task characteristics in practice sessions.

Key words

  • speed
  • variability
  • regularity
  • behaviour
  • positioning
Open Access

Shaq is Not Alone: Free-Throws in the Final Moments of a Basketball Game

Published Online: 13 Jun 2018
Page range: 135 - 144

Abstract

Abstract

It has been previously observed that basketball free-throw (FT) shooting efficiency decreases towards the end of the game. The aim of the current study was to explore possible determinants for this distinctive pattern during close games (point differential of equal or under 2 points during the final minute of the game). A sample of shots attempted by 92 players in the Spanish professional basketball league (ACB) was collected. Several personal (age, experience, playing position and career FT percentage) and contextual (team ability, competition stage, game location, seconds remaining and score differential) variables were considered for the analysis of the data. The effects of the predictor variables on the players’ performance were analyzed according to two game contexts (FT attempted during the final minute or the last pair of FTs) using binomial logistic regression analysis. The results showed that during the final minute the only statistically significant variable was being in the center playing position (OR = 1.58), which decreased the FT shooting percentage compared to forwards and guards. In addition, the results during the last pair of FTs showed that the playing position of guards (OR = 1.70) and centers (OR = 2.22) was significant (a decrease in their FT percentage). Conversely, the score differential when tied (OR = -1.17) or losing (OR = -2.43) was significant, reflecting a lower probability of missing the shot. The results were interpreted and discussed from the viewpoints of crisis theory and the literature on choking in athletic performance.

Key words

  • performance analysis
  • choking
  • pressure conditions
Open Access

Analysis of Training Plans in Basketball: Gender and Formation Stage Differences

Published Online: 13 Jun 2018
Page range: 123 - 134

Abstract

Abstract

Scientific literature has stated the presence of various stages in athletes sportive development, with different objectives in each one of them. This should lead coaches to different training plans according to the athlete’s formation stage. The aim of this study was to analyse training plans and identify differences in basketball objectives according to formative stages (U’12 and U’14) in boys and girls. A total of 1,976 training tasks were collected and analysed, for a total of four teams (girls and boys of U’12 and U’14 categories) during an entire season. Pedagogical variables, game phases, game situations, training means and content were studied. The results showed significant differences between genders. Girls’ teams performed more tasks on offense and technical skills. By contrast, boys’ teams performed more defensive tasks and tactical contents. The 1-on-0 and 1-on-1 were the most repeated game situations in all teams. Coaches used different training tasks according to gender and age. In male U’12 teams, drills predominated, whereas in the other categories, games predominated. For boys’ teams, the contents were tactical oriented, and for girls’ teams, the contents were oriented toward skill acquisition. Studying the pedagogical variables of the training process allowed for identification of the utility of training, assessment, and modification of this process.

Key words

  • sports initiation
  • early stages
  • tasks
  • pedagogical variables
Open Access

What are the Most Widely Used and Effective Attack Coverage Systems in Men’s Volleyball?

Published Online: 13 Jun 2018
Page range: 111 - 121

Abstract

Abstract

In volleyball, attack coverage is one of the play actions most neglected in coaching and research. The purpose of this study was to find out which attack coverage systems are used by high-level men’s teams in different game situations and the characteristics of the most effective systems. We analysed 15 matches from the 2010 Men’s Pan-American Volleyball Cup, with a total of 1,415 coverage actions. Chi-square tests for independence, adjusted residuals analysis and calculations of standardised mean difference were performed. The results show that high-level men’s volleyball uses many coverage systems other than the traditional 3-2-0 and 2-3-0. At this level of play, the most frequent systems were 1-3-1 and 1-2-2, which occurred significantly often at the culmination of a third-tempo attack at the wing. The most effective systems consisted of three coverage lines, with fewer than five players covering the spiker and at least one player in the first coverage line, in both the attack and counterattack phases. Given the large number of coverage systems identified in different game situations, we recommend flexible, loosely structured training in these systems, based on a set of guiding principles that all players on a team must internalise for the specific position they are playing. Regarding the systems’ efficacy, the main watchword is that on each coverage line there should always be at least one player, but the first line should not be exposed.

Key words

  • performance analysis
  • game patterns
  • collective behaviour
  • team sports
Open Access

The Reliability of Technical and Tactical Tagging Analysis Conducted by a Semi-Automatic VTS In Soccer

Published Online: 13 Jun 2018
Page range: 103 - 110

Abstract

Abstract

The Video Tracking multiple cameras system (VTS) is a technology that records two-dimensional position data (x and y) at high sampling rates (over 25 Hz). The VTS is of great interest because it can record external load variables as well as collect technical and tactical parameters. Performance analysis is mainly focused on physical demands, yet less attention has been afforded to technical and tactical factors. Digital.Stadium® VTS is a performance analysis device widely used at national and international levels (i.e. Italian Serie A, Euro 2016) and the reliability evaluation of its technical tagging analysis (e.g. shots, passes, assists, set pieces) could be paramount for its application at elite level competitions, as well as in research studies. Two professional soccer teams, with 30 male players (age 23 ± 5 years, body mass 78.3 ± 6.9 kg, body height 1.81 ± 0.06 m), were monitored in the 2016 season during a friendly match and data analysis was performed immediately after the game ended. This process was then replicated a week later (4 operators conducted the data analysis in each week). This study reports a near perfect relationship between Match and its Replication. R2 coefficients (relationships between Match and Replication) were highly significant for each of the technical variables considered (p < 0.001). In particular, a high score of interclass correlation and a small coefficient of variation were reported. This study reports meaningless differences between Match and its Replication (intra-day reliability). We concluded that the semi-automatic process behind the Digital.Stadium® VTS was more than capable of recording technical tagging data accurately.

