Human Movement Science

Patients recovering from hemiparetic stroke have been shown to benefit from mirror therapy in terms of improving their motor function. The clinical improvement in motor function may differ depending on the mirror therapy protocol used. Previous studies have shown that four parameters are influential: the size of the mirror (large and small), manipulation of objects (with or without), the complexity of action (simple and complex), and movement execution (unilateral and bilateral). We examined the impact of these parameters on the subjective quality (believability) of the mirror illusion in unimpaired participants. Forty healthy participants completed 16 different combinations of the four parameters during mirror visual feedback. Participants rated each trial for its level of believability on a 10-point Likert scale. A repeated measures ANOVA was used to examine the data. The large mirror consistently elicited higher ratings than the small mirror. And while bimanual movements generally elicited higher ratings than unimanual movements, ratings for bimanual movements were significantly reduced when participants made complex movements with objects. We attributed these results to the congruency of multisensory information. Conditions that elicit congruency between illusory information and other sensory inputs appear to maximise believability over the illusory hand. The findings of this study reveal the parameters maximising illusion believability in unimpaired participants and have implications for optimal mirror therapy conditions in patients groups.

BackgroundChildren with unilateral spastic cerebral palsy (USCP) often rely on trunk compensation due to impaired upper limb control, but current clinical tools do not directly capture trunk involvement. Marker-based systems are challenging to use with children, while computer vision methods like OpenPose offer a promising, scalable alternative for kinematic analysis but need to be validated. PurposeWe validated OpenPose for quantifying trunk recruitment during bimanual play in children with USCP and examined how the interventions Constraint-Induced Movement Therapy (CIMT) and Hand-Arm Bimanual Intensive Therapy (HABIT) influence trunk use. MethodsWe analyzed videos of children with USCP who underwent CIMT or HABIT. OpenPose was used to extract trunk displacement angle (TDA) and trunk rotation angle (TRA), which were compared to hand function scores. OpenPose was validated against a 3D motion analysis system in typically developing adults. Reach-phase kinematic variables were also assessed. ResultsOpenPose showed high validity for TDA and lower validity for multi-planar TRA. TDA and TRA did not correlate with baseline hand function. HABIT reduced TDA, while CIMT slightly increased it. No significant changes were found in velocity, movement time, or variability. ConclusionsOpenPose is a viable tool for capturing gross trunk motion. Trunk recruitment patterns differed by intervention, supporting the need for personalized approaches.

Head-eye coordination during ball interception depends on both task demands and motor experience. The purpose of this study is to determine how these factors influence head-eye contributions to gaze control. Twenty-five female university students (novices with no ball sport experience, n = 13; experienced softball players, n = 12) performed two tasks: visually tracking an approaching ball (tracking task) and, in addition, moving the hand to the ball's landing position (reaching task). Head, eye, and gaze velocities, cross-correlation coefficients between gaze and head velocity, and gaze-head lag time were analyzed using linear mixed models. The results showed that although gaze velocity remained unchanged regardless of tasks or groups, decomposing gaze into head and eye components revealed task-dependent contributions. Compared with the tracking task, the reaching task showed significantly larger head velocity and smaller eye velocity, indicating complementary adjustments that were not revealed by gaze movements alone. The cross-correlation between head and gaze was significantly higher in the reaching task than the tracking task, indicating stronger temporal coupling under greater task demand. Furthermore, the experienced group showed greater task-dependent modulation of eye velocity than the novice group, demonstrating greater flexibility in adjusting the magnitude of head-eye movements to task demands. In addition, the experienced group showed a consistently near-zero gaze-head lag regardless of task, whereas the novice group showed a prolonged gaze-leads-head interval. These findings suggest that ball sport experience shapes two distinct aspects of head-eye coordination: task-dependent flexibility in movement magnitude, and stable, temporally synchronized gaze-head control.

