Vision has previously been correlated with performance in acrobatic sports, highlighting visuomotor expertise adaptations. However, we still poorly understand the visuomotor strategies athletes use while executing twisting somersaults, even though this knowledge might be helpful for skill development. Thus, the present study sought to identify the differences in gaze behavior between elite and sub-elite trampolinists during the execution of four acrobatics of increasing difficulty. Seventeen inertial measurement units and a wearable eye-tracker were used to record the body and gaze kinematics of 17 trampolinists (8 elites, 9 sub-elites). Six typical metrics were analyzed using a mixed analysis of variance (ANOVA) with the Expertise as inter-subject and the Acrobatics as intra-subject factors. To complement this analysis, advanced temporal eye-tracking metrics are reported, such as the dwell time on areas of interest, the scan path on the trampoline bed, the temporal evolution of the gaze orientation endpoint (SPGO), and the time spent executing specific neck and eye strategies. A significant main effect of Expertise was only evidenced in one of the typical metrics, where elite athletes exhibited a higher number of fixations compared to sub-elites (p = 0.033). Significant main effects of Acrobatics were observed on all metrics (p < 0.05), revealing that gaze strategies are task-dependent in trampolining. The recordings of eyes and neck movements performed in this study confirmed the use of "spotting" at the beginning and end of the acrobatics. They also revealed a unique sport-specific visual strategy that we termed as self-motion detection. This strategy consists of not moving the eyes during fast head rotations, a strategy mainly used by trampolinists during the twisting phase. This study proposes a detailed exploration of trampolinists' gaze behavior in highly realistic settings and a temporal description of the visuomotor strategies to enhance understanding of perception-action interactions during the execution of twisting somersaults.

The purpose of this study was to investigate the optimal challenge point for learning motor skills in children with and without attention deficit/hyperactivity disorder (ADHD). Ninety-six 9- to 10-year-old children, including 48 children with ADHD and 48 neurotypical children, were randomly assigned to one of four practice groups with varying levels of nominal and functional task difficulty. They performed 63 trials of a dart throwing task in the acquisition phase and 18 trials in the retention and transfer tests a day later. The results showed that neurotypical children outperformed children with ADHD in all phases of the study. Both groups improved in the acquisition phase and performed better in the retention and transfer tests. Interestingly, low nominal task difficulty was associated with better learning for both groups, despite lower average performance for children with ADHD. Thus, despite their performance differences, we did not find a difference in the effective challenge point between children with ADHD and their neurotypical peers.

The study aimed to assess the validity and accuracy of estimating running jump (RJ) height using the high-speed camera of a smartphone and to evaluate the effectiveness of oral and visual feedback via a smartphone in enhancing RJ movements and height in skilled athletes. Twenty male college basketball players were randomly assigned to either the Oral Feedback (OF) or Oral and Visual Feedback (OVF) group. Initially, participants performed RJs on force plates while being recorded with an iPhone (240 fps). Jump heights were estimated using the video, force plate data, and position data from pelvic markers (JH, JH, and JH, respectively). Subsequently, each group received tailored feedback based on the RJ video. After feedback, participants performed RJs again, and jump heights were re-estimated. The JH measurements were systematically higher but showed acceptable random errors compared to JH, with excellent reproducibility and strong positive correlations with JH and JH. Only the OVF group showed significant improvements in jump height post-feedback. Our results indicate that JH is a valuable and accurate tool for sports settings. Additionally, the results demonstrated that visual feedback using a smartphone is effective and should complement oral feedback to enhance RJ jump height in real sports settings.

