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Background: Falls are common in a range of clinical cohorts, where routine risk assessment often comprises subjective visual observation only. Typically, observational assessment involves evaluation of an individual's gait during scripted walking protocols within a lab to identify deficits that potentially increase fall risk, but subtle deficits may not be (readily) observable. Therefore, objective approaches (e.g., inertial measurement units, IMUs) are useful for quantifying high resolution gait characteristics, enabling more informed fall risk assessment by capturing subtle deficits. However, IMU-based gait instrumentation alone is limited, failing to consider participant behaviour and details within the environment (e.g., obstacles). Video-based eye-tracking glasses may provide additional insight to fall risk, clarifying how people traverse environments based on head and eye movements. Recording head and eye movements can provide insights into how the allocation of visual attention to environmental stimuli influences successful navigation around obstacles. Yet, manual review of video data to evaluate head and eye movements is time-consuming and subjective. An automated approach is needed but none currently exists. This paper proposes a deep learning-based object detection algorithm (VARFA) to instrument vision and video data during walks, complementing instrumented gait., Method: The approach automatically labels video data captured in a gait lab to assess visual attention and details of the environment. The proposed algorithm uses a YoloV8 model trained on with a novel lab-based dataset., Results: VARFA achieved excellent evaluation metrics (0.93 mAP50), identifying, and localizing static objects (e.g., obstacles in the walking path) with an average accuracy of 93%. Similarly, a U-NET based track/path segmentation model achieved good metrics (IoU 0.82), suggesting that the predicted tracks (i.e., walking paths) align closely with the actual track, with an overlap of 82%. Notably, both models achieved these metrics while processing at real-time speeds, demonstrating efficiency and effectiveness for pragmatic applications., Conclusion: The instrumented approach improves the efficiency and accuracy of fall risk assessment by evaluating the visual allocation of attention (i.e., information about when and where a person is attending) during navigation, improving the breadth of instrumentation in this area. Use of VARFA to instrument vision could be used to better inform fall risk assessment by providing behaviour and context data to complement instrumented e.g., IMU data during gait tasks. That may have notable (e.g., personalized) rehabilitation implications across a wide range of clinical cohorts where poor gait and increased fall risk are common., (© 2024. The Author(s).)

Objective . Gait assessments have traditionally been analysed in laboratory settings, but this may not reflect natural gait. Wearable technology may offer an alternative due to its versatility. The purpose of the study was to establish the validity and reliability of temporal gait outcomes calculated by the DANU sports system, against a 3D motion capture reference system. Approach . Forty-one healthy adults (26 M, 15 F, age 36.4 ± 11.8 years) completed a series of overground walking and jogging trials and 60 s treadmill walking and running trials at various speeds (8-14 km hr -1 ), participants returned for a second testing session to repeat the same testing. Main results . For validity, 1406 steps and 613 trials during overground and across all treadmill trials were analysed respectively. Temporal outcomes generated by the DANU sports system included ground contact time, swing time and stride time all demonstrated excellent agreement compared to the laboratory reference (intraclass correlation coefficient (ICC) > 0.900), aside from ground contact time during overground jogging which had good agreement (ICC = 0.778). For reliability, 666 overground and 511 treadmill trials across all speeds were examined. Test re-test agreement was excellent for all outcomes across treadmill trials (ICC > 0.900), except for swing time during treadmill walking which had good agreement (ICC = 0.886). Overground trials demonstrated moderate to good test re-test agreement (ICC = 0.672-0.750), which may be due to inherent variability of self-selected (rather than treadmill set) pacing between sessions. Significance . Overall, this study showed that temporal gait outcomes from the DANU Sports System had good to excellent validity and moderate to excellent reliability in healthy adults compared to an established laboratory reference., (Creative Commons Attribution license.)