Key words

  • team sports
  • time-motion analysis
  • match analysis
Open Access

The Effectiveness of Land and Water Based Resistance Training on Shoulder Rotator Cuff Strength and Balance of Youth Swimmers

Published Online: 13 Jun 2018
Page range: 91 - 102

Abstract

Abstract

The continuous execution of swimming techniques, supported mainly by the upper limbs, may cause shoulder rotator muscle imbalances, which leads to injuries. The aim of this study was to evaluate and compare the effects of two training programs on strength, balance and endurance of shoulder rotator cuff muscles in youth swimmers. Twenty-five male swimmers were evaluated and randomly divided into two groups – the land group (n = 13), which conducted a conventional dry-land training program with elastic bands, and the water group (n = 12), which conducted a water resistance program. In both groups, the level of strength of the shoulder rotators was evaluated with an isokinetic dynamometer on two occasions (baseline and after 10 weeks) using two protocols: i) three repetitions at 60o/s; ii) twenty repetitions at 180o/s. The land group significantly increased the unilateral ratios compared to the water group. The land group also decreased the external rotator levels of muscular fatigue. The dry-land training program conducted proved to be more effective than the one conducted in the water, allowing to reduce the muscle imbalance and to decrease muscle fatigue.

Key words

  • swimming
  • sports injuries
  • shoulder rotators
  • isokinetic strength
24 Articles

Section I – Kinesiology

Open Access

Comparison of Core Muscle Activation Between a Prone Bridge and 6-RM Back Squats

Published Online: 13 Jun 2018
Page range: 43 - 53

Abstract

Abstract

The purpose of this study was to compare core muscle activation during a prone bridge (plank) until failure and 6-RM back squats. Twelve resistance-trained males (age 23.5 ± 2.6 years, body mass 87.8 ± 21.3 kg, body height 1.81 ± 0.08 m) participated in this study. Total exercise time and EMG activity of the rectus abdominis, external abdominal oblique and erector spinae were measured during 6-RM back squats and a prone bridge with a weight of 20% of participants’ body mass on their lower back. The main findings showed non-significant differences between the exercises in the rectus abdominis or external oblique, but greater erector spinae activation in squatting. Furthermore, in contrast to the prone bridge, the erector spinae and rectus abdominis demonstrated increasing muscle activation throughout the repetitions while squatting, whereas the prone bride demonstrated increasing external oblique activation between the beginning and the middle of the set. It was concluded that since squatting resulted in greater erector spine activation, but similar rectus abdominis and oblique external activation as the prone bridge, high-intensity squats rather than isometric low intensity core exercises for athletes would be recommended.

Key words

  • EMG
  • core stability
  • core strength
  • performance
Open Access

Changes in Injury Risk Mechanisms After Soccer-Specific Fatigue in Male Youth Soccer Players

Published Online: 13 Jun 2018
Page range: 33 - 42

Abstract

Abstract

The aim of this study was to examine the acute effects of soccer specific fatigue on muscular and neuromuscular function in male youth soccer players. Elite soccer players (n = 20; age 15.7 ± 0.5 y; body height 177.75 ± 6.61 cm; body mass 67.28 ± 8.29 kg) were measured before and after soccer specific exercise (SAFT90). The reactive strength index (RSI) was determined by a drop jump test, leg stiffness (LS) by a 20 sub-maximal two-legged hopping test, and a functional hamstring to quadriceps strength ratio from isokinetic concentric and eccentric strength of the dominant and non-dominant leg (measured at angular velocities of 1.05 rad · s−1 and 3.14 rad · s−1). Metabolic response to the SAFT90 was determined by blood lactate and perceived exertion was assessed by the Borg scale. After simulated match play, a significant decrease in absolute LS (t = 4.411; p < 0.001; ω2 = 0.48) and relative LS (t = 4.326; p < 0.001; ω2 = 0.49) was observed and the RSI increased significantly (t = 3.806; p = 0.001; ω2 = 0.40). A reduction in LS found after the SAFT90 indicates possible reduction in dynamic knee stabilization. However, if we consider the changes in other observed variables, the present study did not clearly confirm that fatigue induced by a soccer specific protocol increased the risk of ACL and hamstring injury. This may be attributed to the simulated rather than actual match play used in the present study.

Key words

  • leg stiffness
  • reactive strength
  • neuromuscular function
  • isokinetic
  • ACL
Open Access

How To Maintain Maximal Straight Path Running Speed on a Curved Path in Sprint Events

Published Online: 13 Jun 2018
Page range: 23 - 31

Abstract

Abstract

This study aims to clarify the ideal technique for running on a curved path during sprinting events. Participants were twelve male track and field athletes including long jumpers and sprinters. The participants performed a 60-m sprint with maximal effort on straight and curved paths. Participants were divided into “good curve runners” and “poor curve runners” according to the curved path running speed relative to that of the straight path. Kinematic variables and ground reaction forces (GRFs) were registered and compared between the groups and paths. The running speed, step length, and flight distance of the outside leg on the curved path were lower than on the straight path only in poor curve runners. The medial-lateral GRF and impulse showed an increase during curved path running for both groups. However, the maximum posterior GRF and impulse decreased only in poor curve runners. The ideal technique for running on a curved path is to maintain the same kinematics and kinetics in the sagittal plane as on a straight path.

