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Older adults with type II diabetes (T2D) are at risk of developing nerve disorders that result in functional impairment. Most work in proprioceptive dysfunction in older adults with T2D has focused on functional deficits of the lower limb. The purpose of this study was to examine proprioceptive effects of T2D on the upper limb in older adults. Kinematic performance of a reach-to-pinch action toward a virtual target was assessed in a T2D group (60+ years old with T2D) and a healthy age- and sex-matched control group. Tactile and vibratory thresholds did not differ between T2D and controls. Task accuracy via mean pinch location was significantly worse for persons with T2D (pwT2D) with differences in wrist extension/flexion (ex/fl), wrist abduction/adduction (ab/ad), 1st carpometacarpal (CMC) ab/ad, 2nd metacarpophalangeal (MCP2) ex/fl, MCP2 ab/ad, and digit 1 and hand transport trajectories. Group differences persisted with consideration of body mass index; sex differences in task accuracy emerged. Findings indicate that proprioception of the upper extremity is altered in pwT2D such that they exhibit a unique aperture position and aiming strategy during a reach-to-pinch action. These findings characterize functional sensorimotor impairment of the upper limb in pwT2D with respect to workspaces without visual or tactile feedback. [ABSTRACT FROM AUTHOR]

We asked whether the quantitative kinematics of standing postural activity might be related to short-term learning of affordances. Standing participants viewed a narrow path for 15 s, and then gave perceptual reports about the distance that they could walk along the path while wearing a weighted vest (novel affordance) or while not wearing the vest (familiar affordance). In a control condition, participants gave perceptual reports about egocentric distance along the path. During the 15 s viewing intervals, we measured the kinematics of head and torso movement as standing participants made a series of 12 perceptual reports. Perceptual reports improved across trials, but only in the condition in which participants were asked to perceive a novel affordance. The dynamical complexity of head movement changed across trials as participants gave perceptual reports about the novel affordance, but did not change systematically when perceiving a familiar affordance, or a non-affordance egocentric distance. We argue that the dynamical complexity of postural activity may have served an exploratory function supporting the learning of a novel affordance. Our results are consistent with the broader hypothesis that affordances are learned through active engagement with the environment, rather than (for example) through abstract cognitive processing. [ABSTRACT FROM AUTHOR]

We tested twenty-one 6- to 10-month-old infants with a wide range of sitting experience in forward and rightward reaching during unsupported sitting on the floor. Sessions were video-recorded for further behavioral and machine learning-based kinematic analyses. All infants, including novice sitters, successfully touched and grasped toys in both directions. Infant falls, hand support, and base of support changes were rare. Infants with more sitting experience showed better upright posture than novice sitters. However, we found no differences in trunk displacement or reaching kinematics between directions or across sitting experience. Thus, multi-directional reaching is functional in both novice and experienced infant sitters. We suggest that trunk and arm stability in sagittal and frontal planes is integral to learning to sit. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine how instructions promoting different attentional foci influence joint coordination patterns and trial-to-trial coordination variability during landing. Sixteen females performed drop landings with their typical technique (baseline) and after receiving instructions promoting an internal focus and an external focus. The coordination patterns, and trial-to-trial coordination variability, of the sagittal plane hip-knee, hip-ankle, and knee-ankle angle pairings were compared across conditions. While there was no difference in the joint coordination patterns among the conditions, subjects exhibited greater hip-ankle and knee-ankle trial-to-trial coordination variability for the external focus condition, vs. the baseline and internal focus conditions, which may help to explain the improved motor learning outcomes for athletes who train with an external focus. [ABSTRACT FROM AUTHOR]

This study investigated biomechanical characteristics of Speed Rope Skipping (RS) and estimated the contribution of the lower and upper limbs to overall performance. Lower (jumping), upper (turning), and whole-body (skipping) performance were examined in 23 rope skippers. All tests were recorded by 2 D video and nine skipping tests were performed in a 3 D motion capture system. Similar movement patterns were observed for the lower limbs in all participants, while handle trajectories differed in shape and symmetry according to performance. In general, turning unlike jumping performance was close to and significantly correlated with skipping performance. Therefore, it appears that lower extremity movement may be adapted to the limiting capacity of the upper extremity to maintain movement stability. [ABSTRACT FROM AUTHOR]

Stepping in place without vision is a spatial orientation task that is associated with unperceived foot displacements. This study was aimed at determining whether foot displacement variability is modified by a concurrent cognitive task. Fourteen young adults stepped for 50 steps with their vision blocked and performed a continuous mental counting task. 3-D Kinematic data from both feet (heel and big toe) was recorded. The variability of foot displacements was either unchanged or slightly lower in dual task, while the foot displacements were significantly shorter (p < 0.05) in dual task than without the cognitive task. The results suggest that the concurrent cognitive task might have allowed a better control of the repetitive lower limb movements. [ABSTRACT FROM AUTHOR]

Constraining knee flexion of non-disabled individuals could further our understanding regarding the importance of knee joint during gait, which is a common disturbance in individuals with gait impairment. In this study we investigated whether a mechanical constraint of knee flexion in non-disabled adults would lead to compensatory strategies. Eleven non-disabled male adults walked without and with an orthosis that permitted full extension and limited knee flexion up to either 45° or 30°. We analyzed the temporal organization of lower limb kinematics and electromyograms of the rectus femoris, vastus medialis and lateralis, tibialis anterior, semitendinosus, biceps femoris, and gastrocnemius medialis and lateralis. Non-disabled adults compensated for the reduced knee flexion by increasing hip and ankle joint excursions and ankle flexor activation amplitude. Also, these adults shortened pre-swing and lengthened swing duration in the constrained limb and increased the activity of bifunctional hip extensor and knee flexor muscles in the constrained limb in relation to the unconstrained limb. The use of an orthosis that limited knee flexion in non-disabled adults leaded to compensatory strategies in the temporal organization of joint excursions and muscle activations in the constrained limb. The compensatory effects were correlated with the extent of knee flexion constraint. [ABSTRACT FROM AUTHOR]

