Journal of Motor Behavior最新文献

The strategy used by the brain to organize human goal-directed movements is still debated. Here, I argue that without the knowledge of this strategy, teaching movement skills required in complex sports activities and for rehabilitation of motor disorders remains an art and can often result in inefficient techniques and misleading instructions. However, the leading joint hypothesis offers a solution to this problem. It suggests that the control strategy consists in rotation of a single ('leading') joint actively and using the biomechanical effect produced by the leading joint as the primary contributor to motion of the other ('trailing') joints. This "trailing joint control pattern" was found in a large variety of movement types. This pattern is simple even for seemingly complex movements, it can be easily verbalized, and it requires focusing attention during learning only on one or two movement elements at a time. The use of the trailing joint control strategy therefore allows development of better targeted techniques of motor learning and rehabilitation.

Treadmills are important rehabilitation tools used with or without handrails. The handrails could be used to attain balance, prevent falls, and improve the walking biomechanics of stroke survivors, but it is yet unclear how the treadmill handrails impact their stability margins. Here, we investigated how 3 treadmill handrail-use conditions (no-hold, self-selected support, and light touch) impact stroke survivors' margins of stability (MoS). The anteroposterior MoS significantly increased for both legs with self-selected support while the mediolateral MoS of the unaffected leg decreased significantly when the participants walked with self-selected support in comparison to no-hold in both cases. We concluded that the contextual use of the handrail should guide its prescription for fall prevention or balance training in rehabilitation programs.

Consolidation has been associated with performance gains without additional practice (i.e., off-line learning). However, the movement characteristics improving off-line remain poorly understood. To investigate this question, participants were trained to produce a sequence of planar reaching movements toward four different visual targets. The training session with feedback required them to learn the relative time of the movements, the total movement time and aim accurately at each target. The retention test was performed either 10-min or 24-h after. Results revealed that a 24-h consolidation interval did not result in better temporal or spatial accuracy. This finding suggests that off-line learning may be restricted to sequence production tasks in which the different segments must be regrouped ("chunked") together to accelerate their execution.

The role of cognition in balance control suggests that mental fatigue may negatively affect balance. However, cognitive involvement in balance control varies with the type or difficulty of the balance task and age. Steady-state balance tasks, such as quiet standing, are well-learned tasks executed automatically through reflex activities controlled by the brainstem and spinal cord. In contrast, novel, and challenging balance tasks, such as proactively controlling balance while walking over rugged terrain or reacting to unexpected external perturbations, may require cognitive processing. Furthermore, individuals with preexisting balance impairments due to aging or pathology may rely on cognitive processes to control balance in most circumstances. This systematic review and meta-analysis investigated the effect of mental fatigue on different types of balance control tasks in young and older adults. A literature search was conducted in seven electronic databases and 12 studies met eligibility criteria. The results indicated that mental fatigue had a negative impact on both proactive (under increased cognitive load) and reactive balance in young adults. In older adults, mental fatigue affected steady-state and proactive balance. Therefore, mentally fatigued older individuals may be at increased risk of a loss of balance during steady-state balance task compared to their younger counterparts.

This study focused on explicit instruction and evaluated the differences in task performance between participants who were instructed to employ the change and those who were not. Ninety-three healthy young adults were assigned to the accurate information group (AG; n = 31), misinformation group (MG; n = 31), and non-information group (NG; n = 31). All participants manipulated a mouse to track a moving target on a screen with a cursor. The cursor was rotated to 60° in the clockwise direction from the actual mouse position during the 1st to 5th blocks (i.e., motor adaptation task). Subsequently, in the 6th block (i.e., transfer task), we gradually changed the angle of rotation from 60° to 80° to prevent from noticing the change. Participants in the AG were instructed accurate experimental information. Participants in the MG were instructed that the angle of rotation was 60° during the 1st to 6th blocks. Participants in the NG were instructed to manipulate the cursor movement only. The results indicated that an average error distance in the AG was significantly lower than that in the NG in the 6th block. This study suggested that explicit instruction may impair the transfer of motor adaptation in this setting.

We tested if the movement slowness of individuals with Parkinson's disease is related to their decreased ability to generate adequate net torques and linearly coordinate them between joints. This cross-sectional study included ten individuals with Parkinson's disease and ten healthy individuals. They performed planar movements with a reversal over three target distances. We calculated joint kinematics of the elbow and shoulder using spatial orientation. The muscle, interaction, and net torques were integrated into the acceleration/deceleration phases of the fingertip speed. We calculated the linear correlations of those torques between joints. Both groups modulated the elbow and shoulder net torques with target distances. They linearly coupled the production of torques. Both groups did not modulate the interaction torques. The movement slowness in Parkinson's disease was related to the difficulty in generating the appropriate muscle and net torques in the task. The interaction torques do not seem to play any role in movement control.