Key words

  • curved path
  • running technique
  • maximal running speed
  • sprinting
Open Access

Balance and Lower Limb Muscle Activation Between in-Line and Traditional Lunge Exercises

Published Online: 13 Jun 2018
Page range: 15 - 22

Abstract

Abstract

In-line and traditional lunge exercises present differences in technique as lower limb positioning (anterioposterior), and medio-lateral (ML) balance may differentially affect primary and stabilizer muscles. The purposes of this study were to examine ML balance and muscle activation in anterior and posterior leg positions between in-line and traditional lunge exercises. Fifteen young, healthy, resistance-trained men (25 ± 5 years) performed 2 different lunge exercises (in-line and traditional) at their 10 repetition maximum in a randomized, counterbalanced fashion. Surface electromyography measured muscle activation of the vastus lateralis, biceps femoris, gluteus maximus, and gluteus medius. ML balance was measured with a Wii Fit Balance Board. The vastus lateralis activity was not significantly different between exercises or leg positions. The biceps femoris activity was not significantly different between exercises, however, it was significantly greater in the anterior compared to the posterior position for the in-line (p = 0.003), and traditional lunge (p < 0.001). The gluteus maximus activity was not significantly different between exercises, however, it was significantly greater in the anterior compared to posterior position for the in-line (p < 0.001) and traditional lunge (p < 0.001). ML balance was significantly greater in the in-line exercise in the anterior limb (p = 0.001). Thus, both in-line and traditional lunge exercises presented similar overall levels of muscle activation, yet the anterior limb generated the highest biceps femoral and gluteus maximus muscle activation when compared to the posterior limb. The in-line lunge presents greater ML balance when compared to the traditional lunge exercise.

Key words

  • electromyography
  • strength
  • performance
Open Access

The Effects of Repeated Sprints on the Kinematics of 3-Point Shooting in Basketball

Published Online: 13 Jun 2018
Page range: 5 - 14

Abstract

Abstract

Fatigue modifies the kinematics of various sports-related movements. Basketball induces fatigue, however, the effects of fatigue on the kinematics of shooting have never been studied. This study analysed the effects of fatigue induced by repeated sprints on the kinematics of 3-point shooting (3PS) in young, elite basketball players (U18 level). 3D joint angles were calculated at the maximum and minimum heights of the centre of mass during 3PS, using inertial measurement units (Biomech system, Xsens Technologies BV, Enschede, The Netherlands). Height, velocity and the angle of the ball at the time of release were extrapolated from the wrist joint angles. All players performed four 3PS actions in dynamic conditions before and after a fatigue protocol at 70% of their maximal exercise capacity. The fatigue protocol consisted of a shuttle test with repeated 20-m sprints interspersed with sets of 5 jumps. There was no change in the kinematics of 3PS (p > 0.05), or the ball release variables (p > 0.05) following the fatigue protocol. This suggests that elite basketball players are able to cope with physical fatigue while performing coordinated movements such as 3PS.

Key words

  • biomechanics
  • team sport
  • kinematics
  • elite players
  • fatigue

Section II – Exercise Physiology & Sports Medicine

Open Access

Skeletal Muscle Cell Damage Indicators in Volleyball Players after the Competitive Phase of the Annual Training Cycle

Published Online: 13 Jun 2018
Page range: 81 - 90

Abstract

Abstract

The aim of the study was to evaluate the impact of the competitive phase on physiological and metabolic indices and selected markers of skeletal muscle damage in male volleyball players. The study group consisted of 24 young male volleyball players. During the study, participants underwent two series of measurements, before and after the competitive phase of the annual training cycle. In both study terms, players performed an incremental treadmill running test to determine their ventilatory threshold and maximal oxygen uptake. Venous and capillary blood samples were taken for biochemical analysis. There was no significant difference in the physical fitness level, values of biochemical variables and the level of antioxidant status in the surveyed athletes between the two study terms. Significant changes within skeletal muscle damage markers were observed between the beginning and the end of the competitive period: an increase in the concentration of cellular DNA damage products (8-hydroxy-2′-deoxyguanosine; p < 0.0001) and a decrease in muscle activity of creatine kinase (p<0.05). In spite of the increment in cell damage markers, the unaffected level of physiological and biochemical markers may indicate that the experienced cell destruction did not negatively affect the level of physical fitness. When designing the annual training plan, coaches and athletes need to take into consideration that temporary physiological states – oxidative stress and inflammation – may be required to attain training adaptation.

