Detection of Parkinsonian Motor Symptoms Using Non-Invasive Motion Sensing Technology

Parkinson’s Disease (PD) is characterized by impaired movement, resting tremor, and muscle rigidity. The Unified PD Rating Scale (UPDRS) is a standardized protocol used by neurologists to measure progression of disease as well as evaluation of treatments. However, this examination is subjective, time consuming, and results can be affected by stress, diet, or sleep. Our goal is to develop a non-invasive device that can record objective clinically-relevant measurements during subtasks of the UPDRS to allow for remote evaluations, which would be beneficial considering the frequency of clinical visits for medication adjustments. Five healthy individuals (ages 21-59) completed UPDRS tasks 3.6 (pronation/supination of hands) and 3.17 (rest tremor amplitude). Participants performed these tasks twice, first normally and second simulating PD patients (tremor, bradykinesia, reduction of movement amplitude) after viewing example videos. Motion data including linear and angular accelerations in 3 dimensions was acquired using a lightweight wrist-mounted motion sensor. Three features were extracted: (1) Power of higher frequency components of the linear acceleration signal (rest task), as a measure of resting tremor amplitude. (2) Power of higher frequency components of the rotational acceleration signal (pronation/supination task), as a measure of bradykinesia. (3) Standard deviation of the local maxima of the rotational acceleration (pronation/supination task), as a measure of reduction in movement speed and amplitude. These features were used to correctly differentiate trials completed with and without simulated PD symptoms, using an SVM classifier with leave-one-out cross validation accuracy of 95%. These findings suggest it is possible to capture clinical features of PD using motion sensors. Future work in PD patients will examine how these measures correlate with UPDRS evaluations and whether they will be helpful in providing a quick, objective telehealth measure of progression and treatment response that can supplement current tools.

Laboratory Validation of Instrumented Mouthguard for Use in Sport

Concussion is an inherent risk of participating in contact, combat, or collision sports, within which head impacts are numerous. Kinematic parameters such as peak linear and rotational acceleration represent primary measures of concussive head impacts. The ability to accurately measure and categorise such impact parameters in real time is important in health and sports performance contexts. The purpose of this study was to assess the accuracy of the latest HitIQ Nexus A9 instrumented mouthguard (HitIQ Pty. Ltd. Melbourne Australia) against reference sensors in an aluminium headform. The headform underwent drop testing at various impact intensities across the NOCSAE-defined impact locations, comparing the peak linear and rotational acceleration (PLA and PRA) as well as the shapes of the acceleration time-series traces for each impact. Mouthguard PLA and PRA measurements strongly correlated with (R2 = 0.996 and 0.994 respectively), and strongly agreed with (LCCC = 0.997) the reference sensors. The root mean square error between the measurement devices was 1 ± 0.6g for linear acceleration and 47.4 ± 35 rad/s2 for rotational acceleration. A Bland–Altman analysis found a systematic bias of 1% for PRA, with no significant bias for PLA. The instrumented mouthguard displayed high accuracy when measuring head impact kinematics in a laboratory setting.

Head Impact Biomechanics in Youth Flag Football: A Prospective Cohort Study

Background: Youth flag football participation has rapidly grown and is a potentially safer alternative to tackle football. However, limited research has quantitatively assessed youth flag football head impact biomechanics. Purpose: To describe head impact biomechanics outcomes in youth flag football and explore factors associated with head impact magnitudes. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We monitored 52 player-seasons among 48 male flag football players (mean ± SD; age, 9.4 ± 1.1 years; height, 138.6 ± 9.5 cm; mass, 34.7 ± 9.2 kg) across 3 seasons using head impact sensors during practices and games. Sensors recorded head impact frequencies, peak linear ( g) and rotational (rad/s2) acceleration, and estimated impact location. Impact rates (IRs) were calculated as 1 impact per 10 player-exposures; IR ratios (IRRs) were used to compare season, event type, and age group IRs; and 95% CIs were calculated for IRs and IRRs. Weekly and seasonal cumulative head impact frequencies and magnitudes were calculated. Mixed-model regression models examined the association between player characteristics, event type, and seasons and peak linear and rotational accelerations. Results: A total of 429 head impacts from 604 exposures occurred across the study period (IR, 7.10; 95% CI, 4.81-10.50). Weekly and seasonal cumulative median head impact frequencies were 1.00 (range, 0-2.63) and 7.50 (range, 0-21.00), respectively. The most frequent estimated head impact locations were the skull base (n = 96; 22.4%), top of the head (n = 74; 17.2%), and back of the head (n = 66; 15.4%). The combined event type IRs differed among the 3 seasons (IRR range, 1.45-2.68). Games produced greater IRs (IRR, 1.24; 95% CI, 1.01-1.53) and peak linear acceleration (mean difference, 5.69 g; P = .008) than did practices. Older players demonstrated greater combined event–type IRs (IRR, 1.46; 95% CI, 1.12-1.90) and increased head impact magnitudes than did younger players, with every 1-year age increase associated with a 3.78 g and 602.81-rad/s2 increase in peak linear and rotational acceleration magnitude, respectively ( P≤ .005). Conclusion: Head IRs and magnitudes varied across seasons, thus highlighting multiple season and cohort data are valuable when providing estimates. Head IRs were relatively low across seasons, while linear and rotational acceleration magnitudes were relatively high.