Gravity is a ubiquitous external force that must be considered when producing coordinated movements. Drop-landing is a popular task to study how humans cope with gravity, because anticipatory muscle activations can be released before the estimated ground contact. But the consequences of these anticipatory muscle activations have only been interpreted in terms of stiffening the lower-limbs in preparation for ground contact, without considering potential anticipatory kinematic consequences. The objective of this study is to quantify the kinematic consequences of anticipatory muscle activations in two different landing tasks, to clarify whether anticipatory muscle activations are adapted to cope with gravity, to the dynamic constraints of the movement to perform, or both. Twenty young athletes performed drop-landing and drop-jumping from a 35 cm elevated platform. Sagittal angles and angular velocities of the hip, knee, and ankle joints, and acceleration of the foot were computed, as well as the onset of joint flexions and onset of foot vertical acceleration change. We found the same pattern of anticipatory hip and knee flexion, both starting before ground contact in all participants and in both tasks. We found no anticipatory kinematics for the ankle joint. Consecutive to the hip and knee flexion, the foot accelerated upwards before ground contact. Our results show that anticipatory muscle activations used by humans have systematic and invariant kinematic consequences during the air-time phase to cope with gravity: they initiate the hip and knee joints flexion before ground contact. This strategy likely limits the amount of ground reaction forces developed to oppose the gravity external force, and completes the stiffening role already described in the literature. These two complementary consequences -rotation and stiffening- seem to serve the same purpose of protecting the skeletal system. Since gravity is ubiquitous, these automated movements must be considered in other movements involving landing phases, such as heel strikes during gait.

Cycling requires the integration of gaze behaviors, body movements, and bicycle movements. However, whether these movements contribute to skilled cycling performance, such as cycling on straight and narrow paths are uncertain. The present study aimed to differentiate optokinetic nystagmus (OKN) from vestibulo-ocular reflex (VOR) that characterize the relationship between eye and head movements during cycling on straight and narrow path, and to identify gaze behaviors, body movements, and bicycle movements that contribute to cycling performance. Nineteen participants with no prior competitive experience cycled three times on a 12-cm wide path. The participants were asked to avoid deviating from the path as much as possible. The measured variables were gaze behavior in a sagittal plane, body movement, and bicycle movement. As a result, OKN was observed among 16 of the 19 participants. The cross-correlation between the eye and head did not show negative value, indicating the absence of VOR. These results suggest that the participants moved their eyes while keeping their heads stable during cycling on a straight and narrow path. In the results of the multiple regression analysis, the variables with small standard deviations (SD) of the steering angle and upward eye position were related to a lower deviation from the path. These results suggest that a small SD of the steering angle and directed gaze in the forward direction may contribute to skilled cycling.

The Fitts' task is a simple and effective method for evaluating motor capacity that can be used to reveal detailed aspects of visuomotor control when hand and eye kinematics are recorded simultaneously. With advances in technology, the classical Fitts' reciprocal tapping task was modified for use with digitizer tablets and computer screens that require sliding rather than tapping hand movements, which may rely on different visuomotor control strategies. Given the ubiquity of digital devices and touchscreens that often require execution of sliding movements, it is important to compare the underlying visuomotor control and eye-hand coordination involved in reciprocal sliding and tapping movements, which was the aim of the current study. Twelve young adults performed both tasks while their hand and eye movements were recorded. Results revealed motor capacity was significantly higher (p < 0.0001, d = 2.67) in the tapping task (19.62 ± 5.89 bits/s) compared to the sliding task (7.87 ± 2.02 bits/s). Examining hand kinematics showed the deceleration interval was significantly longer in the sliding compared to the tapping task at the lowest task difficulty (ID 2.28: 0.160 s ± 0.026 vs 0.129 s ± 0.017; p < 0.01), which was exacerbated as task difficulty increased (ID 6.97: 0.355 s ± 0.059 vs 0.226 s ± 0.020, p < 0.0001), indicating greater reliance on visual feedback during the sliding task. Examining temporal eye-hand coordination pattern showed that hand movement initiation tended to precede eye movement in both tasks. Overall, the results of this study provide a comprehensive examination of eye and hand kinematics demonstrating salient differences in visuomotor control between tapping and sliding movements. The findings also reveal a novel insight into the temporal pattern of eye-hand coordination for reciprocal tapping and sliding movements, which is in contrast to previous studies that examined discrete (rather than reciprocal) target-directed pointing movements where the eyes typically precede the hand by approximately 100 ms. In conclusion, the current study revealed substantial differences between the two tasks, one major finding being the sliding movements were performed slower compared to parabolic tapping hand movements, which may have implications for designing interactive digital devices and assessment of eye-hand coordination.

Recent studies suggest that muscle synergy patterns can be a guide for diagnosis and rehabilitation.