Background. Gait impairments are common in Parkinson's disease (PD) and increase falls risk. Visual cues can improve gait in PD, particularly freezing of gait (FOG), but mechanisms involved in visual cue response are unknown. This study aimed to examine brain activity in response to visual cues in people with PD who do (PD+FOG) and do not report FOG (PD-FOG) and explore relationships between attention, brain activity and gait. Methods . Mobile EEG measured brain activity during gait in 20 healthy older adults and 43 PD participants (n=22 PD+FOG, n=21 PD-FOG). Participants walked for 2-minutes with and without visual cues (transverse lines to step over). We report power spectral density (PSD) in Delta (1-4 Hz), Theta (4-7 Hz), Alpha (8-12 Hz), Beta (14-24 Hz) and Gamma (30-50 Hz) bands within clusters of similarly brain localized independent component sources. Results . PSDs within the parietal and occipital lobes were altered when walking with visual cues in PD, particularly in PD+FOG. Between group, differences suggested that parietal sources in PD, particularly with PD+FOG, had larger activity compared to healthy older adults when walking. Within group, visual cues altered brain activity in PD, particularly in PD+FOG, within visual processing brain regions. In PD participants, brain activity differences with cues correlated with gait improvements, and in PD+FOG those with worse attention required more visual attentional processing (reduced alpha PSD) in the occipital lobe. Conclusions . Visual cues improve gait and influence brain activity during walking in PD, particularly in PD+FOG. Findings may allow development of more effective therapeutics.

There is a dearth of knowledge about how symptom severity affects gait in the chronic (>3 months) mild traumatic brain injury (mTBI) population despite up to 53% of people reporting persisting symptoms after mTBI. The aim of this investigation was to determine whether gait is affected in a symptomatic, chronic mTBI group and to assess the relationship between gait performance and symptom severity on the Neurobehavioral Symptom Inventory (NSI). Gait was assessed under single- and dual-task conditions using five inertial sensors in 57 control subjects and 65 persons with chronic mTBI (1.0 year from mTBI). The single- and dual-task gait domains of Pace, Rhythm, Variability, and Turning were calculated from individual gait characteristics. Dual-task cost (DTC) was calculated for each domain. The mTBI group walked (domain z-score mean difference, single-task = 0.70; dual-task = 0.71) and turned (z-score mean difference, single-task = 0.69; dual-task = 0.70) slower ( p  < 0.001) under both gait conditions, with less rhythm under dual-task gait (z-score difference = 0.21; p  = 0.001). DTC was not different between groups. Higher NSI somatic subscore was related to higher single- and dual-task gait variability as well as slower dual-task pace and turning ( p  < 0.01). Persons with chronic mTBI and persistent symptoms exhibited altered gait, particularly under dual-task, and worse gait performance related to greater symptom severity. Future gait research in chronic mTBI should assess the possible underlying physiological mechanisms for persistent symptoms and gait deficits.

Background: Walking abnormalities in people with Parkinson's disease (PD) are characterized by a shift in locomotor control from healthy automaticity to compensatory prefrontal executive control. Indirect measures of automaticity of walking (eg, step-to-step variability and dual-task cost) suggest that freezing of gait (FoG) may be associated with reduced automaticity of walking. However, the influence of FoG status on actual prefrontal cortex (PFC) activity during walking remains unclear., Objective: To investigate the influence of FoG status on automaticity of walking in people with PD., Methods: Forty-seven people with PD were distributed into 2 groups based on FoG status, which was assessed by the New Freezing of Gait Questionnaire: PD-FoG (n = 23; UPDRS-III = 35) and PD+FoG (n = 24; UPDRS-III = 43.1). Participants walked over a 9-m straight path (with a 180° turn at each end) for 80 seconds. Two conditions were tested off medication: single- and dual-task walking (ie, with a concomitant cognitive task). A portable functional near-infrared spectroscopy system recorded PFC activity while walking (including turns). Wearable inertial sensors were used to calculate spatiotemporal gait parameters., Results: PD+FoG had greater PFC activation during both single and dual-task walking than PD-FoG ( P = .031). There were no differences in gait between PD-FoG and PD+FoG. Both groups decreased gait speed ( P = .029) and stride length ( P < .001) during dual-task walking compared with single-task walking., Conclusions: These findings suggest that PD+FoG have reduced automaticity of walking, even in absence of FoG episodes. PFC activity while walking seems to be more sensitive than gait measures in identifying reduction in automaticity of walking in PD+FoG.

