Anthropometric and physical characteristics allow differentiation of young female volleyball players according to playing position and level of expertise.

The aim of our study was to determine the differences in some anthropometric and physical performance variables of young Croatian female volleyball players (aged 13 to 15) in relation to playing position (i.e., independent variable) and performance level within each position (i.e., independent variable). Players were categorized according to playing position (i.e., role) as middle blockers (n=28), opposite hitters (n=41), passer-hitters (n=54), setters (n=30), and liberos (n=28). Within each position, players were divided into a more successful group and a less successful group according to team ranking in the latest regional championship and player quality within the team. Height and body mass, somatotype by the Heath-Carter method, and four tests of lower body power, speed, agility and upper body power (i.e., dependent variables) were assessed. Players in different positions differed significantly in height and all three somatotype components, but no significant differences were found in body mass, body mass index or measured physical performance variables. Players of different performance level differed significantly in both anthropometric and physical performance variables. Generally, middle blockers were taller, more ectomorphic, less mesomorphic and endomorphic, whereas liberos were shorter, less ectomorphic, more mesomorphic and endomorphic than players in other positions. More successful players in all positions had a lower body mass index, were less mesomorphic and endomorphic, and more ectomorphic than less successful players. Furthermore, more successful players showed better lower body power, speed, agility and upper body power. The results of this study can potentially provide coaches with useful indications about the use of somatotype selection and physical performance assessment for talent identification and development.

Measurement errors when estimating the vertical jump height with flight time using photocell devices: the example of Optojump.

Common methods to estimate vertical jump height (VJH) are based on the measurements of flight time (FT) or vertical reaction force. This study aimed to assess the measurement errors when estimating the VJH with flight time using photocell devices in comparison with the gold standard jump height measured by a force plate (FP). The second purpose was to determine the intrinsic reliability of the Optojump photoelectric cells in estimating VJH. For this aim, 20 subjects (age: 22.50±1.24 years) performed maximal vertical jumps in three modalities in randomized order: the squat jump (SJ), counter-movement jump (CMJ), and CMJ with arm swing (CMJarm). Each trial was simultaneously recorded by the FP and Optojump devices. High intra-class correlation coefficients (ICCs) for validity (0.98-0.99) and low limits of agreement (less than 1.4 cm) were found; even a systematic difference in jump height was consistently observed between FT and double integration of force methods (-31% to -27%; p<0.001) and a large effect size (Cohen's d>1.2). Intra-session reliability of Optojump was excellent, with ICCs ranging from 0.98 to 0.99, low coefficients of variation (3.98%), and low standard errors of measurement (0.8 cm). It was concluded that there was a high correlation between the two methods to estimate the vertical jump height, but the FT method cannot replace the gold standard, due to the large systematic bias. According to our results, the equations of each of the three jump modalities were presented in order to obtain a better estimation of the jump height.

Neuromuscular and inflammatory responses to handball small-sided games: the effects of physical contact.

The aim of this study was to investigate the influence of physical contact on neuromuscular impairments and inflammatory response during handball small-sided games. Using a counterbalanced design, 12 elite male junior handball players were divided into two groups: contact (C-SSG) and no-contact (NC-SSG), performing both contact and no-contact small-sided games, in reverse order on two training sessions separated by 5 days. The methodology and rules were identical for the two SSG regimens, with the only difference being the inclusion or prohibition of upper body use for physical contacts. Upper and lower body neuromuscular performances and blood concentrations of inflammatory cytokine IL-6 were assessed before and immediately after the games. During small-sided games, video analysis was used to establish the physical contact counts. Significant differences were found in most upper and lower limbs muscles kinetic variables and in the physical contact events (all P < 0.001) following the two training regimens. There was an increase in IL-6 after C-SSG and no changes following NC-SSG (P < 0.05 and P = 0.12, respectively). Moreover, a strong correlation was found between the number of physical contacts and IL-6 responses (r = 0.971, P < 0.001) in C-SSG. This study indicates that an inflammatory response and large upper and lower body neuromuscular impairments result from physical contact in elite handball players. These outcomes outline the specific physiological profile of C-SSG that, in turn, might be used by practitioners and coaches as a practical approach to strategically select exercises in athlete's overall training program.

