Acute effect of stretching modalities on global coordination and kicking accuracy in 12–13 year-old soccer players

The aim of the study was to compare the effect of stretching procedures on global coordination and accuracy in instep soccer kicks achieved in different stress conditions. Twenty male young soccer players completed the global coordination test (GC), the instep kicking accuracy test in free (FKA) and in time-pressure (TPKA) conditions, either after static (SS), dynamic (DS), ballistic (BS) or no-stretching (CTR) protocols, on nonconsecutive days and in a randomized order. After performing a 5 min standardized intensity jogging (70% of MAV), followed by stretching exercises for 10 min, each participant completed, successively, the GC, FKA and TPKA tests. Accuracy data, heart-rate, rating of perceived exertion and task difficulty perception were recorded and analyzed using a two-way ANOVA. GC scores were analyzed using one way ANOVA with repeated measures. The results showed higher GC and TPKA performances after DS and BS procedures. However, there was no effect of the stretching procedures on FKA. The GC scores increased by 10.8% and 7.2% after DS and BS, respectively, but were not affected by SS. Compared to FKA, the TPKA accuracy significantly decreased by 20.2% after CTR (p < 0.01) and 30.7% SS (p < 0.001) with no significant difference after DS (10.1%; p > 0.05) and BS (11.0%; p > 0.05). The use of dynamic and ballistic stretching yielded to better GC scores and helped reducing the adverse effect of time-pressure on instep kicking accuracy. Consequently, dynamic and ballistic exercises can be recommended before practicing activities requiring coordination and lower limbs speed and accuracy.     

Differentiating technical skill and motor abilities in selected and non-selected 3–5 year old team-sports players

This study examined the difference in 22 3–5 year old boys selected to an advanced or non-advanced group on an English community-based professional club training program. Time to complete 15 m linear sprint and 15 m zig-zag agility tests, with and without a ball, were used to assess the children’s technical skill and motor ability. Age and body mass of both groups were the same, whereas height was greater and BMI was lower in the selected group (p < 0.01). Linear sprint times without and with the ball were 3.98 ± 0.35 and 4.44 ± 0.36 s, respectively for the selected and corresponding times were 4.64 ± 1.04 and 11.2 ± 5.37 s for the non-selected (p < 0.01, ES 0.8, 1.8). Similar results were found when a change of movement was included, both with and without the ball. A model of selection indicated that performance in an agility test with the ball and height had the greatest discriminatory power and explained 95.5% of between group variance. Selected players performed significantly better in tests when ball control was required. These findings suggest that technical proficiency and physical differences may influence team selection in three to five year old children.     

Balance effects of tactile stimulation at the foot

Balance relies on several types of sensory information, including somatosensory senses such as touch and position sense (proprioception). As these senses decline in older adults, there is a question of whether shoes limit somatosensory feedback from the floor. Textured insoles are designed to stimulate the soles of the feet to enhance tactile feedback. Textured insoles have shown balance benefits in some populations, but it is unclear if such tactile stimulation improves a person's balance even in cushioned athletic shoes, which dampen proprioceptive signals. Here we ask whether tactile vs. proprioceptive cues contribute differently to balance control in the healthy somatosensory system. We assessed balance in 20 healthy young adults under four footwear conditions: cushioned shoes with regular insoles, cushioned shoes with textured insoles, barefoot, and minimalist shoes. Each condition was evaluated using the Y-Balance Test (YBT) and the Balance Error Scoring System (BESS), validated tests of dynamic and static balance, respectively. YBT is a dynamic reaching test performed on one leg. The BESS includes various stance conditions with eyes closed. The results showed that footwear influenced dynamic balance only, with textured insoles leading to significantly better performance than barefoot and minimalist shoes did in the YBT. These results suggest that at least for dynamic balance, balance benefits of tactile stimulation from the textured insoles offset any dampening of proprioception caused by the athletic shoes' cushioning. Future research on how these conditions compare in older adults may lead to improved footwear recommendations to reduce fall risk and injuries for that population.     

