Pedaling time variability is increased in dropped riding position

Variability of cycle-to-cycle duration during a pedaling task is probably related to the rhythmic control of the lower limb muscles as in gait. Although walking variability has been extensively studied for its clinical and physiological implications, pedaling variability has received little attention. The present contribution determines the variability of the cycling time during a 10-min exercise as a function of upper body position. Nine healthy males were required to pedal on cycle-ergometer at a self-selected speed for 10 min in two different upper body positions [hands on upper handlebars (UP) or lower handlebars (DP)]. Time domain measures of cycling variability [total standard deviation (SDtot), mean standard deviation cycle-to-cycle intervals over 100 cycles (SD100), standard deviation of the average cycle-to-cycle intervals over 100 cycles (SDA100)] were measured. Moreover, the same time domain measures were also calculated for heart rate in order to discriminate possible involvements of autonomic regulation. Finally, the structure of the cycle variations has been analyzed in the framework of deterministic chaos calculating the maximum Lyapunov exponents. Significant increases in cycle-to-cycle variability were found for SDtot, SD100 in DP compared to UP, whereas cardiac parameters and other cycling parameters were not changed in the two positions. Moreover, the maximum Lyapunov exponent was significantly more negative in DP. The results suggest that small perturbations of upper body position can influence the control of cycling rhythmicity by increasing the variability in a dissipative deterministic regimen

The effect of uphill stride manipulation on race walking gait

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

Validity and reliability of a light-based electronic target for testing response time in fencers

Response time is a fencing fundamental sensorimotor skill. Therefore, the aim of the current study was to examine the efficacy of a light-based electronic target in fencers, designed to measure and train this entity. Ninety-five fencers (M=53; F=42) were tested in regard to their response time, using a light-based electronic target, for three different attack types: simple attack, the lunge, and an attack following a 1.5-m thrust. All participants were divided into elite vs. novice fencers. Elite fencers had national and international rankings, and were again divided with regard to used weapon: épéeists (n=32; M=19; F=13) and foilists (n=30; M=13; F=17). Measurement was evaluated for validity/reliability, sensitivity/specificity, and correlation. Reliability was high for all attack types (ICC 0.94-0.96). Lower response times were found in males for two attack types with good sensitivity (81-93%)/specificity (50-91%) for all attack types. Elite fencers responded faster than novice fencers for all attack types (P<0.001), whereas elite males were faster than females for two attack types (P<0.01). Lower response times in females correlated with level for one attack type (r=0.797, P<0.05). In conclusion, the light-based electronic target system was found to be highly reliable and therefore could be used by fencing athletes as a further measure of performance

Motion analysis of elite Polish soccer goalkeepers throughout a season

The study aims were to determine the distance covered by goalkeepers during matches in the context of game duration and result, to identify the area of their most frequent activity, and to assess goalkeepers' involvement in games finished with a win, draw, or loss. The investigation was based on two innovative tools: the goalkeeper's activity index (GAI) and an analysis of 5-min periods. A video tracking system was used to monitor 17 goalkeepers from Polish National League teams during 15 matches. The GAI was applied to assess their involvement in the game. Elite goalkeepers covered 72.7%, 25.8%, and 2.5% of the distance during the game by walking/jogging, running, and sprinting, respectively. The distances covered in lost, won, and drawn matches turned out similar (mean \ub1 SD: 4800 \ub1 906 m, 4696 \ub1 1033 m, and 4660 \ub1 754 m, respectively). There were no significant differences between the distances covered in the first and second halves. The area of most frequent activity was the middle sector of the penalty area between the goal and penalty area lines. ANOVA results showed that in drawn matches, goalkeepers' activity significantly differed in mean values of the GAI in comparison with that in won and lost games (p = 0.034, p = 0.039, respectively). It was noted that goalkeepers tended to intervene more often in games where their team was winning rather than in those with a losing result. Their direct involvement in defending the goal was the lowest in drawn games

