IMU Data-Driven and PCA-Based Approach to Establish Quantifiable and Practically Applicable Measures for V2 Technique Elements in Cross-Country Skiing.

Quantifying movement coordination in cross-country (XC) skiing, specifically the technique with its elemental forms, is challenging. Particularly, this applies when trying to establish a bidirectional transfer between scientific theory and practical experts' knowledge as expressed, for example, in ski instruction curricula. The objective of this study was to translate 14 curricula-informed distinct elements of the V2 ski-skating technique (horizontal and vertical posture, lateral tilt, head position, upper body rotation, arm swing, shoulder abduction, elbow flexion, hand and leg distance, plantar flexion, ski set-down, leg push-off, and gliding phase) into plausible, valid and applicable measures to make the technique training process more quantifiable and scientifically grounded. Inertial measurement unit (IMU) data of 10 highly experienced XC skiers who demonstrated the technique elements by two extreme forms each (e.g., anterior versus posterior positioning for the horizontal posture) were recorded. Element-specific principal component analyses (PCAs)-driven by the variance produced by the technique extremes-resulted in movement components that express quantifiable measures of the underlying technique elements. Ten measures were found to be sensitive in distinguishing between the inputted extreme variations using statistical parametric mapping (SPM), whereas for four elements the SPM did not detect differences (lateral tilt, plantar flexion, ski set-down, and leg push-off). Applicability of the established technique measures was determined based on quantifying individual techniques through them. The study introduces a novel approach to quantitatively assess V2 ski-skating technique, which might help to enhance technique feedback and bridge the communication gap that often exists between practitioners and scientists.

Response of Knee Joint Biomechanics to Landing Under Internal and External Focus of Attention in Female Volleyball Players.

The aim of this study was to examine the effect of attentional focus instructions on the biomechanical variables associated with the risk of anterior cruciate ligament injury of the knee joint during a drop landing task using a time series analysis. Ten female volleyball players (age: 20.4 ± 0.8 years, height: 169.7 ± 7.1 cm, mass: 57.6 ± 3.1 kg, experience: 6.3 ± 0.8 years) performed landings from a 50 cm height under three different attentional focus conditions: (1) external focus (focus on landing as soft as possible), (2) internal focus (focus on bending your knees when you land), and (3) control (no-focus instruction). Statistical parameter mapping in the sagittal plane during the crucial first 30% of landing time showed a significant effect of attentional focus instructions. Despite the similarity in landing performance across foci instructions, adopting an external focus instruction promoted reduced vertical ground reaction force and lower sagittal flexion moment during the first 30% of execution time compared to internal focus, suggesting reduced knee loading. Therefore, adopting an external focus of attention was suggested to reduce most biomechanical risk variables in the sagittal plane associated with anterior cruciate ligament injuries, compared to internal focus and control condition. No significant differences were found in the frontal and horizontal planes between the conditions during this crucial interval.

Exercise Influences the Brain's Metabolic Response to Chronic Cocaine Exposure in Male Rats.

Cocaine use is associated with negative health outcomes: cocaine use disorders, speedballing, and overdose deaths. Currently, treatments for cocaine use disorders and overdose are non-existent when compared to opioid use disorders, and current standard cocaine use disorder treatments have high dropout and recidivism rates. Physical exercise has been shown to attenuate addiction behavior as well as modulate brain activity. This study examined the differential effects of chronic cocaine use between exercised and sedentary rats. The effects of exercise on brain glucose metabolism (BGluM) following chronic cocaine exposure were assessed using Positron Emission Tomography (PET) and [18F]-Fluorodeoxyglucose (FDG). Compared to sedentary animals, exercise decreased metabolism in the SIBF primary somatosensory cortex. Activation occurred in the amygdalopiriform and piriform cortex, trigeminothalamic tract, rhinal and perirhinal cortex, and visual cortex. BGluM changes may help ameliorate various aspects of cocaine abuse and reinstatement. Further investigation is needed into the underlying neuronal circuits involved in BGluM changes and their association with addiction behaviors.

In-vivo 3-dimensional spine and lower body gait symmetry analysis in healthy individuals.