Key words

  • training
  • team sports
  • injury
  • prevention
  • biochemical variables
Open Access

Epidemiology of Time-Loss Injuries in Senior and Under-18 Portuguese Male Rugby Players

Published Online: 13 Jun 2018
Page range: 73 - 80

Abstract

Abstract

Rugby union has one of the highest injury incidence rates in team sports, however, most of the available data focus on the epidemiology of injuries in countries where rugby is popular. We aimed to report the incidence rate and relevant epidemiological aspects of injuries occurred in a group of Portuguese male rugby players. A prospective cohort study was conducted with a group of 45 senior and 32 under-18 male players (total of 77 players). Outcome measures included injury incidence, position, type, location and severity of injuries. The match injury incidence for all players was 55.84 per 1000 player match-hours (66.66 for seniors, 42.85 for under-18), while mean time-loss for injury was 20.79 days. No statistical differences were found between groups. Lower limb injuries accounted for 60.5% of all injuries, while joint/ligament injuries were the most prevalent type. Contact events were responsible for 65.1% of injuries. Despite the limitations, the obtained data are consistent with the literature. Time-loss injuries seem highly prevalent in rugby union and the incidence rates found in this Portuguese-based study were lower than the reported for international and senior men’s professional rugby union, but higher than those occurring in community rugby in tier-1 countries. The authors believe these data reinforce the need to develop and implement effective injury surveillance and prevention programs.

Key words

  • athletic injuries
  • injury surveillance
  • rugby union
Open Access

Interactions Between COL5A1 Gene and Risk of the Anterior Cruciate Ligament Rupture

Published Online: 13 Jun 2018
Page range: 65 - 71

Abstract

Abstract

Collagen alpha-1(V) chain, encoded by the COL5A1 gene, plays a crucial role in abundant fibrillar collagens supporting many tissues in the body containing type I collagen and appears to regulate the association between heterotypic fibers composed of both type I and type V collagen occurring among others in muscles, tendons and ligaments. Taking this fact into consideration we decided to examine the association between COL5A1 rs12722 and rs13946 polymorphisms, individually and as inferred haplotypes, with anterior cruciate ligament rupture risk (ACLR) in professional soccer players. A total of 134 male professional soccer players with surgically diagnosed primary anterior cruciate ligament ruptures and 211 apparently healthy male professional soccer players, who were without any self-reported history of ligament or tendon injury, were included in the study. Both the cases and the healthy controls were recruited from the same soccer teams, of a similar age category, and had a comparable level of exposure to anterior cruciate ligament injury. Genomic DNA was extracted from oral epithelial cells using GenElute Mammalian Genomic DNA MiniprepKit. All samples were genotyped for the rs12722 and rs13946 polymorphisms using a Rotor-Gene realtime polymerase chain reaction. Statistically significant differences in the genotype frequencies for the COL5A1 rs13946 polymorphisms in dominant modes of inheritance occurred (p = 0.039). Statistically significant differences were documented only in the dominant model under the representation tendency of the C-C haplotype in the ACLR group compared to controls (p = 0.038). Our results suggest that variation in the COL5A1 gene may be one of the non-modifiable factors associated with the ACL injury in professional soccer players. The C-C rs12722-rs13946 haplotype provides a protective effect against the ACL tear.

Key words

  • COL5A1
  • ACLR
  • soccer players
  • injuries
Open Access

Thermal Sensations During a Partial-Body Cryostimulation Exposure in Elite Basketball Players

Published Online: 13 Jun 2018
Page range: 55 - 63

Abstract

Abstract

Partial-body cryostimulation is used to improve recovery after exercise, especially during competitions or heavy training; however, a limited number of studies have been conducted with international-level athletes in situ during competitions. This study was undertaken to assess the thermal sensation ratings during 3 min of cold exposure (at –130°C) in 24 international-level athletes during the European Basketball Championship. The mean thermal sensation score, measured using a perceptive scale, increased significantly (p < 0.05) during partial-body cryostimulation exposure in athletes from 3.0 ± 1.7 at 30 s to 5.7 ± 2.3 at 3 min (maximal observed value = 10.0). The mean value of 5.7 is considered a “cold” sensation on the scale (ranging from 0 = neutral sensation to 10 = very cold). However, we observed a large inter-individual variation in the perceived thermal sensations. The body mass index was significantly and negatively correlated with the thermal sensation value after 2 min 30 s and 3 min of exposure in females (r = –0.61, n = 13, p < 0.05; r = –0.56, n = 13, p = 0.054, respectively). Three participants reported high perceived thermal sensation after 30 s of exposure and their cold-induced discomfort worsened as the exposure continued. In conclusion, a 3-min exposure is globally well tolerated by athletes and can be used during a heavy competition period and/or during a training period. However, special attention should be given to female athletes with a low body mass index as they seem to be much more sensitive to cold.

Key words

  • competition
  • cryotherapy
  • international-level athletes
  • perceived cold sensation
  • recovery

Section III – Sports Training

Open Access

Does Tempo of Resistance Exercise Impact Training Volume?

