Arm Swing Research Articles

Effect of 12weeks of complex training on occupational activities, strength, and power in professional firefighters.

Objective: This study examined the effects of 12-week complex training (CT) programs on professional firefighters’ occupational activities, strength, and power. Methods: Thirty men professional firefighters were randomly assigned to the CT group (n = 15) and control group (n = 15). The CT group performed complex training and the control group completed resistance training (RT) twice a week over 12 weeks. The occupational activities, strength, and power were assessed at baseline and immediately after the intervention by measuring the performance of 100 m load-bearing run (100 m LR), 60 m shoulder ladder run (60 m SLR), 5 m × 20 m shuttle run (5 m × 20 m SR), 4th-floor climbing rope (4th-floor CR), countermovement jump with arm swing (CMJas), seated medicine-ball throw (SMT), one-repetition maximum bench press (1RM BP), and one-repetition maximum back squat (1RM BS). Results: The results showed that compared to RT, CT induced significantly greater improvements in 60 m SLR (p = 0.007), 4th-floor CR (p = 0.020), CMJas (p = 0.001), and SMT (p < 0.001). Conclusion: These findings suggest that CT is a novel intervention with great promise of improving professional firefighters’ occupational activities, strength, and power.

Dynamics of pendulum-based systems under human arm rotational movements

Wearable devices have applications in health monitoring and patient assistance devices. Harvesting energy from human motion kinetic energy by the pendulum-based electromagnetic generator is a promising way of extending the battery life of these devices. In this paper, the oscillatory and rotary dynamical response of pendulum-based systems under an open-circuit condition is investigated for two different models considering the lower arm’s rotation. The arm pitching model (in-plane excitation) represents the swing of the lower arm during walking. The arm rolling rotation model (out-of-plane excitation) represents the twisting type of motion of the lower arm movement associated with a specific kind of disorder, for example, tremors experienced by Parkinson’s patients. The governing equations of motion around stable equilibria are derived using Lagrange formulation, and their nondimensional forms are introduced for the two models. A special case of these models is developed for experimental validation and system identification, where the system parameters are identified by fitting frequency response functions on the experimental data. The system’s nonlinear dynamical response shows various bifurcations, including limit point bifurcation (i.e., saddle-node bifurcation), pitchfork bifurcation, a cascade of period-doubling bifurcations under amplitude or frequency sweeps. When the system shows a bi-stable response, the rotary response usually has a higher angular velocity amplitude than the oscillatory response. Basins of attraction plots for different operating conditions are presented to show the effect of initial conditions on the system’s type of steady-state response: oscillatory or rotary.

Manual stabilization reveals a transient role for balance control during locomotor adaptation.

A fundamental feature of human locomotor control is the need to adapt walking patterns in response to changes in the environment. For example, when people walk on a split-belt treadmill, which has belts that move at different speeds, they adapt to the asymmetric speed constraints by reducing spatiotemporal asymmetry. Here, we aim to understand the role of balance control as a potential factor driving this adaptation process. We recruited 24 healthy, young adults to adapt to walking on a split-belt treadmill while either holding on to a handrail or walking with free arm swing. We measured whole body angular momentum and step length asymmetry as measures of dynamic balance and spatiotemporal asymmetry, respectively. To understand how changes in intersegmental coordination influenced whole body angular momentum, we also measured segmental angular momenta and the coefficient of cancellation. When participants were initially exposed to the asymmetry in belt speeds, we observed an increase in whole body angular momentum that was due to both an increase in the momentum of individual segments and a reduction in the coefficient of cancellation. Holding on to a handrail reduced the perturbation to asymmetry during the early phase of adaptation and resulted in a smaller aftereffect during early postadaptation. In addition, the stabilization provided by holding on to a handrail led to reductions in the coupling between angular momentum and asymmetry. These results suggest that regulation of dynamic balance is most important during the initial, transient phase of adaptation to walking on a split-belt treadmill.NEW & NOTEWORTHY We investigated the role of dynamic balance during adaptation to a split-belt treadmill by measuring whole body angular momentum with or without holding on to a handrail. The initial step length asymmetry and associations between balance and asymmetry reduced when holding on to a handrail during early adaptation. These findings indicate that dynamic balance mostly contributes to the initial phase of adaptation when people are exposed to an asymmetric walking constraint.

