Motor Control最新文献

Bilateral gait symmetry is an essential requirement for normal walking since asymmetric gait patterns increase the risk of falls and injuries. While human gait control heavily relies on the contribution of sensory inputs, the role of sensory systems in producing symmetric gait has remained unclear. This study evaluated the influence of vision as a dominant sensory system on symmetric gait production. Ten healthy adults performed treadmill walking with and without vision. Twenty-two gait parameters including ground reaction forces, joint range of motion, and other spatial-temporal gait variables were evaluated to quantify gait symmetry and compared between both visual conditions. Visual block caused increased asymmetry in most parameters of ground reaction force, however mainly in the vertical direction. When vision was blocked, symmetry of the ankle and knee joint range of motion decreased, but this change did not occur in the hip joint. Stance and swing time symmetry decreased during no-vision walking while no significant difference was found for step length symmetry between the two conditions. This study provides a comprehensive analysis to reveal how the visual system influences bilateral gait symmetry and highlights the important role of vision in gait control. This approach could be applied to investigate how vision alters gait symmetry in patients with disorders to help better understand the role of vision in pathological gaits.

This study aimed to determine the acute effects of high-intensity forward-backward and low-intensity side-to-side plyometric jumps performed following the warm-up on sprint (5, 10, and 15 m) and change-of-direction (COD) (T-half test and repeated T-half tests) performance in youth volleyball players. After a familiarization week, 30 male volleyball players (age = 12.04 ± 1.03 years) performed three randomized conditions (no-plyometrics, high-intensity plyometrics, and low-intensity plyometrics) in three sessions. In a within-subject design, three sets of six repetitions of forward-backward 30-cm hurdle jumps (high-intensity) and side-to-side 20-cm hurdle jumps (low-intensity) were completed. Sprint and COD were tested after each of the conditions with a 2-min rest. A significant effect of the plyometric condition was observed on sprint (p < .001, ηp2 range: .56-.70) and COD (p < .01, ηp2=.24), but not on repeated COD. More specifically, the high-intensity plyometric condition exhibited significantly better results compared with the low-intensity plyometric (Cohen's d range: 0.73-1.21) and control conditions (Cohen's d range: 0.91-2.21). Due to the importance of speed and COD in volleyball, these results suggest that young volleyball players may benefit from high-intensity forward-backward plyometric protocols following the warm-up to improve subsequent performance.

The present study aimed to analyze the effects of conducting a warm-up (WC) or not (WWC) on students of the Science Degree in Physical Activity and Sport before starting a practical class. Thirty-two students of the Science Degree in Physical Activity and Sport (age: 22.38 ± 1.81 years; height: 176.09 ± 8.52 cm; weight: 22.38 ± 1.81 kg; body fat: 25.17 ± 3.20%) participated in a counterbalanced cross-sectional study in which three conditions were tested: (a) basal lineal, (b) WC, and (c) WWC. Participants recorded longer times (worse performance) in the Illinois dribbling test (basal lineal condition [20.17 ± 1.35], WWC [20.13 ± 1.37], and WC [19.32 ± 1.35]) and the Psychomotor Vigilance Task test (basal lineal condition [397.88 ± 75.98 ms]; WWC [412.19 ± 91.39 ms], and WC [368.53 ± 68.65 ms]). The warm-up prior to physical activity classes had positive effects on vigilance linked to executive functioning, and physical performance. In this sense, more research on different types of warm-up may be in order to contrast them with each other, as well as to carry out attention measurements according to the content to be imparted after the warm-ups. The present study represents a big opportunity for all physical education teachers due to warm-up is a crucial aspect that occurs in all practical sessions, also linked to the attention processes and motivational factors of the students.