The effect of slope on repeated sprint ability in young soccer players.

This study aimed to describe a gradient repeated sprint ability (RSA) test in comparison with a standard level one by investigating performance, metabolic demand and muscular jumping performance as a proxy for running mechanics. Eighteen athletes performed two level RSA tests (40 m × 6) - for reliability evaluation - and one ±5% gradient RSA test, second leg downhill (RSAgrad). Rating of perceived exertion (RPE), blood lactate concentration (BLa) concentration, vertical jump heights were assessed as well. Level test measures resulted highly reliable (Intra-class correlation coefficient (ICC) ≥0.96). RSAgrad worsened only first sprints' performance (-2%) but not overall test performance (~45 s). RSAgrad resulted to be less deteriorating in terms of fatigue index (FI) (-36%), BLa (-23%), RPE (-11%), jumping performance (RSAgrad post-/pre-squat jump, countermovement jump heights (CMJh): -3%, -6%, respectively). RSAgrad could be used to diversify common training protocol without stressing excessively athletes' current metabolic-anaerobic capacity. Such physical conditioning procedures could improve acceleration/braking capability.

Reliability and criterion-related validity of a new repeated agility test.

The study aimed to assess the reliability and the criterion-related validity of a new repeated sprint T-test (RSTT) that includes intense multidirectional intermittent efforts. The RSTT consisted of 7 maximal repeated executions of the agility T-test with 25 s of passive recovery rest in between. Forty-five team sports players performed two RSTTs separated by 3 days to assess the reliability of best time (BT) and total time (TT) of the RSTT. The intra-class correlation coefficient analysis revealed a high relative reliability between test and retest for BT and TT (>0.90). The standard error of measurement (<0.50) showed that the RSTT has a good absolute reliability. The minimal detectable change values for BT and TT related to the RSTT were 0.09 s and 0.58 s, respectively. To check the criterion-related validity of the RSTT, players performed a repeated linear sprint (RLS) and a repeated sprint with changes of direction (RSCD). Significant correlations between the BT and TT of the RLS, RSCD and RSTT were observed (p<0.001). The RSTT is, therefore, a reliable and valid measure of the intermittent repeated sprint agility performance. As this ability is required in all team sports, it is suggested that team sports coaches, fitness coaches and sports scientists consider this test in their training follow-up.

MAOD Determined in a Single Supramaximal Test: a Study on the Reliability and Effects of Supramaximal Intensities.

The main barrier to the wide use of maximal accumulated oxygen deficit (MAOD) is the considerable time required to apply several sub- and supra-maximal exercise sessions. The main question of this study was whether the determination of MAOD using a single supramaximal exercise session (MAODALT) is valid and reliable in running. We investigated the effects of the supramaximal exercise intensity (A) and the reliability of a single supramaximal exercise session (B) to assess MAOD in treadmill running. For this aim 29 subjects participated in A & B studies with single allocation "A" (n=15) and "B" (n=14). The conventional MAOD and 8 MAODALT were determined in exhaustive efforts varying between 100-150% at an intensity associated with maximal oxygen uptake (i+V˙O2MAX). In B study 2 supramaximal efforts were applied to analyze the test-retest reliability. Non-significant differences were found between MAOD and the 8 values of MAODALT. Despite the MAOD being statistically correlated with the MAODALT 100% i+V˙O2MAX (0.490.59), MAODALT determined at 115% of i+V˙O2MAX (52.4±1.7 mL·kg(-1)) presented the higher correlation values (0.650.77) and concordance. In addition, the MAOD at 115% of i+V˙O2MAX presented high test-retest reliability. MAODALT determined at 115% of i+V˙O2MAX was a valid and reliable method to assess MAOD in running.

Age- and gender-related development of stretch shortening cycle during a sub-maximal hopping task.

