Combination of narrow and wide bandwidth knowledge of performance in the acquisition of a complex sports motor skill.

OBJECTIVES: This study tested the effects of combining two bandwidth knowledge of performance (KP) on a complex sports motor skill. METHOD: Twenty-two elementary students were divided into combined wide and narrow bandwidth KP (WNG) and control group (CG). The task was the volleyball serve, whose goal was to hit the bull's eye center of a target lying on the floor on the opposite side of the court. The study was composed of a pre-test, acquisition phase and retention test, and had three measures (pre-test, intermediate test, and retention test) with 15 serves recorded each. The acquisition phase consisted of 252 trials. The WNG had a wide bandwidth KP in the first half of the acquisition phase and a narrow one in the second. The CG received KP in all trials. The effects of bandwidth KP were analyzed separately to infer parameters and skill structure learning. RESULTS: Both groups improved the skill structure from the first to the intermediate test, but only WNG also improved on the retention test. The parameters accuracy improved only on retention compared to the pre-test and intermediate test but had no difference between groups. CONCLUSION: Providing information using the bandwidth KP led to an initial engagement and prioritization of skill structure learning.

The relationship between internal and external loads as a tool to monitor physical fitness status of team sport athletes: a systematic review.

The efficiency index (Effindex) combines internal and external loads, and it has been considered a promising tool to evaluate physical fitness status. However, its real applicability and limitations have not been elucidated yet. To examine and discuss the findings from studies that used Effindex as a tool for the evaluation of physical fitness status in team sports. A systematic search was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The databases conferred were PubMed, Scopus, Web of Science, SPORTDiscus, MEDLINE and CINAHL. The articles selected were published up to March 2021. Fourteen articles were included after meeting the inclusion criteria. A wide variety of combinations of external and internal loading parameters to calculate Effindex were found. The pooled sample included 349 male participants (23 ± 3 years). Fifty-nine percent of the sample were soccer players, 20% rugby players, 10% Australian football players, 7% hurling players, and 4% basketball players. Most Effindex calculations used total distance (TD) divided by heart rate derived parameters. However, recent studies have suggested the use of accelerations as the external load parameter. Effindex is a simple and powerful tool for the evaluation of physical fitness status in team sports athletes. The disparity of external and internal loading parameters used to calculate Effindex may affect its sensitivity to detect changes in fitness status in different team sport settings. More studies with indoor team sports and female athletes are warranted.

Coordenação motora de crianças com transtorno do espectro autista: efeitos de um programa de jiu-jitsu / Motor coordenation of children with autism spectrum disorder: effects of a jiu-jitsu program

Crianças autistas apresentam não somente limitações sociais e na forma de comunicação/ linguagem, mas também comprometimentos na coordenação motora. O objetivo deste estudo foi verificar os efeitos de um programa de jiu-jitsu na coordenação motora de crianças com Transtorno do Espectro Autismo Participaram seis crianças, na faixa etária de 7-12 anos (8,6 ± 3,07), sendo três praticantes de jiu-jitsu e outras três sem qualquer experiência em atividades relacionadas a lutas. O instrumento utilizado para a coleta de dados foi o teste de coordenação motora Korperkoordination test fur Kinder (KTK). O teste envolve componentes da coordenação corporal como: o equilíbrio, o ritmo, a força, a lateralidade, a velocidade e a agilidade. Os resultados apontaram que a prática de jiu-jitsu influenciou positivamente a coordenação motora das crianças. Apesar disso, a coordenação motora de ambos os grupos foi classificada como insuficiente.(AU)

Autistic children not only present social issues and form of communication and language, but also commitments in motor coordination. The aim of this study was to verify the effects of a jiu-jitsu program to coordinate children with Autism Spectrum Disorder. He participated in six children, aged 7 to 12 years (8.6 ± 3.07), three of whom were practicing jiu-jitsu and three others with no experience in activities related to fights. The instrument used for data collection was the motor coordination test Korperkoordination Kinder Test (KTK). The test involves components of body coordination such as: balance, rhythm, strength, laterality, speed and agility. The results showed that the practice of jiu-jitsu positively influenced children's motor coordination. Despite this, motor coordination in both groups was used as insufficient.(AU)

Eccentric Strength Assessment of Hamstring Muscles with New Technologies: a Systematic Review of Current Methods and Clinical Implications.