This study investigated the scaling of upper arm kinematics, joint motion, and muscle activation for three-dimensional (3D) reaches to targets of increasing distance. Fifteen participants completed 108 total reaches to targets placed 7, 14, and 21 cm across midline. Peak velocity, acceleration, and time to peak velocity scaled to both target and movement distance. Shoulder and elbow excursion scaled to target distance and were highly coordinated. Anterior deltoid activation scaled to both target and movement distance in the early and late phases of reach control. Biceps and triceps activation scaled to movement distance primarily in the late phase. Scaling of these outcome variables provides a model for understanding the control of reach distance in a 3D environment. [ABSTRACT FROM AUTHOR]

Music and metronomes differentially impact movement performance. The current experiment presented metronome and drum beats in simple and complex rhythms before goal-directed reaching movements, while also quantifying enjoyment. Auditory conditions were completed with and without visual feedback and were blocked and counterbalanced. There were no differences between simple and complex rhythms, indicating that rhythmic information alone is sufficient to benefit performance. The drum elicited shorter movement times and higher peak velocities, without an increase in spatial variability. Reaction times were moderately correlated with ratings of enjoyment. These data provide evidence that the source of an auditory stimulus impacts movement performance of a goal-directed reaching task. Results are contextualized within models of goal-directed reaching to elucidate mechanisms contributing to performance improvements. [ABSTRACT FROM AUTHOR]

In speed-based sports that require fast reactions, the most accurate predictions are made once the players have seen the ball trajectory. However, waiting for the ball trajectory does not leave enough time for appropriate reactions. Expert athletes use kinematic information which they extract from the opponent's movements to anticipate the ball trajectory. Temporal occlusion, where only a part of the full movement sequence is presented, has often been used to research anticipation in sports. Unlike many previous studies, we chose occlusion points in video-stimuli of penalty shooting in handball based on the domain-specific analysis of movement sequences. Instead of relying on randomly chosen occlusion points, each time point in our study revealed a specific chunk of information about the direction of the ball. The multivariate analysis showed that handball goalkeepers were not only more accurate and faster than novices overall when predicting where the ball will end up, but that experts and novices also made their decisions based on different kinds of movement sequences. These findings underline the importance of kinematic knowledge for anticipation, but they also demonstrate the significance of carefully chosen occlusion points. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the motor control strategies employed to control the degrees of freedom when performing a lower limb task with constraints applied at the hip, knee, and ankle. Thirty-five individuals performed vertical jumping tasks: hip flexed, no knee bend, and plantar flexed. Joint moment data from the hip, knee, and ankle were analyzed using principal component analysis (PCA). In all PCA performed, a minimum of two and maximum of six principal components (PC) were required to describe the movements. Similar reductions in dimensionality were observed in the hip flexed and no knee bend conditions (3PCs), compared to the plantar flexed condition (5PCs). A proximal to distal reduction in variability was observed for the hip flexed and no knee bend conditions but not for the plantar flexed condition. Collectively, the results suggest a reduction in the dimensionality of the movement occurs despite the constraints imposed within each condition and would suggest that dimensionality reduction and motor control strategies are a function of the task demands. [ABSTRACT FROM AUTHOR]

The aim was to determine whether operating a feedforward schema for generating movement pattern parameters was more successful than an open loop strategy for coping with uncertain initial conditions. A computer simulation model was used to determine the optimal solutions that maximised the likelihood of performing a successful upstart. Feedforward schema were established between movement pattern parameters and initial angular velocity. The success of modifying a pre-planned movement pattern based on the parameter relationships (feedforward) was compared with optimal solutions unable to adapt (open loop) to initial angular velocity. The open loop solution was successful 28% and 20% of the time for a full strength (elite) and weaker gymnast. The feedforward strategy had success rates of 99% and 96% respectively. [ABSTRACT FROM AUTHOR]

We examined potentially deceptive influences of the vertical-horizontal (V-H) illusion on manual length estimations. When viewing V-H illusory configurations, people perceive that the bisecting segment length exceeds the bisected segment length when segments are actually equal. Participants used downward or rightward pointing movements to manually estimate the length of a short bisecting segment of the V-H illusion in upright or rotated configurations. Participants directed their gaze freely, on the configuration, or on the movement space. Manual length estimations for upright and rotated configurations depended on gaze direction, revealing bisection influences only for restricted viewing. People produced illusory influences on perceptuomotor control only when gaze was directed toward V-H configurations or their movement. Exploitation of deceptive visual cues can direct upper limb control for sensorimotor coordination. [ABSTRACT FROM AUTHOR]

In this study, we acquired and processed trunk accelerations during level walking in 85 children aged 8-13 years to calculate spatio-temporal parameters and Harmonic Ratio (HR), which is a metrics representative of gait smoothness and step-to-step symmetry. The results show that while spatio-temporal parameters remain unchanged once normalized considering individuals' anthropometry, significantly higher values of HR for both the antero-posterior and vertical directions were found in participants aged 12-13 with respect to those of 8-9. This indicates an improvement of gait symmetry, which suggests that the gait maturation process is still ongoing for the age ranges tested here. [ABSTRACT FROM AUTHOR]