Virtual Reality Locomotion in Place for Virtual Museum Exhibitions of Culture Heritage: Comparing Joystick Controller, Point &amp; Teleport and Arm Swinging

Locomotion methods are user interaction approaches that assist users in navigating the virtual environment when using virtual reality display device of HMDs (head-mounted displays). Most previous studies have been focused on the locomotion techniques with joystick and teleport in general and gaming context. However, there are lack study of locomotion techniques in virtual museum for context of culture heritage. In this study, this paper presents a comparative evaluation with sixty participants of the three locomotions: Joystick Controller, Point &amp; Teleport and Arm Swinging to measure sickness, presence and flow state. In order to evaluate, this paper developed the virtual museum of Himmapan animals (https://angkaew.com/Hinmapan_vr/) which consisted of digital paint art, digitization objects, animation and digitization books. The results showed that Point &amp; teleport less sickness of nausea than other techniques and Point &amp; teleport also highest in perceived enjoyment than other techniques. However, we found no significant difference in presence. Finally, this paper suggested implementing Point &amp; Teleport locomotion techniques in the application of virtual museums

7-T Neuromelanin and R2* MRI in Parkinson Disease.

HomeRadiologyVol. 305, No. 2 PreviousNext Reviews and CommentaryFree AccessImages in Radiology7-T Neuromelanin and R2* MRI in Parkinson DiseaseDhairya A. Lakhani, Erik H. Middlebrooks Dhairya A. Lakhani, Erik H. Middlebrooks Author AffiliationsFrom the Department of Radiology, West Virginia University, Morgantown, W.Va. (D.A.L.); and Department of Radiology, Mayo Clinic College of Medicine and Science, 4500 San Pablo Rd, Jacksonville, FL 32224 (E.H.M.).Address correspondence to E.H.M. (email: [email protected]).Dhairya A. LakhaniErik H. Middlebrooks Published Online:Aug 2 2022https://doi.org/10.1148/radiol.220230MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In A 76-year-old man presented with worsening balance, shuffling gait, and right-hand tremor, beginning 3 years before evaluation. On examination, he had reduced facial expressions, reduced blink rate, and hypophonic voice. His gait was slow and shuffling, with bilateral reduced arm swing. He also had rigidity and bradykinesia in all four extremities, greater on the right. His examination features were typical of the akinetic-rigid subtype of Parkinson disease (PD). He underwent brain MRI to support the diagnosis and to assess for other etiologies, such as an atypical parkinsonian syndrome.In this case, we used a high-spatial-resolution multiecho gradient-echo sequence with magnetization transfer pulse at 7 T to image neuromelanin in the substantia nigra, which normally has a high concentration of neuromelanin-rich cells. Neuromelanin imaging stands to benefit from 7-T MRI due to higher signal-to-noise ratio, tissue contrast, and spatial resolution. Reduced size and signal intensity of the substantia nigra were consistent with PD (Figure). Additionally, the multiecho sequence allowed for the quantification of the R2*, which reveals elevated iron deposition in this case, another histopathologic feature of PD (Figure). The combination of both biomarkers has potential to be a powerful tool for diagnosis and monitoring progression of PD.Images in a 76-year-old man with akinetic-rigid subtype Parkinson disease (PD) with symptoms greater on the right side. (A) Axial neuromelanin-sensitive MRI scan derived from rigid subtype PD shows reduced size and signal intensity of the substantia nigra (SN) (arrows) on the first echo image of a neuromelanin-sensitive three-dimensional multiecho fast low-angle shot, or FLASH, MRI scan with magnetization transfer pulse (7-T Siemens MAGNETOM Terra [Siemens Healthineers]; repetition time, 52 m/sec; echo time, 2.18, 4.15, and 7.09 m/sec; section thickness, 1.5 mm; flip angle, 16°; averages, 1; interpolated voxel size, 0.4 × 0.4 × 1.5 mm; acquisition time, 10 minutes and19 seconds). (B) MRI scan in a 73-year-old woman with the diagnosis of essential tremor is shown for illustration of the normal appearance of the substantia nigra (arrows) as comparison. (C) Plot graph of the substantia-nigra signal intensity (normalized by the adjacent cerebral-peduncle signal intensity) over the three echoes shows decreased neuromelanin in the patient with PD (greater decrease in the left substantia nigra) on the first echo neuromelanin-sensitive image. There is also a more rapid decrease in signal intensity over the second and third echoes, reflecting increased R2* effect from elevated iron deposition.Download as PowerPointOpen in Image Viewer Disclosures of conflicts of interest: D.A.L. No relevant relationships. E.H.M. Clinical trial and research funding paid to institution by Varian Medical Systems and Boston Scientific; unrelated consultant fees from Boston Scientific.Article HistoryReceived: Feb 1 2022Revision requested: Mar 7 2022Revision received: Mar 15 2022Accepted: Mar 18 2022Published online: Aug 02 2022Published in print: Nov 2022 FiguresReferencesRelatedDetailsRecommended Articles Substantia Nigra Volumetry with 3-T MRI in De Novo and Advanced Parkinson DiseaseRadiology2020Volume: 296Issue: 2pp. 401-410Differential Effect of Iron and Myelin on Susceptibility MRI in the Substantia NigraRadiology2021Volume: 301Issue: 3pp. 682-691High-Spatial-Resolution Diffusion MRI in Parkinson Disease: Lateral Asymmetry of the Substantia NigraRadiology2019Volume: 291Issue: 1pp. 149-157Imaging the Substantia Nigra in Parkinson Disease and Other Parkinsonian SyndromesRadiology2021Volume: 300Issue: 2pp. 260-278Is High-Spatial-Resolution Diffusion MRI Applicable for the Diagnosis of Parkinson Disease?Radiology2019Volume: 292Issue: 1pp. 267-268See More RSNA Education Exhibits Parkinsonian Syndromes: The Past, Present, and FutureDigital Posters2019Contemporary MRI Imaging in Parkinson's DiseaseDigital Posters2019The Role of MR-guided Focused Ultrasound as a Symptomatic Treatment for Parkinson's Disease: Behind and BeyondDigital Posters2020 RSNA Case Collection Primary HemochromatosisRSNA Case Collection2021NeuroferritinopathyRSNA Case Collection2021Multiple System Atrophy (MSA)RSNA Case Collection2021 Vol. 305, No. 2 Metrics Altmetric Score PDF download

