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Knowledge of results (KR), particularly its informational role, has often been regarded as redundant for learning interception-like tasks, such as coincidence–anticipation timing tasks. However, it is possible that the KR's guiding effect might be detrimental to motor adaptation, instead of only redundant, leading to a dependency on KR and steering the sensorimotor system away from relevant information of the task. In this study, we aimed to investigate KR's effect on learning a coincidence–anticipation timing tasks and on the adaptation to unpredictable perturbations. Two groups of participants practiced a coincidence–anticipation timing tasks with or without KR on 1 day and underwent testing the next day for learning (Retention test) and for adaptation to unpredictable perturbations (Exposure phase). Both groups exhibited similar learning results but failed to adapt to the perturbations, contradicting the assumption of negative guidance effects of KR and the positive effects of relying solely on intrinsic information (no KR). These findings suggest that motor adaptation may require specific information during the acquisition process, highlighting for more systematic analyses to understand this phenomenon better. Such insights could have practical implications in contexts like sports and rehabilitation, by providing learners with appropriate information for acquiring adaptive internal representations of tasks. [ABSTRACT FROM AUTHOR]

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 (M age = 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: The role of Knowledge of Result (KR) on motor learning has been extensively investigated. However, its effects on motor adaptation to unpredictable perturbations are not known. Motor adaptation requires the sensorimotor system to overcome perturbations by using information from the task/environment. Some studies indicate that KR is redundant in the learning of interception-like tasks, such as coincidence-anticipation timing tasks (CATT), because of the powerful information intrinsic to these tasks. Others have demonstrated that erroneous KR causes errors that persist in retention/transfer tests. Therefore, KR may drive the sensorimotor system away from the intrinsic information of the task, which would be detrimental, not redundant, to motor adaptation as opposed to no KR. Aim: to investigate the effects of KR in the learning of a CATT and the adaptation to unpredictable perturbations. Material and methods: Sixteen undergraduate students divided into two groups practiced a CATT and received no KR (0-KR, n=8) or quantitative KR (Qt-KR, n=8). The CATT was to touch a sequence of five sensors while a series of 96 LEDs flashed towards the participant simulating a moving object. Participants should finish the sequence coinciding with the last LED. In the Acquisition phase (AcqP), there were 39 trials and the timing constraint of the CATT was constant (2250ms). In the Exposure phase (ExpP) eighteen perturbation trials (nine fast -- Pert1; timing constraint = 1750ms, and nine slow -- Pert2; timing constraint = 2750ms) were unpredictably presented after every six control trials (same as in the AcqP), and no KR was provided. The first control trials were a retention test (Ret). Measures: Absolute (AE) and Variable Errors (VE) indicated, respectively, overall performance and overall performance consistency in the AcqP and ExpP. Constant Error (CE) indicated the direction of the errors caused by the perturbations in the ExpP. Reaction Time (RT) and Movement Time (MT) indicated differences in strategies of control. Analysis: We analyzed AE and VE with 2-way ANOVAs (groups x blocks) with repeated measures for blocks in the AcqP and between the last block of AcqP and the Ret. In the ExpP we separated Pert1 and Pert2, and their immediately preceding (Pre) and following (Post) trials because of opposite error bias. We analyzed each variable (AE, CE, VE, RT, and MT) in Pre-, Pert, and Post trials also using 2-way repeated-measures ANOVAs (groups x blocks). Significance was set as p < 0.05. Results: Groups performed similarly throughout the experiment. Performance/Consistency increased during the acquisition (small errors) and persisted in the Ret, but none of the groups adapted to the unpredictable perturbations as indicated by large errors (AE, CE, and VE). Response adjustments, although inefficient, occurred during movement execution as indicated by the MT, but not in the RT. Conclusion: Our results did not show the differences in favor of no KR. However, it indicates that neither the intrinsic information alone nor the supplementary quantitative KR allowed good adaptation in CATT. Further research will help understand the role of information in motor adaptation. [ABSTRACT FROM AUTHOR]