Recognizing and understanding the actions of others through motion information are vital functions for social adaptation. Conditions like neurological disorders and motor impairments can impact sensitivity to biological motion, highlighting the intricate relationship between perceiving and executing movements. Our study centred on assessing the ability of children, encompassing both those with typical development and those diagnosed with cerebral palsy due to periventricular leukomalacia (PVL), to discriminate between depicted grasping of a small cylinder and a large cube. This discrimination task involved observing a point-light animation depicting an actor grasping the object, presented from either an allocentric perspective (observing others) or an egocentric viewpoint (observing oneself). Notably, children with PVL exhibited a pronounced and specific impairment in this task, irrespective of the viewpoint, as evidenced by thresholds increasing by nearly a factor of two. When comparing this impairment to difficulties in form or motion perception, we identified a robust correlation between egocentric biological motion and form sensitivity. However, there was no similar correlation between motion and biological motion sensitivity, suggesting a deficit in the visual system rather than the visuo-motor control system. These findings contribute to our understanding of the intricate interplay between motor and visual processing in individuals with congenital brain lesions, shedding light on the significant involvement of the visual system in cases of PVL.

Falls are a significant health risk in older adults, and forward and backward falls each account for more than 40 % of falls. Dynamic stability, limb support, and impact energy absorption are crucial balance regulatory components and likely vary with the direction of imbalance. Understanding how perturbation direction influences these key components of balance stability regulation is crucial. This study investigated the balance stability, lower limb impact energy absorption, and limb support in forward and backward directions of balance perturbations in younger versus older adults. Thirteen healthy old and thirteen healthy young adults participated in this study. Participants stood on two adjacent perturbation platforms in modified tandem stance. The leading or trailing limb support surface dropped 76.2 mm vertically at an unknown time to impose body shift. Two-way (direction X group) mixed ANOVA was performed to analyze the anterior margin of stability (MoS), trunk angular displacement, peak negative power at the hip, knee, and ankle, and the peak vertical ground reaction forces (VGRF). Compared to forward perturbation, backward perturbation induced greater MoS (P < 0.01), peak VGRF (P < 0.01), and peak ankle (P < 0.05) and hip (P < 0.05) joint power. Older adults showed decreased MoS (P < 0.05), perturbed limb peak VGRF (P < 0.05), and ankle (P < 0.05) and knee (P < 0.05) joint peak power compared to younger adults. Forward perturbations induced greater challenges for dynamic stability, possibly due to trunk motion characteristics, while backward perturbations posed challenges in limb support and impact energy absorption. In addition, age-related deficits in balance stability regulation were observed in both perturbation directions.

Vertical ground reaction force (vGRF) is a main kinetic gait analysis explaining body weight loading patterns. The study primarily aimed to understand effects of Freezing of gait (FoG) on vGRF in Parkinson's disease (PD). A secondary analysis for a walking dataset including biomechanical analyses for 26 PD participants (13 with FoG) was performed. Considering the normal pattern of vGRF curve, peaks during early stance (F1) and late stance (F3), and slope in- during mid-stance (F2) were used to represent the change in kinetic forces. vGRF parameters were compared between FoG and non-FoG participants, and at off- and on-medication. FoG participants showed higher vGRFs during mid-stance F2 magnitude (p = 0.003), and weaker vertical propulsion; F3 magnitude (p < 0.001). This coincided with delayed weight acceptance; F1 timing (p = 0.019), and midstance peaks; F2 timing (p = 0.004). At off-medications, the F2 magnitude was significantly higher (p = 0.006), F3 magnitude lower (p = 0.001), and F1 time slower (p = 0.034) in FoG. At on-medication, F3 magnitude was still significantly lower (p = 0.017), and F2 time was slower (p = 0.037) in FoG. This study reveals that FoG significantly affects vGRF, particularly F3 magnitude during the push-off phase. Analyzing vGRF is crucial for understanding and managing FoG, allowing for more targeted interventions to improve FoG outcomes.