Effects of Task Constraints on Countermovement Jump Kinematics Following a Short-Term Training

In previous studies, the acute effects of movement constraints on the countermovement jump performance are investigated; however, the longitudinal effects of implementing the constraint in a training regimen are not well studied. The purpose of this study was to examine the phenomenon of motor learning development due to application of task constraint in a training regimen following 6 weeks of training. Forty-five healthy adult males were randomly assigned to a control or one of two experimental constraint training groups (i.e., no arm swing or restricted knee flexion). Pre- and posttraining jump height and kinematic variables of six maximum effort countermovement jumps were compared longitudinally within the groups, and also compared between the groups. The findings of this study indicated that jump height significantly increased in all the groups while in the unrestricted control group it was increased greater than the experimental conditions (21% compared with 12% and 5.5%). However, the applied task constraints significantly improved some of the contributors to jump performance, establishing specific adaptation of kinematic variables to the constraint training. Therefore, constraint training approach could be suggested in case of demanding specific adaptation of kinematic variables of countermovement jump in a training regimen.

Enhanced assessment of human dynamic stability by eliminating the effect of body height: modeling and experiment study

Margin of stability (MOS) is one of the essential indices for evaluating dynamic stability. However, there are indications that MOS was affected by body height and its application in identifying factors on dynamic stability other than body height is restricted. An inverted pendulum model was used to simulate human walking and investigate the relevance between MOS and body height. Eventually, a height-independent index in dynamic stability assessment (named as Angled Margin of Stability, AMOS) was proposed. For testing, fifteen healthy young volunteers performed walking trials with normal arm swing, holding arms, and anti-normal arm swing. Kinematic parameters were recorded using a gait analysis system with a Microsoft Kinect V2.0 and instrumented walkway. Both simulation and test results show that MOS had a significant correlation with height during walking with normal arm swing, while AMOS had no such significant correlation. Walking with normal arm swing produced significantly larger AMOS than holding arms and anti-normal arm swing. However, no significant difference showed up in MOS between normal arm swing and holding arms. The results suggest that AMOS is not affected by body height and has the potential to identify the variations in dynamic stability caused by physiological factors other than body height.