The objective of this study was to examine the effects of muscle strength training on knee kinematics/kinetics and muscle activation patterns during anticipated side-step cutting. Three-dimensional knee kinematics/kinetics data and muscle activation of selected lower extremity muscles were measured while performing cutting before and after completing 10-week circuit strength training mixed typical resistance training and power training (intervention) or no training (control) from 25 female subjects. The muscle strength of quadriceps and hamstrings were measured before and after training using isokinetic dynamometer. No statistically significant differences were observed in quadriceps and hamstrings muscle strength, all kinematic/kinetic variables, and muscle activation for the control group. Both quadriceps (p = 0.005) and hamstrings (p = 0.030) muscle strength were increased after training. An increased biceps femoris (p = 0.003) and H:Q ratio of activation (p = 0.016), as well as decreased gastrocnemius muscle activation (p = 0.012) during pre-activation phase in intervention group were found. No significant differences were found in knee kinematics and kinetics both at the time frame of the initial contact and the peak tibial anterior shear force after training. In conclusion, muscle strength training altered some muscle activations of lower extremity muscles, which might affect the risk of ACL injury, but it did not change the kinematic/kinetic parameters. [ABSTRACT FROM AUTHOR]

The avoidance of a hole in the pathway while walking has been systematically investigated; however, depending on the dimensions of the hole, the option to avoid it is infeasible, and it is necessary to use the so-called accommodation strategy to step into the hole. We investigated the critical point between the avoidance and accommodation strategies when dealing with a hole in the ground during locomotion of young and older adults. Young and older adults performed two tasks: verbal estimation and walking. We used holes of different lengths and constant depth (12 cm). In the verbal estimation task, participants stood and looked at each hole and verbally respond if they would step into or avoid it. In the walking task, they walked and chose to either step or avoid the hole. Both age groups preferred to step into the hole when it was larger than 1.3 times their foot length in both tasks. The perception of affordances of young and older adults to step into a hole was similar, and it was unaffected by the investigated tasks. Thus, our participants preferred to have a safety margin that was large enough to guarantee that the whole foot would accommodate within the hole. [ABSTRACT FROM AUTHOR]

Recent evidence suggests that visual feedback influences the adjustment of grip force to the changing load force exerted by a grasped object as it is manipulated. The current project investigated how visual feedback of object kinematics affects the coupling of grip force to load force by scaling the apparent displacements of the object viewed in virtual reality. Participants moved the object to manually track a moving virtual target. The predictability of the changing load force exerted by the object was also manipulated by altering the nature of target trajectories (and therefore the nature of object motions). When apparent object displacements increased in magnitude, grip force became more tightly coupled to load force over time. Furthermore, when load force variations were less predictable, the magnitude of apparent object displacements affected the relative degree of continuous versus intermittent coupling of grip force to load force. These findings show that visual feedback of object motion affects the ongoing dynamical coupling between grip force control and load force experienced during manipulation of a grasped object. [ABSTRACT FROM AUTHOR]

In this work, we describe a method for estimating the muscle activity without drawing any assumptions regarding optimality principles in human motor control strategies; further, the method does not require any neural circuitry modeling which limits the neurophysiological terms and estimability of the method. We introduce the concept of system observability, which can reconstruct states from outputs and their derivatives based on system dynamics. Based on neuromuscular system observability, we estimate the muscle activity from joint torques and kinematics of multiple locomotive gaits, while considering the unknown neural inputs as system disturbances. Moreover, to quantify the robustness of the method, the degree of observability and parameter sensitivity are evaluated. Finally, the neurophysiological implications and generality of the method are addressed. [ABSTRACT FROM AUTHOR]

Complex wrist motions are needed to complete various daily activities. Analyzing the multidimensional motion of the wrist is crucial for understanding our functional movement. Several studies have shown that numerous activities of daily livings (ADLs) are performed using an oblique plane of wrist motion from radial-extension to ulnar-flexion, named the Dart Throwing Motion (DTM) plane. To the best of our knowledge, the DTM plane angle performed during ADLs has not been compared between different heights (e.g. table, shoulder and head height), as is common when performing day-to-day tasks. In this study, we compared DTM plane angles when performing different ADLs at three different heights and examined the relationship between DTM plane angles and limb position. We found that height had a significant effect on the DTM plane angles - the mean DTM plane angle was greater at the lower level compared to the mid and higher levels. A significant effect of shoulder orientation on mean DTM plane angles was shown in the sagittal and coronal planes. Our findings support the importance of training daily tasks at different heights during rehabilitation following wrist injuries, in order to explore a large range of DTM angles, to accommodate needs of common ADLs. [ABSTRACT FROM AUTHOR]

Motor control is classically described as relying on two components: anticipatory control (feedforward processing) and online control (feedback processing). Here we aimed to unveil the developmental steps of both feedback and feedforward control in 5-10 years old children, using a simple and ecological task. We manipulated object's weight in a reach-to-displace paradigm. When the weight was known before lifting it, anticipatory processes were quantifiable during the reaching phase. Conversely, an unknown weight triggered online corrections during the displacing phase. Movement kinematics revealed that children anticipate this objet property as young as 5 y-o. This anticipation becomes adequate around 7 y-o and is paralleled by poor online corrections. This simple yet relevant paradigm should allow quantifying deviations from neurotypical patterns in disorders of motor control. [ABSTRACT FROM AUTHOR]