This study investigated the acute effects of barefoot (BF) running on biomechanical parameters and cytokine concentrations. Seventy-one habitually shod runners had biomechanical parameters evaluated during running shod (SH) and BF, while a sub-group of 19 runners had their inflammatory profile analyzed before and after a running session, using their habitual shoes or barefoot. Running BF changed spatiotemporal and joint kinematics, including the stride frequency (increased) and length (decreased), and foot strike pattern (more plantarflexed ankle at initial contact). An increased impact force was observed (p < 0.05), while joint moment, power, and work were also affected by BF running: a shift of joint load from the knee and hip to the ankle occurred (p < 0.05). In cytokine levels, maintenance (all cytokines, except Eotaxin, IL-12p40, IL-2, IL5, and MIP-1 beta) or reductions (IL-12p40, IL-2, and IL5) were observed as an acute response to BF running, what means to keep or reduce the levels of pro-inflammatory cytokines and immunological/chemoattraction proteins when compared to SH. Summarily, a single session of BF running may not represent enough stress to induce changes in the inflammatory profile. Besides the increased impact force, the joint load was reduced during short-term BF running. Nevertheless, short-term BF running should be cautiously applied due to the shift of joint load from the knee and hip to the ankle.

Previous research suggests that affective factors may influence perception of potential movement differently compared to perception during movement itself. To build on this the current study investigated the roles of general and movement-specific anxiety, self-efficacy, general resilience and motor control in how 41 adults with typical motor skills thought they would behave (perceptual judgement) and how they actually behaved (executed action). Participants completed several standardised scales and two movement-specific scales, a perceptual judgement task and an executed action task. In the perceptual judgement task participants judged whether they would need to turn their shoulders to walk through different sized apertures between 0.9 and 1.9 their shoulder width-to-aperture ratio. This involved a static (standing still) and a dynamic (walking towards) condition. The executed action task involved actually walking through the different sized gaps between the doors. Findings were discussed within an ecological framework drawing strongly on Newell's constraints-based approach (1986). Results indicated a relationship between higher movement-specific anxiety and bigger safety margins. This highlights the importance of measure specificity in being able to detect nuanced relationships between affective factors and the perception-action cycle. Notable differences were also shown in the point of behaviour change (critical ratio) between perceptual judgement and executed action, illustrating the importance of studying perception and action together since they can be subject to different constraints. The findings contribute novel insights into the roles of these factors in how adults with typical motor skills perceive and realise their intentions and abilities to act in the world.

An external focus of attention, enhanced expectancies, and autonomy support (i.e., OPTIMAL factors) are key factors to optimise motor performance and uncover latent movement capabilities. However, research on the combination of OPTIMAL factors, particularly in children's dynamic movement settings is limited. Therefore, this study examined the combined effects of OPTIMAL factors on children's performance on a dynamic movement assessment battery, hypothesising higher performance scores in the optimised version of the assessment battery versus standardised version of the assessment. Forty-nine children (15 boys, 34 girls; mean age 10.61 ± 1.38 years) completed the Dragon Challenge (DC) dynamic movement assessment battery. Performance was measured via a summation of movement process (technique), outcome, and time-to-completion scores (max score N = 54) with higher scores representing better performance. Participants completed a standardised and an optimised version of the DC in a counterbalanced fashion. For the latter, DC protocols were optimised via the provision of choice (autonomy support); external focus instructions augmented by simple knowledge statement, positive feedback and promotion of a growth mindset (Enhanced expectancies). Results indicate that motor performance (DC score) was better in the optimised (M = 31.08 ± 6.66) vs. standardised (M = 29.04 ± 5.88). The findings indicate that the combination of OPTIMAL factors can improve children's motor performance in dynamic movement settings and that standardised motor assessment may not reveal children's true movement capabilities.

To investigate the effect of concentric fatigue on proprioception, motor control and performance of the shoulder in healthy young adults.

To characterize the interference of reactive stepping kinematics related to the increase or maintenance of the number of steps in response to a large perturbation during dual tasks among older adults.

An optimal proprioceptive reweighting strategy is necessary to maintain posture. A suboptimal strategy was associated with injury determinants and whether the strategy can be modified is unknown. Muscle fatigue can be used to investigate proprioceptive reweighting. The aims of this study were to evaluate the effects of local fatigue on proprioceptive reweighting strategies and postural stability as well as relationships between fatigue and these postural parameters.