Background: Numerous research studies have delved into the biomechanics of walking, focusing on the spine and lower extremities. However, understanding the symmetry of walking in individuals without health issues poses a challenge, as those with normal mobility may exhibit uneven movement patterns due to inherent functional differences between their left and right limbs. The goal of this study is to examine the three-dimensional kinematics of gait symmetry in the spine and lower body during both typical and brisk overground walking in healthy individuals. The analysis will utilize statistical methods and symmetry index approaches. Furthermore, the research aims to investigate whether factors such as gender and walking speed influence gait symmetry. Methods: Sixty young adults in good health, comprising 30 males and 30 females, underwent motion capture recordings while engaging in both normal and fast overground walking. The analysis focused on interlimb comparisons and corresponding assessments of side-specific spine and pelvis motions. Results: Statistical Parametric Mapping (SPM) predominantly revealed gait symmetries between corresponding left and right motions in the spine, pelvis, hip, knee, and ankle during both normal and fast overground walking. Notably, both genders exhibited asymmetric pelvis left-right obliquity, with women and men showing an average degree of asymmetry between sides of 0.9 ± 0.1° and 1.5 ± 0.1°, respectively. Furthermore, the analysis suggested that neither sex nor walking speed appeared to exert influence on the 3D kinematic symmetry of the spine, pelvis, and lower body in healthy individuals during gait. While the maximum normalized symmetry index (SInorm) values for the lower thorax, upper lumbar, lower lumbar, pelvis, hip, knee, and ankle displayed significant differences between sexes and walking speeds for specific motions, no interaction between sex and walking speed was observed. Significance: The findings underscore the potential disparities in data interpretations between the two approaches. While SPM discerns temporal variations in movement, these results offer valuable insights that may enhance our comprehension of gait symmetry in healthy individuals, surpassing the limitations of straightforward discrete parameters like the maximum SInorm. The information gleaned from this study could serve as reference indicators for diagnosing and evaluating abnormal gait function.

The impact of pediatric obesity on biomechanical differences across the gait cycle at three walking speeds.

BACKGROUND: Obesity impacts a child's ability to walk with resulting biomechanical adaptations; however, existing research has not comprehensively compared differences across the gait cycle. We examined differences in lower extremity biomechanics across the gait cycle between children with and without obesity at three walking speeds. METHODS: Full gait cycles of age-matched children with obesity (N = 10; BMI: 25.7 ± 4.2 kg/m2) and without obesity (N = 10; BMI: 17.0 ± 1.9 kg/m2) were analyzed at slow, normal, and fast walking speeds. Main and interaction effects of group and speed across hip, knee, and ankle joint angles and moments in sagittal, frontal, and transverse planes were analyzed using one-dimensional statistical parametric mapping. FINDINGS: Compared to children without obesity, children with obesity had greater hip adduction during mid-stance, while also producing greater hip extensor moments during early stance phase, abductor moments throughout most of stance, and hip external rotator moments during late stance. Children with obesity recorded greater knee flexor, knee extensor and knee internal rotator moments during early stance, and knee external rotator moments in late stance than children without obesity; children with obesity also demonstrated greater ankle plantarflexor moments throughout mid and late stance. Interaction effects existed within joint kinetics data; children with obesity produced greater hip extensor moments at initial contact and toe-off when walking at fast compared to normal walking speed. INTERPRETATION: While few kinematic differences existed between the two groups, children with obesity exhibited greater moments at the hip, knee, and ankle during critical periods of controlling and stabilizing mass.

Trial- vs. cycle-level detrending in the analysis of cyclical biomechanical data.

Biomechanical time series may contain low-frequency trends due to factors like electromechanical drift, attentional drift and fatigue. Existing detrending procedures are predominantly conducted at the trial level, removing trends that exist over finite, adjacent time windows, but this fails to consider what we term 'cycle-level trends': trends that occur in cyclical movements like gait and that vary across the movement cycle, for example: positive and negative drifts in early and late gait phases, respectively. The purposes of this study were to describe cycle-level detrending and to investigate the frequencies with which cycle-level trends (i) exist, and (ii) statistically affect results. Anterioposterior ground reaction forces (GRF) from the 41-subject, 8-speed, open treadmill walking dataset of Fukuchi (2018) were analyzed. Of a total of 552 analyzed trials, significant cycle-level trends were found approximately three times more frequently (21.1%) than significant trial-level trends (7.4%). In statistical comparisons of adjacent walking speeds (i.e., speed 1 vs. 2, 2 vs. 3, etc.) just 3.3% of trials exhibited cycle-level trends that changed the null hypothesis rejection decision. However 17.6% of trials exhibited cycle-level trends that qualitatively changed the stance phase regions identified as significant. Although these results are preliminary and derived from just one dataset, results suggest that cycle-level trends can contribute to analysis bias, and therefore that cycle-level trends should be considered and/or removed where possible. Software implementing the proposed cycle-level detrending is available at https://github.com/0todd0000/detrend1d.