A subset of bilateral tasks requires one arm to perform a stabilizing role while the other completes a movement, such as slicing a loaf of bread. Visual attention during bilateral tasks has previously been examined with bilateral reaching tasks, demonstrating that visual attention switches between the two target locations. The goal of this study was to characterize visual attention during a cooperative mechanically coupled bilateral "stabilizing and reach" task to determine how visual attention is divided between the two limbs when one limb plays a stabilizing role. Twenty-six healthy young adults completed a robotic task in which the hands were coupled with a haptic spring. Participants were instructed to keep one hand stationary in a target while they reached for a target with the other hand, thus stretching the spring and applying a force to both arms. We found that individuals primarily fixated their gaze on the reaching target, only fixating on the stabilizing target for approximately 10% of the reaching time. Longer fixations on the reaching target were associated with faster reaching times, while longer fixations on the stabilizing target were associated with slower reaching times. While the performance of the stabilizing hand differed between the dominant and non-dominant limbs, visual strategies did not vary based on which hand was stabilizing. These results demonstrate that unlike bilateral reaching tasks in which the eyes frequently saccade between the two targets, visual guidance is primarily used for the reaching hand while minimal overt visual attention is directed to the stabilizing hand.

ObjectivesThis study aimed to compare the effects of short versus intensive bimanual training on spatiotemporal features of bimanual coordination in children with unilateral cerebral palsy (UCP). MethodsIn a prospective, repeated-measures design, 28 children with UCP completed two training regimens: a short dose (75 repetitions of speed stacking; [~]1-1.5 hours) and an intensive dose (30 hours of Hand arm bimanual intensive training). Bimanual learning was indexed by average time to complete nine stacking trials. Spatiotemporal kinematics were evaluated using three-dimensional motion analysis. For the bimanual coordination task, (3-2-1 stacking) outcomes included normalized movement overlap, total task duration, and participation time. For a symmetric bimanual task (simultaneous two-cup transfer), task synchronization and completion time were analyzed. Peak tangential velocity and hand trajectory were assessed across both tasks. General linear models with repeated measures were used to analyze the effects of training dose and extremity. ResultsThere was a significant main effect of training dose on movement time (p < 0.001), with both doses improving bimanual learning. The intensive dose yielded significantly greater gains in normalized movement overlap, total task duration, hand trajectory, and participation time (all p = 0.001) during the bimanual coordination task. A dose-by-extremity interaction was identified for peak tangential velocity (p = 0.03), demonstrating greater velocity gains in the more affected limb. In the symmetric task, a main effect of dose was found only for hand trajectory (p < 0.03). ConclusionsBoth short and intensive bimanual training enhanced bimanual learning and coordination in children with UCP. While intensive training yielded greater improvements, even brief, ecologically valid tasks produced measurable gains, highlighting the importance of training intensity and task specificity in pediatric neurorehabilitation.

BackgroundDuring hand reaching movements in people with stroke, the coordination of trunk, shoulder, and elbow muscles changes as a function of target height. However, it is not known whether target height also influences non-use, defined as the difference between two coordinations aiming at the same target. MethodsTwenty-two individuals with stroke (> 1 month) completed the Proximal Arm Non-Use (PANU) test in two conditions: high target (80 cm) and low target (67 cm). Elbow, shoulder, and trunk use was recorded using motion capture. ResultsTrunk compensation and non-use of the shoulder and elbow joints were found to depend on target height. ConclusionsBecause trunk bending forward goes against the need to elevate the hand, a sufficiently low target is necessary to unmask the presence of shoulder-elbow non-use. We provide novel recommendations for assessing compensations and non-use during hand reaching. Clinical Trial: NCT04747587.

The evolution of virtual reality (VR) has created the opportunity for a relatively low-cost and accessible method to practice motor skills. Previous studies have demonstrated how motor skill practice in non-immersive virtual environments transfers to physical environments. Though minimal research has investigated motor learning and transfer within immersive VR, multiple experiments provide empirical evidence of positive transfer effects. To enhance the similarities between virtual and physical environments, most studies have used software engines and modified hardware. However, many learners and practitioners are currently using commercially available VR with the goal of enhancing real-world performance, though there is very little evidence to support the notion of positive transfer for these systems. Therefore, the purpose of this experiment was to investigate how motor skill practice using a commercially available VR system improved real-world performance and how that compared to physical practice. Participants (n = 68) were randomly selected into one of two groups: virtual reality (VR) practice (n = 33) or real-world (RW) practice (n = 35). The experiment took place over two consecutive days with a pretest, posttest, and practice phase occurring on both days. The pre- and post-testing phases were identical for both groups and consisted of putting a golf ball 10 times on a carpeted surface towards the center of a target. The practice phases consisted of 60 total putts per day in the respective environment (VR or RW). Participants continuously alternated golf putting holes from three different distances until they accrued 60 total putts. Participants in the RW group performed golf putts to three targets. Participants in the VR group also performed golf putts on three different miniature golf putting holes, using the commercially available Oculus Rift and the Cloudlands VR Minigolf game. The VR putting targets were designed to replicate the putting holes in the physical environment. Separate 2 (condition) x 4 (test phase) repeated measures ANOVAs were used to assess accuracy and club head kinematics. The results revealed a significant main effect for test phase, but not for condition. Post hoc analyses revealed both groups significantly improved their putting accuracy and club head kinematics at similar rates. The results from this study indicate that the transfer of learning that occurred from the commercially available VR practice was equally effective when compared to RW practice.