THE RELATIONSHIP BETWEEN JUMP PERFORMANCE, SPEED AND COD SPEED IN ELITE FEMALE SOCCER PLAYERS

The purpose of this study was to present the physical performance of elite female soccer players and to analyze the relationship between jump performance, speed and COD ability. Sixteen elite female soccer players (age: 20.05±2.85; height: 166.47±4.83cm; body weight: 60.52±8.30kg, BMI 21.88±2.86) from a women's club who played the highest rank of the competition took part in this study. The jump, speed and COD abilities of each player were determined using: (1) the Squat jump (SJ), (2) Countermovement Jump (CMJ), countermovement jump with arm swing (CMJA), (2) running speed at 30-m with passing time at 10m and 20m, (3) the pro agility test (pro), (4) zig-zag test (zig-zag), (5) 9-6-3-6-3 sprint (9-6-3-6-9). The results of Pearson’s correlation indicated moderate significant relationships between the 10m running speed and pro agility test (r=0.59; p&lt;0.01), as well as the zig-zag test (r=0.55; p&lt;0.01), and also between the 30m and all COD tests (pro agility r=0.66; p&lt;0.01, zig-zag r=0.59; p&lt;0.01 and 9-6-3-6-9 r=0.58; p&lt;0.05). A small correlation (r=0.49; p&lt;0.03) was noticed between the 10m running test and 9-6-3-6-9 agility test, and also between the CMJA (r=0.45; p&lt;0.05) and the 9-6-3-6-9 agility test. The findings of the present study indicated a significant correlation between speed and all of the COD tests, additionally between the CMJA and 9-6-3-6-9 COD test. Therefore, elite female soccer players with higher maximum acceleration rates and speed tend to perform better in change of direction tests. On the other hand, jump performance does not significantly correlate with COD ability.

Differences in the Biomechanics of the Vertical Jumps in Young Adult Handball Players: Effect of the Countermovement and the Arm Swing

The purpose of the study was to examine the sex and jump test effect on the biomechanics of vertical jump performance in young adult&#x0D; handball players. Nineteen men and 19 women handball players were tested in the squat jump (SQJ) and the countermovement jump with (CMJF) and without (CMJ) an arm swing. Results indicated a significant (p &lt; .05) sex and jump test main effect on jump height and power output. Also, a significant (p &lt; .05) sex, jump test, and sex-jump test interaction were revealed for impulse time, time to achieve maximum force, and work output. No sex differences (p &gt; .05) were observed for the jump height increment when using a countermovement and an arm swing. The differences found suggest that sex-specific training should be applied to optimize jumping ability in young adult handball players.

Countermovement Jump in Female Sprinters: Kinetic Parameters and Asymmetry

Analyzing asymmetry from biomechanical parameters of the lower extremities has become a standard practice for accurate assessment of athletic performance, injury prevention, and rehabilitation. The aims of this study were (1) to determine differences between explosive strength and asymmetry of the lower extremities using kinetic parameters of the CMJ jump test in young female athletics, and (2) to investigate correlation between speed and asymmetry, as speed and kinetic parameters. The two groups of nine female sprinters (mean ± SD; G1-age 15.6 ± 1.34 years, height 170.1 ± 0.57 cm, body mass 62.54 ± 7.73 kg, and BMI 21.6 ± 2.05; G2-age 16.2 ± 1.3 years, height 168.4 ± 0.61 cm, body mass 57.69 ± 3.12 kg, and BMI 20.37 ± 1.38) performed the CMJ test without using an arm swing, as well as a 100 m test. Two tensiometric platforms were used for the kinetic parameters and asymmetry. Asymmetry was calculated by an AI equation, and the values of the takeoff velocities and jump height parameters were obtained by integral formula and the trapezoidal rule of impulse-momentum methods. The results show differences in four kinetic parameters: height (G1- 26.82 ± 3.56 cm, vs. G2- 17.45 ± 2.01 cm), concentric impulse, (G1- 96.05 ± 16.95 N⋅s, vs. G2- 68.41 ± 4.77 N⋅s), takeoff velocity, (G1- 2.29 ± 0.14 m/s, vs. 1.83 ± 0.12 m/s), and concentric velocity, m/s (G1- 1.5 ± 0.175 m/s, vs. 1.17 ± 0.122 m/s), as well as a negative strong and very strong correlation between asymmetry and kinetic parameters for three parameters: Peak Force (G1- r = −0.878, and all subjects r = −0.633), Eccentric Impulse of left leg (G1- r = −0.865) and Concentric Impulse of right leg (G2- r = −0.878), (p &lt;.05). The younger sprinters did not show the principle of muscle activation in the form of a longer preparatory phase of contact time, eccentric and concentric phase, as well as a force impulse that is optimal. There was no correlation between asymmetry and sprint performance.