Finger forces in fastball baseball pitching

Forces imparted by the fingers onto a baseball are the final, critical aspects for pitching, however these forces have not been quantified previously as no biomechanical technology was available. In this study, an instrumented baseball was developed for direct measurement of ball reaction force by individual fingers and used to provide fundamental information on the forces during a fastball pitch. A tri-axial force transducer with a cable having an easily-detachable connector were installed in an official baseball. Data were collected from 11 pitchers who placed the fingertip of their index, middle, ring, or thumb on the transducer, and threw four-seam fastballs to a target cage from a flat mound. For the index and middle fingers, resultant ball reaction force exhibited a bimodal pattern with initial and second peaks at 38–39 ms and 6–7 ms before ball release, and their amplitudes were around 97 N each. The ring finger and thumb produced single-peak forces of approximately 50 and 83 N, respectively. Shear forces for the index and middle fingers formed distinct peak at 4–5 ms before release, and the peaks summed to 102 N; a kinetic source for backspin on the ball. An additional experiment with submaximal pitching effort showed a linear relationship of peak forces with ball velocity. The peak ball reaction force for fastballs exceeded 80% of maximum finger strength measured, suggesting that strengthening of the distal muscles is important both for enhancing performance and for avoiding injuries.     

Children’s age modulates the effect of part and whole practice in motor learning

Motor skills can be learned by practicing the whole or part of a movement. In whole practice (WP), a skill is acquired by practicing the movement in its entirety, whereas in part practice (PP), a task is learned by practicing its components before combining them. However, the effectiveness of WP and PP in children is unclear. We, therefore, examined the effects of WP and PP on the learning of juggling among first-, third-, and fifth-graders. Children of each grade were pseudo-randomly assigned to the WP or PP group to learn cascade juggling in 6 days. After baseline assessments, the WP learners practiced three-beanbag juggling. The PP learners practiced one-beanbag juggling on the first 2 days, two-beanbag juggling on the following 2 days, and three-beanbag juggling on the last 2 days. Practice consisted of 40 trials each day. Skill retention and transfer trials (juggling in the opposite direction) were measured 24 h after training (number of catches). There was no significant difference between WP and PP in skill retention (WP: 1.28 ± 0.73; PP: 1.42 ± 046, p = .40) and transfer (WP: 1.31 ± 0.78; PP: 1.37 ± 0.55, p = .49). However, a time × grade × group interaction (p < .001) was observed in retention. Children of different grades received differential benefits from the WP and PP regimens. The fifth-graders learned better using WP, whereas the first- and third-graders showed better learning with PP. We discuss the three possible explanations for the results (neural maturity, explicit learning, and coordination capabilities).     

Profiling movement quality and gait characteristics according to body-mass index in children (9–11 y)

Obese children move less and with greater difficulty than their normal-weight counterparts. Whilst the effect of high BMI on cardiovascular fitness is well known, the effect on movement quality characteristics during a standardised fitness test has not been investigated. The aims of this study were, to characterise the movement quality of children performing the multi-stage fitness test (MSFT), and, report how movement quality characteristics cluster according to weight status. One hundred and three children (10.3 ± 0.6 y, 1.42 ± 0.08 m, 37.8 ± 9.3 kg, BMI; 18.5 ± 3.3 kg m²) performed the MSFT whilst wearing an ankle mounted accelerometer. BMI groups were used to classify children as underweight (UW), normal weight (NW), overweight (OW) and obese (OB). Characteristics of movement were profiled using a clustering algorithm. Spearman’s rho was used to assess relationship with BMI group, and a Mann-Whitney U test was used to assess differences between BMI groups. Obese children had significantly lower spectral purity than every other group and significantly lower time to exhaustion (TTE) than UW and NW children (P < 0.05). BMI was clustered with stride profile and TTE with spectral purity. Significant negative correlations (P < 0.05) were found between BMI and TTE (r = −0.25), spectral purity (r = −0.24), integrated acceleration (r = −0.22), stride angle (r = −0.23) and stride variability (r = −0.22). This was the first study to report the spectral purity of children’s gait. Further analysis unveiled key performance characteristics that differed between BMI groups. These were (i) representative of children’s performance during the MSFT and, (ii) significantly negatively correlated with BMI.     