Background: Unprecdicatle perturbations occur often in the performance of interceptive actions and impose specific sensorimotor demands like motor adjustments after the movement onset. These online adjustments of an ongoing action are highly demanding and require a robust and flexible internal model of the tasks. Practice until performance stabilization allows the building of a consistent internal model, and when practice continues to a level beyond stabilization, or superstabilization, the internal representation seems to gain flexibility. If so, performance superstabilization would favor sensorimotor adjustments to unpredictable perturbations. Aim: We sought to investigate the effects of practicing an interception task up to performance stabilization or superstabilization on the sensorimotor adjustments to unpredictable perturbations. Material and methods: Forty participants performed a virtual interception task (VIT) until performance stabilization (SG; n=20) or superstabilization (SSG; n=20). The VIT was to hit a target (4 x 6 cm) that moved along a horizontal rail projected on the screen by moving an interceptor controlled by a digital pen in a predefined course on a drawing tablet. The target moved at a constant speed (145 cm.s-1) in all the trials. After super/stabilizing performance in this constant practice context, both groups performed the VIT in an unpredictable context (Exposition phase), identical for both groups. The Exposition Phase consisted of 111 control trials with the same 145 cm.s-1 target speed interspersed by 18 unpredictable perturbation trials in which target velocity randomly changed after the movement onset to either a higher (PertI = 200 cm.s-) or a lower (PertII = 90 cm.s-) speed. Visual knowledge of results was provided after every trial. Measures: Constant Error (CE) indicated the magnitude and direction of the errors; the relative time to peak velocity (tPV %) and the number of corrective sub-movements (N-cor), indicated the strategies and the mechanisms of control, respectively. Analysis: We separated PertI and PertII and their immediately preceding (Pre) and following (Post) trials because of opposite error bias. We compared the CE and %tPV in Pre-, Pert, and Post trials along and across the groups in three distinct moments of the Exposure Phase (early, intermediate, and late Exposure Phase) using 2-way ANOVAs (2 groups x 3 blocks) with repeated measures for blocks. For the N-cor we considered the average number of corrections in each Pert trial and applied Student's t-tests for independent samples to compare the groups in the early, intermediate, and late Exposure Phase. The significance level was p < 0.05. Results: Superstabilization favored performance (smaller CE) under and after unpredictable perturbations (PertII). These advantages are related to sensorimotor adjustments. The smaller %tPV of the SSG is a strategy that allows more time to perform online corrections, which is confirmed by the higher number of corrections (N-cor) performed by this group. Conclusion: These results indicate that learning is a continuous process that extends beyond performance stabilization and allows for the use of more flexible strategies and mechanisms of control, which favor the sensorimotor system to couple with unpredictable perturbations. [ABSTRACT FROM AUTHOR]

Aim: The aim of the present study was to investigate the relationship between strength capacity and motor performance through machine learning model and linear regression in the gymnastic handstand. Material and methods: Thirty-two university students, 16 of whom were female and 16 were male (24.03 ± 4.74 years of age) participated in the study. The perform the handstand was through absolute error of difference in the three angles produced by the model (video) and the three angles produced by the performer. Four strength tests were conducted: explosive force, maximum force right-hand, maximum force left-hand and resistance force. The machine learning model was then trained using 10 of the folds and cross-validated and a linear regression test was performed using motor performance (absolute error) and strength tests (explosive force, maximum force right-hand, maximum force left-hand and resistance force). Results:The results obtained revealed that the machine learning model indicated low relationship between strength capacity and motor performance. Also, the motor performance was not related to the level of strength capacity. Conclusion: The results of this study gave support to the theory of specific capacities which are based on the perspective of multiple capacities. [ABSTRACT FROM AUTHOR]

The efficiency index (Eff index ) 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 Eff index 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 Eff index 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 Eff index 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. Eff index 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 Eff index 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., Competing Interests: Author Adriano Lima Alves was employed by the company Associação Chapecoense de Futebol and University Federal of Minas Gerais; Author João Gustavo Claudino was employed by the company Load Control and School of Physical Education and Sport University of São Paulo. Authors Eduardo Mendonça Pimenta was employed by the company University Federal of Minas Gerais. Author: Crislaine Couto Rangel was employed by the company Centro Universitário Metodista Izabela Hendrix. Author Francisco Teixeira was employed by the Universidade Federal do Triângulo Mineiro. Daniel Boullosa was employed by the company Instituto Integrado de Saúde, Universidade Federal de Mato Grosso do Sul. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © Biology of Sport 2022.)