The ability to self-evaluate motor performance or estimate performance errors is beneficial for motor learning or relearning in the context of neurologic injury. Some evidence suggests those with injury like stroke may be unable to accurately self-evaluate their performance; however, it is unclear if individuals who are absent of injury are accurate in this domain. We aimed to investigate the accuracy of self-evaluation and potential influencing factors by conducting a systematic search to identify literature involving the self- and objective-evaluation of upper-extremity motor tasks. Twenty-three studies satisfied inclusion criteria. Data revealed a moderate positive correlation between self- and objective evaluations across a variety of tasks, from trivial button pressing to specialized surgical suturing. Both under- and overestimation of performance was found across the papers. Key factors identified to influence the accuracy of self-evaluation were the task purpose, familiarity, difficulty, and whether an individual received a demonstration. This review identified some limitations in this field of research. Most notably, we found that very few studies have investigated the accuracy of self-evaluation of motor performance with the primary goal of comparison to objective performance. Many studies reported the data but did not make direct statistical comparisons. Moreover, due to inconsistencies between how self and objective-evaluations were conducted, we argue that in this area of investigation self-evaluation tools need to replicate the objective evaluation method, or at minimum the self-evaluation tool should ask questions specific to the construct of performance that is being measured objectively.

BACKGROUNDAutistic Spectrum Disorder (ASD) presents with a multitude of problems such as physical, social, emotional, psychological, etc. Most common physical problems are impairments in standing balance and posture. It is unknown whether these impairments have any association between tactile sensation or are purely due to deficits in sensory processing and integration. We hypothesized that foot tactile sensation in ASD is positively correlated to performance in standing balance as measured by Pediatric Balance scale. METHODSThe data collected at Heartshare Human Services of New York was used for secondary analysis. It consisted of 12 participants and included: 1. Muscle and joint ROM testing to rule out any muscle involvement in balance problems. 2. Tactile sensation testing at four sites on sole of foot bilaterally using Semmes Weinstein monofilament. 3. Pediatric Balance Scale (PBS) for balance testing. RESULTSWe found significant positive correlation between cutaneous tactile sensation (SWF) and Pediatric Balance scale (PBS) measures in our participants i.e., reduced tactile sensation was moderately associated with impaired balance score. CONCLUSIONSWe propose that during conventional clinical assessment for individuals with ASD, foot tactile sensation should not be overlooked, and included as a part of somato-sensory assessment. In addition, enhancing foot tactile sensation could also be used for targeted interventions to improve balance in children with ASD.

Walking is an attentionally demanding process that draws from a limited pool of attentional resources. Dual-task assessments, where individuals perform a cognitive task while walking, often reveal changes in gait and balance due to competing attentional demands. As cognitive task difficulty increases, the attentional resources necessary to complete the task also increase, leading to greater interference with gait and balance. However, these interactions are typically examined using contrived lab-based tasks, leaving it unclear how the cognitive processes engaged during real-world movement impact walking. In the present study, we investigated whether increasing the attentional demand of spatial navigation, a cognitive process intrinsically linked to movement, interferes with gait and balance. Healthy adults completed an ambulatory virtual reality homing task in which they walked through a virtual environment and navigated to previously visited locations while wearing ankle and lumbar trackers. We increased the attentional demand of navigation by removing sensory cues during this homing phase: full cues, visual cues only, or self-motion cues only. Navigation performance declined as sensory cues were removed, but we observed no corresponding changes in their spatiotemporal gait and balance metrics. These results show that, in healthy adults, increasing the attentional demand of spatial navigation does not interfere with gait and balance during real-world movement. This finding suggests that locomotor control may be robust to navigation-related cognitive demands. Further research is needed to determine why navigation did not interfere with mobility and to clarify the relationship between these two interconnected processes.