The effects of curve registration on linear models of jump performance and classification based on vertical ground reaction forces

Functional principal components define modes of variation in time series, which represent characteristic movement patterns in biomechanical data. Their usefulness however depends on the prior choices made in data processing. Recent research showed that better curve alignment achieved with registration (dynamic time warping) reduces errors in linear models predicting jump height. However, the efficacy of registration in different preprocessing combinations, including time normalisation, padding and feature extraction, is largely unknown. A more comprehensive analysis is needed, given the potential value of registration to machine learning in biomechanics. We evaluated popular preprocessing methods combined with registration, creating 512 models based on ground reaction force data from 385 countermovement jumps. The models either predicted jump height or classified jumps into those performed with or without arm swing. Our results show that the classification models benefited from registration in various forms, particularly when landmarks were placed at critical points. The best classifier achieved a 5.5 percentage point improvement over the equivalent unregistered model. However, registration was detrimental to the jump height models, although this performance variable may be a special case given its direct relationship with impulse. Our meta-models revealed the relative contributions made by various preprocessing operations, highlighting that registration does not generalise so well to new data. Nonetheless, our analysis shows the potential for registration in further biomechanical applications, particularly in classification, when combined with the other appropriate preprocessing operations.

Relationship of Vertical Jump Performance and Ankle Joint Range of Motion: Effect of Knee Joint Angle and Handedness in Young Adult Handball Players.

The purpose of the study is to examine the effect of the ankle joint range of motion (ROM) on the vertical jump (VJ) performance of adult handball players. The active (ACT) and passive (PAS) ankle joint ROM of 12 male members of the U21 National Handball Team with the knee joint at 0°, 40°, and 90° flexion (0° = fully extended knee) was evaluated using a video analysis measuring method. Participants also performed maximum VJ with (CMJ) and without (SQJ) countermovement, as well as with (AS) and without (NAS) an arm swing. Statistical analyses included 2 × 2 × 3 MANOVA, 2 × 2 repeated measures ANOVA, and Pearson’s correlation. Results reveal that PAS-ROM was larger (p < 0.05) in all knee joint flexion angles. ROM was smaller (p < 0.05) by approximately 10° at 0° compared to 90° knee flexion. No lateral effects on ROM due to the handedness of the players were observed. AS and CM resulted in increased jump height (p < 0.05). Finally, ACT-ROM when the knee joint was flexed at 40° was highly correlated (r ≥ 0.66, p < 0.05) with VJ performance except for CMJ-AS. In conclusion, the differences in the bi-articular gastrocnemius muscle flexibility due to the alteration of the angular position of the examined joints affected the ability to generate impulse during the VJ tests.

Consequences of the SARS-CoV-2 Infection on Anaerobic Performances in Young Elite Soccer Players.