Brain 18 F-FDG PET reveals cortico-subcortical hypermetabolic dysfunction in juvenile neuropsychiatric systemic lupus erythematosus.

BACKGROUND: In juvenile systemic lupus erythematosus (j-SLE) with neuropsychiatric (NP) symptoms, there is a lack of diagnostic biomarkers. Thus, we study whether PET-FDG may identify any metabolic dysfunction in j-NPSLE. METHODS: A total of 19 18FDG-PET exams were consecutively performed using PET-MRI system in 11 non-sedated patients presenting with j-NPSLE (11-18y) for less than 18 months (m) and without any significant lesion at MRI. Psychiatric symptoms were scored from 0 (none) to 3 (severe) at PET time. PET images were visually analyzed and voxel-based analyses of cerebral glucose metabolism were performed using statistical parametric mapping (spm) with an age-matched control group, at threshold set > 50 voxels using both p < 0.001 uncorrected (unc.) and p < 0.05 corrected family wise error (FWE). RESULTS: Patients exhibited mainly psychiatric symptoms, with diffuse inflammatory j-NPSLE. First PET (n = 11) was performed at a mean of 15y of age, second/third PET (n = 7/n = 1) 6 to 19 m later. PET individual analysis detected focal bilateral anomalies in 13/19 exams visually but 19/19 using spm (unc.), mostly hypermetabolic areas (18/19). A total of 15% of hypermetabolic areas identified by spm had been missed visually. PET group analysis (n = 19) did not identify any hypometabolic area, but a large bilateral cortico-subcortical hypermetabolic pattern including, by statistical decreasing order (unc.), thalamus, subthalamic brainstem, cerebellum (vermis and cortex), basal ganglia, visual, temporal and frontal cortices. Mostly the subcortical hypermetabolism survived to FWE analysis, being most intense and extensive (51% of total volume) in thalamus and subthalamus brainstem. Hypermetabolism was strictly subcortical in the most severe NP subgroup (n = 8, scores 2-3) whereas it also extended to cerebral cortex, mostly visual, in the less severe subgroup (n = 11, scores 0-1), but difference was not significant. Longitudinal visual analysis was inconclusive due to clinical heterogeneity. CONCLUSIONS: j-NPSLE patients showed a robust bilateral cortico-subcortical hypermetabolic network, focused subcortically, particularly in thalamus, proportionally to psychiatric features severity. Further studies with larger, but homogeneous, cohorts are needed to determine the sensitivity and specificity of this dysfunctional pattern as a potential biomarker in diffuse inflammatory j-NPSLE with normal brain MRI.

The relationship between manual ability, dystonia and choreoathetosis severity and upper limb movement patterns during reaching and grasping in children and young adults with dyskinetic cerebral palsy.

INTRODUCTION: Impaired upper limb movements are a key feature in dyskinetic cerebral palsy (CP). However, information on how specific movement patterns relate to manual ability, performance and underlying movement disorders is lacking. Insight in these associations may contribute to targeted upper limb management in dyskinetic CP. This study aimed to explore associations between deviant upper limb movement patterns and (1) manual ability, (2) severity of dystonia/choreoathetosis, and (3) movement time/trajectory deviation during reaching and grasping. PARTICIPANTS/METHODS: Participants underwent three-dimensional upper limb analysis during reaching forwards (RF), reaching sideways (RS) and reach-and-grasp vertical (RGV) as well as clinical assessment. Canonical correlation and regression analysis with statistical parametric mapping were used to explore associations between clinical/performance parameters and movement patterns (mean and variability). RESULTS: Thirty individuals with dyskinetic CP participated (mean age 16±5 y; 20 girls). Lower manual ability was related to higher variability in wrist flexion/extension during RF and RS early in the reaching cycle (p < 0.05). Higher dystonia severity was associated with higher mean wrist flexion (40-82 % of the reaching cycle; p = 0.004) and higher variability in wrist flexion/extension (31-75 %; p < 0.001) and deviation (2-14 %; p = 0.007/60-73 %; p = 0.006) during RF. Choreoathetosis severity was associated with higher elbow pro/supination variability (12-19 %; p = 0.009) during RGV. Trajectory deviation was associated with wrist and elbow movement variability (p < 0.05). CONCLUSION: Current novel analysis of upper limb movement patterns and respective timings allows to detect joint angles and periods in the movement cycle wherein associations with clinical parameters occur. These associations are not present at each joint level, nor during the full movement cycle. This knowledge should be considered for individualized treatment strategies.