The task of transporting objects is a fundamental part of daily living activities. Previous kinematic studies focusing on tasks such as pointing, reach-to-grasp, and drinking have not fully captured the motor behaviors involved in object transportation, including placing a cup on a table or storing items in specific places. Hence, this study aimed to analyze the motor behavior associated with transporting a mug using upper limb kinematic variables. Fifteen healthy adults were instructed to transport an open-handle mug across a table. The kinematic metrics evaluated included object end-error for accuracy, frontal and lateral end-range for precision, movement time, peak velocity, time to peak velocity for control strategy, object path ratio for efficiency, and interjoint coordination. The stability of motor behavior was assessed through a test-retest analysis. The mug transporting task achieved accuracy with a radius <10 mm around the target, a peak velocity of ∼0.4 m/s, a control strategy where acceleration time constituted about 30% of the movement time, and a slightly curved trajectory. The test-retest analysis confirmed stable motor behavior across all kinematic metrics (ICCs > 0.75). Thus, the mug transporting task exhibited unique and stable kinematic characteristics, distinguishing it from non-transport activities and effectively mirroring transporting activities of daily living.

Police officers during dynamic and stressful encounters are required to make rapid decisions that rely on effective decision-making, experience, and intuition. Tactical decision-making is influenced by the officer's capability to recognize critical visual information and estimation of threat. The purpose of the current study is to investigate how visual search patterns using cluster analysis and factors that differentiate expertise (e.g., years of service, tactical training, related experiences) influence tactical decision-making in active-duty police officers (44 active-duty police officers) during high stress, high threat, realistic use of force scenario following a car accident and to examine the relationships between visual search patterns and physiological response (heart rate). A cluster analysis of visual search variables (fixation duration, fixation location difference score, and number of fixations) produced an Efficient Scan and an Inefficient Scan group. Specifically, the Efficient Scan group demonstrated longer total fixation duration and differences in area of interests (AOI) fixation duration compared to the Inefficient Scan group. Despite both groups exhibiting a rise in physiological stress response (HR) throughout the high-stress scenario, the Efficient Scan group had a history of tactical training, improved return fire performance, had higher sleep time total, and demonstrated increased processing efficiency and effective attentional control, due to having a background of increased tactical training.

This study aimed to investigate the electroencephalographic profile of elite and non-elite basketball players seconds before and during the basketball free throw. Sixteen male subjects in the elite group (national team/premier league players with an average age of 22.06 ± 1.56) and 16 male non-elite subjects (university players with an average age of 22.37 ± 1.45) voluntarily participated in this research. Electroencephalographic data were measured from 28 cortical areas using a mobile wireless device. ANOVA with repeated measures were also performed to investigate the characteristics of theta, alpha, and beta frequency bands. The findings showed the higher cortical activity of the elite group. Different frequency bands exhibited similar asymmetry patterns, suggesting the higher activity of the left hemisphere in most of the homologous sites. Moreover, the activity of frequency bands in the left hemisphere rose by approaching the moment of throw. Furthermore, the activity of a limited number of right hemisphere sites increased by getting closer to the moment of action. In general, hemispheric asymmetry in favor of the left hemisphere has a cortical pattern, reflecting high-performance activities. In addition, the characteristics of different frequency bands of hemispheres are directed toward increasing cognitive processing, attention focusing, and inhibiting irrelevant information.

Balance and functional impairment could occur due to the weakness of the gastrocsoleus muscles in acute stroke patients. This study was planned to determine the muscle architecture and its relationship to balance and functional strength functional ability in patients with acute stroke. A cross-sectional analysis of 22 stroke patients (68.59 ± 8.16) was performed in this study. Gastrocnemius muscle thickness and cross-sectional area were significantly greater on the non-paretic than on the paretic sides (p = 0.004, p = 0.005, respectively). Partial correlation analysis showed that soleus muscle thickness and cross-sectional area was significantly correlated with Berg Balance Scale, Single Leg Stance Test, Five Times Sit to Stand Test and Tandem test results in the paretic side (r = 0.49-0.77, p < 0.05). The gastrocnemius muscle thickness of the non-paretic side had a significant relationship with balance (r = 0.45-0.65, p < 0.05). The muscle thickness and cross-sectional area of the soleus muscle on the paretic sides was significantly related with the functional strength and balance after stroke. It may be beneficial to develop clinical assessment and intervention programs focusing on distal plantar flexor muscle groups in order to improve the functional status and balance.