Human Movement Science最新文献

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.

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.

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.

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.

When fatigued, the wrist extensors, which are the primary wrist stabilizers, impair distal upper limb motor performance in a surprisingly similar way as when fatiguing the wrist flexors. It is possible that the wrist extensors are so active as antagonists that they develop an equal degree of fatigue during wrist flexion contractions, making it difficult to truly isolate their impact on performance. Thus, the purpose of this study was to examine how wrist flexion/extension forces are impaired following either agonist or antagonist sustained submaximal wrist contractions. 13 male participants attended four laboratory sessions. In these sessions, fatigue was induced via a sustained submaximal isometric contraction of either wrist flexion or extension. These contractions were held for up to 10 min at 20% of the participant's baseline maximal voluntary contraction (MVC) force. Throughout the sustained contraction, intermittent agonist (matching the sustained contraction) or antagonist (opposing the sustained contraction) MVCs were performed. Unsurprisingly, agonist MVC forces decreased significantly more than antagonist (Agonist: 58.5%, Antagonist: 86.5% of MVC, P < 0.001). However, while there were no differences in antagonist wrist extension and flexion MVC decreases (Wrist Flexion: 87.5%, Wrist Extension: 85.5%, P = 0.41), wrist extension MVCs did decrease significantly more than wrist flexion MVCs when forces were expressed relative to the agonist (P = 0.036). These findings partially support the hypothesis that the wrist extensors may be more susceptible to developing fatigue when functioning as antagonists than the wrist flexors. This work will help equip future research into the motor control of the upper limb and the prevention of forearm-related musculoskeletal disorders.

In this study, we investigated the combined effects of age, dual-tasking (DT) and a passive hip exoskeleton on gait patterns among senior (SA) and young adults (YA). It was hypothesized that SA will be more affected by DT and that wearing the exoskeleton will improve gait patterns for both groups during DT. Twenty-two SA and twenty-six YA performed a single task (normal walking) and DT walking at their preferred speed with an exoskeleton (EXO), without (noEXO), and a sham version (SHAM) in a randomized and balanced order. Speed, cadence, double support time (DST), step length, hip joint power, range of motion (ROM), and moments (mom), as well as DT performance, were extracted using mocap, force plates (1000 Hz), and a voice recorder. Three-way MANOVA with group × device × condition was conducted (p < .05, inferred significance). Results showed a predominantly significant main effect of group for step length, speed, DST, ROM, and mom (p ≤ .01), main effect of condition for cadence, DST, speed, and mom (p < .01) and a main effect of the device for ROMz and mom (p < .05). Age-related changes were seen by decreased walking speed and step length, independent of DT and use of exoskeleton. Wearing the EXO aided the SA group to maintain similar levels of cadence from single to DT and decreased the hip internal rotation mom by 65%. There was no difference in DT performance between groups. In conclusion, SA showed a decline in gait patterns during DT that was somewhat mitigated by wearing an EXO.

Background

This study aimed to explore the associations between brain structures, cognition, and motor control in participants with mild cognitive impairment (MCI), with a focus on dual-task performance.

Methods

Thirty MCI patients and thirty healthy controls were enrolled. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA). Structural magnetic resonance imaging data were analyzed using voxel-based morphometry (VBM) to calculate brain parenchyma volume and gray matter volume (GMV). Participants performed single- and dual-task Timed Up and Go (TUG) tests, and the correlations between significant GMV differences and task execution time was analyzed.

Results

MCI patients showed significantly lower MoCA scores, particularly in visuospatial/executive, attention, and delayed recall domains (p < 0.05). Dual-task TUG execution time was significantly increased in MCI patients (p < 0.05). The GMV in the right anterior lobe of the cerebellum and both insulae was positively correlated with visuospatial/executive scores (FDR-corrected, p < 0.05). The GMV of the right cerebellar anterior lobe and insula were significantly reduced in MCI patients (p < 0.05). The GMV of the right cerebellar anterior lobe was negatively correlated with dual-task execution time (r = −0.32, p = 0.012).

Conclusion

Smaller GMV in the right anterior lobe of the cerebellum was associated with impaired dual-task performance, which may provide more evidence for the neural mechanisms of cognitive and motor function impairments in MCI.

Purpose

To determine whether the application of continuous lateral trunk support forces during walking would improve trunk postural control and improve gait performance in children with CP.

Materials and methods

Nineteen children with spastic CP participated in this study (8 boys; mean age 10.6 ± 3.4 years old). Fourteen of them were tested in the following sessions: 1) walking on a treadmill without force for 1-min (baseline), 2) with lateral trunk support force for 7-min (adaptation), and 3) without force for 1-min (post-adaptation). Overground walking pre/post treadmill walking. Five of them were tested using a similar protocol but without trunk support force (i.e., control).

Results

Participants from the experimental group showed enhancement in gait phase dependent muscle activation of rectus abdominis in late adaptation period compared to baseline (P = 0.005), which was retained during the post-adaptation period (P = 0.036), reduced variability of the peak trunk oblique angle during the late post-adaptation period (P = 0.023), and increased overground walking speed after treadmill walking (P = 0.032). Participants from the control group showed modest changes in kinematics and EMG during treadmill and overground walking performance. These results suggest that applying continuous lateral trunk support during walking is likely to induce learning of improved trunk postural control in children with CP, which may partially transfer to overground walking, although we do not have a firm conclusion due to the small sample size in the control group.