High impact forces during running have been associated with tibial stress injuries. Previous research has demonstrated increasing step rate will decrease impact forces during running. However, no research has determined the cognitive demand of gait retraining. The primary purpose was to determine the cognitive demand and effectiveness of field-based gait retraining. We hypothesized that in-field gait retraining would alter running mechanics without increasing cognitive workload as measured by EEG following learning. Runners with a history of tibial injury completed a gait retraining protocol which included a baseline run, retraining phase, practice phase, and re-assessment following retraining protocol. Results demonstrated an increase in the theta, beta, and gamma power within prefrontal cortex during new learning and corresponding return to baseline following skill acquisition and changes across alpha, beta, gamma, mu, and theta in the motor cortex (p < .05). In the midline superior parietal cortex, spectral power was greater for theta activity during new learning with a corresponding alpha suppression. Overall, the results demonstrated the use of EEG as an effective tool to measure cognitive demand for implicit motor learning and the effectiveness of in-field gait retraining. [ABSTRACT FROM AUTHOR]

Recent studies examining children diagnosed with Autism Spectrum Disorder (ASD) have revealed kinematic markers highlighting deficits in the preparatory and online phases of upper extremity movements. In the following study, 12 children with high functioning ASD were first assessed (pre-test) on 15 trials of a reciprocal upper extremity Fitts Law target task by flexing and extending their right arm in the horizontal plane between two targets as fast and accurately as possible. Following the initial assessment, the children either continued with 30 additional trials of the target task (control) or were asked to track a sine wave template (experimental). All participants were then assessed on 15 trials of the target test (post-test). Results reveal that tracking the sine wave template during training not only produced faster movements compared to the control but also produced these movements in a more harmonic way. [ABSTRACT FROM AUTHOR]

Backward walking (BW) has been extensively used in athletic training and orthopedic rehabilitation as it may have value for enhancing balance. This study identified the differences in foot intersegment kinematics (forward walking (FW) vs. time-reversed BW) and plantar pressure parameters of 16 healthy habitually shod individuals walking FW and BW using flexible shoes (SH) and under barefoot conditions (BF). BW was found to have shorter stride length (SL) and higher stride frequency (SF) under BF conditions compared with SH, which indicates a better BW gait stability under BF conditions. Decreased HX/FF dorsiflexion at HO in BW induces less plantar aponeurosis tension which may inhibit the windlass mechanism compared to FW walking. Increased forefoot relative to hindfoot (FF/HF) pronation and sequentially hindfoot relative to tibia (HF/TB) eversion combined with medially distributed plantar pressure and a higher plantar contact area in the medial side in BW-BF maybe beneficial in maintaining balance. These results indicate that BW training may be more reliable under BF conditions compared to the SH conditions based on greater sensory information feedback from the plantar area resulting in better biomechanical behavior. [ABSTRACT FROM AUTHOR]

The continuous pointing task uses target-directed pointing responses to determine how perceived distance traveled is estimated during forward linear walking movements. To more precisely examine the regulation of this online process, the current study measured upper extremity joint angles and step-cycle kinematics in full vision and no-vision continuous pointing movements. Results show perceptual under-estimation of traveled distance in no-vision trials compared to full vision trials. Additionally, parsing of the shoulder plane of elevation trajectories revealed discontinuities that reflected this perceptual under-estimation and that were most frequently coupled with the early portion of the right foot swing phase of the step-cycle. This suggests that spatial updating may be composed of discrete iterations that are associated with gait parameters. [ABSTRACT FROM AUTHOR]

This study compared Lower Quarter Y-Balance Test (YBT-LQ) performance and leg muscle kinetics between children with and without developmental coordination disorder (DCD), and investigated the association between YBT-LQ performance and muscle kinetics in children with DCD. Forty-eight children with DCD and 51 children without DCD participated in the study. Leg muscle kinetics were measured using surface electromyography when performing YBT-LQ. Children with DCD exhibited an overall lower YBT-LQ scores than controls. They had a lower peak gastrocnemius medialis activation for YBT-LQ posteromedial direction and shorter duration for the muscle to reach peak torque for YBT-LQ anterior direction. No relationship was found between YBT-LQ performance and leg muscle activations in children with DCD. Children with DCD exhibited a less competent YBT-LQ performance with atypical neuromuscular control. [ABSTRACT FROM AUTHOR]

The purpose of this study was to explore the extent of multifractality in unperturbed and constrained locomotion, and to determine if multifractality predicted gait adaptability. Young, healthy participants (n = 15) walked at preferred and slow speeds, as well as asymmetrically (one leg at half speed) on a split-belt treadmill. Stride time multifractality was assessed via local detrended fluctuation analysis, which evaluates the evolution of fluctuations both spatially and temporally. Unperturbed walking exhibited monofractal behavior. Asymmetric walking displayed greater multifractality in the faster moving limb, indicating more intermittent periods of extreme high or low variance. Multifractality was not associated with adaptation to asymmetric walking. These findings further suggest that unperturbed locomotion is monofractal and establish that perturbed walking yields multifractal behavior. [ABSTRACT FROM AUTHOR]

Locomotion requires both proactive and reactive control strategies to maintain balance. The current study aimed to: (i) ascertain upper body postural responses following first exposure to a forward (slip) support-surface perturbation; (ii) investigate effects of repeated perturbation exposure; (iii) establish relationships between arms and other response components (trunk; center of mass control). Young adults (N = 11) completed 14 walking trials on a robotic platform; six elicited a slip response. Kinematic analyses were focused on extrapolated center of mass position (xCoM), bilateral upper- and forearm elevation velocity, trunk angular velocity, and step parameters. Results demonstrated that postural responses evoked in the first slip exposure were the largest in magnitude (e.g., reduced backward stability, altered reactive stepping, etc.) and preceded by anticipatory anterior adjustments of xCoM. In relation to the perturbed leg, the large contra- and ipsilateral arm responses observed (in first exposure) were characteristically asymmetric and scaled to the degree of peak trunk extension. With repeated exposure, xCoM anticipatory adjustments were altered and in turn, reduced posterior xCoM motion occurred following a slip (changes plateaued at second exposure). The few components of the slip response that persisted across multiple exposures did so at a lesser magnitude (e.g., step length and arms). [ABSTRACT FROM AUTHOR]