Sprinting at maximum velocity requires fast angular motion of the thigh and effective hamstring function for optimum performance and injury prevention. In this cross-sectional investigation of 21 male sprinters, we acquired thigh angular kinematics while sprinting at top speed (range: 8.96-10.17 m/s), and then measured eccentric hamstring strength capacities using an isokinetic dynamometer during the same test session. In agreement with the hypotheses, thigh angular motion rates and the associated eccentric hamstring strength capacities were both significantly correlated with top speed (r-values: ∼0.5; p < 0.05). Additionally, when the participants were sorted by top speed, there were significant differences between the faster group and the slower group. Notably, on average the faster group showed faster thigh motion (angular acceleration: 10.3 kdeg/s, 11 % greater than slower group) and higher eccentric hamstring strength capacities (peak moment: 2.26 Nm/kg, 14 % greater than slower group). This investigation indicates that fast thigh angular motion and eccentric hamstring strength are both important for sprint performance.

External, environmental perturbations (e.g., slips) account for >60% of falls and lead to severe health-related consequences. Perturbation training paradigms are known to reduce slip-related fall risk by improving two key aspects of reactive balance control: center of mass (COM) stability and limb support. However, perturbation training requires complex technology and is difficult to implement outside of the laboratory. This study examined if key reactive balance mechanisms could also be improved via more clinically translatable balance exercises targeting both volitional and reactive balance control (i.e., domain-specific balance training).

Joint position sense (JPS) is crucial for maintaining posture, protecting joints, and carrying out daily activities such as walking. Studies show that exercises to strengthen muscles and improve proprioception can positively impact JPS during passive and less complex activities. Evidence suggests that motor training can effectively enhance sensory function, including JPS, due to the extensive connections between the motor cortex and somatosensory areas. Gait retraining using real-time feedback has improved outcomes among patients with musculoskeletal disorders. The effect of gait retraining on JPS has not been investigated. This study assessed the effects of gait retraining to reduce knee extension in joint position sense in individuals with knee hyperextension walking patterns.

Movement variability describes an individual's capacity to repeatedly perform motor skills and provides better understanding of coordination during a task. The purpose of this research was to assess the impact that task type and sex assigned at birth have on movement variability and load symmetry in healthy younger adults. It was hypothesized that the between trial variability of peak impact force and average loading rate would not differ between sexes or between tasks (level walking, stair ascent, stair descent, and sit-to-stand) and that load symmetry would not differ between the four tasks for an individual participant using a level of significance of α = 0.05. Peak impact force (PIF) and average loading rate (ALR) were measured during level walking, stair ascent and descent, and sit-to-stand using loadsol® sensors collecting at 200 Hz (Novel Electronics, Pittsburg, PA, USA). Coefficients of variation (CV) and the Absolute Symmetry Index (ASI) were used to assess symmetry and movement variability. Between the 39 female and 33 male young adults that participated in this study, significant differences (p < 0.001) were observed between groups for mass, height, and limb length. PIF did not show an interaction between sex and task (p = 0.627) or between sexes (p = 0.685) but did show between-task differences (p < 0.001). The PIF ASI also showed a difference between tasks (p < 0.001). Tukey's post hoc testing showed that the PIF ASI differences between the sit-to-stand task and the other tasks were clinically meaningful (d > 0.8). The ALR did not show an interaction between sex and task (p = 0.069) or between sexes (p = 0.624) but did show between-task differences (p < 0.001). Tukey's showed that the ALR was different between tasks and was clinically meaningful (d > 0.8) except between level walking and stair ascent (p = 0.546). The ALR ASI showed a different between tasks (p < 0.001). Tukey's showed that the ALR ASI differences between tasks were all clinically meaningful (d > 0.8) except between level walking and stair ascent (p = 0.220).These findings suggest that the movement variability for all loading metrics that existed between tasks could be due to difference in motor control and the width of the base of support needed to complete the various tasks. For example, the joint coordination to complete a sit-to-stand task is different than what is needed during walking, stair ascent and stair descent. Understanding variability observed between daily tasks helps identify movement patterns that could be potential risk factors for injury.