Published Online: 13 Jun 2018
Page range: 241 - 250

Abstract

Abstract

Volume and intensity of exercise are the basic components of training loads, having a direct impact on adaptive patterns. Exercise volume during resistance training has been conventionally evaluated as a total number of repetitions performed in each set, regardless of the time and speed of performing individual exercises. The aim of this study was to evaluate the effect of varied tempos i.e. regular (REG) 2/0/2/0, medium (MED) 5/0/3/0 and slow (SLO) 6/0/4/0 during resistance exercise on training volume, based on the total number of performed repetitions (REPsum1-5) and time under tension (TUTsum1-5). Significant differences in TUT (s) were found in particular sets for each tempo of 2/0/2/0, 5/0/3/0 and 6/0/4/0 (p < 0.001). The ANOVA also revealed substantial differences in the REP for individual sets (p < 0.001). Post-hoc analyses showed that TUT for each set and total TUTsum1-5 were significantly higher in the 5/0/3/0 and 6/0/4/0 tempos compared to 2/0/2/0 (p < 0.001). REP was significantly higher for the 2/0/2/0 tempo compared to 5/0/3/0 and 6/0/4/0 tempo in each set. Total REPsum1-5, TUTsum1-5 between 5/0/3/0 and 6/0/4/0 tempos were not significantly different. The main finding of this study is that the movement tempo in strength training impacts training volume, both in terms of repetitions and total time under tension.

Key words

  • resistance training
  • tempo
  • volume
  • time under tension
Open Access

Effects of Single versus Multiple Bouts of Resistance Training on Maximal Strength and Anaerobic Performance

Published Online: 13 Jun 2018
Page range: 231 - 240

Abstract

Abstract

This study examined the effects of one single bout daily versus triple bouts of resistance exercise for 12 weeks on muscular strength and anaerobic performance of the upper body. Twenty young male adults (age: 22.0 ± 1.0 years, bench press: 44.0 ± 10.3 kg) were randomly assigned to a single bout (SB) or triple bouts (TB) of resistance exercise group. Maximal strength and anaerobic performance of the upper body using the bench press (one-repetition maximum) and the modified 30 s Wingate test were determined before and after the intervention. Additionally, changes in lactate levels before and after the Wingate test were measured. Although the SB and TB groups showed a significant increase in maximal strength (post-intervention, SB: 67.2 ± 9.2 and TB: 67.6 ± 7.6 kg, respectively) compared with the values at pre-intervention (SB: 44.6 ± 11.4 and TB: 43.9 ± 8.7 kg, respectively), there was no significant difference for this variable between the two groups post-intervention (p > 0.05). The anaerobic performance of the upper body in the SB and TB groups also displayed improvements without significant difference between the two groups after the completion of different training regimes. On the basis of the same training volume, multiple bouts of resistance training showed similar improvements in maximal strength and anaerobic performance to one bout of resistance training in young adult men without prior experience in resistance training

Key words

  • muscular performance
  • Wingate test
  • training frequency
Open Access

Discriminatory Power of Women’s Handball Game-Related Statistics at the Olympic Games (2004-2016)

Published Online: 13 Jun 2018
Page range: 221 - 229

Abstract

Abstract

Sports performance analysis has been a growing field of study in the last decade. However, the number of studies in handball is small. The aims of this present study were (i) to compare handball game-related statistics by the match outcome (winning and losing teams) and (ii) to identify characteristics that discriminated performance in elite women’s handball. The game-related statistics of the 236 matches played in the last four Olympic Games (Athens, Greece, 2004; Beijing, China, 2008; London, United Kingdom, 2012; and Rio de Janeiro, Brazil, 2016) were analysed. Differences between match outcomes (winning or losing teams) were determined using the chi-squared statistic, also calculating the effect sizes of the differences. A discriminant analysis was then performed applying the sample-splitting method according to match outcomes. The results showed the differences between winning and losing teams were red cards and assists. Also, the discriminant analysis selected five variables (shots, goalkeeper-blocked shots, technical fouls, steals, and goalkeeper-blocked fast-break shots) that classified correctly 83% of matches. The selected variables included offensive and defensive predictors. Coaches and players can use these results as a reference against which to assess their performance and plan training.

Key words

  • performance analysis
  • notational analysis
  • discriminant analysis
  • match analysis
  • goalkeeper
Open Access

Correlation Between Match Performance and Field Tests in Professional Soccer Players

Published Online: 13 Jun 2018
Page range: 213 - 219

Abstract

Abstract

The aim of this study was to investigate possible correlations between aerobic and anaerobic fitness (in field tests) with performance during a 90 min friendly match, through the following variables: total distance covered, maximal running speed, number of high-intensity actions and number of sprints. Eighteen professional soccer players from a Brazilian elite team (age 23 ± 3 years, body mass 77.5 ± 8.9 kg) participated in the study. The athletes performed a Yo-Yo Endurance Test (aerobic fitness) and a Running Anaerobic Sprint Test (six maximal 35 m efforts separated by 10 s of passive recovery, anaerobic fitness). Data were collected during friendly matches using a GPS with 5 Hz technology. To establish the correlation between the variables determined during the matches, the Pearson correlation coefficient was used (significance level of p ≤ 0.05). A high correlation was found between distance covered in the Yo-Yo endurance test and total distance covered (r = 0.72; p < 0.05), number of high-intensity actions (r = 0.78; p < 0.05) and number of sprints (r = 0.88; p < 0.01) in the soccer matches. The RAST variables did not relate to the standards set during the matches (p < 0.05). From the results of the present study, it may be concluded that there is no correlation between RAST and friendly match data variables. However, better results in the Yo-Yo endurance test correlate with total distance, number of high-intensity actions and sprints during matches.