The aim of this study was to analyse the effects of age and gender (and their interaction) on a stretch shortening cycle solicited during a hopping task. For this aim, 147 girls and 148 boys aged 11 to 20 years, who were enrolled in middle school or secondary school with no experience in sport activity, or training less than three times per week, performed 3×5 hops in place. Leg-stiffness, jump-height and reactive-strength indices were assessed using an accelerometer (Myotest). The participants were selected in order to form five age groups: 11 12, 13-14, 15-16, 17-18 and 19-20 years. Regression analysis between force and centre of mass displacement revealed spring-mass behaviour for all groups (r(2)=.73-.89), meaning that beginning at the age of 11 years, children are able to perform complex inter-muscular coordination of the lower limbs, revealing efficient neural control early in childhood. Leg stiffness increased from 24.7 ± 10.6 kN · m(-1) at 11-12 years to 44.1 ± 14 kN · m(-1) in boys, with a small increase until 16 years (+17%) and a large increase between 17 and 20 years (+32.7%). In girls, leg stiffness increased from 26.6 ± 9 kN · m(-1) at 11-12 years to 39.4 ± 10.9 kN · m(-1) at 19-20 years, with a curious decrease in leg stiffness at 17-18 years, probably due to an increase in the percentage of fat at this age (25%). While no gender effect was found, the reactive-strength index revealed that, from 15-16 years onward, boys were better able to produce high levels of force in a shorter time than girls. The age of 15-16 years is a threshold of maturity and gender differentiation, where the boys investigated are more efficient in the stretch shortening cycle.

The effect of uphill stride manipulation on race walking gait.

UNLABELLED: Stride length analysis represents an easy method for assessing race walking kinematics. However, the stride parameters emerging from such an analysis have never been used to design a training protocol aimed at increasing stride length. With this aim, we investigated the effects of stride frequency manipulation during three weeks of uphill (2%) training on stride length at iso-efficiency speed. Twelve male race walkers were randomly allocated to one of two training groups: stride frequency manipulation (RWM, n=6) and free stride frequency (RWF, n=6). RESULTS: Kinematic parameters measured before and after the 3-week training in RWM showed increased stride length (4.54%; p<0.0001) and contact time (4.58%; p<0.001); inversely, a decreased stride frequency (4.44%; p<0.0001) and internal work (7.09%; p<0.05) were found. In RWF the effect of the training showed a decrease in stride length (1.18%; p<0.0001) and contact time (<1%; p<0.0001) with respect to baseline conditions and an increased stride frequency and internal work of 1.19% (p<0.0001). These results suggest that using slopes (2%) as RWM could help coaches to provide some training methods that would improve an athlete's performance, through increasing stride length without altering his or her race walking technique or metabolic demands.

Present status of accelerator-based BNCT: Focus on developments in Argentina.

In this work we provide some information on the present status of accelerator-based BNCT (AB-BNCT) worldwide and subsequently concentrate on the recent accelerator technology developments in Argentina.

Repeated sprint ability related to recovery time in young soccer players.

This study aimed to describe the influence of recovery duration during a repeated sprint ability (RSA) test (6 × 40 m) by investigating a number of variables, such as general performance, metabolic demand, and muscular stretch-shortening performance. Seventeen male soccer outfield players (16 ± 0 years, 66 ± 10 kg) performed three field shuttle-running tests with 15, 20, and 25-sec recoveries. In addition to specific shuttle test's variables, blood lactate concentration and vertical jump height were assessed. Resulting measures were highly reliable (intra-class correlation coefficient up to 0.86). 25-sec recovery improved test performance (-3% total time from 15-sec to 25-sec recovery), vertical jump height (+7% post-test height from 15-sec to 25-sec recovery), and decreased blood lactate accumulation (-33% post-test from 15-sec to 25-sec recovery). Study findings suggest that metabolic acidosis plays a role in worsening performance and fatigue development during the shuttle test. A 25-sec recovery duration maximized performance, containing metabolic-anaerobic power involvement and muscular stretch-shortening performance deterioration during a RSA test.

The Impact of Jumping during Recovery on Repeated Sprint Ability in Young Soccer Players.