Interlimb kinetic asymmetries during the tuck jump assessment are more exposed following kinetic stabilization.

OBJECTIVE: To analyse interlimb kinetics and asymmetries during the tuck jump assessment (TJA), before and after kinetic stabilization, to identify injury risk in healthy female athletes. DESIGN: Cross-sectional study. SETTING: Laboratory. PARTICIPANTS: Twenty-five healthy females (age 21.0 ± 1.83 yrs; height 1.68 ± 0.06 m; body mass 69.4 ± 10.7 kg). MAIN OUTCOME MEASURES: Kinetics were measured during 10-s trials of the TJA and absolute asymmetries compared, before and after kinetic stabilization using paired sample t-tests. Statistical parametric mapping (SPM) compared vertical ground reaction force (VGRF) data for each limb during the jumping cycles before and after stabilization. RESULTS: Small to moderate increases in interlimb asymmetries were observed after stabilization for VGRF, relative vertical leg stiffness, average loading rate, total and propulsive impulse, peak braking and propulsive force (p < 0.05). SPM revealed significant interlimb differences between 77-98% and 83-99% of ground contact for the jumping cycles pre- and post-stabilization respectively. CONCLUSIONS: Larger asymmetries were evident after kinetic stabilization, with increased VGRF in the non-dominant limb. We speculate that participants sacrificed interlimb landing symmetry to achieve kinetic stability, which may reflect a primal landing strategy that forgoes movement quality. Assessing lower limb biomechanics using the TJA should involve examining kinetic stability and interlimb kinetic asymmetries.

Performance and micro-pacing in sprint cross-country skiing: A comparison of individual time-trial and head-to-head race formats.

This study compared performance strategies and sub-technique selection in cross-country skate skiing sprint races, specifically individual time-trial (ITT) and head-to-head (H2H) formats. Fourteen male cross-country skiers from the Chinese national team participated in the FIS-sanctioned sprint race day. GNSS and heart rate sensors recorded positioning, skiing speeds, heart rate, sub-technique usage, and skiing kinematics. Statistical parametric mapping (SPM) was used to determine the course positions (clusters) where instantaneous skiing speed was significantly associated with section time. One-way analyses of variance were used to examine differences between the ITT and H2H. H2H race speeds were 2.4 ± 0.2% faster than the ITT race (p < 0.05).Variations in sub-technique and skiing kinematics were observed between race formats, indicating different strategies and tactics employed by athletes. SPM identified specific clusters (primarily uphill) where the fastest athlete gained significant time over the slowest. The greatest time gains were associated with higher G3 sub-technique usage and longer G3 cycle length on steep uphill terrain (9-13% gradients). Integrating SPM analyses and sub-technique assessments can help optimise performance and tactics in sprint races. This study enhances our understanding of cross-country skiing dynamics and performance variations among elite competitors.

Enhancing biomechanical machine learning with limited data: generating realistic synthetic posture data using generative artificial intelligence.

Objective: Biomechanical Machine Learning (ML) models, particularly deep-learning models, demonstrate the best performance when trained using extensive datasets. However, biomechanical data are frequently limited due to diverse challenges. Effective methods for augmenting data in developing ML models, specifically in the human posture domain, are scarce. Therefore, this study explored the feasibility of leveraging generative artificial intelligence (AI) to produce realistic synthetic posture data by utilizing three-dimensional posture data. Methods: Data were collected from 338 subjects through surface topography. A Variational Autoencoder (VAE) architecture was employed to generate and evaluate synthetic posture data, examining its distinguishability from real data by domain experts, ML classifiers, and Statistical Parametric Mapping (SPM). The benefits of incorporating augmented posture data into the learning process were exemplified by a deep autoencoder (AE) for automated feature representation. Results: Our findings highlight the challenge of differentiating synthetic data from real data for both experts and ML classifiers, underscoring the quality of synthetic data. This observation was also confirmed by SPM. By integrating synthetic data into AE training, the reconstruction error can be reduced compared to using only real data samples. Moreover, this study demonstrates the potential for reduced latent dimensions, while maintaining a reconstruction accuracy comparable to AEs trained exclusively on real data samples. Conclusion: This study emphasizes the prospects of harnessing generative AI to enhance ML tasks in the biomechanics domain.