Background and Purpose: Gait and turning impairments are common in people with Parkinson disease (PwPD). Tactile cues delivered in open- or closed-loop modalities may improve gait and turning in PwPD, but underlying mechanisms are unclear. Attention stemming from the prefrontal cortex (PFC) may play a role in cue response, but PFC contributions to specific cue modalities are unclear. Examining how open- and closed-loop cueing influences PFC activity during walking and turning in PwPD may elucidate mechanisms involved in cue response, which could advance development of effective therapeutics. We examined PFC activity during walking and turning in response to open- and closed-loop cueing in PwPD, and explored relationships between PFC activity and behavioral measures., Methods: A mobile functional near-infrared spectroscopy device measured PFC activity during walking and turning in 25 PwPD (n = 13 freezers, n = 12 nonfreezers). Participants performed 180° and 360° turns while walking, and a 2-minute walk under single- and dual-task (AX-CPT) conditions with and without an open- (metronome-like vibration) or closed-loop (biofeedback vibration) tactile cue., Results: PFC activity did not change when walking or turning in PwPD; freezing status or task demands did not influence PFC activity. With both open- and closed-loop cueing dual-task cost of gait significantly improved, whereas turning slowed., Discussion and Conclusions: Our preliminary results indicate that both open- and closed-loop cueing can improve gait without additional burden to the PFC beyond usual walking. However, turning while walking slowed with cueing with no PFC activity change. Further investigations are necessary to establish these findings in a larger cohort.Video Abstract available for more insights from the authors (see Supplemental Digital Content 1, the Video, available at: http://links.lww.com/JNPT/A280).

Objective: Saccadic (fast) eye movements are a routine aspect of neurological examination and are a potential biomarker of mild traumatic brain injury (mTBI). Objective measurement of saccades has become a prominent focus of mTBI research, as eye movements may be a useful assessment tool for deficits in neural structures or processes. However, saccadic measurement within mobile infra-red (IR) eye-tracker raw data requires a valid algorithm. The objective of this study was to validate a velocity-based algorithm for saccade detection in IR eye-tracking raw data during walking (straight ahead and while turning) in people with mTBI and healthy controls., Approach: Eye-tracking via a mobile IR Tobii Pro Glasses 2 eye-tracker (100 Hz) was performed in people with mTBI (n  =  10) and healthy controls (n  =  10). Participants completed two walking tasks: straight walking (walking back and forth for 1 min over a 10 m distance), and walking and turning (turns course included 45°, 90° and 135° turns). Five trials per subject, for one-hundred total trials, were completed. A previously reported velocity-based saccade detection algorithm was adapted and validated by assessing agreement between algorithm saccade detections and the number of correct saccade detections determined from manual video inspection (ground truth reference)., Main Results: Compared with video inspection, the IR algorithm detected ~97% (n  =  4888) and ~95% (n  =  3699) of saccades made by people with mTBI and controls, respectively, with excellent agreement to the ground truth (intra-class correlation coefficient 2,1   =  .979 to .999)., Significance: This study provides a simple yet highly robust algorithm for the processing of mobile eye-tracker raw data in mTBI and controls. Future studies may consider validating this algorithm with other IR eye-trackers and populations.

Objective: To examine whether horizontal head turns while seated or while walking, when instrumented with inertial sensors, were sensitive to the acute effects of concussion and whether horizontal head turns had utility for concussion management., Setting: Applied field setting, athletic training room., Participants: Twenty-four collegiate athletes with sports-related concussion and 25 healthy control athletes., Design: Case-control; longitudinal., Main Measures: Peak head angular velocity and peak head angle (range of motion) when performing head turns toward an auditory cue while seated or walking. Gait speed when walking with and without head turns., Results: Athletes with acute sports-related concussion turned their head slower than healthy control subjects initially (group β = -49.47; SE = 16.33; P = .003) and gradually recovered to healthy control levels within 10 days postconcussion (group × time β = 4.80; SE = 1.41; P < .001). Peak head velocity had fair diagnostic accuracy in differentiating subjects with acute concussion compared with controls (areas under the receiver operating characteristic curve [AUC] = 0.71-0.73). Peak head angle (P = .17) and gait speed (P = .64) were not different between groups and showed poor diagnostic utility (AUC = 0.57-0.62)., Conclusion: Inertial sensors can improve traditional clinical assessments by quantifying subtle, nonobservable deficits in people following sports-related concussion.