This study compared the effect of counter-movement-jump (CMJ)-based recovery on repeated-sprint-ability (RSA). Eighteen male footballers (16 ± 0 years, 65 ± 10 kg, 1.74 ± 0.10 m) performed three RSA-tests. RSA-1/-3 were performed according to standard procedures, while three CMJs (over 10″) - as a potential fatigue-determinant and/or running mechanics interference--were administered during RSA-2 recoveries. RSA performance, exercise effort (fatigue index [FI], rating of perceived exertion [RPE], blood lactate concentration [BLa]), simple kinematics (steps number), vertical-jump characteristics (stretch-shortening-cycle-efficiency [SSCE] assessed before/after RSA) were investigated. ANOVA showed no differences between RSA-1,-3. During RSA-2, performance was lower than RSA-1/-3, while steps number did not change. During RSA-2, FI, BLa, RPE were higher than RSA-1/-3 (FI +21.10/+20.43%, P<0.05; BLa +16.25/+13.34%, P<0.05; RPE +12.50/+9.57%, P<0.05). During RSA-2, SSCE, as the CMJ/squat-jump-height-ratio, was not significantly different from RSA-1/-3. Passive recovery RSA allows better performance. Yet, RSA CMJ-based recovery is effective in increasing training load (FI, BLa, RPE) without perturbing running mechanics (simple kinematics, SSCE).

Validity of the MarkWiiR for kinematic analysis during walking and running gaits.

The aim of this study was to validate the MarkWiiR (MW) captured by the Nintendo Wii-Remote (100-Hz) to assess active marker displacement by comparison with 2D video analysis. Ten participants were tested on a treadmill at different walking (1<6 km · h(-1)) and running (10<13 km · h(-1)) speeds. During the test, the active marker for MW and a passive marker for video analysis were recorded simultaneously with the two devices. The displacement of the marker on the two axes (x-y) was computed using two different programs, Kinovea 0.8.15 and CoreMeter, for the camera and MW, respectively. Pearson correlation was acceptable (x-axis r≥0.734 and y-axis r≥0.684), and Bland-Altman plots of the walking speeds showed an average error of 0.24±0.52% and 1.5±0.91% for the x- and y-axis, respectively. The difference of running speeds showed average errors of 0.67±0.33% and 1.26±0.33% for the x- and y-axes, respectively. These results demonstrate that the two measures are similar from both the x- and the y-axis perspective. In conclusion, these findings suggest that the MarkWiiR is a valid and reliable tool to assess the kinematics of an active marker during walking and running gaits.

Bench press exercise: the key points.

The bench press exercise (BPE) is receiving increasing interest as a field testing, training/therapeutic modality to improve neuromuscular performance or to increase bone mass density. Several studies have been performed using BPE as a standard for increasing upper-limb strength. For this purpose, the position of the bar, the loads, the sets, the number of repetitions, the recovery time in-between sets, the movement speed, the muscular work and the use of the determination of the one repetition maximum (1-RM) are the classical tools investigated in the literature that have been shown to affect the BPE effect on neuromuscular. The goal of the present short review is to make a picture of the current knowledge on the bench press exercise, which could be very helpful for a better understanding of this standard movement and its effects. Based on the related literature, several recommendations on these key points are presented here.

High frequency performance analysis of professional soccer goalkeepers: a pilot study.

AIM: High-speed video analysis was performed during ten official-matches, to assess the performance of ten goalkeepers (GK) from Italian third/fourth divisions (C-D). METHODS: The variables studied were: number (N.) of frontal and lateral actions with distance covered (speed during first-last meter) and total distance covered during match. RESULTS: Match analysis showed that N. of lateral (right/left) changes of direction in GK-C was 48% (P<0.005) lower, and forward changes of action 53% greater (P<0.001) compared to GK-D. N. of forward and lateral actions in GK-C was 49% and 67% (P<0.001 and P<0.0001) greater than GK-D, respectively. Particularly, in GK-C the covered average distance, frontal and lateral, was 27% and 58% (P<0.005 and P<0.001) greater than in GK-D, respectively. Velocity of first meter of forward and lateral actions for GK-C were 9% and 27% lower (P>0.05 and P>0.05) than GK-D, respectively. Last meter of forward and lateral actions for GK-C was 57% greater and 43% lower (P<0.001 and P<0.005) than GK-D, respectively. Finally, total covered distance, considering all actions, was 60% greater for GK-C compared to GK-D (P<0.001). CONCLUSION: The work presented in this paper identifies the relevant aspects of the goalkeeper game that are valuable for a coach in terms of team and individual performance analysis.