Influence of prolonged wearing of unstable shoes on upright standing postural control

ObjectiveTo study the influence of prolonged wearing of unstable shoes on standing postural control in prolonged standing workers.MethodsThe participants were divided into two groups: one wore unstable shoes while the other wore conventional shoes for 8 weeks. Stabilometry parameters related to centre of pressure (CoP), rambling (RM) and trembling (TR) as well as the total agonist/antagonist muscle activity, antagonist co-activation and reciprocal activation were evaluated during upright standing, before and after the 8 weeks period. In both moments, the subjects were evaluated wearing the unstable shoes and in barefoot.ResultsThe unstable shoe condition presented increased CoP displacement related variables and decreased co-activation command compared to barefoot before and after the intervention. The prolonged wearing of unstable shoes led to: (1) reduction of medial–lateral CoP root mean square and area; (2) decreased anteroposterior RM displacement; (3) increased anteroposterior RM mean velocity and mediolateral RM displacement; (4) decreased anteroposterior TR RMS; and (5) increased thigh antagonist co-activation in the unstable shoe condition.ConclusionThe unstable shoe condition is associated to a higher destabilising effect that leads to a selection of more efficient and accurate postural commands compared to barefoot. Prolonged wearing of unstable shoes provides increased effectiveness and performance of the postural control system, while wearing of unstable shoes in upright standing, that are reflected by changes in CoP related variables and by a reorganisation of postural control commands.     

Goal equivalent manifold analysis of task performance in non-specific LBP and healthy subjects during repetitive trunk movement: Effect of load,velocity, symmetry

Motor abundance allows reliability of motor performance despite its variability. The nature of this variability provides important information on the flexibility of control strategies. This feature of control may be affected by low back pain (LPB) and trunk flexion/extension conditions.Goal equivalent manifold (GEM) analysis was used to quantify the ability to exploit motor abundance during repeated trunk flexion/extension in healthy individuals and people with chronic non-specific LBP (CNSLBP).Kinematic data were collected from 22 healthy volunteers and 22 CNSLBP patients during metronomically timed, repeated trunk flexion/extension in three conditions of symmetry, velocity, and loading; each at two levels. A goal function for the task was defined as maintaining a constant movement time at each cycle. Given the GEM, flexibility index and performance index were calculated respectively as amounts of goal-equivalent variability and the ratio of goal-equivalent to non-goal-equivalent variability.CNSLBP group was as similar as healthy individuals in both flexibility index (p = 0.41) and performance index (p = 0.24). Performance index was higher in asymmetric (p < 0.001), high velocity (p < 0.001), and loaded (p = 0.006) conditions.Performance and flexibility in using motor abundance were influenced by repeated trunk flexion/extension conditions. However, these measures were not significantly affected by CNSLBP.     

Long-term effectiveness of the SpeechEasy fluency-enhancement device

The SpeechEasy has been found to be an effective device for reduction of stuttering frequency for many people who stutter (PWS); published studies typically have compared stuttering reduction at initial fitting of the device to results achieved up to one year later. This study examines long-term effectiveness by examining whether effects of the SpeechEasy were maintained for longer periods, from 13 to 59 months. Results indicated no significant change for seven device users from post-fitting to the time of the study (t = ?.074, p = .943); however, findings varied greatly on a case-by-case basis. Most notably, when stuttering frequency for eleven users and former users, prior to device fitting, was compared to current stuttering frequency while not wearing the device, the change over time was found to be statistically significant (t = 2.851, p = .017), suggesting a carry-over effect of the device. There was no significant difference in stuttering frequency when users were wearing versus not wearing the device currently (t = 1.949, p = 0.92). Examinations of these results, as well as direction for future research, are described herein.Educational objectives: The reader will be able to: (a) identify and briefly describe two types of altered auditory feedback which the SpeechEasy incorporates in order to help reduce stuttering; (b) describe the carry-over effect found in this study, suggest effectiveness associated with the device over a longer period of time than previously reported, as well as its implications, and (c) list factors that might be assessed in future research involving this device in order to more narrowly determine which prospective users are most likely to benefit from employing the SpeechEasy.     