Performance of several tasks simultaneously (dual-tasks) is common in everyday walking. Studies indicate that dual-task walking performance declines with age together with cognitive function, but neural mechanisms underpinning deficits remain unclear. Recent developments in mobile imaging techniques, such as functional near infrared spectroscopy (fNIRS), allow real-time monitoring of cortical activity during walking. This study aimed to: 1) examine activity in motor and cognitive cortical regions when walking with a dual-task in young and older adults; and 2) determine the effect of cognition on dual-task cortical activity changes. Seventeen young (20.3 ± 1.2 years) and eighteen older adults (72.6 ± 8.0 years) performed dual-task conditions, lasting 5 min, with alternating 30-second experimental blocks. The primary outcome was cortical activity, assessed by measuring changes in oxygenated haemoglobin (HbO 2 ) concentrations. Cortical regions of interest (ROI) included motor regions (premotor cortex (PMC), supplementary motor area (SMA), primary motor cortex (M1)), and cognitive regions (prefrontal cortex (PFC)). Cognitive domains were assessed using standard tests and accelerometers were used to extract gait features. Cortical activity increased with a dual-task in PMC, SMA and M1 but not in PFC regions across groups, with response most evident with initial task exposure. Older adults did not increase SMA activity with a dual-task to the same level as young adults. Dual-task cortical response was consistently associated with greater executive function across groups. In conclusion, both young and older adults responded in a similar manner to dual-task conditions. Dual-task walking activated multiple motor regions in both groups, but no significant change occurred for cognitive region activation. Cortical activation with a dual-task related to executive function., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Aging is associated with declining mobility, which negatively affects quality of life and incurs substantial economic costs. Techniques to maintain safe mobility in older adults are therefore essential. Rhythmic auditory cueing (RAC) can improve walking patterns in older adults. However, the neural correlates associated with RAC, how they are influenced by repeated exposure and their relationships with gait response, cognitive function, and depressive symptoms are unclear., Objectives: This study aimed to investigate the effects of RAC during walking on cortical activation and the relationship between RAC-related cortical changes and cognitive function, depressive symptoms, and gait response., Methods: Seventeen young adults and eighteen older adults walked on a motorized treadmill for 5 minutes (5 trials with alternating 30-second blocks of usual walking and RAC walking). Changes in oxygenated hemoglobin (HbO 2 ) in the frontal cortex were recorded using functional near-infrared spectroscopy. Cognitive domains were assessed through validated tests. A triaxial accelerometer measured gait parameters., Results: Gait variability decreased and prefrontal HbO 2 levels increased during cued walking relative to usual walking. Older adults showed greater HbO 2 levels in multiple motor regions during cued walking although the response reduced with repeated exposure. In older adults, lower depression scores, higher cognitive functioning, and reduced gait variability were linked with increased HbO 2 levels during RAC walking., Conclusion: These findings suggest that walking improves with RAC in older adults and is achieved through increased activity in multiple cortical areas. The cortical response decline with repeated exposure indicates older adults' ability to adapt to a new task.

An emerging body of literature has examined cortical activity during walking and balance tasks in older adults and in people with Parkinson's disease, specifically using functional near infrared spectroscopy (fNIRS) or electroencephalography (EEG). This review provides an overview of this developing area, and examines the disease-specific mechanisms underlying walking or balance deficits. Medline, PubMed, PsychInfo and Scopus databases were searched. Articles that described cortical activity during walking and balance tasks in older adults and in those with PD were screened by the reviewers. Thirty-seven full-text articles were included for review, following an initial yield of 566 studies. This review summarizes study findings, where increased cortical activity appears to be required for older adults and further for participants with PD to perform walking and balance tasks, but specific activation patterns vary with the demands of the particular task. Studies attributed cortical activation to compensatory mechanisms for underlying age- or PD-related deficits in automatic movement control. However, a lack of standardization within the reviewed studies was evident from the wide range of study protocols, instruments, regions of interest, outcomes and interpretation of outcomes that were reported. Unstandardized data collection, processing and reporting limited the clinical relevance and interpretation of study findings. Future work to standardize approaches to the measurement of cortical activity during walking and balance tasks in older adults and people with PD with fNIRS and EEG systems is needed, which will allow direct comparison of results and ensure robust data collection/reporting. Based on the reviewed articles we provide clinical and future research recommendations., (Copyright © 2018. Published by Elsevier B.V.)