This cross-sectional study analyzed the influence of chronic shoulder pain (CSP) on movement variability/kinematics during humeral elevation, with the trunk and elbow motions constrained to avoid compensatory strategies. For this purpose, 37 volunteers with CSP as the injured group (IG) and 58 participants with asymptomatic shoulders as the control group (CG) participated in the study. Maximum humeral elevation (Emax), maximum angular velocity (Velmax), variability of the maximum angle (CVEmax), functional variability (Func_var), and approximate entropy (ApEn) were calculated from the kinematic data. Patients' pain was measured on the visual analogue scale (VAS). Compared with the CG, the IG presented lower Emax and Velmax and higher variability (i.e., CVEmax, Func_var, and ApEn). Moderate correlations were achieved for the VAS score and the kinematic variables Emax, Velmax and variability of curve analysis, Func_varm, and ApEn. No significant correlation was found for CVEmax. In conclusion, CSP results in a decrease of angle and velocity and an increased shoulder movement variability when the neuromuscular system cannot use compensatory strategies to avoid painful positions. [ABSTRACT FROM AUTHOR]

Pedestrians can avoid collisions with other pedestrians by modifying some combination of their velocity and their path. The authors investigated how path constraints (constrained or unconstrained), interferer velocity (slow or fast), and vision (looking or not looking; time spent looking at the interferer) influenced collision avoidance to an oblivious interferer walking on a perpendicular path. Ten participants walked 6 m to either a point or line target on either a constrained or unconstrained path while wearing an eye-tracking device and avoiding an oblivious interferer that walked at 2 speeds. Looking behavior and interferer velocity were reliable predictors of determining whether a pedestrian would pass in front of or behind the interferer, while path constraints were less reliable. These findings highlight the degeneracy in human movement systems and suggest that, in complex environments, behavior may not always be optimized for efficiency. [ABSTRACT FROM AUTHOR]

The primary goal of this study was to examine the relations between limb control and handedness in adults. Participants were categorized as left or right handed for analyses using the Edinburgh Handedness Inventory. Three-dimensional recordings were made of each arm on two reach-to-place tasks: adults reached to a ball and placed it into the opening of a toy (fitting task), or reached to a Cheerio inside a cup, which they placed on a designated mark after each trial (cup task). We hypothesized that limb control and handedness were related, and we predicted that we would observe side differences favoring the dominant limb based on the dynamic dominance hypothesis of motor lateralization. Specifically, we predicted that the dominant limb would be straighter and smoother on both tasks compared with the nondominant limb (i.e., right arm in right-handers and left arm in left-handers). Our results only partially supported these predictions for right-handers, but not for left-handers. When differences between hands were observed, the right hand was favored regardless of handedness group. Our findings suggest that left-handers are not reversed right-handers when compared on interlimb kinematics for reach-to-place tasks, and reaffirm that task selection is critical when evaluating manual asymmetries. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine whether women demonstrate decreased rate of torque development (RTD) of the hip and knee extensors and altered onset timing of the vastus lateralis and gluteus maximus during a drop-jump task when compared with men. On average, women demonstrated significantly lower normalized RTD of the hip extensors (women: 11.6 ± 1.3 MVT.s-1, men: 13.1 ± 0.9 MVT.s-1; p ≤ .01); however, there was no significant difference in knee extensor RTD. Women also demonstrated significantly earlier activation of their vastus lateralis (women: 206.0 ± 130.6 ms, men: 80.9 ± 69.6 ms; p ≤ .01) and gluteus maximus (women: 85.7 ± 58.6 ms, men: 54.5 ± 35.4 ms; p = .02). In both men and women, there was a significant negative correlation between the hip extensor RTD and the vastus lateralis electromyographic onset time (men: r = -.386, p = .046; women: r = -.531, p = .008). The study findings suggest that women may utilize a feedforward control strategy in which they activate their knee extensors earlier than men to compensate for deficits in hip extensor RTD. The impaired capacity to rapidly stabilize the hip and knee joints during dynamic maneuvers may contribute to the increased risk of anterior cruciate ligament injury observed in women. [ABSTRACT FROM AUTHOR]

When we reach to grasp something, we need to take into account both the properties of the object we are grasping and the intention we have in mind. Previous research has found these constraints to be visible in the reach-to-grasp kinematics, but there is no consensus on which kinematic parameters are the most sensitive. To examine this, a systematic literature search and meta-analyses were performed. The search identified studies assessing how changes in either an object property or a prior intention affect reach-to-grasp kinematics in healthy participants. Hereafter, meta-analyses were conducted using a restricted maximum likelihood random effect model. The meta-analyses showed that changes in both object properties and prior intentions affected reach-to-grasp kinematics. Based on these results, the authors argue for a tripartition of the reach-to-grasp movement in which the accelerating part of the reach is primarily associated with transporting the hand to the object (i.e., extrinsic object properties), the decelerating part of the reach is used as a preparation for object manipulation (i.e., prepare the grasp or the subsequent action), and the grasp is associated with manipulating the object's intrinsic properties, especially object size. [ABSTRACT FROM PUBLISHER]