The COVID-19 pandemic required local confinement measures reducing sport practice with possible consequences on the athletes’ performances. Furthermore, anaerobic detraining was underestimated and poorly known in adolescents. This article aimed to assess the effects of SARS-CoV-2 infection and 1-month COVID-19 confinement on jump testing in young elite soccer players despite a 1-month multimodal training program followed by a 1-month soccer retraining period. Thirty-one elite soccer players aged 14 were included; 16 were infected by the SARS-CoV-2 and compared with 15 non-infected elite soccer players before and after 1 month of COVID-19 confinement, and after 1 month of a soccer retraining period. Squat jumps (SJ), countermovement jumps with (CMJs) and without arm swinging (CMJ) and multiple consecutive jumps (stiffness) were used to explore the anaerobic performances. Analysis of variance for repeated measures was used to compare the positive and negative SARS-CoV-2 groups, taking into account the confinement period (low training) and the retraining soccer period. The jump tests were not altered in the positive SARS-CoV-2 group compared to the negative SARS-CoV-2 group after confinement (SJ: 31.6 ± 5.6 vs. 32.7 ± 3.7; CMJ: 34.1 ± 6.9 vs. 34.2 ± 2.6; CMJs: 38.6 ± 6.8 vs. 40.3 ± 3.9; stiffness: 28.5 ± 4.3 vs. 29.1 ± 3.7) and at 1 month of this period (SJ: 33.8 ± 5.5 vs. 36.2 ± 4.6; CMJ: 34.7 ± 5.5 vs. 36.4 ± 3.5; CMJs: 40.4 ± 6.7 vs. 42.7 ± 5.5; stiffness: 32.6 ± 4.7 vs. 34.0 ± 4.3). The SARS-CoV-2 infection had no consequence on anaerobic performances assessed by jump tests in adolescent soccer players. The adolescents’ growth could explain the absence of alteration of jump performances during the COVID-19 confinement. These results can be useful to manage the recovery of the anaerobic fitness after SARS-CoV-2 infection occurring in adolescent athletes.

Machine Learning Classifiers to Evaluate Data From Gait Analysis With Depth Cameras in Patients With Parkinson's Disease.

IntroductionThe assessments of the motor symptoms in Parkinson’s disease (PD) are usually limited to clinical rating scales (MDS UPDRS III), and it depends on the clinician’s experience. This study aims to propose a machine learning technique algorithm using the variables from upper and lower limbs, to classify people with PD from healthy people, using data from a portable low-cost device (RGB-D camera). And can be used to support the diagnosis and follow-up of patients in developing countries and remote areas.MethodsWe used Kinect®eMotion system to capture the spatiotemporal gait data from 30 patients with PD and 30 healthy age-matched controls in three walking trials. First, a correlation matrix was made using the variables of upper and lower limbs. After this, we applied a backward feature selection model using R and Python to determine the most relevant variables. Three further analyses were done using variables selected from backward feature selection model (Dataset A), movement disorders specialist (Dataset B), and all the variables from the dataset (Dataset C). We ran seven machine learning models for each model. Dataset was divided 80% for algorithm training and 20% for evaluation. Finally, a causal inference model (CIM) using the DoWhy library was performed on Dataset B due to its accuracy and simplicity.ResultsThe Random Forest model is the most accurate for all three variable Datasets (Dataset A: 81.8%; Dataset B: 83.6%; Dataset C: 84.5%) followed by the support vector machine. The CIM shows a relation between leg variables and the arms swing asymmetry (ASA) and a proportional relationship between ASA and the diagnosis of PD with a robust estimator (1,537).ConclusionsMachine learning techniques based on objective measures using portable low-cost devices (Kinect®eMotion) are useful and accurate to classify patients with Parkinson’s disease. This method can be used to evaluate patients remotely and help clinicians make decisions regarding follow-up and treatment.

Deep Brain Stimulation and Levodopa Affect Gait Variability in Parkinson Disease Differently