The highs and lows of lifting loads: SPM analysis of multi-segmental spine angles in healthy adults during manual handling with increased load.

Introduction: Manual handling personnel and those performing manual handling tasks in non-traditional manual handling industries continue to suffer debilitating and costly workplace injuries. Smart assistive devices are one solution to reducing musculoskeletal back injuries. Devices that provide targeted assistance need to be able to predict when and where to provide augmentation via predictive algorithms trained on functional datasets. The aim of this study was to describe how an increase in load impacts spine kinematics during a ground-to-platform manual handling task. Methods: Twenty-nine participants performed ground-to-platform lifts for six standardised loading conditions (50%, 60%, 70%, 80%, 90%, and 100% of maximum lift capacity). Six thoracic and lumbar spine segments were measured using inertial measurement units that were processed using an attitude-heading-reference filter and normalised to the duration of the lift. The lift was divided into four phases weight-acceptance, standing, lift-to-height and place-on-platform. Statistical significance of sagittal angles from the six spine segments were identified through statistical parametric mapping one-way analysis of variance with repeated measures and post hoc paired t-tests. Results: Two regions of interest were identified during a period of peak flexion and a period of peak extension. There was a significant increase in spine range of motion and peak extension angle for all spine segments when the load conditions were increased (p < 0.001). There was a decrease in spine angles (more flexion) during the weight acceptance to standing phase at the upper thoracic to upper lumbar spine segments for some condition comparisons. A significant increase in spine angles (more extension) during the place-on-platform phase was seen in all spine segments when comparing heavy loads (>80% maximum lift capacity, inclusive) to light loads (<80% maximum lift capacity) (p < 0.001). Discussion: The 50%-70% maximum lift capacity conditions being significantly different from heavier load conditions is representative that the kinematics of a lift do change consistently when a participant's load is increased. The understanding of how changes in loading are reflected in spine angles could inform the design of targeted assistance devices that can predict where and when in a task assistance may be needed, possibly reducing instances of back injuries in manual handling personnel.

Hip and Pelvis Movement Patterns in Patients With Femoroacetabular Impingement Syndrome Differ From Controls and Change After Hip Arthroscopy During a Step-Down Pivot-Turn Task.

Background: Alterations in hip kinematics during functional tasks occur in positions that cause anterior impingement in patients with femoroacetabular impingement (FAI) syndrome. However, tasks that do not promote motions of symptomatic hip impingement remain understudied. Purpose: To compare movement patterns of the hip and pelvis during a step-down pivot-turn task between patients with FAI and controls as well as in patients with FAI before and after hip arthroscopy. Study Design: Controlled laboratory study. Methods: Three-dimensional motion capture was acquired in 32 patients with FAI and 27 controls during a step-down pivot-turn task. An FAI subsample (n = 14) completed testing 9.2 ± 2.0 months (mean ± SD; range, 5.8-13.1 months) after hip arthroscopy. Statistical parametric mapping analysis was used to analyze hip and pelvis time series waveforms (1) between the FAI and control groups, (2) in the FAI group before versus after hip arthroscopy, and (3) in the FAI group after hip arthroscopy versus the control group. Continuous parametric variables were analyzed by paired t test and nonparametric variables by chi-square test. Results: There were no significant differences in demographics between the FAI and control groups. Before hip arthroscopy, patients with FAI demonstrated reduced hip flexion (P = .041) and external rotation (P = .027), as well as decreased anterior pelvic tilt (P = .049) and forward rotation (P = .043), when compared with controls. After hip arthroscopy, patients demonstrated greater hip flexion (P < .001) and external rotation of the operative hip (P < .001), in addition to increased anterior pelvic tilt (P≤ .036) and pelvic rise (P≤ .049), as compared with preoperative values. Postoperatively, the FAI group demonstrated greater hip flexion (P≤ .047) and lower forward pelvic rotation (P = .003) as compared with the control group. Conclusion: Movement pattern differences between the FAI and control groups during the nonimpingement-related step-down pivot-turn task were characterized by differences in the sagittal and transverse planes of the hip and pelvis. After hip arthroscopy, patients exhibited greater hip flexion and external rotation and increased pelvic anterior tilt and pelvic rise as compared with presurgery. When compared with controls, patients with FAI demonstrated greater hip flexion and lower pelvic forward rotation postoperatively. Clinical Relevance: These findings indicate that hip and pelvis biomechanics are altered even during tasks that do not reproduce the anterior impingement position.