We validate a novel algorithm to detect saccades from raw data obtained during walking from a mobile infra-red eye-tracking device. The algorithm was based on a velocity threshold detection method, which excluded artefacts such as blinks and flickers using specific criteria. Mobile infra-red eye-tracking was performed with a group of healthy older adults (n=5) and Parkinson's disease (n=5) subjects. Saccades determined from raw eye tracker data obtained during walking using the algorithm were compared to a ground truth dataset defined as frame-by-frame visual inspection of raw eye-tracking videos. 100 trials from 10 subjects were analyzed and compared. The algorithm was highly reliable when compared to the ground truth (ICC(2,1) = 0.94), with an overall correct saccade detection percentage of 85%. This provides a simple yet robust algorithm for the analysis of mobile eye-tracking data.

• Neck posture improved immediately with the UpRight in Parkinson's disease (PD) during sitting and standing. • Neck, trunk and low back posture did not improve with the UpRight during walking in PD. • Gait was worse when walking with the UpRight device compared to without in PD. • Postural improvement related to attentional capabilities of people with PD. • Self-reported feedback suggests that participants felt the UpRight was beneficial. This interventional pilot study aimed to 1) examine whether a novel wearable vibro-tactile feedback device ('UpRight Go') is effective and feasible to improve postural alignment in Parkinson's disease (PD); 2) explore relationships between postural alignment and attention in PD; 3) explore effect of vibro-tactile device on balance and gait; and 4) gain initial feedback on the use of the vibro-tactile device in the laboratory and at home. 25 people with PD sat, stood and walked for two-minutes without and with the UpRight device attached to their upper backs to provide feedback on postural alignment in the laboratory. A sub-group (n = 12) wore the UpRight device at home for 60 min. per day for 7-days of postural feedback. Subjective feedback on use of the device was obtained in the laboratory and at the end of the 7-day period. The primary outcome for this study was posture measured by verticality of inertial measurement units (IMUs) at the neck, trunk and low back, which was done with and without the UpRight device. Secondary outcomes included clinical measures of posture, subjective feedback on the device, computerized attention measures, gait and balance. Neck postural alignment in PD was significantly improved (reduced neck flexion) with the UpRight during sitting and standing in both clinical measures (p = 0.005) and IMU outcomes (p = 0.046), but trunk and low back posture did not change. There was no change in postural alignment during walking with the UpRight. Postural alignment response was related to attentional capabilities. Many subjects (68 %) reported that they felt a benefit from the UpRight and most participants reported that the device was acceptable (Lab use; 72 %, Home use; 75 %). The UpRight Go feedback device may improve neck/upper-back posture in PD during sitting and standing, but not during walking. Postural alignment response to the device may depend on attentional mechanisms. [ABSTRACT FROM AUTHOR]

Introduction: Mobility declines with age and further with neurodegenerative disorders, such as Parkinson's disease (PD). Walking and turning ability, in particular, are vital aspects of mobility that deteriorate with age and are further impaired in PD. Such deficits have been linked with reduction in automatic control of movement and the need for compensatory cognitive cortical control via the pre-frontal cortex (PFC), however the underlying neural mechanisms remain unclear. Establishing and using a robust methodology to examine PFC activity during continuous walking and turning via mobile functional near infra-red spectroscopy (fNIRS) may aid in the understanding of mobility deficits and help with development of appropriate therapeutics. This study aimed to: (1) examine test re-test reliability of PFC activity during continuous turning and walking via fNIRS measurement; and (2) compare PFC activity during continuous turning and walking in young, old and Parkinson's subjects. Methods: Twenty-five young (32.3 ± 7.5 years), nineteen older (65.4 ± 7.0 years), and twenty-four PD (69.3 ± 4.1 years) participants performed continuous walking and 360° turning-in-place tasks, each lasting 2 min. Young participants repeated the tasks a second time to allow fNIRS measurement reliability assessment. The primary outcome was PFC activity, assessed via measuring changes in oxygenated hemoglobin (HbO2) concentrations. Results: PFC activity during continuous walking and turning was moderately reproducible (Intra-class correlation coefficient = 0.67). The PD group had higher PFC activation than young and older adults during walking and turning, with significant group differences for bilateral PFC activation (p = 0.025), left PFC activation (p = 0.012), and the early period (first 40 s) of walking (p = 0.007), with greater activation required in PD. Interestingly, older adults had similar PFC activation to young adults across conditions, however older adults required greater activation than young adults during continuous turning, specifically the early period of the turning task (Cohens d = 0.86). Conclusions: PFC activity can be measured during continuous walking and turning tasks with acceptable reliability, and can differentiate young, older and PD groups. PFC activation was significantly greater in PD compared to young and older adults during walking, particularly when beginning to walk. [ABSTRACT FROM AUTHOR]