The action/perception theory of cortical organization is supported by the finding that pantomime hand movements of reaching and grasping are different from real movements. Frame-by-frame video analysis and MATLAB(R) based tracking examined real/pantomime differences in a bilaterally movement, string-pulling, pulling down a rope with hand-over-hand movements. Sensory control of string-pulling varied from visually-direct when cued, visually-indirect when non cued and somatosensory controlled in the absence of vision. Cued grasping points were visual tracked and the pupils dilated in anticipation of the grasp, but when noncued, visual tracking and pupil responses were absent. In real string-pulling, grasping and releasing the string featured an arpeggio movement in which the fingers close and open in the sequence 5 through 1 (pinki first, thumb last); in pantomime, finger order was reversed, 1 through 5. In real string-pulling, the hand is fully opened and closed to grasp and release; in pantomime, hand opening was attenuated and featured a gradual opening centered on the grasp. The temporal structure of arm movements in real string-pulling featured up-arm movements that were faster than down-arm movement. In pantomime, up/down movements had similar speed. In real string-pulling, up/down arm movements were direct and symmetric; in pantomime, they were more circular and asymmetric. That pantomime string-pulling featured less motoric and temporal complexity than real string-pulling is discussed in relation to the action/perception theory and in relation to the idea that pantomimed string-pulling may feature the substitution of gestures for real movement.\n\nSignificant StatementMost laboratory studies investigating hand movements made by humans feature single hand movements, the current study presents a novel string-pulling task to study bimanual coordination of left and right hands in real and pantomime conditions. The results show that pantomime string-pulling featured less motoric and temporal complexity than real string-pulling. These findings are relevant to the contemporary theory of action and perception that the dorsal stream (parietal cortex) is related to actions and the ventral stream (temporal cortex) is related to perception.

Combined action observation and motor imagery (AOMI) facilitates corticospinal excitability (CSE). This study used single-pulse transcranial magnetic stimulation (TMS) to explore changes in CSE for coordinative AOMI of a single-leg sit-to-stand (SL-STS) movement. Twenty-one healthy adults completed two testing sessions, where they engaged with baseline (BL), action observation (AO), and motor imagery (MI) control conditions, and three experimental conditions where they observed a slow-paced SL-STS while simultaneously imagining a slow- (AOMIHICO), medium- (AOMIMOCO), or fast-paced (AOMILOCO) SL-STS. A TMS pulse was delivered to the right leg representation of the left primary motor cortex at three stimulation timepoints aligned with peak EMG activity of the knee extensor muscle group for the slow-paced (T3), medium-paced (T2), and fast-paced (T1) SL-STS during each condition. Motor evoked potential (MEP) amplitudes were recorded from the knee extensor muscle group as a marker of CSE for all stimulation timepoints and conditions. A main effect for experimental condition was reported for all stimulation timepoints. MEP amplitudes were significantly greater for AOMIHICO at T1 and T3, and AOMIMOCO and AOMILOCO at all stimulation timepoints, when compared with control conditions. This study provides neurophysiological evidence supporting the use of coordinative AOMI as an alternative method for movement (re)learning.

The human shoulder likely evolved under selective pressures favouring diverse tasks that require high mobility, speed, and torque. For example, humans are uniquely adept at high-speed and accurate throwing. Prior work has aimed to quantify the kinematics and kinetics of upper limb movements in isometric or uniplanar motions. However, we still do not fully understand the trade-offs of shoulder torque and power with angular velocity during functional tasks that are reflective of demands that may be relevant to the shoulders evolution. We developed a novel approach for upper limb 3D inverse dynamic calculations by integrating motion capture with an instrumented cable machine. Twenty-five participants performed a crossbody, isokinetic upper limb motion at various cable speeds in a rigid and free torso condition (self-imposed). Shoulder torque decreased significantly (p < 0.05) with increasing angular velocity in 19 and 16 participants for the constrained and unconstrained conditions, respectively. Shoulder power increased significantly (p < 0.05) with angular velocity for 6 and 11 participants for constrained and unconstrained, respectively. T-tests revealed no statistical difference between the torso conditions for torque and power against angular velocity. Our findings suggest that despite having a trade-off in torque and velocity, the shoulder may be tuned to produce power over a wide range of velocities independent of energy transfer from the lower extremities.