Does scapular dysfunction alter scapular muscles activity and kinematics during swim stroke motion on adolescent swimmers?

Scapular dyskinesis (SD) indicates dysfunction of the scapular muscle activity during the arm elevation, resulting in altered scapular kinematics. This study examined whether SD alters scapular muscle activity and kinematics during swim stroke motion. Seventeen swimmers (mean age: 13 ± 1 years) were divided into SD (n = 8) and control (n = 9) groups. Scapular muscle activity (the upper, middle, and lower trapezius and the serratus anterior muscle) and kinematics data were collected and time-normalised (0-100%) during swim stroke motion by swim-bench on land. Scapular kinematics were calculated for upward rotation, internal rotation, posterior tilt, and arm elevation angles. To compare patterns of muscle activity and kinematics with and without SD, statistical parametric mapping unpaired t-test was used. The scapular upward rotation angle was decreased in SD compared to control in the 0-10% of the swim stroke phase (p = 0.041, t* = 3.018), and the internal rotation angle was increased in 0-15% of the phase (p = 0.033, t* = 2.994). Scapular posterior tilt and muscle activity showed no significant differences. These results suggested that SD altered scapular upward rotation and internal rotation at the initial phase of the swim stroke motion in adolescent swimmers and might potentially provoke a risk of subacromial impingement.

One-dimension statistical parametric mapping in lower limb biomechanical analysis: A systematic scoping review.

BACKGROUND: Biomechanics significantly impacts sports performance and injury prevention. Traditional methods like discrete point analysis simplify continuous kinetic and kinematic data, while one-dimensional Statistical Parametric Mapping (spm1d) evaluates entire movement curves. Nevertheless, spm1d's application in sports and injury research is limited. As no systematic review exists, we conducted a scoping systematic review, synthesizing the current applications of spm1d across various populations, activities, and injuries. This review concludes by identifying gaps in the literature and suggesting areas for future research. RESEARCH QUESTION: What research exists using spm1d in sports biomechanics, focusing on the lower limbs, in what populations, and what are the current research gaps? METHODS: We searched PubMed, Embase, Web of Science, and ProQuest databases for the following search string: "(((knee) OR (hip)) OR (ankle)) OR (foot) OR (feet) AND (statistical parametric mapping)". English peer-reviewed studies assessing lower limb kinetics or kinematics in different sports or sports-related injuries were included. Reviews, meta-analyses, conference abstracts, and grey literature were excluded. RESULTS: Our search yielded 165 papers published since 2012. Among these, 112 examined healthy individuals (67 %), and 53 focused on injured populations (33 %). Running (n = 45), cutting (n = 25), and jumping/landing (n = 18) were the most common activities. The predominant injuries were anterior cruciate ligament rupture (n = 21), chronic ankle instability (n = 18), and hip-related pain (n = 9). The main research gaps included the unbalanced populations, underrepresentation of common sports and sport-related injuries, gender inequality, a lack of studies in non-laboratory settings, a lack of studies on varied sports gear, and a lack of reporting standardization. SIGNIFICANCE: This review spotlights crucial gaps in spm1d research within sports biomechanics. Key issues include a lack of studies beyond laboratory settings, underrepresentation of various sports and injuries, and gender disparities in research populations. Addressing these gaps can significantly enhance the application of spm1d in sports performance, injury analysis, and rehabilitation.

Were Frailty Identification Criteria Created Equal? A Comparative Case Study on Continuous Non-Invasively Collected Neurocardiovascular Signals during an Active Standing Test in the Irish Longitudinal Study on Ageing (TILDA).