The coupling between gaze behavior and opponent kinematics during anticipation of badminton shots

PurposeWe examined links between the kinematics of an opponent’s actions and the visual search behaviors of badminton players responding to those actions.MethodA kinematic analysis of international standard badminton players (n = 4) was undertaken as they completed a range of serves. Video of these players serving was used to create a life-size temporal occlusion test to measure anticipation responses. Expert (n = 8) and novice (n = 8) badminton players anticipated serve location while wearing an eye movement registration system.ResultsDuring the execution phase of the opponent’s movement, the kinematic analysis showed between-shot differences in distance traveled and peak acceleration at the shoulder, elbow, wrist and racket. Experts were more accurate at responding to the serves compared to novice players. Expert players fixated on the kinematic locations that were most discriminating between serve types more frequently and for a longer duration compared to novice players. Moreover, players were generally more accurate at responding to serves when they fixated vision upon the discriminating arm and racket kinematics.ConclusionsFindings extend previous literature by providing empirical evidence that expert athletes’ visual search behaviors and anticipatory responses are inextricably linked to the opponent action being observed.     

Multifractal foundations of visually-guided aiming and adaptation to prismatic perturbation

Visually-guided action of tossing to a target allows examining coordination between mechanical information for maintaining posture while throwing and visual information for aiming. Previous research indicates that relationships between visual and mechanical information persist in tossing behavior long enough for mechanical cues to prompt recall of past visual impressions. Multifractal analysis might model the long-term coordinations among movement components as visual information changes. We asked 32 adult participants (6 female, 25 male, one not conforming to gender binary; aged M = 19.77, SD = 0.88) to complete an aimed-tossing task in three blocks of ten trials each. Block 1 oriented participants to the task. Participants wore right-shifting goggles in Block 2 and removed them for Block 3. Motion-capture suits collected movement data of the head, hips, and hands. According to regression modeling of tossing performance, multifractality at hand and at hips together supported use of visual information, and adaptation to wearing/removing of goggles depended on multifractality across the hips, head, and hands. Vector-autoregression modeling shows that hip multifractality promoted head multifractality but that hand fluctuations drew on head and hip multifractality. We propose that multifractality could be an information substrate whose spread across the movements systems supports the perceptual coordination for the development of dexterity.     

Trunk coordination in healthy and chronic nonspecific low back pain subjects during repetitive flexion–extension tasks: Effects of movement asymmetry,velocity and load

Multiple joint interactions are critical to produce stable coordinated movements and can be influenced by low back pain and task conditions. Inter-segmental coordination pattern and variability were assessed in subjects with and without chronic nonspecific low back pain (CNSLBP). Kinematic data were collected from 22 CNSLBP and 22 healthy volunteers during repeated trunk flexion–extension in various conditions of symmetry, velocity, and loading; each at two levels. Sagittal plane angular data were time normalized and used to calculate continuous relative phase for each data point. Mean absolute relative phase (MARP) and deviation phase (DP) were derived to quantify lumbar–pelvis and pelvis–thigh coordination patterns and variability. Statistical analysis revealed more in-phase coordination pattern in CNSLBP (p = 0.005). There was less adaptation in the DP for the CNSLBP group, as shown by interactions of Group by Load (p = .008) and Group by Symmetry by Velocity (p = .03) for the DP of pelvis–thigh and lumbar–pelvis couplings, respectively. Asymmetric (p < 0.001) and loaded (p = 0.04) conditions caused less in-phase coordination. Coordination variability was higher during asymmetric and low velocity conditions (p < 0.001). In conclusion, coordination pattern and variability could be influenced by trunk flexion–extension conditions. CNSLBP subjects demonstrated less adaptability of movement pattern to the demands of the flexion–extension task.     