Key words

  • Yo-Yo Endurance Test
  • RAST
  • soccer evaluation
  • GPS
Open Access

An Accurate and Rapid System to Identify Play Patterns in Tennis Using Video Recording Material: Break Point Situations as a Case Study

Published Online: 13 Jun 2018
Page range: 199 - 212

Abstract

Abstract

The goal of this study was to present an accurate and rapid detection system to identify patterns in tennis, based on t-pattern analysis. As a case study, the break point situations in the final matches of the clay court tournaments played during the seasons 2011 and 2012 between the tennis players Novak Djokovic and Rafael Nadal were chosen. The results show that Nadal achieves a higher conversion rate with respect to Djokovic in the break point situations, independent of the outcome of the match. Some repetitive patterns of both players were revealed in break point circumstances. In long rally sequences (higher than seven hits), the Spanish player won more break points, both serving and receiving, as a result of unforced errors of his opponent’s backhand. In medium rally sequences (between four and seven hits), other factors such as the type, direction or serve location have shown to play an important role in the outcome of the point. The study also reveals that Djokovic frequently commits double faults in these critical situations of the match. This is the first time that t-patterns have been used to analyze the sport of tennis. The technique is based on computer vision algorithms and video recording material to detect particular relationships between events and helps to discover the hidden mechanistic sequences of tennis players.

Key words

  • tennis
  • break point
  • observation
  • t-patterns
  • Novak Djokovic and Rafael Nadal
Open Access

The Impact of Nonlinear Pedagogy on Decision-Making and Execution in Youth Soccer Players According to Game Actions

Published Online: 13 Jun 2018
Page range: 185 - 198

Abstract

Abstract

The aim of this study was to analyze the effect of a teaching program, based on Non-Linear Pedagogy, on decision-making and performance in youth soccer players as a function of the type of play action. Our participants were 19 players from the U12 age category. The teaching program, which was based on the application of modified games characterized by a numerical superiority in attack, was used for 14 training sessions. This program was conducted in two phases (preparation-for-intervention and intervention). Decision-making and execution for pass and dribbling actions were evaluated through the Game Performance Evaluation Tool. The results showed significant differences in favour of the experimental group in decision-making (p < .000) and the execution of passes (p = .003) after the intervention. However, such differences were not found for dribbling (decision-making, p = .402 and execution, p = .143). These findings demonstrate the effectiveness of this type of program for teaching actions with a high tactical component, such as the pass, and a different approach must be considered in actions with a high technical component, such as dribbling. It is necessary to continue developing studies in this line to clarify these issues.

Key words

  • non-linear pedagogy
  • modified games
  • training categories
  • youth soccer
Open Access

Seasonal Body Composition Variation Amongst Elite European Professional Soccer Players: An Approach of Talent Identification

Published Online: 13 Jun 2018
Page range: 177 - 184

Abstract

Abstract

The primary aim of the investigation was to study the seasonal changes in body composition in elite European soccer players and identify key playing positional differences. Twenty-two players (age = 24 ± 3.7 years, body height = 180.45 ± 5.12 cm, body mass = 76.66 ± 5.34 kg) were tested. Players’ mass (kg), lean body mass (LBM), fat free mass (FFM), fat mass (FM), muscle girths (MG) and sum of 8 skinfolds (mm) were measured across 5 time points (T0 = Start of pre-season training; T1 = End of pre-season training; T2 = Mid-season; T3 = End of mid-season break; T4 = End of season). Players were divided into their tactical positional roles for analysis. The specific positions they were divided into included defenders (n = 8), midfielders (n = 8) and forwards (n = 6). Assessment of training and matchplay exposure were also recorded. Sites-4, Sites-7, Sites-8 and Fat Mass decreased dramatically from T0 to T1 and T2 in all playing positions (p < 0.01), while no remarkable differences were found between T2, T3 and T4. Except for defenders, calf girth and lean mass were higher in T2, T3 and T4 compared to T0 and T1 (p < 0.01). Midfielders were found to be leaner than forwards and defenders in all data collection time point sessions. Defenders showed higher values in calf girth and lean body mass than midfielders and forwards. It can be concluded from this investigation that there are large variances n positional body composition profiles amongst professional European soccer players. Furthermore, significant changes are prevalent and occur across the season from LBM, FFM, MG and skinfold assessment amongst European elite level soccer players.

Key words

  • human performance
  • positional analysis
  • anthropometry
Open Access

Soccer Small-Sided Games Activities Vary According to the Interval Regime and their Order of Presentation within the Session

Published Online: 13 Jun 2018
Page range: 167 - 175

Abstract

Abstract

In order to investigate the physical demands of widely used in soccer small-sided games (SSGs), we compared game variations performed under different interval (fixed or variable) and timing regimens (beginning or end of a training session). Twelve male players wore GPS devices during the SSGs to record total distance, relative distance, distance at different speeds, and maximum velocity variables. Four variations of SSGs (4x4) were randomly applied: beginning of a training session with fixed and variable recovery, or end of a training session with fixed and variable recovery. During the beginning or end of a training session settings with fixed recovery duration, 2-min of playing and 2-min of recovery were provided. During the beginning and end of a training session settings with variable recovery, athletes kept playing until a goal was scored, or up to 2-min if no goals were scored. Results were analysed using MANOVA. Total distance and relative distance were higher in the beginning compared to end of training sessions for both fixed and variable recovery duration (small to moderate effect sizes). Distance at various speed ranges (i.e., 13-18 km/h and >18 km/h) was higher (p ≤ 0.01) at the beginning than at the end of training sessions with variable recovery. In addition, distance >18 km/h was higher at the beginning of a training session with variable recovery than fixed recovery and at the end of a training session with variable recovery than fixed recovery. In conclusion, several physical demand characteristics are affected by the moment of SSG application, while others respond to the recovery regime during SSGs, thus providing indications to the coaches to prescribe the intended training intensity by manipulating the context.