On the Concept of Gravito-Rotational Acceleration and its Consequences for Compact Stellar Objects

In a previous series of papers relating to the Combined Gravitational Action (CGA), we have exclusively studied orbital motion without spin. In the present paper, we apply CGA to any self-rotating material body, i.e., an axially spinning massive object, which itself may be locally seen as a gravito-rotational source because it is capable of generating the gravito-rotational acceleration, which seems to be unknown to previously existing theories of gravity. The consequences of such an acceleration are very interesting, particularly for Compact Stellar Objects. Independently of the equation of state, it is found that the minimum radius of a stable neutron star is three times its gravitational radius, Rmin = 3GMNS/c2, and its critical and maximum internal magnetic field strength cannot exceed the value of 3×1018 G.

Concept of Gravito-Rotational Acceleration and its Consequences for Compact Stellar Objects

In a previous series of papers relating to the Combined Gravitational Action (CGA), we have exclusively studied orbital motion without spin. In the present paper, we apply CGA to any self-rotating material body, i.e., an axially spinning massive object, which itself may be locally seen as a gravito-rotational source because it is capable of generating the gravito-rotational acceleration, which seems to be unknown to previously existing theories of gravity. The consequences of such an acceleration are very interesting, particularly for Compact Stellar Objects. Independently of the equation of state, it is found that the critical and maximum internal magnetic field strength of a stable neutron star cannot exceed the value of 3x1018G.

Investigation of the Head’s Dynamic Response to Boxing Punch Using Computer Simulation

Head injuries are dangerous injuries that are common in combat sports. Nevertheless, the mechanisms of concussion in sport have are not precisely known. Thus, this study aimed to investigate the dynamic response of the head based on linear and rotational accelerations in boxing using computer simulation. The ADAMS software model was used to determine the linear and rotational acceleration of boxing’s straight punch. The peak linear acceleration, average linear acceleration, peak rotational acceleration, and average rotational acceleration resulted from the straight punch to head were obtained: 75 g, 20 g, 4036 rad/s², 1140 rad/s², respectively; the impact times were 30 ms and 3 ms, respectively. The comparison of acceleration tolerance thresholds of head injury and obtained results of this study showed the rotational acceleration only leads to head injury. Furthermore, it is biomechanically improbable that the head would be moved only translationally or rotationally as a result of a straight punch. Therefore, both rotational and linear accelerations should be observed together for future studies.

Impact Performance Comparison of Advanced Snow Sport Helmets with Dedicated Rotation-Damping Systems

Rotational acceleration of the head is a principal cause of concussion and traumatic brain injury. Several rotation-damping systems for helmets have been introduced to better protect the brain from rotational forces. But these systems have not been evaluated in snow sport helmets. This study investigated two snow sport helmets with different rotation-damping systems, termed MIPS and WaveCel, in comparison to a standard snow sport helmet without a rotation-damping system. Impact performance was evaluated by vertical drops of a helmeted Hybrid III head and neck onto an oblique anvil. Six impact conditions were tested, comprising two impact speeds of 4.8 and 6.2 m/s, and three impact locations. Helmet performance was quantified in terms of the linear and rotational kinematics, and the predicted probability of concussion. Both rotation-damping systems significantly reduced rotational acceleration under all six impact conditions compared to the standard helmet, but their effect on linear acceleration was less consistent. The highest probability of concussion for the standard helmet was 89%, while helmets with MIPS and WaveCel systems exhibited a maximal probability of concussion of 67 and 7%, respectively. In conclusion, rotation-damping systems of advanced snow sport helmets can significantly reduce rotational head acceleration and the associated concussion risk.

The effect of surface roughness on oblique bicycle helmet impact tests

The friction between a helmet and impact surface affects the accelerations imparted to the head. The roughness of the impact surface is, therefore, a consideration when developing oblique impact standards. An 80-grit abrasive paper is commonly used in oblique impact tests to simulate a road surface, but has not been validated for bicycle impacts and may not accurately represent real road surfaces. In the following study, a helmeted NOCSAE headform with a Hybrid III neck was dropped onto a 45° anvil at 6.5 m/s using a twin wire guided drop tower. Helmeted drops were performed in two orientations (frontal and side) on road surfaces, roughened steel surfaces, 80-grit abrasive paper and a low friction surface. For each impact, measures of linear and rotational acceleration were obtained. These metrics were compared across impact orientations and surfaces to assess the influence of surface roughness on headform impact response. Frontal impacts were less sensitive to the impact surface roughness than side impacts across metrics. Among metrics, rotational acceleration showed the largest effect due to surface roughness. Compared to the road surface, peak rotational acceleration from impacts on the 80-grit surface were 6.5% less and 48% greater for frontal and side impacts, respectively. Based on consideration of the peak and cumulative impact measures, steel impact surfaces appear to better simulate road impact than the commonly used 80-grit abrasive paper.