BACKGROUND: Given the severe economic and performance implications of hamstring injuries, there are different attempts to identify their risk factors for subsequently developing injury prevention strategies to reduce the risk of these injuries. One of the strategies reported in the scientific literature is the application of interventions with eccentric exercises. To verify the effectiveness of these interventions, different eccentric strength measurements have been used with low-cost devices as alternatives to the widespread used isokinetic dynamometers and the technically limited handheld dynamometers. Therefore, the purpose of the present systematic review was to summarize the findings of the scientific literature related to the evaluation of eccentric strength of hamstring muscles with these new technologies. METHODS: Systematic searches through the PubMed, Scopus, and Web of Science databases, from inception up to April 2020, were conducted for peer reviewed articles written in English, reporting eccentric strength of hamstrings assessed by devices, different to isokinetic and handheld dynamometers, in athletes. RESULTS: Seventeen studies were finally included in the review with 4 different devices used and 18 parameters identified. The pooled sample consisted of 2893 participants (97% male and 3% female: 22 ± 4 years). The parameters most used were peak force (highest and average), peak torque (average and highest), and between-limb imbalance (left-to-right limb ratio). There is inconsistency regarding the association between eccentric hamstrings strength and both injury risk and athletic performance. There is no standardized definition or standardization of the calculation of the used parameters. CONCLUSIONS: The current evidence is insufficient to recommend a practical guide for sports professionals to use these new technologies in their daily routine, due to the need for standardized definitions and calculations. Furthermore, more studies with female athletes are warranted. Despite these limitations, the eccentric strength of hamstring muscles assessed by different devices may be recommended for monitoring the neuromuscular status of athletes.

Enhanced Performance Stabilization Increases Performance Variability in a Virtual Interception Task.

Performing a motor task depends on the level of performance stabilization and movement control, and both aspects of motor behavior are related to motor learning (retention and transfer) and adaptation (predictable and unpredictable perturbations). Yet few studies have further investigated the underlying dynamics that may elicit these benefits. In this study, we investigated the effects of two levels of performance stabilization on motor performance and control while learning to intercept a virtual moving target. We randomly divided 40 participants of both sexes (Mage = 26.02 years, SD = 2.02) into a Stabilization Group (SG) and a Superstabilization Group (SSG). We considered the performance stabilized when a moving target was intercepted three times in a row and superstabilized when the same criterion was repeated six times. We analyzed outcome variables related to performance accuracy (absolute spatial error) and variability(coefficient of variation) and motor control (relative time to peak velocity-tPV% and its coefficient of variation) on both the first and last blocks of practice trials. Both groups showed comparable increases in performance accuracy from the first to the last block (p = .001, ηp2 = 1.00), but SSG presented higher variability than SG (p = .05, ηp2 = .70). Concerning motor control, both groups started the experiment with low tPV% and finished with comparably high tPV% and variability. Thus, although practicing two levels of performance stabilization led to similar performance accuracy and movement control, superstabilization resulted in higher performance variability with no loss of accuracy. Enhanced stabilization may increase the ability to adapt to environmental changes, but more research is needed to demonstrate this. These findings add to an understanding of the relationship between levels of performance stabilization and performance variability and may have implications for professional interventions (e.g. sports, rehabilitation) in considering the benefits of practice beyond performance stabilization.

The level of performance stabilization influences motor adaptation on an isometric force control task.

This study compared the effects of two levels of performance stabilization on the adaptation to unpredictable perturbations in an isometric control force task with the goal of controlling 40% of the maximum force. The experiment consisted of pre-exposure and exposure phases. In the pre-exposure two levels of performance stabilization were manipulated: a stabilization group (SG) performed three trials in a row while maintaining 40% of the maximum force for three seconds and an absolute error less than or equal to 5% (i.e., the criteria of performance), and a superstabilization group (SSG) performed six blocks of the same criteria. During the exposure phase, the task was the same as that in the pre-exposure phase; however, it was inserted 9 trials of perturbations when the task goal changed to 60% of the maximum force. We measured the %RMSE, RMS from the biceps and triceps brachii and co-contraction. In the pre-exposure phase, both groups showed similar performance and muscle activity. When exposed to the perturbations, SSG performance more quickly returned to the previous level of accuracy, showed lower muscle activation and demonstrated a greater muscle co-contraction than did SG. The results give support to the adaptive process model on motor learning.