BackgroundBoth dopaminergic medication and subthalamic nucleus (STN) deep brain stimulation (DBS) can improve the amplitude and speed of gait in Parkinson disease (PD), but relatively little is known about their comparative effects on gait variability. Gait irregularity has been linked to the degeneration of cholinergic neurons in the pedunculopontine nucleus (PPN). ObjectivesThe STN and PPN have reciprocal connections, and we hypothesized that STN DBS might improve gait variability by modulating PPN function. Dopaminergic medication should not do this, and we therefore sought to compare the effects of medication and STN DBS on gait variability. Materials and MethodsWe studied 11 patients with STN DBS systems on and off with no alteration to their medication, and 15 patients with PD without DBS systems on and off medication. Participants walked for two minutes in each state, wearing six inertial measurement units. Variability has previously often been expressed in terms of SD or coefficient of variation over a testing session, but these measures conflate long-term variability (eg, gradual slowing, which is not necessarily pathological) with short-term variability (true irregularity). We used Poincaré analysis to separate the short- and long-term variability. ResultsDBS decreased short-term variability in lower limb gait parameters, whereas medication did not have this effect. In contrast, STN DBS had no effect on arm swing and trunk motion variability, whereas medication increased them, without obvious dyskinesia. ConclusionsOur results suggest that STN DBS acts through a nondopaminergic mechanism to reduce gait variability. We believe that the most likely explanation is the retrograde activation of cholinergic PPN projection neurons.

A single smartwatch-based segmentation approach in human activity recognition

The development of smart wearable devices has driven the rapid progress of activity recognition. However, existing activity recognition methods are still struggling to recognize single arm swings due to coarse-grained sensor data segmentation. Refined arm-swing-wise data segmentation is vital in some specific cases, such as the rehabilitation of disabled patients. In this paper, we propose a smartwatch-based arm-swing-wise data segmentation approach for human activity recognition, which converts original sensor signals into square-wave signals to detect the cut-off points of each arm swing. Particularly, our method can adaptively adjust the window size and step size of a sliding window without considering the change of swing speed. Empirical evaluation on two datasets, a self-collected dataset and a publicly-available benchmark dataset, shows superior performance of our approach over other methods under different settings, such as classifiers, features, and wearing positions.

Dancers utilize a ‘whip-like effect’ to increase arm angular momentum during multiple-revolution pirouette en dehors

ABSTRACT A pirouette en dehors (PeDh) is multiple turns using the angular momentum generated by swinging the arms with both feet on the ground. The purpose of this study was to investigate how the arm swing facilitates increasing peak angular momenta of both arms during multiple PeDh. Upper body movements in single to six-revolutions clockwise (as seen from above) PeDhs were analysed to determine arm’s angular momentum induced by the individual joint torque, gravitational force and motion-dependent terms. The horizontal abduction and adduction torques of the right and left shoulder joints, respectively, and clockwise torsional torque of the upper torso induced the clockwise angular momentum (CWAM) of the arms in the horizontal plane, about the vertically upward axis. The motion-dependent term induced the CWAMs after joint torques and contributed to the maximum total CWAM of both arms substantially. The CWAMs induced by the motion-dependent term increased with joint torques up to the triple PeDh in the right arm but independently from the left shoulder joint torque up to the sextuple PeDh in the left arm. Using a whip-like motion of the arm, increasing the arm joint torques would not be required necessarily when performing, i.e., more than quaruple PeDhs.

Sensor-based gait analysis in the premotor stage of LRRK2 G2019S-associated Parkinson's disease

IntroductionThere is a need for biomarkers to monitor the earliest phases of Parkinson's disease (PD), especially in premotor stages. Here, we studied whether there are early gait alterations in carriers of the G2019S mutation of LRRK2 that can be detected by means of an inertial sensor system. MethodsTwenty-one idiopathic PD patients, 20 LRRK2-G2019S PD, 27 asymptomatic carriers of LRRK2-G2019S mutation (AsG2019S) and 36 controls walked equipped with 16 lightweight inertial sensors in three different experiments: i/normal gait, ii/fast gait and iii/dual-task gait. In the AsG2019S group, DaT-SPECT (123I-ioflupane) with semi-quantitative analysis was carried out. Motor and cognitive performance were evaluated using MDS-UPDRS-III and MoCA scales. We employed neural network techniques to classify individuals based on their walking patterns. ResultsPD patients and controls showed differences in speed, stride length and arm swing amplitude, variability and asymmetry in all three tasks (p < 0.01). In the AsG2019S group, the only differences were detected during fast walking, with greater step time on the non-dominant side (p < 0.05), lower step/stride time variability (p < 0.01) and lower step time asymmetry (p < 0.01). DaT uptake showed a significant correlation with step time during fast walking on the non-dominant side (r = −0.52; p < 0.01). The neural network was able to differentiate between AsG2019S and healthy controls with an accuracy rate of 82.5%. ConclusionOur sensor-based analysis did not detect substantial and robust changes in the gait of LRRK2-G2019S asymptomatic mutation carriers. Nonetheless, step or stride time during fast walking, supported by the observed correlation with striatal DaT binding deserves consideration as a potential biomarker in future studies.