Acute effects of jaw clenching using a customized mouthguard on anaerobic ability and ventilatory flows

The latest findings on the ergogenic effects of a dentistry-design, bite-aligning mouthpiece require additional research to assess its impact on anaerobic ability and ventilatory parameters. This paper was aimed at determining the ergogenic acute effects of wearing a custom-made mouthpiece on oral airflow dynamics, 30-s Wingate Anaerobic Test performance parameters.Twenty-eight healthy and physically-active male subjects (age: 24.50 ± 3.32, height: 181.34 ± 7.4, weight: 78.14 ± 8.21), were voluntarily studied. The subjects were first briefed on the test protocols, and then performed the 30 s Wingate test and Spirometer test. The experimental trials were performed in a random counterbalanced order. We evaluate maximum expiratory volume (V_Emax L min⁻¹), mean power (W kg⁻¹), peak power (W kg⁻¹), time to peak (s), rate to fatigue (W s⁻¹) and lactate production (mMol L⁻¹), rate of perceived exertion (RPE).There were significant differences between mouthguard and no-mouthguard conditions in mean power (W kg⁻¹), peak power (W kg⁻¹), time to peak (s), and rate to fatigue (W s⁻¹) for the 30-s Wingate Anaerobic Test. Significantly lower lactate production (mMol L⁻¹) was observed, in mouthguard condition but no significant differences were found in RPE. In airflow dynamics, the V_Emax L min⁻¹ was significantly higher when comparing the mouthguard and the no mouthguard conditions in both forced and unforced conditions.In conclusion, wearing a customized mouthguard improves anaerobic ability and increases forced expiratory volume. This study will help practitioners improve athlete’s performance in anaerobic activities where high intensity action might provoke jaw-clenching, contributing in reductions of lactate and fatigue, and improving ventilatory parameters.     

Effects of different swimming race constraints on turning movements

The aim of this study was to investigate the effects of different swimming race constraints on the evolution of turn parameters. One hundred and fifty-eight national and regional level 200-m (meters) male swimming performances were video-analyzed using the individualized-distance model in the Open Comunidad de Madrid tournament. Turn (p < .001, ES = 0.36) and underwater distances (p < .001, ES = 0.38) as well as turn velocity (p < .001, ES = 0.69) significantly dropped throughout the race, although stroke velocity and underwater velocity were maintained in the last lap of the race (p > .05). Higher expertise swimmers obtained faster average velocities and longer distances in all the turn phases (p < .001, ES = 0.59), except the approach distance. In addition, national level swimmers showed the ability to maintain most of the turn parameters throughout the race, which assisted them in improving average velocity at the end of races. Therefore, the variations in the turning movements of a swimming race were expertise-related and focused on optimizing average velocity. Turning skills should be included in the swimming race action plan.     

Match play demands of 11 versus 11 professional football using Global Positioning System tracking: Variations across common playing formations

This study aimed to examine Global Positioning System (GPS) determined movement patterns across the 5 most common playing formations (4-4-2; 4-3-3; 3-5-2; 3-4-3; 4-2-3-1) employed in 11 versus 11 football match play in England. Elite male footballers (n = 46) were monitored over the course of a season; total distance (TD), high speed running (HSR), high metabolic load distance (HMLD), high speed accelerations (Acc) and decelerations (Dec) data was collected for analysis. It was found that 3-5-2 formation elicited higher TD (10528 ± 565 m, p = 0.05), HSR (642 ± 215 m, p = 0.001), and HMLD (2025 ± 304 m, p = 0.001) than all other formations and above average Acc and Dec (34 ± 7, p = 0.036 and 57 ± 10, p = 0.006), with 4-2-3-1 eliciting the highest Acc and Dec (38 ± 8 and 61 ± 12). Positional data showed that CM in 4-3-3 covered >11% TD than in 4-4-2 (p = 0.012). FW in 3-5-2 covered >45% HSR than in 4-2-3-1 (p = 0.004). CM in 4-3-3 covered >14% HMLD than in 4-4-2 (p = 0.367). FW in 4-3-3 performed >49% accelerations than in 4-2-3-1 (p = 0.293). WD in 3-5-2 performed >20% more decelerations than in 4-4-2 (p = 0.161). This study is important for coaches understanding, that positional physical characteristics are influenced by the demands of playing in different formations during match play.     