Humans are remarkably adept at extracting latent dynamic information from purely visual cues. Prior work shows that people can innately estimate differences in limb stiffness using solely their visual observation of movement, which suggests that components of mechanical impedance may be embedded within humans internal predictive models of movement. We tested whether humans can similarly perceive damping, a force-velocity relationship, and whether targeted coaching can enhance this visual ability. Specifically, 30 participants observed abstract two-link arm simulations with systematically varied elbow damping and rated their perceived level of damping for several trials. Participants completed two sessions separated by one of three brief coaching interventions: (1) no coaching, (2) coaching to attend to hand velocity, or (3) coaching to attend to elbow-angle velocity. Results reveal that (1) humans can innately perceive changes in arm damping using solely their visual observation of motion and (2) coaching further improved performance, with the elbow-angle coaching group showing a significantly greater increase in rating accuracy compared to the other two groups. This work extends our understanding of how action-perception coupling supports inference of mechanical impedance. Moreover, we demonstrated that perceptual strategies for estimating damping are malleable and can be systematically improved through coaching. We not only identified the visual cues observers relied on but also guided them toward more classifiable features, effectively strengthening their perceptual models of limb dynamics. Author summaryHumans are remarkably adept at understanding an objects latent dynamic properties simply by watching it move, even when the underlying forces are unseen. In this paper, we demonstrated that people can notice differences in how "damped" a moving limb is using vision alone. Moreover, we found that brief coaching helped participants focus on the most informative features, significantly improving their ability to differentiate the damping levels. These results demonstrate how people can visually infer aspects of movement that are normally thought to require physical interaction, offering insight into how the motor system links action and perception. They also show that strategies can be shaped and improved, supporting real-world healthcare applications. In stroke rehabilitation, physical therapists physically assess the resistance of a patients limb, so better guidance on the most relevant visual cues can help clinicians learn faster and even provide care remotely. In robot-assisted surgery, surgeons operate a console to perform procedures with limited or no force feedback, so they must estimate tissue dynamics properties largely from visual observation. Understanding how people visually estimate these dynamics can inform training for more precise surgical decisions. Overall, our findings clarify how humans interpret movement dynamics and how coaching can support more consistent and accurate perceptual decisions.

Degraded vision (caused by pathological reasons or monocular viewing) has been shown to affect fine motor control. However, there is a dearth of work examining the effects of "cataract-like" blur on reach-to-grasp performance. There is, however, a trend towards amblyopic blur being associated with deficits in reach-to-grasp performance, suggesting that timely intervention in treating cataracts is likely to be essential to maintain a functional ageing population. 18 participants performed a reach-to-grasp task. They reached for and precision grasped high and low-contrast cuboid targets under three visual conditions: binocular blur, monocular blur (full vision in the other eye) and full vision. They also performed contrast sensitivity, stereoacuity and visual acuity tests. Visual blur was associated with changes to the kinematics of prehensile movements early/acceleration stage (maximum acceleration and maximum velocity) and maximum grip aperture. Visual blur also caused the period from first contact with the target to the time it was lifted (dwell time) to be elongated. These results suggest that changes in prehension associated with visual blur are linked to differences in the planning and online control of prehension movements.

BackgroundSensory information processing plays a crucial role in monitoring the timing of external and internal events, including the control of balance. While previous research has investigated the role of vision in the perceived timing of postural instability onset with eyes closed and open, it is important to further explore the influence of visual context. Virtual reality offers a unique opportunity to manipulate visual information and assess its impact on balance control and the perceived timing of sensory events. Research QuestionDoes visual information, particularly visual threat presented in virtual reality, alter the perceived timing of postural instability onset? MethodsTwo temporal order judgment tasks were conducted using virtual reality to manipulate visual information. Participants were placed on a virtual skyscraper to induce visual threat. The experiments investigated the impact of visual information on the perceived onset of postural instability while manipulating the presence/absence of visual threat. ResultsWith vision available but without visual threat, the onset of a postural perturbation needed to occur 10.71-12.33 ms before a reference sound stimulus to be perceived as simultaneous. With visual threat, the onset needed to occur 4.45 ms before auditory cue onset to be perceived as simultaneous. While these delays were not significantly different from true simultaneity of perturbation and sound onset, participants were significantly more precise in their judgments when threatening visual information was present. SignificanceOur results show that visual context, particularly visual threat presented in virtual reality, may alter the perception of perturbation onset and the precision of judgments made. This has implications for understanding the role of vision in balance control and developing interventions to improve balance and prevent falls.

