In order to address whether increased levels of movement output variability indicate pathological performance, we systematically reviewed and synthesized meta-analysis data on healthy and pathological motor behavior. After screening up to 24'000 reports from four databases, 85 studies were included containing 2409 patients and 2523 healthy asymptomatic controls. The optimal thresholds of variability with uncertainty boundaries (in % Coefficient of Variation ± Standard Error) were estimated in 7 parameters: stride time (2.34 ± 0.21), stride length (2.99 ± 0.37), step length (3.34 ± 0.84), swing time (2.94 ± 0.60), step time (3.35 ± 0.23), step width (15.87 ± 1.86), and dual-limb support time (6.08 ± 2.83). All spatio-temporal parameters exhibited a positive effect size (pathology led to increased variability) except step width variability (Effect Size = -0.21). By objectively benchmarking thresholds for pathological motor variability also presented through a case-study, this review provides access to movement signatures to understand neurological changes in an individual that are apparent in movement variability. The comprehensive evidence presented now qualifies stride time variability as a movement biomarker, endorsing its applicability as a viable outcome measure in clinical trials.

Background. Subthalamic deep brain stimulation (STN-DBS) is an effective treatment for selected Parkinson’s disease (PD) patients. Gait characteristics are often altered after surgery, but quantitative therapeutic effects are poorly described. Objective. The goal of this study was to systematically investigate modifications in asymmetry and dyscoordination of gait 6 months postoperatively in patients with PD and compare the outcomes with preoperative baseline and to asymptomatic controls without PD. Methods. A convenience sample of thirty-two patients with PD (19 with postural instability and gait disorder (PIGD) type and 13 with tremor dominant disease) and 51 asymptomatic controls participated. Parkinson patients were tested prior to the surgery in both OFF and ON medication states, and 6-months postoperatively in the ON stimulation condition. Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) I to IV and medication were compared to preoperative conditions. Asymmetry ratios, phase coordination index, and walking speed were assessed. Results. MDS-UPDRS I to IV at 6 months improved significantly, and levodopa equivalent daily dosages significantly decreased. STN-DBS increased step time asymmetry (hedges’ g effect sizes [95% confidence interval] between pre- and post-surgery: .27 [-.13, .73]) and phase coordination index (.29 [-.08, .67]). These effects were higher in the PIGD subgroup than the tremor dominant (step time asymmetry: .38 [-.06, .90] vs .09 [-.83, 1.0] and phase coordination index: .39 [-.04, .84] vs .13 [-.76, .96]). Conclusions. This study provides objective evidence of how STN-DBS increases asymmetry and dyscoordination of gait in patients with PD and suggests motor subtypes‐associated differences in the treatment response.

Clinical Gait Analysis is essential for understanding functional ability and diagnosing neuromotor conditions but remains resource-intensive, often requiring expensive, immobile equipment. Wearable inertial measurement units (IMUs) offer a promising alternative for real-world functional assessment, yet a lack of standardisation in sensor placement presents a significant challenge. This study aimed to develop and evaluate deep learning models (specifically convolutional neural networks (CNN) and temporal convolutional networks (TCN),) by comparing F1 scores and temporal error percentile between predicted and target gait events using IMUs placed at clinical locations (head, pelvis, wrist, and feet) in young and older adults. Our findings demonstrated that TCN consistently scored higher F1 scores with lower standard error across both young and older adult groups. Specifically, the TCN with head sensor achieved the highest F1 scores of 95.9% in younger individuals and 93.8% in older participants for heel strike, highlighting the robustness of TCN models in capturing temporal dependencies for accurate gait event detection. In contrast, CNN models exhibited higher standard of error, with up to 20% differences between age groups showing age depedent influence. Temporal error analysis showed comparable performance between CNN and TCN models across most placements. Integrating gyroscope data with accelerometer signals improved F1 score, particularly for head and foot sensors. This research systematically evaluates optimal sensor placements and demonstrates the robust performance of TCN models, laying a foundation for future research. Expanded cohorts and validation in free-living environments are needed to enhance the generalisability of IMU-based gait analysis.