Although studied at level surface, the trunk kinematics and pelvis-shoulder coordination of incline walking are unknown. The aim of this study was to evaluate the speed effects on pelvis-shoulder coordination and trunk movement and the cost of transport (C) during unloaded and loaded (25% of body mass) 15% incline walking. We collected 3-dimensional kinematic and oxygen consumption data from 10 physically active young men. The movements were analyzed in the sagittal plane (inclination and range of trunk motion) and the transverse plane (range of shoulder and pelvic girdle motion and phase difference). The rotational amplitude of the shoulder girdle decreased with load at all speeds, and it was lower at the highest speeds. The rotational amplitude of the pelvic girdle did not change with the different speeds. The phase difference was greater at optimal speed (3 km.hr-1, at the lowest C) in the loaded and the unloaded conditions. The trunk inclination was greater with load and increased with speed, whereas the range of trunk motion was lower in the loaded condition and decreased with increasing speed. In conclusion, the load decreased the range of girdles and trunk motion, and the pelvis-shoulder coordination seemed to be critical for the incline walking performance. [ABSTRACT FROM AUTHOR]

Investigations of gait in older adults with diabetes mellitus (DM) have been primarily focused on lower limb biomechanical parameters. Yet, the upper body accounts for two thirds of the body's mass, and head and trunk control are critical for balance. The authors examined head and trunk control during self-selected comfortable, fast, and dual-task walking and the relationship between balance confidence and potential head-trunk stiffening strategies in older adults with DM without diagnosed diabetic peripheral neuropathy (DPN). Twelve older adults with DM without diagnosed DPN (DM group) and 12 without DM (no-DM group) were recruited. Walking speed, peak-to-peak head and trunk roll displacement, head and trunk roll velocity, and head-trunk correlation were measured while walking at a self-selected comfortable or fastest possible speed with or without a secondary cognitive task. The Activities-specific Balance Confidence scale measured balance confidence. Subtle group differences in axial segmental control (lower trunk roll velocity; higher head-trunk correlation) were apparent in older adults with DM even in the absence of DPN. Balance confidence was 19% lower in the DM group than in the no-DM group, and partially explained (34%) the group difference in head-trunk stiffening. These results emphasize the need for proactive monitoring of postural control and balance confidence before the onset of DPN. [ABSTRACT FROM AUTHOR]

Mastery of many tasks in daily life requires role differentiated bimanual hand use with high spatiotemporal cooperation and minimal interference. The authors investigated developmental changes in the performance of a disparate bimanual movement task requiring sequenced movements. Age groups were attributed to changes in CNS structures critical for bimanual control such as the corpus callosum (CC) and the prefrontal cortex; young children (5-6 years old), older children (7-9 years old), and adolescents (10-16 years old). Results show qualitative changes in spatiotemporal sequencing between the young and older children which typically marks a phase of distinct reduction of growth and myelination of the CC. Results show qualitative changes in spatiotemporal sequencing between the young and older children, which coincides with distinct changes in the growth rate and myelination of the CC. The results further support the hypothesis that CC maturation plays an important role in the development of bimanual skills. [ABSTRACT FROM AUTHOR]

It is difficult to walk without vision to a nearby destination if there is a time delay between watching the destination and walking toward it. Indeed, path deviation occurred when delays were introduced before initiating straight ahead blindfolded walking (R. A. Tyrrell, K. K., Rudolph, B. G., Eggers, & H. W. Leibowitz, 1993 ). The questions are whether the location of a 60-s delay in the walking path and whether performing a cognitive task during the delay influence the accuracy in reaching a previously seen target while walking without vision. Thirty young adults walked blindfolded and stopped when they believed they had reached a target at 8 m. Delays were 60 s in duration, were located at 0, 4, and 7 m, and involved waiting or backward counting. Significant differences were found between 0-m and 4-m delay locations for distance to target, distance travelled and path deviation (p < .05). Significant effect of backward counting during the 60-s delay was found at the 0-m delay for distance travelled (p < .05). The interaction between retaining visual guidance information during 60 s and performing a cognitive task likely influenced target-directed blind navigation. [ABSTRACT FROM AUTHOR]

The authors investigated postural and arm control in seated reaches while providing trunk support at midribs and pelvic levels in adults. Kinematics and electromyography of the arm and ipsiliateral and contralateral paraspinal muscles were examined before and during reaching. Kinematics remained constant across conditions, but changes were observed in neuromuscular control. With midribs support, the ipsilateral cervical muscle showed either increased anticipatory activity or earlier compensatory muscle responses, suggesting its major role in head stabilization. The baseline activity of bilateral lumbar muscles was enhanced with midribs support, whereas with pelvic support, the activation frequency of paraspinal muscles increased during reaching. The results suggest that segmental trunk support in healthy adults modulates ipsilateral or contralateral paraspinal activity while overall kinematic outputs remain invariant. [ABSTRACT FROM AUTHOR]

The aim of this research was to quantify the coordination pattern between thorax and pelvis during a golf swing. The coordination patterns were calculated using vector coding technique, which had been applied to quantify the coordination changes in coupling angle (γ) between two different segments. For this, fifteen professional and fifteen amateur golfers who had no significant history of musculoskeletal injuries. There was no significant difference in coordination patterns between the two groups for rotation motion during backswing (p= 0.333). On the other hand, during the downswing phase, there were significant differences between professional and amateur groups in all motions (flexion/extension: professional [γ] = 187.8°, amateur [γ] = 167.4°; side bending: professional [γ] = 288.4°, amateur [γ] = 245.7°; rotation: professional [γ] = 232.0°, amateur [γ] = 229.5°). These results are expected to be a discriminating measure to assess complex coordination of golfers' trunk movements and preliminary study for interesting comparison by golf skilled levels. [ABSTRACT FROM PUBLISHER]