BACKGROUND: In this observational study, we compared continuous physiological signals during an active standing test in adults aged 50 years and over, characterised as frail by three different criteria, using data from The Irish Longitudinal Study on Ageing (TILDA). METHODS: This study utilised data from TILDA, an ongoing landmark prospective cohort study of community-dwelling adults aged 50 years or older in Ireland. The initial sampling strategy in TILDA was based on random geodirectory sampling. Four independent groups were identified: those characterised as frail only by one of the frailty tools used (the physical Frailty Phenotype (FP), the 32-item Frailty Index (FI), or the Clinical Frailty Scale (CFS) classification tree), and a fourth group where participants were not characterised as frail by any of these tools. Continuous non-invasive physiological signals were collected during an active standing test, including systolic (sBP) and diastolic (dBP) blood pressure, as well as heart rate (HR), using digital artery photoplethysmography. Additionally, the frontal lobe cerebral oxygenation (Oxy), deoxygenation (Deoxy), and tissue saturation index (TSI) were also non-invasively measured using near-infrared spectroscopy (NIRS). The signals were visualised across frailty groups and statistically compared using one-dimensional statistical parametric mapping (SPM). RESULTS: A total of 1124 participants (mean age of 63.5 years; 50.2% women) were included: 23 were characterised as frail only by the FP, 97 by the FI, 38 by the CFS, and 966 by none of these criteria. The SPM analyses revealed that only the group characterised as frail by the FI had significantly different signals (p < 0.001) compared to the non-frail group. Specifically, they exhibited an attenuated gain in HR between 10 and 15 s post-stand and larger deficits in sBP and dBP between 15 and 20 s post-stand. CONCLUSIONS: The FI proved to be more adept at capturing distinct physiological responses to standing, likely due to its direct inclusion of cardiovascular morbidities in its definition. Significant differences were observed in the dynamics of cardiovascular signals among the frail populations identified by different frailty criteria, suggesting that caution should be taken when employing frailty identification tools on physiological signals, particularly the neurocardiovascular signals in an active standing test.

A ROI-based quantitative pipeline for 18F-FDG PET metabolism and pCASL perfusion joint analysis: Validation of the 18F-FDG PET line.

In Mild Cognitive Impairment (MCI), the study of brain metabolism, provided by 18F-FluoroDeoxyGlucose Positron Emission Tomography (18F-FDG PET) can be integrated with brain perfusion through pseudo-Continuous Arterial Spin Labeling Magnetic Resonance sequences (MR pCASL). Cortical hypometabolism identification generally relies on wide control group datasets; pCASL control groups are instead not publicly available yet, due to lack of standardization in the acquisition parameters. This study presents a quantitative pipeline to be applied to PET and pCASL data to coherently analyze metabolism and perfusion inside 16 matching cortical regions of interest (ROIs) derived from the AAL3 atlas. The PET line is tuned on 36 MCI patients and 107 healthy control subjects, to agree in identifying hypometabolic regions with clinical reference methods (visual analysis supported by a vendor tool and Statistical Parametric Mapping, SPM, with two parametrizations here identified as SPM-A and SPM-B). The analysis was conducted for each ROI separately. The proposed PET analysis pipeline obtained accuracy 78 % and Cohen's к 60 % vs visual analysis, accuracy 79 % and Cohen's к 58 % vs SPM-A, accuracy 77 % and Cohen's к 54 % vs SPM-B. Cohen's к resulted not significantly different from SPM-A and SPM-B Cohen's к when assuming visual analysis as reference method (p-value 0.61 and 0.31 respectively). Considering SPM-A as reference method, Cohen's к is not significantly different from SPM-B Cohen's к as well (p-value = 1.00). The complete PET-pCASL pipeline was then preliminarily applied on 5 MCI patients and metabolism-perfusion regional correlations were assessed. The proposed approach can be considered as a promising tool for PET-pCASL joint analyses in MCI, even in the absence of a pCASL control group, to perform metabolism-perfusion regional correlation studies, and to assess and compare perfusion in hypometabolic or normo-metabolic areas.

Effects of a Total Motion Release (TMR®) Protocol for the Single Leg Squat on Asymmetrical Movement Patterns.