Improving neuromuscular performance in young basketball players: plyometric vs. technique training.

AIM: The aim of this study was to compare the effects of plyometric training versus basketball technique training on improving neuro-muscular performance. METHODS: Thirty-six (age 14.9±0.9 years, body height 164.0±7.6 cm, body weight 54.0±8.7 kg, BMI 20.1±2.4 kg·m-2) basketball players girls were randomly allocated to 2 groups: Basketball Plyometric Training (BPT, N.=18) and Basketball Technique Training (BTT, N.=18). The players were tested by two specific tests: counter movement jump (CMJ) and squat jump (SJ) before and after 6 training weeks. RESULTS: The jump height, as dependent variable, showed a different trend as an effect of the different training protocols, in contrast with the current knowledge. Manova did not show significant interactions between the two groups for the height of jumps, while significant differences were found for interaction time × training (P<0.05) and for main effect × time (P<0.001). After training, the BPT group increased significantly CMJ performance by 11.3% (P<0.05), whereas the BTT group increased by 4.6%. Likewise, the BPT group demonstrated a significant greater improvement of jump height than BTT group (an increase of 15.4% vs. 7.5%, P<0.01; respectively). CONCLUSION: These results suggest that both training protocols proposed in this study improved vertical jump performance. However, a combination of the two protocols, plyometric training and sport-specific-exercises, could be useful to optimize performance by an easy transition from controlled a-specific to sport-specific performance requirements. In conclusion, BPT is a safe and effective method of achieving a favourable neuro-muscular performance than BTT in female basketball players.

Acute effects of two different initial heart rates on testing the Repeated Sprint Ability in young soccer players.

AIM: The aim of this paper was to investigate the acute effects of two different initial heart rates intensities when testing the repeated sprint ability (RSA) performances in young soccer players. METHODS: Since there are many kinds of pre-match warm-ups, we chose to take as an absolute indicator of internal load the heart rate reached at the end of two different warm-up protocols (60 vs. 90% HRmax) and to compare the respective RSA performances. The RSA tests were performed on fifteen male soccer players (age: 17.9±1.5 years) with two sets of ten shuttle-sprints (15+15 m) with a 1:3 exercise to rest ratio, in different days (randomized order) with different HR% (60 & 90% HRmax). In order to compare the different sprint performances a Fatigue Index (FI%) was computed, while the blood lactate concentrations (BLa-) were measured before and after testing, to compare metabolic demand. RESULTS: Significant differences among trials within each sets (P<0.01) were found. Differences between sets were also found, especially comparing the last five trials for each set (Factorial ANOVA; P<0.01), effect size values confirming the relevance of these differences. Although the BLa- after warm-up was higher (36%) between 90% vs. 60% HRmax, after the RSA test the differences were considerably low (7%). CONCLUSION: Based on physiological information's this methodological approach (testing with initial 90%HRmax) reflects more realistically the metabolic background in which a soccer player operates during a real match. This background may be partially reproduced by warming up protocols that, by duration and metabolic commitment, can reproduce conveniently the physiological conditions encountered in a real game (e.g. HRmax≈85-95%; BLa->4 mmol/L(-1)).

THE EFFECT OF MATURITY ON HEART RATE RESPONSES DURING TRAINING AND TESTING IN POSTPUBESCENT FEMALE VOLLEYBALL PLAYERS.