Change in task conditions leads to changes in intermittency in intermittent feedback control employed by CNS in control of human stance.

Event-driven intermittent feedback control is a form of feedback control in which the corrective control action is only initiated intermittently when the variables of interest exceed certain threshold criteria. It has been reported in the literature that the CNS uses an event-driven intermittent control strategy to stabilize the human upright posture. However, whether the threshold criteria may change under different postural task conditions is not yet well understood. We employ a numerical study with inverted pendulum models and an experimental study with 51 young healthy individuals (13 females and 38 males; age: 27.8 ± 6.5 years) with stabilogram-diffusion, temporal and spectral analysis applied to COP (Center of Pressure) trajectories measured from these experiments to examine this aspect. The present study provides compelling evidence that inducing a natural arm swing during quiet stance appears to lead to higher sensory dead zone in neuronal control reflecting higher intermittency thresholds in active feedback control and a corresponding lower sensory dependence. Beyond the obvious scientific interest in understanding this aspect of how CNS controls the standing posture, an investigation of the said control strategy may subsequently help uncover insights about how control of quiet stance degrades with age and in diseased conditions. Additionally, such an understanding will also be of interest to the humanoid robotics community as it may lead to insights leading to improving control strategies for posture control in robots.

These Are Not the Droids You Are Looking For: Mechanical Variant of Cotard’s Syndrome

Cotard's syndrome is a nihilistic delusion where the individual believes they are dead, partly dead, or replaced by an animal. The delusion that their body has been replaced by a purely inanimate azooic (but physical entity), such as a robot or a droid, has not hitherto been described. Case study: This 60-year-old, right-handed, female, with a past history of schizophrenia presented with complaints of depression, irritability, and anger. When confronted with commitment papers signed by her father, she denied their truthfulness, insisting that he had been replaced by an imposter. This belief persisted unabated, despite treatment with 20mg of haloperidol per day. Over time, she expressed the belief that she had been replaced by another person, whom she refused to identify. The following day she refused all food and water proclaiming that she had died and been replaced by a machine revealing, "I am not her. I am a robot." Soon thereafter she developed tremulousness, stiffness, and rigidity. After haloperidol was decreased and benztropine started, these parkinsonism symptoms subsided, but her delusions persisted. Abnormalities in physical examination: General: decreased blink frequency. Neurologic examination: Mental status examination: bradyphrenia, hypoverbal, blunted affect. Oriented ×2. Motor examination: bradykinetic, cogwheel rigidity in both upper extremities. Gait examination: slow shuffling gait, reduced bilateral arm swing. Cerebellar examination: resting tremor in both upper extremities at 3 cycles per second. Other: EEG: focal sharp transients in the left temporal region. MRI with and without contrast: normal. Toxicological, metabolic, endocrine screening: normal. This illustrated sequential presentations of three delusions of misidentification. Upon presentation, she exhibited Capgras syndrome, the delusional belief that a familiar person has been replaced by a double. The nidus for this may have been the discovery that her father had signed her commitment papers. This was followed by the belief she was a double of herself, which is the syndrome of Reverse Subjective Doubles. Finally, she manifested Cotard's syndrome in a previously undescribed manner, believing she had died and become a robot. Cotard's and Capgras syndromes are known to present sequentially rather than concurrently, whereas the patient presented concurrently with all three syndromes. Drug-induced parkinsonism may have made the patient subjectively feel stiff, which she interpreted as being rigid like a robot. She was bradykinetic, did not eat or drink, and had rigidity, suggesting that these were somatic manifestations of her underlying delusion of being a robot or alternatively, may have been the somatic nidus for the delusion. Those who present with Cotard's syndrome warrant evaluation for underlying medical conditions, serving as a substrate for this delusion. No funding.