BACKGROUND: Improving single leg squat (SLS) movement symmetry may benefit rehabilitation protocols. The Total Motion Release® (TMR®) protocol has been theorized to evaluate and improve patient-perceived movement asymmetries. HYPOTHESIS/PURPOSE: The purpose of this study was to evaluate whether perceived asymmetries identified by a TMR® scoring protocol were related to biomechanical asymmetries and whether improving perceived asymmetries influenced movement mechanics. It was hypothesized that participants with perceived asymmetries would also present with biomechanical asymmetries. A secondary hypothesis was that participants would reduce their perceived asymmetries after performing the TMR® protocol and subsequently have greater biomechanical symmetry. STUDY DESIGN: Descriptive Cohort (Laboratory Study). METHODS: Twenty participants (10 female, 10 male) with self-identified bilateral differences of 10 points or greater on the TMR® scoring scale were recruited for the study. The non-preferred side was defined as the side that scored higher. 3Dimensional motion capture was used to bilaterally assess baseline SLS depth as well as hip, knee, and ankle kinematics and kinetics. For the TMR® protocol, sets of 10 SLSs were performed on the preferred leg until their perceived asymmetries were resolved (i.e., both sides scored equally), or four sets had been completed. Kinematics and kinetics were collected immediately after the intervention and after a 10-minute rest period. RESULTS: Participants had biomechanical asymmetries at baseline for knee flexion, ankle flexion, and knee moments. Following the intervention, participants had reduced TMR® scores on the non-preferred leg, and this coincided with increased knee joint moments on that side. Although perceived asymmetries were resolved after the intervention, kinematic and kinetic asymmetries at the knee and ankle were still present. CONCLUSIONS: A TMR® intervention could benefit rehabilitation protocols by reducing factors of dysfunction and increasing the ability of patients to load the non-preferred knee. Further investigations are necessary to elucidate the importance of asymmetrical movement patterns. LEVEL OF EVIDENCE: 3b.

Differences between lower extremity joint running kinetics captured by marker-based and markerless systems were speed dependent.

BACKGROUND: The development of computer vision technology has enabled the use of markerless movement tracking for biomechanical analysis. Recent research has reported the feasibility of markerless systems in motion analysis but has yet to fully explore their utility for capturing faster movements, such as running. Applied studies using markerless systems in clinical and sports settings are still lacking. Thus, the present study compared running biomechanics estimated by marker-based and markerless systems. Given running speed not only affects sports performance but is also associated with clinical injury prevention, diagnosis, and rehabilitation, we aimed to investigate the effects of speed on the comparison of estimated lower extremity joint moments and powers between markerless and marker-based technologies during treadmill running as a concurrent validating study. METHODS: Kinematic data from marker-based/markerless technologies were collected, along with ground reaction force data, from 16 young adults running on an instrumented treadmill at 3 speeds: 2.24 m/s, 2.91 m/s, and 3.58 m/s (5.0 miles/h, 6.5 miles/h, and 8.0 miles/h). Sagittal plane moments and powers of the hip, knee, and ankle were calculated by inverse dynamic methods. Time series analysis and statistical parametric mapping were used to determine system differences. RESULTS: Compared to the marker-based system, the markerless system estimated increased lower extremity joint kinetics with faster speed during the swing phase in most cases. CONCLUSION: Despite the promising application of markerless technology in clinical settings, systematic markerless overestimation requires focused attention. Based on segment pose estimations, the centers of mass estimated by markerless technologies were farther away from the relevant distal joint centers, which led to greater joint moments and powers estimates by markerless vs. marker-based systems. The differences were amplified by running speed.

Acute effects of robot-assisted body weight unloading on biomechanical movement patterns during overground walking.

Body weight unloading (BWU) is used in rehabilitation/training settings to reduce kinetic requirements, however different BWU methods may be unequally capable of preserving biomechanical movement patterns. Biomechanical analysis of both kinetic and kinematic movement trajectories rather than discrete variables has not previously been performed to describe the effect of BWU on gait patterns during horizontal walking. The aim of the present study was to investigate how robot-assisted BWU producing an dynamic unloading force on the body centre of mass, affects kinematic, kinetic, and spatiotemporal gait parameters in healthy young adults by use of time-continuous analysis. Twenty participants walked overground in a 3-D motion-capture lab at 0, 10, 20, 30, 40, and 50 % BWU at a self-selected speed. Vertical and anterior-posterior ground reaction forces (GRFs) and lower limb internal joint moments were obtained during the stance phase, while joint angles were obtained during entire strides. Time-continuous data were analysed using Statistical Parametric Mapping (SPM) and discrete data using conventional statistics to compare different BWU conditions by means of One-Way Repeated Measures Anova. With increasing BWU, corresponding reductions were observed for GRFs, internal joint moments, joint angles, walking speed, stride/step length and cadence. Observed effects were partially caused by decreased walking speed and increased BWU. While amplitude reductions were observed for kinetic and kinematic variables, trajectory shapes were largely preserved. In conclusion, dynamic robot-assisted BWU enables reduced kinetic requirements without distorting biomechanically normal gait patterns during overground walking in young healthy adults.