An isokinetic-related parameter termed the difference between eccentric-concentric strength ratios at two distinct test velocities (DEC) based on 60° (standard) range of motion (RoM) has been proven to be highly efficient detecting feigned muscular efforts. This study aimed to verify whether a DEC derived from a much shorter test RoM (20°) was equally useful than a long RoM–derived one. Eighteen healthy men (32.4 ± 6.4 years old) took part in a study focusing on shoulder external rotation isokinetic strength. Participants performed a genuine shoulder external rotator maximal effort (eight pairs of concentric and eccentric contractions at high and low velocities at short and long RoM) and then instructed to feign maximal effort. Contraction velocities were adjusted accordingly by applying a 1:4 gradient and peak moments registered. Both condition DEC was then calculated by subtracting the eccentric and concentric strength ratios at low velocities from those at high velocities. DEC scores in the feigned effort were significantly higher than maximal effort ones in both conditions in men. It enabled the setting of specific cutoff levels for separating the efforts. Both approaches revealed a coincident sensitivity (78%) whereas short RoM showed an even higher specificity: 88% versus 78%. Thus, the short RoM protocol provides clinically acceptable detection power. [ABSTRACT FROM PUBLISHER]

Knee rehabilitation exercises to improve motor control, target movement fluency, and displacement variability. Although knee movement in the frontal plane during exercise is routinely assessed in clinical practice, optimal knee control remains poorly understood. In this study, 29 healthy participants (height: 1.73 ± 0.11 m, mass: 73.5 ± 16.4 kg, age: 28.0 ± 6.9 years) performed 4 repetitions of 5 rehabilitation exercises while motion data were collected using the VICON PlugInGait full-body marker set. Fluency and displacement variability were calculated for multiple landmarks, including center of mass (CoM) and knee joint centers. Fluency was calculated as the inverse of the average number of times a landmark velocity in the frontal plane crossed zero. Variability was defined as the standard deviation of the frontal plane movement trajectories. CoM fluency and displacement variability were significantly different between tasks (p < .001). CoM displacement variability was consistently smallest compared to the constituent landmarks (p < .005). This was interpreted as a whole body strategy of compensatory variability constraining CoM frontal plane movement. Ipsilateral knee fluency (p < .01) and displacement variability (p < .001) differed substantially between tasks. The role of the weight-bearing knee seemed dependent on task constraints of the overall movement and balance, as well as constraints specific for knee joint stability. [ABSTRACT FROM AUTHOR]

Switching between contexts affects the mechanisms underlying motion planning, in particular it may entail reranking the variables to be controlled in defining the motor solutions. Three astronauts performed multiple sessions of whole-body pointing, in normogravity before launch, in prolonged weightlessness onboard the International Space Station, and after return. The effect of gravity context on kinematic and dynamic components was evaluated. Hand trajectory was gravity independent; center-of-mass excursion was highly variable within and between subjects. The body-environment effort exchange, expressed as inertial ankle momentum, was systematically lower in weightlessness than in normogravity. After return on Earth, the system underwent a rapid 1-week readaptation. The study indicates that minimizing the control effort is given greater weight when optimizing the motor plan in weightlessness compared to normogravity: the hierarchies of the controlled variables are gravity dependent. [ABSTRACT FROM AUTHOR]

The authors explored how trunk compensation and hand symmetry in stroke survivors and healthy controls were affected by the distance and height of virtual targets during a bimanual reaching task. Participants were asked to reach to 4 different virtual targets set at: 90% of their arm length at shoulder, xiphoid process, and knee height, and 50% of their arm length at xiphoid process height. For the stroke group, for all targets, the hands' movements were more asymmetrical than those of the healthy group, with more asymmetry observed in the direction of gravity, and trunk forward displacement values were larger and more variable. The knee targets had the largest trunk displacement values; index of curvature and trunk displacement were strongly correlated with participants' impairment scores. A strong correlation was found between the hands' asymmetry in the anterior or posterior direction for the shoulder targets, and the impairment scores. The results suggest that target height influences the degree of trunk compensation and hand symmetry during bimanual reaching by hemiparetic participants. [ABSTRACT FROM AUTHOR]

Measures of walking such as the timed 25-ft walk test (T25FWT) may not be able to detect subtle impairment in lower limb function among people with multiple sclerosis (MS). We examined bipedal hopping to determine to what extent people with mild (Expanded Disease Severity Scale ≤ 3.5) MS (n = 13) would differ compared to age-, gender-, and education-matched controls (n = 9) and elderly participants (n = 13; ≥ 70 years old). We estimated lower limb power (e.g., hop length, velocity), consistency (e.g., variability of hop length, time), and symmetry (ratio of left to right foot). Participants completed the T25FWT and, after a rest, they then hopped using both feet 4 times along the walkway. We found that although all groups scored below the 6 -s cutoff for T25FWT, the elderly group had significantly shorter hop lengths, more variability, and more asymmetry than the controls. The results of the MS group were not significantly different from the elderly or controls in most measures and most of their values fell between the control and elderly groups. Hop length, but not measures of walking predicted Expanded Disease Severity Scale score (R2 = .38, p = .02). Bipedal hopping is a potentially useful measure of lower limb neuromuscular performance. [ABSTRACT FROM AUTHOR]