The main aim was to assess the effects of motor imagery (MI) and action observation (AO) plus physical exercise (PE) on pelvic floor and related structures. Forty-four healthy women were randomized into three groups: MI, AO, or sham observation (SO) group. The outcome measures included the pelvic floor muscles (PFM) condition (including basal tone and strength), lumbo-pelvic motor control, and pain sensitivity. All women performed six sessions at the rate of 3 s/week (for 2 weeks). An initial assessment was carried out (T0), another one 1-week after starting the study (T1), and a third one at the end (T2). Results showed significant PFM strength gains in MI and AO groups, but not in the SO group. Regarding lumbo-pelvic motor control, both MI and AO groups obtained statistically significant changes between pre- and post-intervention Additionally, only the AO group showed significant improvements already at 1-week of intervention. Finally, all groups showed improved pain sensitivity in the likely area of referred menstrual pain post-intervention, with only the MI group showing changes 1 week after starting the intervention. In conclusion, results showed that adding MI and AO to PE program leads to an improvement of sensorimotor function of PFM and related structures in general. Despite finding no statistically significant inter-group differences, some findings such as strength gains or the lumbo-pelvic motor control improvements were only found in MI and AO groups, and this should be considered clinically.

Despite the widespread research about the effects of attentional focus on balance control in different populations, to the best of our knowledge, no study has yet investigated the effects of attentional focus instructions on balance control in individuals with chronic low back pain (CLBP). Therefore, this study was aimed to compare the effects of internal focus (IF) and external focus (EF) of attention on quiet standing balance control between individuals with CLBP and healthy controls. Twenty individuals with CLBP and 20 healthy controls were enrolled in this quasi-experimental study. The participants were asked to stand still with eyes open and eyes closed while performing three tasks: baseline standing with no focus instructions, internally focusing on their feet, and externally focusing on two markers were placed on the force platform. Statistical analyses showed a significant main effect of group for mean total velocity (p = 0.02), area (p = 0.01), and displacement in mediolateral (ML) direction (p = 0.003). Moreover, a significant main effect of vision was observed for mean total velocity (p < 0.001), area (p < 0.001), and displacement in anteroposterior (AP) (p < 0.001) and ML directions (p < 0.001). Also, the results revealed a significant main effect of attentional focus for mean total velocity (p < 0.001), area (p < 0.001), and displacement in AP (p < 0.001) and ML directions (p = 0.01). Our results showed that in both healthy controls and individuals with CLBP, EF led to improve quiet standing balance control compared to IF and control conditions. From a clinical perspective, it may be useful for physical therapists to consider the use of instruction cues that direct performer's attention away from the body for improving quiet standing balance control in individuals with CLBP.

The distribution of motor errors can influence optimal motor planning (where to aim). In football instep kicking, it was shown that ball landing locations exhibit the right-up-left-down elliptical distribution in right-footed kickers and vice versa. However, this was reported as a result of mixed multiple kickers; the individual-level error distribution has been unclear. Here we show substantial inter-individual variability in error shape and error direction in the 30 kicks aimed at a target (1.7 m high, 11.0 m in front) by 27 male football players. All players exhibit right-up-left-down distributions with ellipticity (minor/major radius ratio of the 95% confidence ellipse) ranging from 0.25 to 0.77 and major axis angle ranging from 13 to 67° from the horizontal axis. The mean absolute error and the area of the 95% confidence ellipse are not significantly correlated with major axis angle (ρ ≤ 0.312) and ellipticity (|r| ≤ 0.343). By simulating shots aimed at the top-right and top-left edges of a goal with these observed ranges and normalised ellipse area, we reveal a wide range of probability of shots on goal (top-right: 2.7-fold difference, top-left: 1.5-fold difference) due to inter-individual variability in error shape and direction independent of error size. Further simulation shows that, depending on the shape-direction combination, the aiming points with the same 80% probability of shots on goal change by up to 0.3 m vertically, even for the same minimal error size. We highlight the importance for football players to consider not only accuracy/precision, but also error shape and direction to optimise motor planning.

Cervical spine mobility assessment is crucial in rehabilitation to monitor patient progress. This study introduces the DidRen VR test, a virtual reality (VR) adaptation of the conventional DidRen laser test, aimed at evaluating cervical spine mobility. We conducted a cross-sectional study involving fifty healthy participants that underwent the DidRen VR test. The satisfaction of Fitts' law within this VR adaptation was examined and we analyzed the effects of age and sex on the sensorimotor performance metrics. Our findings confirm that Fitts' law is satisfied, demonstrating a predictable relationship between movement time and the index of difficulty, which suggest that the DidRen VR test can simulate real-world conditions. A clear influence of age and sex on performance was observed, highlighting significant differences in movement efficiency and accuracy across demographics, which may necessitate personalized assessment strategies in clinical rehabilitation practices. The DidRen VR test presents an effective tool for assessing cervical spine mobility, validated by Fitts' law. It offers a viable alternative to real-world method, providing precise control over test conditions and enhanced engagement for participants. Since age and sex significantly affect sensorimotor performance, personalized assessments are essential. Further research is recommended to explore the applicability of the DidRen VR test in clinical settings and among patients with neck pain.