Key words

  • youth athletes
  • soccer
  • game-based training
  • movement patterns
Open Access

Effect of Pitch Size on Technical-Tactical Actions of the Goalkeeper in Small-Sided Games

Published Online: 13 Jun 2018
Page range: 157 - 166

Abstract

Abstract

The aim of this paper was to determine how the size of the pitch affected technical and tactical actions of the goalkeeper when playing small-sided games. The participants were 13 male youth players, including 3 goalkeepers. Three different pitch sizes were used (62 x 44 m; 50 x 35 m; 32 x 23 m). On each pitch, the players played three matches of 8 minutes, with 5-minute breaks between matches. Numerous variables were recorded and examined: defensive and offensive technical and tactical actions, opponent’s shooting zone, length and zone of the offensive action, and goal zone where the shoot was directed. An ad hoc observational tool was used. A descriptive analysis was described. The Fisher’s exact test was used when the expected distribution was below 5 or included values below 1%. Statistical significance was set at p < 0.05. The results showed that the technical-tactical actions of the goalkeeper differed among pitch sizes. In defensive actions, when the pitch was larger, the 1-on-1 situations took precedence, whereas when the pitch was smaller, the proportion of blocks increased. In offensive actions, the goalkeepers did not show a wide variety of actions when the pitch was larger, but when the pitch was smaller, passes with a hand or foot increased. These results show that the size should be taken into account when planning and designing tasks.

Key words

  • performance analysis
  • soccer
  • tasks
Open Access

Changes in Effective Playing Space When Considering Sub-Groups of 3 to 10 Players in Professional Soccer Matches

Published Online: 13 Jun 2018
Page range: 145 - 155

Abstract

Abstract

Success in soccer is much dependent on how players and teams create and restrict space and time. In match situations, players constitute small sub-groups to improve their collective synchronization and achievement of specific goals. This study aimed to identify changes in the effective playing space (EPS, defined as the smallest polygonal area delimited by the peripheral outfield players) when considering sub-groups of 3 to 10 players. Twenty outfield professional players participated in this study. The EPS, its regularity pattern (measured by the approximate entropy), coefficient of variation and players’ mean speed were calculated for sub-groups of 3, 4, 5, 6, 7, 8, 9 and 10 players, considering the smallest inter-player distance as the criterion. The EPS presented a most likely increase with a higher number of players, especially considering the transition from 3 to 4 players (~440% of variation, very large). As the EPS increased with the number of players, the correspondent regularity presented a trend of a most likely increase (from EPS3 vs. EPS4: ~25%, very large; to EPS9 vs. EPS10: ~11%, moderate). The mean speed results suggest that players may achieve different states of collective coordination, mainly between ~6 to 8 km.h-1. Overall, three different match scenarios should require additional attention when aiming to design more match transferable tasks: i) transition from EPS3 to EPS4; ii) transition from EPS4 up to EPS8; and iii) transition from EPS8 to EPS9. These results help to understand match self-organized behaviours and, consequently, allow to optimize task characteristics in practice sessions.

Key words

  • speed
  • variability
  • regularity
  • behaviour
  • positioning
Open Access

Shaq is Not Alone: Free-Throws in the Final Moments of a Basketball Game

Published Online: 13 Jun 2018
Page range: 135 - 144

Abstract

Abstract

It has been previously observed that basketball free-throw (FT) shooting efficiency decreases towards the end of the game. The aim of the current study was to explore possible determinants for this distinctive pattern during close games (point differential of equal or under 2 points during the final minute of the game). A sample of shots attempted by 92 players in the Spanish professional basketball league (ACB) was collected. Several personal (age, experience, playing position and career FT percentage) and contextual (team ability, competition stage, game location, seconds remaining and score differential) variables were considered for the analysis of the data. The effects of the predictor variables on the players’ performance were analyzed according to two game contexts (FT attempted during the final minute or the last pair of FTs) using binomial logistic regression analysis. The results showed that during the final minute the only statistically significant variable was being in the center playing position (OR = 1.58), which decreased the FT shooting percentage compared to forwards and guards. In addition, the results during the last pair of FTs showed that the playing position of guards (OR = 1.70) and centers (OR = 2.22) was significant (a decrease in their FT percentage). Conversely, the score differential when tied (OR = -1.17) or losing (OR = -2.43) was significant, reflecting a lower probability of missing the shot. The results were interpreted and discussed from the viewpoints of crisis theory and the literature on choking in athletic performance.