The authors' purpose was to investigate if there is a speed accuracy trade-off in soccer kicking by using instructions prioritizing velocity, accuracy, or both upon soccer kicking performance and kicking direction in experienced soccer players. In addition, kinematics were measured to investigate the eventual differences in performance. Thirteen experienced male footballers performed penalty kicks with different instructions prioritizing velocity, accuracy or both. Three-dimensional kinematics, together with maximal ball velocity and hitting accuracy, were measured on all kicks. The main findings were that when the main aim was accuracy, accuracy increased, while the velocity reduced, which supports Fitts' law (Fitts, 1954 ). In addition, kicking accuracy was higher when kicking to the contralateral side. The slower ball velocity was caused by lower segmental and in run velocities. These lower segmental velocities were mainly caused by the lower maximal knee extension and pelvis rotation during the accuracy priority kicks. [ABSTRACT FROM AUTHOR]

This study aimed to explore the effect of local muscle fatigue on the unipedal stance in men with intellectual disability (ID). The Centre of pressure (CoP) excursions and the isometric maximal voluntary contraction (MVC) were measured before and after a fatiguing exercise. Higher baseline values of CoP excursions and lower MVC values were recorded in the ID group. After the fatiguing exercise, this group showed higher MVC decrease and higher percentage of increase of the mean CoP velocity. In conclusion, men with ID are more vulnerable to the disturbing effects of fatigue during the unipedal stance compared to men without ID. [ABSTRACT FROM PUBLISHER]

The authors aimed to investigate female balance or stability control with comparative analysis of the center of pressure trajectory and plantar pressure distribution with different high-heeled shoes while standing on a dynamic surface with multidirectional perturbations. College females with at least 2 years' history of wearing high-heel shoes voluntarily participated in the test with a Novel Pedar insole (Novel, GmBH, Munich, Germany. With heels height increasing, the pressure time integral obviously transfer to the medial forefoot region, with center of pressure trajectory medially deviated significantly, either under anteroposterior or mediolateral perturbations. The passive plantarflexion position of ankle incurred by high heel increased the range of motion in the frontal plane but decreased ankle stability, thus increasing the challenge of body balance maintenance. [ABSTRACT FROM PUBLISHER]

The process by which the brain controls single-joint movements (SJM) is still not well understood. Some studies have defined rules describing the duration and magnitude of the agonist and antagonist muscles. Therefore, the purpose of this study was to analyze scientific publications about the electromyographic characteristics of SJM performed by patients with Parkinson's disease. A bibliographical review of the years 1989–2015 was performed using keywords such as electromyography, upper limb, and Parkinson's disease. After applying the inclusion criteria, 8 articles were included for analysis. The literature indicates that despite the lack of studies, it is possible to assume that considering the SJM, those with Parkinson's disease only control the magnitude of electromyography activation, being consistent only with the pulse-height theory control. [ABSTRACT FROM PUBLISHER]

The purpose of this study was to evaluate the effects of a warm-up and fatigue protocol on the vertical jump and knee joint position sense of sprinters. Thirty-two sprinters were randomly allocated to either a control group (CONT) or a plyometric group (PLYO) that performed a warm-up, followed by a high-intensity plyometric protocol. Absolute (AAE), relative (RAE), and variable (VAE) angular errors and vertical jump were evaluated before and after the warm-up, as well as after the plyometric protocol and again 5 min later. After the warm-up, athletes improved RAE and jump performance. After the plyometric protocol, scores on the RAE, VAE, and the vertical jump performance worsened compared to the control group and to the values obtained after the warm-up. Five minutes later, RAE and vertical jump continued to be impaired. AAE did not show significant differences. The vertical jump is improved after the warm-up, although it is deteriorated after high-intensity plyometry. Regarding knee proprioception, the lack of impairments in the AAE make unclear the effects of the plyometric exercises on knee proprioception. [ABSTRACT FROM PUBLISHER]

Energy optimization in goal-directed aiming has been demonstrated as an undershoot bias in primary movement endpoint locations, especially in conditions where corrections to target overshoots must be made against gravity. Two-component models of upper limb movement have not yet considered how joint angles are organized to deal with the energy constraints associated with moving the upper limb in goal-directed aiming tasks. To address this limitation, participants performed aiming movements to targets in the up and down directions with the index finger and two types of rod extensions attached to the index finger. The rod extensions were expected to invoke different energy optimizing strategies in the up and down directions by allowing the distal joints the opportunity to contribute to end effector displacement. Primary movements undershot the farthest target to a greater extent in the downward direction compared to the upward direction, showing that movement kinematics optimize energy expenditure in consideration of the effects of gravity. As rod length increased, shoulder elevation was optimized in movements to the far-up target and elbow flexion was optimally minimized in movements to the far-down target. The results suggest energy optimization in the control of joint angles independent of the force of gravity. [ABSTRACT FROM PUBLISHER]

Integration of research in the fields of neural control of movement and biomechanics (collectively referred to as movement science) with the field of human occupation directly benefits both areas of study. Specifically, incorporating many of the quantitative scientific methods and analyses employed in movement science can help accelerate the development of rehabilitation-relevant research in occupational therapy (OT) and occupational science (OS). Reciprocally, OT and OS, which focus on the performance of everyday activities (occupations) to promote health and well-being, provide theoretical frameworks to guide research on the performance of actions in the context of social, psychological, and environmental factors. Given both fields’ mutual interest in the study of movement as it relates to health and disease, the authors posit that combining OS and OT theories and principles with the theories and methods in movement science may lead to new, impactful, and clinically relevant knowledge. The first step is to ensure that individuals with OS or OT backgrounds are academically prepared to pursue advanced study in movement science. In this article, the authors propose 2 strategies to address this need. [ABSTRACT FROM PUBLISHER]