ERICA– an instrument to measure individual and collective regulation of learning

IntroductionThis paper presents two studies that aimed at validating the Individual and Collective Regulation of Learning Scale – ERICA.ObjectiveThe scale was developed to measure learner perceptions of macro-level co-regulation strategies in conjunction with self-regulation strategies learners use.MethodStudies in two separate educational settings are presented. The first with undergraduate psychology students (n = 547) tested the factorial structure and reliability that confirmed its psychometric qualities. The second with undergraduate healthcare students (n = 191) provided for tests of convergent and discriminant validity.ResultsThe studies confirm a six-dimensional structure that stands up to tests of validity for structure, consistency and convergence.ConclusionThe scale is suitable for use in various educational contexts and environments with large cohorts to study perceptions learners have of the strategies learners use related to planning, monitoring, assessment and decision-making regulation phases.     

Effects of experience on the coordination of internally and externally timed soccer kicks

The authors investigated differences in the soccer kick between 8 experienced and 10 less experienced participants in 2 different task conditions (kicking a stationary ball or a moving ball at a target). The experienced participants were more accurate than their less experienced counterparts, whereas there were no differences in maximum foot velocity between groups or between conditions. When compared with their performance in the stationary condition, participants kicked the moving ball with a smaller range of movement at the knee of the kicking leg, maintaining a proximodistal coordination pattern. Because of their significantly shorter knee-flexion phase, the participants in the experienced group displayed a significantly shorter time between initiation of the forward swing of the kick and ball contact than that of those in the less experienced group. The rapid knee flexion may have been a strategy of exploiting passive dynamics to increase accuracy rather than velocity. Members of both groups showed a proximodistal initiation sequence in the kicking leg, which suggests that players can acquire that coordination pattern with relatively little structured practice and that further practice leads to improvement possibly through the increased exploitation of passive dynamics.     

Ecological validity of the German Bruininks-Oseretsky Test of Motor Proficiency – 2nd Edition

The diagnosis of Developmental Coordination Disorder (DCD) is based on poor motor coordination in the absence of other neurological disorders. In order to identify the presence of movement difficulties, a standardised motor assessment is recommended to determine the extent of movement problems which may contribute to deficits in daily task performance. A German version of the Bruininks-Oseretsky Test of Motor Proficiency, Second Edition (German BOT-2) was recently published. This study aimed to determine the ecological validity of the German BOT-2 by considering the relationship between assessment of fundamental motor skills with the BOT-2 and performance of everyday motor activities as evaluated by parents. This study used data obtained from the German BOT-2 standardisation study (n = 1.177). Subtests were compared with theoretically corresponding tasks via parental ratings of overall fine and gross motor abilities and performance in six typical motor activities. Non-parametric Jonckheere Terpstra test was used to identify differences in ordered contrasts. Subtests reflecting ‘Strength’, ‘Running Speed and Agility’, ‘Upper-Limb Coordination’, ‘Balance’, and ‘Fine Motor Precision’ were associated with parental evaluation of gross motor skills (p < 0.001). The subtest ‘Fine Motor Integration’ significantly correlated with parental ratings of females’ fine motor skills. Parental ratings of males’ fine motor skills were associated with three further subtests. Regarding everyday motor activities, the first three fine motor BOT-2 subtests were associated with parent evaluations of drawing, writing and arts and crafts (p < 0.001). Gross motor subtests of ‘Bilateral Coordination’ and ‘Balance’ showed no relationship to bike riding or performance in sports. Subtests of ‘Upper-Limb Coordination’ and ‘Strength’ showed significant correlations with sports, ball games and cycling. The results of this study suggest that the closer the proximity in the nature of the motor skills assessed in the German BOT-2 to daily motor tasks, the stronger the relationship between the clinical test and parental report of everyday performance of their child. The body functions tested in the German BOT-2, and hypothesized to underpin certain skills, were not automatically relevant for specific activities undertaken by German children. Future research should investigate the relationships of the various BOT-2 constructs for diagnosis of DCD.