The &quot;safe falls, safe schools&quot; multicentre international project: Evaluation and analysis of backwards falling ability in Italian secondary schools

Problem statement: Different studies have reported on the epidemiology related to injuries resulting from falls, which are the most common causes of injury in Italy. The World Health Organization considers falls as the second leading cause of accidental or unintentional deaths worldwide. However, it has been demonstrated that the Safe Fall, Safe Schools Programme (SFSSP) based on 10-min warm-up sessions is able to teach techniques for falling backwards in safe way during physical education (PE) classes. Unfortunately, there are no studies that have analysed extensive warm-up and detraining effects related to the age. Aim: The aim of this study was to assess extensive specific warm-up (20 min) and detraining effects after five weeks on the SFSSP on Italian secondary school students according to age. Methods: Eighty-seven secondary school students took part in this investigation. Students were divided into two groups, equally distributed by age. The trial-control group (TC=39) and the control-trial group (CT=48) performed the same PE lesson for 10 weeks. In the first five weeks, two different 20-min warm-up exercises were performed (TC=SFSSP; CT=conventional warm-up); after five weeks, the warm-ups were inverted (TC=conventional warm-up; CT=SFSSP). The backwards falling ability test carried out among both groups was evaluated in relation to the position of the neck, trunk, knees, hips and hands, before and after five and 10 weeks. Results: McNemar\u2019s test showed significant differences (between pre-and mid-time points, P&lt;0.05) for the neck, trunk, hip and hands, while no significant differences were found in the knee value (P=0.581 in TC). No differences were found between the mid-and post-time points for TC. In CT, no differences were found in-between (pre-and mid-time points, P&gt;0.05) for all variables studied. Significant differences (P&lt;0.05) were found in-between the mid-and post- time points for CT in all variables studied. Analysis of the total scores for SFSSP showed significantly differences in TC and CT (P&lt;0.0001). The Wilcoxon signed-rank test showed no significant differences (total scores: first year=1.68\ub11.05 AU; fifth year=1.47\ub10.86 AU; P=0.34) before the SFSSP intervention, while the SFSSP was able to improve the ability after intervention (total scores: first year=4.47\ub10.84 AU; fifth year=3.91\ub11.40 AU; P&lt;0.01). Conclusions: The SFSSP was able to improve motor ability for both groups and the detraining effect was found to maintain the same ability level compared to that after the SFSSP intervention. Participants started with the same level of backwards falling ability and each group, after the intervention, significantly raised its score, confirming the efficacy of the intervention. Therefore, the SFSSP could be included in the standard national programme without changing the standard training lesson

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

Validity, Reliability, and Usefulness of My Jump 2 App for Measuring Vertical Jump in Primary School Children

There is a persistent need in sport science for developing a measuring tool that is affordable, portable, and easy to use. We aimed to examine the concurrent validity and test-retest reliability of the My Jump 2 app compared to a validated OptoJump instrument for measuring jump performance during the squat jump (SJ), countermovement jump (CMJ), and CMJ free arms (CMJAM) in primary school children. A total of 48 participants (11-14 years age), volunteered to participate in this research. The jumps were recorded with a validated OptoJump photoelectric cell system and a concurrent device (iPhone X through My Jump 2 app) at the same time. The participants repeated the testing procedure after two weeks to assess the reliability of the measurements (ICC). Systematic bias between sessions and tools was evaluated using the paired samples t-test and Bland and Altman analysis. High test-retest reliability (ICC &gt; 0.89) was observed for all measures' in-between conditions. Very large correlations in the total sample were observed between the My Jump 2 app and OptoJump for SJ (r = 0.97, p = 0.001), CMJ (r = 0.97, p = 0.001), and CMJAM (r = 0.99, p = 0.001). Bland and Altman's plot depicting limits of agreement for the total sample between the OptoJump and My Jump 2 show that the majority of data points are within the 95% CIs. The results of this study suggest that My Jump 2 is a valid, reliable, and useful tool for measuring jump performance in primary school children