When individuals stand, they sway and so have to maintain their balance. It is generally expected that task performance is worse when standing and swaying than when sitting and therefore not swaying. In contrast, we hypothesized that greater sway is associated with better task performance in the absence of external perturbations of posture. Twenty-four healthy, young adults performed two goal-directed, modified Stroop tasks (incongruent and reversed incongruent) in four body position conditions (standing against a vertical surface, and standing freely with a wide, standard or narrow stance). Centre of pressure (COP) sway, head sway, eye movements, visual attention, and task performance were recorded. Partial correlation analyses showed significant positive associations between task performance and some COP and head sway variables, after controlling for the level of visual attention. Analyses of variance with three factors (body position, task difficulty, target distance) also showed significant interaction effects between body position (and therefore postural sway) and the number of accurate target findings. The presence of these interactions showed that narrow stance was both the best body position for performing the incongruent task and the worst body position for performing the reversed incongruent task. Overall, COP sway and head sway can increase task performance. Hence, healthy, young adults in quiet stance appear to use sway to explore their environment more effectively. However, it should be borne in mind that our hypothesis was formulated solely with regard to healthy, young adults standing in quiet stance.

Texting while walking (TWW) is a dual-task activity that young adults perform in their everyday lives. TWW has been reported to affect gait characteristics such as gait speed, stride length, and cadence. However, the influence of TWW on lower extremity gait function has not been investigated. Therefore, the purpose of this study was to quantify gait function by examining gait symmetry and using a time series analysis. Twenty-eight young adults (14 males, 14 females) walked at their preferred speed for 10 m as a baseline condition and a 10 m TWW task. Three-dimensional segment tracking was achieved utilizing a lower extremity and trunk marker set and the Model Statistic was used to test for statistical differences between the hip, knee, and ankle angular joint positions. The hip yielded the most asymmetries (25 out of 101 points) throughout the gait cycle, while asymmetries for the knee and ankle joints yielded 16 out of 101 points and 11 out of 101 points, respectively. The outcomes of this study suggest there are differences between baseline and TWW gait symmetry, however, the percentage of the gait cycle affected was less than 25 % - indicating gait function is not strongly influenced by texting while walking in young adults.

Emerging research suggests that muscular and kinematic responses to overhead work display a high degree of variability in fatigue-related muscular and kinematics changes, both between and within individuals when evaluated across separate days. This study examined whether electromyographic (EMG), kinematic, and kinetic responses to an overhead drilling task performed until volitional fatigue were comparable to those of a repeated identical exposure of the task completed 1 week later. Surface EMG and intramuscular EMG, sampled from 7 shoulder muscles, and right upper limb kinematics and kinetics were analyzed from 15 male and 14 female participants. No significant day-to-day changes in EMG mean power frequency (MPF) were observed, though serratus anterior displayed significantly less fatigue-related increase in EMG root-mean-squared (RMS) signal amplitude on day 2. Unfatigued upper kinematics on day 2 featured an increase in thoracohumeral elevation, elbow flexion, and decrease in wrist ulnar deviation compared to unfatigued state on day 1. Fatigue-related changes in shoulder joint flexion moment that were present on day 1 were reduced on day 2, suggesting that a more efficient overhead work strategy was learned and preserved across successive days. Day-to-day changes in upper limb joint angle variability, quantified by median absolute deviation (MdAD), were joint dependent. Despite yielding a variable fatigue-related kinetic strategy on both days, kinematic and kinetic fatigue-related changes on a second day of completing an overhead drilling task suggested a potential kinematic learning effect.

This study examined (i) adaptations in muscle activity following perturbation-based balance training (PBT) using treadmill belt-accelerations or PBT using walkway trips and (ii) whether adaptations during treadmill PBT transfer to a walkway trip.