Human bipedal posture is inherently unstable, making even daily activities potentially lead to falls and serious injuries. Although prior studies have shown that appropriate postural control supports both task success and postural balance during quiet standing or under modest postural demands, it remains unclear how the central nervous system controls whole-body posture under high-demand, near-fall conditions. Here, we investigated how varying postural demands influence postural strategies using a whole-body task in which participants leaned their body mediolaterally to reach a target. We manipulated the required leaning angles and velocities by varying target positions and time constraints to reach a target, thereby introducing different levels of postural demand. The results demonstrated that target position, time constraint, and movement distance significantly affected task performance, defined as reaching accuracy. Specifically, participants could accurately reach targets requiring upright or moderately leaning postures. However, when targets required greater leaning postures, participants failed to reach them. Furthermore, the detrimental effects of shorter time constraints and longer movement distances on task performance became more pronounced when target positions required greater leaning postures. These findings suggest that the central nervous system tolerates low to moderate postural demands to achieve task goals. In contrast, when postural demands exceed a certain threshold, the central nervous system begins to prioritize postural safety over task success. This study highlights the nonlinear effect of postural demands on motor planning during whole-body movements.

BackgroundTraumatic brachial plexus injury (TBPI) causes a sensorimotor deficit in upper limb (UL) movements. ObjectiveOur aim was to investigate the arm-forearm coordination of both the injured and uninjured UL of TBPI subjects. MethodsTBPI participants (n=13) and controls (n=10) matched in age, gender, and anthropometric characteristics were recruited. Kinematics from the shoulder, elbow, wrist and index finger markers were collected while upstanding participants transported a cup to mouth and returned the UL to a starting position. The UL coordination was measured through the relative phase (RP) between arm and forearm phase angles and analyzed as a function of the hand kinematics. ResultsFor all participants, the hand transport had a shorter time to peak velocity (p<0.01) compared to the return. Also, for the control and the uninjured TBPI UL, the RP showed a coordination pattern that favored forearm movements in the peak velocity of the transport phase (p<0.001). TBPI participants injured UL showed a longer movement duration in comparison to controls (p<0.05), but no differences in peak velocity, time to peak velocity and trajectory length, indicating preserved hand kinematics. The RP of the injured UL revealed altered coordination in favor of arm movements compared to controls and to the uninjured UL (p<0.001). Finally, TBPI participants uninjured UL showed altered control of arm and forearm phase angles during the deceleration of hand movements compared to controls (p<0.05). ConclusionThese results suggest that UL coordination is reorganized after a TBPI so as to preserve hand kinematics.

Upright postural control during movement relies on multisensory integration. Yet, the frequency-specific contribution of vision remains poorly characterized in virtual reality (VR). This study investigated how multi-sine visual stimulation amplitude delivered in VR influences standing postural responses. Fifteen healthy adults stood on a force plate wearing a VR headset. Visuo-postural coupling was assessed through coherence and gain analyses between a multi-sine signal (10 sinusoids, 0.12 to 1 Hz) oscillating a virtual environment in one of four amplitudes (0.5, 1, 2, 4 degrees peak-to-peak) and the anteroposterior whole-body angle. All amplitudes elicited measurable postural responses. Increasing amplitude significantly increased postural oscillation and tended to increase coherence, while gain significantly decreased. These results are consistent with a nonlinear control system. The 2 degrees amplitude elicited the largest gain with significant coherence across all stimulated frequencies, suggesting it is suitable for studying visual contributions to postural control during movement execution.

Navigating public environments requires adjustments to ones walking patterns to avoid stationary and moving obstacles. It is known that physical inactivity induces alterations in motor capacities, but the impact of inactivity on anticipatory locomotor adjustments (ALA) has not been studied. The purpose of the present study was to compare ALAs and related muscle co-contraction during a pedestrian circumvention task between active (AA) and inactive young adults (IA). Thirteen AA and thirteen IA were placed in a virtual environment simulating a public park. Participants circumvented virtual pedestrians walking towards them. Walking speed, onset of deviation, clearance, foot placement strategies and muscle co-contraction were analysed. IA exhibited slower walking speeds compared to the AA during circumvention condition but not during unobstructed walking condition. The distance at the onset of trajectory deviation was larger for IA. Both groups increased co-contraction for pedestrian circumvention at the ankle and left hip and IA displayed greater ankle co-contraction overall. No significant group differences were observed in minimum clearance. This study suggests that an inactive lifestyle influences ALAs by inducing a cautious behavior during pedestrian circumvention.