Purpose: Maintaining stable gait patterns is essential for preserving health and well-being throughout the aging process. While several biomechanical models have been developed to describe gait adaptation and stability, the role of reflex control mechanisms remains underexplored. This study aimed to understand the mechanisms by which disturbances to gait patterns (changes to weight-bearing conditions) are influencing gait adaptations, gait variability, and their underlying reflex control mechanisms during treadmill walking in young and older adults. Methods: Twenty young (mean age 25.7 ± 3.3 years) and 20 older adults (62.3 ± 4.3 years) walked on a treadmill under five weight-bearing conditions: normal bodyweight, 20 and 40% additional weight (bodyweight loading), and 20 and 40% reduced weight (bodyweight unloading). Linear mixed-effects models were used to assess spatiotemporal gait parameters, margin of stability, gait variability (standard deviation), and H-reflex amplitudes. Results: Bodyweight unloading significantly reduced antero-posterior margin of stability ( p < 0.01). Compared to young adults, older adults exhibited shorter stride length, longer double-limb support time, larger antero-posterior margin of stability, and increased variability ( p < 0.05). While H-reflex amplitudes increased with increasing weight-bearing in young adults, older adults were less capable to modulate their H-reflex amplitude across weight conditions. Conclusion: These findings suggest that gait adaptations under altered weight-bearing conditions involve shifts in temporal gait regulation and gait strategies. The reduced H-reflex modulation in older adults may indicate a limited ability to adapt spinal-level reflex amplitudes, leading to greater reliance on other balance control mechanisms. Understanding these neuromuscular adaptations is essential for designing prevention programs to enhance stability and prevent falls. Graphical

Children that are diagnosed with Idiopathic Toe walking (cITW) are characterized by persistent toe-to-toe contacts. The objective of this study was to explore whether typical foot contact dynamics during walking predisposes cITW to a higher risk of falling. Twenty cITW and age-matched controls performed typical and toe walking trials. The gait parameters related to foot contact dynamics, vertical force impulses during stance, slip, and trip risk were compared for both groups. We found that cITW manifest less stable gait and produced significantly higher force impulses during push-off. Additionally, we found that cITW had a higher slip-initiation risk that was associated with higher foot contact horizontal and vertical velocities in addition to lower transitional acceleration of center of mass. We found that cITW exhibited a higher trip risk with toe clearance being significantly lower when compared to healthy counterparts. This study allowed for a quantitative description of foot contact dynamics and delineated typical from toe walking among cITW. Overall, the results indicate that cITW are less stable during typical walking and are prone to a higher risk of slip and trip-like falls.

Children with idiopathic toe walking present with reduced ankle mobility, impaired balance, and difficulties in motor control. There is a need to diagnose idiopathic toe walking in a holistic manner and improve the monitoring of interventions. The aim is to assess dynamic stability with measures of margin of stability and whole-body angular momentum and evaluate their clinical relevance. A retrospective cross-sectional study with 35 idiopathic toe walkers (23 male, mean age (SD) 10.0 (2.9) years) and 20 typically developing controls (10 male, 11.4 (2.8) years). All participants had a clinical gait analysis at the local hospital. Dynamic stability was assessed with margin of stability, whole-body angular momentum, GaitSD, and spatiotemporal gait parameters. Student t-tests with adjustments for multiple comparisons were performed. Margin of stability in anterior direction was significantly shorter (ES = 1.29) and whole-body angular momentum in the coronal plane was significantly larger (ES = 0.90) in idiopathic toe walkers compared to typically developing children. No other results were below the set threshold for significance. Children with idiopathic toe walking continue to use an immature, falling forward movement strategy to maintain forward momentum. It is probable that those children adopted toe walking behavior to support increased energy absorption during the initial fall. Furthermore, the addition of dynamic stability measures not only provides insight into their ability to balance, these measures also allow an understanding of the plausible strategies adopted during walking and could potentially improve diagnosis and quantification of therapeutic outcomes.