The aim of this study was to examine the effect of maturity, assessed as difference between chronological age and age at peak height velocity, on heart rate (HR) responses to maximal and submaximal laboratory and field exercises. Twenty-eight postpubescent female volleyball players participated in the present study (age 13.8 (0.6) yr, body mass 62.5 (8.2) kg and height 1.73 (0.05) m; mean (standard deviation)). They were divided into two groups with regards to their maturation: less matured (LM) and more matured (MM). In laboratory, HR was recorded during 5 min rest, physical working capacity in heart rate 170 bpm, 3 min step test, 30 s Bosco test and Wingate anaerobic test (WAnT) were performed. In field, a 70 min training session (consisted by three parts: warm-up, 1 x 1 drills and team drills) was monitored and 20 m shuttle run endurance test was performed. There was significant difference between LM and MM groups over HR responses (%HR reserve, %HRR) to exercise training (F(2,21) = 6.08, p = 0.008, η2 = 0.37). There was a main effect of part session of exercise program on HR responses with the highest intensity recorded in 1 x 1 drills (-75% HRR) and the lowest in team drills (-60% HRR in LM and -65% HRR in MM). There was also a moderate effect of maturity on HR during cycling against 90 W and in the WAnT, and small effect on HR during cycling against 60 W, in the end of the step test, Bosco test and running endurance test, where the highest scores were recorded in LM. Based on the findings of the present study, it was concluded that maturity exerted an effect of small to moderate magnitude on H R responses in a laboratory setting and this should be taken into account by coaches and trainers when evaluating physiological characteristics.

The effects of one-week training camp on motor skills in Karate kids.

AIM: The purpose of this study was to evaluate the effects of short-term increased hours of specific high-intensity karate training on motor skills in young karate athletes aged between 8 and 12 years. METHODS: Seventy-three children, who regularly trained three karate sessions per-week were divided in two groups: high-intensity karate group (HG=53) and low-intensity karate group (LG=20). HG trained for 7 days: with two sessions per-day (one hour per-session) including specific karate techniques as well as coordination, balance, and flexibility exercises. LG, however, followed the same number of karate training sessions as before the beginning of the study (i.e., three sessions per-week with one hour per-session). Participants performed a battery of tests, 24 hours pre- and one week post-training: a medicine ball throw (MBT), standing long jump (SLJ), active joint flexibility (JM) and lateral/frontal jumps (JLT). RESULTS: Significant differences between results of pre and post karate training (ANOVA with repeated measures) included: MBT (P<0.05), SLJ (P<0.0001), JM (P<0.0001), JLT (P<0.0001); whilst the interaction training × time was: MBT (P=0.145), SLJ (P<0.0001), JM (P<0.0001), JLT (P< 0.0001). The HG significantly improved their performance on MBT by 3.23% (P<0.05), SLJ by 5.09% (P<0.001), JM by 1.51% (P<0.001), and JLT by 21.36% (P<0.001). For LG group, there were no significant differences between pre and post-testing in all fitness tests. CONCLUSION: Muscular power, flexibility and coordination represent the basics of karate fitness component. In this regard, short term high-intensity karate training represents an effective method for enhancing muscular power and range of motion (i.e. flexibility) in young karate athletes aged between 8 and 12 years. Further studies are needed to support these findings with deeper data.

Upper-limb power test in rock-climbing.

The goal of the present study was to validate a new ecological power-test on athletes of different levels and to assess rock climbers' profiles (boulderers vs. route climbers). 34 athletes divided into novice, skilled and elite groups performed the arm-jump board test (AJ). Power, time, velocity, and efficiency index were recorded. Validity was assessed by comparing the distance with the value extracted from the accelerometer (500 Hz) and the reliability of intra- and inter-session scores. Moreover, a principal component analysis (PCA) was used to assess the climbers' profiles. The AJ test was quite valid, showing a low systematic bias of -0.88 cm (-1.25%) and low limits of agreement (< 6%), and reliable ( Intra-class correlation coefficient = 0.98 and CV < 5%), and was able to distinguish between the 3 samples (p < 0.0001). There was a good correlation between relative upper-limb power (r = 0.70; p < 0.01) and the AJ score. Moreover, the PCA revealed an explosive profile for boulderers and either a weak and quick or slow profile for route climbers, revealing a biomechanical signature of the sub-discipline. The AJ test provides excellent absolute and relative reliabilities for climbing, and can effectively distinguish between climbing athletes of different competitive levels. Thus, the AJ may be suitable for field assessment of upper limb strength in climbing practitioners.