Eye movements are impaired by Parkinson’s disease (PD) although limited research has explored if PD affects the relevance of visual fixations when walking. Visual fixations may provide crucial contextual information for safe navigation and important insights into fall risk. This study aimed to: investigate visual fixations made while walking under a range of conditions in PD; identify their task relevance; and explore their relationship with clinical features. Thirty-eight people with mild-moderate PD and forty age-matched control participants completed a straight walk with (i) no additional stimuli and (ii) with additional stimuli (visual cues or a high contrast obstacle), whilst wearing a mobile eye-tracker. Fixations were extracted and classified by location and relevance. PD participants made proportionally fewer task-relevant fixations (floor, walls and additional stimuli ahead), caused by significantly more task-irrelevant fixations (floor, walls and ceiling away from waking path) during normal walking ( p  = 0.014). These group differences were not apparent with visual cues ( p  = 0.359). During obstacle crossing trials, PD made significantly more task-relevant fixations than controls ( p  = 0.007). Reduced bilateral visual acuity was associated with fewer fixations in PD. Our findings suggest that people with PD visually explore complex environments less efficiently likely owing to underlying PD pathology. Visual exploration improved with the addition of salient stimuli (for example visual cues or an obstacle) and thus developing and optimising visual interventions could prove critical to improving locomotor safety and reducing falls risk in home environments. [ABSTRACT FROM AUTHOR]

Gait impairment is a core feature of Parkinson's disease ( PD) which has been linked to cognitive and visual deficits, but interactions between these features are poorly understood. Monitoring saccades allows investigation of real-time cognitive and visual processes and their impact on gait when walking. This study explored: (i) saccade frequency when walking under different attentional manipulations of turning and dual-task; and (ii) direct and indirect relationships between saccades, gait impairment, vision and attention. Saccade frequency (number of fast eye movements per-second) was measured during gait in 60 PD and 40 age-matched control participants using a mobile eye-tracker. Saccade frequency was significantly reduced in PD compared to controls during all conditions. However, saccade frequency increased with a turn and decreased under dual-task for both groups. Poorer attention directly related to saccade frequency, visual function and gait impairment in PD, but not controls. Saccade frequency did not directly relate to gait in PD, but did in controls. Instead, saccade frequency and visual function deficit indirectly impacted gait impairment in PD, which was underpinned by their relationship with attention. In conclusion, our results suggest a vital role for attention with direct and indirect influences on gait impairment in PD. Attention directly impacted saccade frequency, visual function and gait impairment in PD, with connotations for falls. It also underpinned indirect impact of visual and saccadic impairment on gait. Attention therefore represents a key therapeutic target that should be considered in future research. [ABSTRACT FROM AUTHOR]

Background: Functional near-infrared spectroscopy (fNIRS) is increasingly used in the field of posture and gait to investigate patterns of cortical brain activation while people move freely. fNIRS methods, analysis and reporting of data vary greatly across studies which in turn can limit the replication of research, interpretation of findings and comparison across works.Research Question and Methods: Considering these issues, we propose a set of practical recommendations for the conduct and reporting of fNIRS studies in posture and gait, acknowledging specific challenges related to clinical groups with posture and gait disorders.Results: Our paper is organized around three main sections: 1) hardware set up and study protocols, 2) artefact removal and data processing and, 3) outcome measures, validity and reliability; it is supplemented with a detailed checklist.Significance: This paper was written by a core group of members of the International Society for Posture and Gait Research and posture and gait researchers, all experienced in fNIRS research, with the intent of assisting the research community to lead innovative and impactful fNIRS studies in the field of posture and gait, whilst ensuring standardization of research. [ABSTRACT FROM AUTHOR]