Key words

  • performance analysis
  • choking
  • pressure conditions
Open Access

Analysis of Training Plans in Basketball: Gender and Formation Stage Differences

Published Online: 13 Jun 2018
Page range: 123 - 134

Abstract

Abstract

Scientific literature has stated the presence of various stages in athletes sportive development, with different objectives in each one of them. This should lead coaches to different training plans according to the athlete’s formation stage. The aim of this study was to analyse training plans and identify differences in basketball objectives according to formative stages (U’12 and U’14) in boys and girls. A total of 1,976 training tasks were collected and analysed, for a total of four teams (girls and boys of U’12 and U’14 categories) during an entire season. Pedagogical variables, game phases, game situations, training means and content were studied. The results showed significant differences between genders. Girls’ teams performed more tasks on offense and technical skills. By contrast, boys’ teams performed more defensive tasks and tactical contents. The 1-on-0 and 1-on-1 were the most repeated game situations in all teams. Coaches used different training tasks according to gender and age. In male U’12 teams, drills predominated, whereas in the other categories, games predominated. For boys’ teams, the contents were tactical oriented, and for girls’ teams, the contents were oriented toward skill acquisition. Studying the pedagogical variables of the training process allowed for identification of the utility of training, assessment, and modification of this process.

Key words

  • sports initiation
  • early stages
  • tasks
  • pedagogical variables
Open Access

What are the Most Widely Used and Effective Attack Coverage Systems in Men’s Volleyball?

Published Online: 13 Jun 2018
Page range: 111 - 121

Abstract

Abstract

In volleyball, attack coverage is one of the play actions most neglected in coaching and research. The purpose of this study was to find out which attack coverage systems are used by high-level men’s teams in different game situations and the characteristics of the most effective systems. We analysed 15 matches from the 2010 Men’s Pan-American Volleyball Cup, with a total of 1,415 coverage actions. Chi-square tests for independence, adjusted residuals analysis and calculations of standardised mean difference were performed. The results show that high-level men’s volleyball uses many coverage systems other than the traditional 3-2-0 and 2-3-0. At this level of play, the most frequent systems were 1-3-1 and 1-2-2, which occurred significantly often at the culmination of a third-tempo attack at the wing. The most effective systems consisted of three coverage lines, with fewer than five players covering the spiker and at least one player in the first coverage line, in both the attack and counterattack phases. Given the large number of coverage systems identified in different game situations, we recommend flexible, loosely structured training in these systems, based on a set of guiding principles that all players on a team must internalise for the specific position they are playing. Regarding the systems’ efficacy, the main watchword is that on each coverage line there should always be at least one player, but the first line should not be exposed.

Key words

  • performance analysis
  • game patterns
  • collective behaviour
  • team sports
Open Access

The Reliability of Technical and Tactical Tagging Analysis Conducted by a Semi-Automatic VTS In Soccer

Published Online: 13 Jun 2018
Page range: 103 - 110

Abstract

Abstract

The Video Tracking multiple cameras system (VTS) is a technology that records two-dimensional position data (x and y) at high sampling rates (over 25 Hz). The VTS is of great interest because it can record external load variables as well as collect technical and tactical parameters. Performance analysis is mainly focused on physical demands, yet less attention has been afforded to technical and tactical factors. Digital.Stadium® VTS is a performance analysis device widely used at national and international levels (i.e. Italian Serie A, Euro 2016) and the reliability evaluation of its technical tagging analysis (e.g. shots, passes, assists, set pieces) could be paramount for its application at elite level competitions, as well as in research studies. Two professional soccer teams, with 30 male players (age 23 ± 5 years, body mass 78.3 ± 6.9 kg, body height 1.81 ± 0.06 m), were monitored in the 2016 season during a friendly match and data analysis was performed immediately after the game ended. This process was then replicated a week later (4 operators conducted the data analysis in each week). This study reports a near perfect relationship between Match and its Replication. R2 coefficients (relationships between Match and Replication) were highly significant for each of the technical variables considered (p < 0.001). In particular, a high score of interclass correlation and a small coefficient of variation were reported. This study reports meaningless differences between Match and its Replication (intra-day reliability). We concluded that the semi-automatic process behind the Digital.Stadium® VTS was more than capable of recording technical tagging data accurately.

Key words

  • team sports
  • time-motion analysis
  • match analysis
Open Access

The Effectiveness of Land and Water Based Resistance Training on Shoulder Rotator Cuff Strength and Balance of Youth Swimmers

Published Online: 13 Jun 2018
Page range: 91 - 102

Abstract

Abstract

The continuous execution of swimming techniques, supported mainly by the upper limbs, may cause shoulder rotator muscle imbalances, which leads to injuries. The aim of this study was to evaluate and compare the effects of two training programs on strength, balance and endurance of shoulder rotator cuff muscles in youth swimmers. Twenty-five male swimmers were evaluated and randomly divided into two groups – the land group (n = 13), which conducted a conventional dry-land training program with elastic bands, and the water group (n = 12), which conducted a water resistance program. In both groups, the level of strength of the shoulder rotators was evaluated with an isokinetic dynamometer on two occasions (baseline and after 10 weeks) using two protocols: i) three repetitions at 60o/s; ii) twenty repetitions at 180o/s. The land group significantly increased the unilateral ratios compared to the water group. The land group also decreased the external rotator levels of muscular fatigue. The dry-land training program conducted proved to be more effective than the one conducted in the water, allowing to reduce the muscle imbalance and to decrease muscle fatigue.

Key words

  • swimming
  • sports injuries
  • shoulder rotators
  • isokinetic strength

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