It is well known that scoliosis adversely affects the functions of the upper extremities. However, the acute effect of rigid braces, which are widely used in the conservative treatment of scoliosis, on upper-extremity functionality remains unknown. The aim of this study was to investigate the acute effect of a rigid thoracolumbosacral brace use on upper-extremity functionality in individuals with adolescent idiopathic scoliosis (AIS). Thirty-eight individuals diagnosed with AIS participated in this cross-sectional study, with a mean age of 14.55 ± 1.90 years and a range of 10-18 years. The upper-extremity functionality was assessed using the Nine-Hole Peg Test and handgrip strength, with assessments conducted under both in-brace (with their own braces) and out-of-brace conditions. Nine-Hole Peg Test durations of the AIS patients for the nondominant side were significantly lower for in-brace conditions compared with out-of-brace conditions (p = .049, effect size = 0.136). The grip strength of the nondominant side was significantly higher for in-brace conditions compared with out-of-brace conditions (p = .025, effect size = 0.365). A weak negative correlation was found between the degree of curvature and the grip strength of the dominant side for in-brace conditions (r = -.323, p = .048). It was concluded that the brace had a positive effect on upper-extremity functionality on the nondominant side by both shortening the Nine-Hole Peg Test duration and increasing grip strength. In AIS patients, the brace may positively affect daily living by improving the functionality of the nondominant extremity.

Background: Understanding postural control in low back pain (LBP) subgroups can help develop targeted interventions to improve postural control. The studies on this topic are limited. Therefore, the primary purpose of this study was to compare the postural control of LBP subgroups with healthy individuals during overhead load lifting and lowering.

Methods: In this cross-sectional study, the participants were 52 with LBP and 20 healthy. The LBP patients were classified based on the O'Sullivan classification system into 21 flexion patterns and 31 active extension patterns. The participants lifted the box from their waists to their overheads and lowered it to their waists. Changes in postural control parameters were measured with a force plate system.

Results: The results of the analysis of variance showed that during load lifting, the mediolateral phase plane (p = .044) and the mean total velocity (p = .029) had significant differences between flexion patterns and healthy. Also, the load-lowering results showed that active extension patterns, compared with healthy, had significant differences in the anteroposterior-mediolateral phase plane (p = .042). The patients showed less postural sway than the healthy.

Conclusions: The results in this work highlight the importance of identifying the homogenous subgroups in LBP and support the classification of heterogeneous LBP. Different subgroups exhibit different postural control behaviors. These behaviors can be due to the loading of various tissues during different tasks.

Athletes must transfer their performance when changing equipment due to innovative developments in sports technology. This kind of transfer has received only moderate attention. The aim of this study was to examine whether a mechanical change in sports equipment disturbs an athlete's performance and affects biomechanical and neurophysiological parameters. Therefore, an experiment was conducted in which 36 participants in three groups pedaled at 70 rounds per minute on a cycling ergometer with a circular and a noncircular (NC) chainring. The dependent variables were the total variability of the cadence, torque effectiveness, and muscle cocontraction (electromyographic cocontraction) of four antagonistic acting muscle pairs. Data were recorded during an acquisition phase, a transfer phase, and a retention phase. The results revealed that practice on a circular chainring induces a positive transfer on the NC chainring for total variability without a proactive interference effect. Torque effectiveness did not change within or between groups during the acquisition, transfer, and retention phases. Torque effectiveness and electromyographic cocontraction were not affected when the chainrings were altered from Day 1 to Day 2. During the retention phase, electromyographic cocontraction was higher when using the NC chainring, but the difference was small in absolute terms. The results regarding transfer and proactive interference seem to be strongly dependent on the movement task and the change in sports equipment. Transfer from the circular to NC chainring indicates refined neuromuscular control and improved movement coordination.

Purpose: The purpose of this study was to examine the balance recovery strategy in children with hearing (HI) and visual impairments (VI) compared with those without these disorders.

Materials and methods: This study featured a cross-sectional design with subjects (N = 45) placed within one of three equally stratified purposive groups (HI, VI, and comparison) within the age range of 9-13 years (mean = 11.43, SD = 1.5). Balance recovery strategy was measured in static and after-perturbation conditions by a four-camera Vicon system used to record three-dimensional lower body kinematic data. A repeated-measures analysis of variance (3 × 2, Group × Condition) was utilized to analyze data. Significance was set at p ≤ .05.

