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Purpose. How demands of precision influence the performance during alternated discrete touching is not well established in the literature. Hence, we compared both hands performance during alternated touching, manipulating the precision demand. Methods. Overall, 23 right-handed adults participated in this study. the first task consisted of alternated touching with a pencil on both sides of a blank paper, performing as fast as possible, considering the first touch as reference for the next ones. Subsequently, touch dispersion and width were measured, and circular targets were drawn with those proportions. the second task consisted of performing as many hits as possible inside those targets. Apart from the delimitated target, increasing precision demand, the task parameters were equal. Results. Movement time increased and the number of touches decreased from the first to the second task. However, the preferred hand displayed greater reductions in performance. Conclusions. the perceptual constraint of adding a visual target affects motor control parameters in alternated touching, causing decrements in performance in both hands, but more evidently in the preferred right hand. [ABSTRACT FROM AUTHOR]

Purpose. Back squat (BS) is a popular exercise owing to its capacity to develop lower limb strength. During BS, trunk inclination and knee range of motion (roM) are relevant aspects of a proper technique, and these movement kinematics parameters can be positively altered with official weightlifting shoes lifting the heel 13 mm above the ground. Wedges are a low-cost alternative to lifting the heel to different heights, but movement kinematics adaptations with higher elevations, above 25 mm, are not well described in the literature. thus, we compared the effect of different heights of heel wedges on BS kinematics. Methods. Fifteen experienced recreational weightlifters (22 ± 5.4 years; 83 ± 11 kg; 179 ± 6 cm; 5 ± 2.1 years of BS experience) were conveniently selected. three randomized conditions were applied: barefoot (B), 25mm (W25), and 50mm wedges (W50). BS movement was assessed by kinematic analysis with an optoelectronic camera system. Results. After ANOVA, the posthoc indicated significant roM differences in reducing trunk (F = 27.27; p < 0.01) and increasing knee (F = 16.87; p < 0.01) flexions between conditions. Posthoc analysis verified decreasing trunk inclination (B > W25 > W50; p < 0.05) and increasing knee (B < W25 < W50; p < 0.05) roM with increasing wedge height. Conclusions. Higher wedges allowed positive adaptations by promoting a more upright trunk position and greater BS depth. Using a heel wedge can be a lowcost and viable strategy to optimize BS technique in a variety of training settings and contexts. [ABSTRACT FROM AUTHOR]

Purpose. Motor learning is the response to a new experience or practice of a skill that results in the production of a new motor skill. the contextual interference (CI) effect is a learning effect which describes the benefits of interference during practice as improved skill retention and skill transfer. though it is an established phenomenon, the efficacy of CI has not yet been proven in complex motor tasks. therefore, the purpose of this study was to analyze the CI effect on motor skill acquisition, retention, and transfer in sport rifle shooting. Methods. 32 subjects were equally divided into two practice groups: high contextual interference (HCI) and low contextual interference (LCI). Four blocks of thirty shots were performed 10 meters from the target. three positions (standing, sitting, and lying down) were used to manipulate the CI effect. the HCI group changed positions before each shot, while the LCI group shot 10 times in the same position before changing to the next one. All conditions were randomized between groups and subjects. One week after the 120 acquisition shots, retention and transfer (15 and 25 meters from the target) tests were carried out. Results. Accuracy between groups during the acquisition phase, retention test results, and transfer test results were similar between groups. therefore, the CI effect was not observed in any of the phases of motor learning in sport rifle shooting. Conclusions. It is possible these results are associated with the amount of practice, level of CI used, and complex characteristic of the task. [ABSTRACT FROM AUTHOR]