Results: In the static condition, the results of the study showed that there was no significant difference between the groups in the ankle joint sway (p > .05). In hip joint sway, VI children had greater sway compared with comparison (p = .001) and HI children (p = .02). Also, HI children had greater sways than comparison (p = .02). In the after-perturbation condition, the results showed that VI children had greater sway in the hip and ankle joints than HI children (p = .001) and comparison (p = .001) to restore and maintain balance.

Conclusion: It seems that comparison as well as higher proportion VI children use a hip strategy to maintain and restore balance. Also, it seems that HI children use a different strategy (ankle strategy) to maintain and restore balance compared with comparison and VI children.

The present study examined how humans use the target information provided immediately before the onset of motor output to prepare the initial motor command in the target force production task. Twenty healthy individuals participated in this study. A target cursor indicating the target force, and a force cursor indicating the force produced with index finger flexion were presented, and participants produced force in response to the appearance of the force cursor so that it moved toward the target cursor as fast as possible. The rate of force development in a time window of 0-100 ms after the onset of force development, representing the intensity of the initial motor command without online feedback adjustment, was measured. The present findings support the hypotheses that humans use the target information provided immediately before the onset of motor output to prepare the initial motor command, and they simultaneously prepare the initial motor command for the intermediate of multiple potential targets using the information of targets provided in previous trials. Another hypothesis, that humans use the information of the target or motor process of the trial immediately before the current trial to prepare the initial motor command, was not supported.

This study aimed to investigate the kinematic changes in obstacle avoidance and prehension tasks performed simultaneously by older adults with a history of falls at different levels of task difficulty. Twenty-six older adults were divided into faller and nonfaller groups. The experimental protocol was divided into two different tasks: walking with obstacle avoidance and walking with obstacle avoidance combined with a reach-to-grasp task. Two types of sensors (Kinect v2 and Leap Motion Controller, respectively) were used to analyze gait and grasp. Fallers presented kinematic changes associated with the grasping task during obstacle avoidance, such as a decrease in the velocity of the center of mass and the step length, an increase in the step width, a decrease in toe-obstacle horizontal distance, and an increase in vertical foot clearance distance, and an increase in movement time in the grasping task compared with nonfallers. To cope with the obstacle avoidance demands of both walking and grasping, fallers turned to a specific sequencing strategy. While slowing down, they attended first to the grasping task and then to crossing the obstacle on the floor.

Several devices (e.g., linear transducers) have been used for predicting resistance training intensity. However, subjective scales, such as rating of perceived exertion (RPE), are proposed as reliable and easier-to-use tools for monitoring intensity during resistance training. Accordingly, different perceptive scales have been presented in previous research for monitoring intensity during resistance training with elastic bands. The aim was to assess the accuracy and reliability of RPE for quantifying the potential maximal repetitions that could be performed at a given RPE (from 2 to 8 of 10) obtained in the first repetition. For this purpose, 13 recreationally active participants (age: 26.33 [6.52] years, body mass index: 24.97 [5.08] kg/m2) were involved in two familiarization and two experimental sessions. In each session, participants randomly performed one set at each intensity of the first repetition from 2/10 to 8/10 until volitional failure in three different exercises (fly, military press, and push-press). An individual grip width of the elastic band was chosen in each set. The number of repetitions and heart rate were assessed. Significance level was set at p < .05. Repetitions decreased when intensity increased (p < .01) and heart rate was higher in the global exercise (i.e., push-press; p < .05), but nonsignificant differences between intensities were reported. The level of experience influenced the number of repetitions performed (p < .05). Intersession reliability was set from good to excellent (range: 0.64-0.91). Therefore, the RPE of the first repetition is a relevant and reliable parameter related to the total number of repetitions performed for each RPE value in trained participants enrolled in elastic bands resistance training.