Comparing Neuromuscular Blockade Measurement Between Upper Arm (TOF Cuff®) and Eyelid (TOF Scan®) Using Mivacurium during General Anesthesia.

BACKGROUND Mivacurium is a non-depolarizing neuromuscular blocking agent. TOF-Cuff® is a device that monitors intraoperative neuromuscular blockade and blood pressure. TOF-Scan® measures muscle relaxation status of an anaesthetized patient. This study included 36 patients aged 18 to 75 years presenting for elective surgery, to compare neuromuscular blockade measured using the TOF-Cuff of the upper arm and the TOF-Scan of the facial corrugator supercilii muscle during general anesthesia and following administration of mivacurium. MATERIAL AND METHODS Train-of-four (TOF) values were obtained every 30 s before intubation and successively every 5 min until extubation. RESULTS The median onset time for TOF-Cuff was longer than for TOF-Scan (210 s vs 90 s, P<0.00001). Multiplying the time to relaxation (according to TOF-Scan) by 1 to 8, respectively, provided concordance with the TOF-Cuff result for the following cumulative percentages of patients: 5.5%, 38.9%, 58.3%, 77.8%, 83.3%, 86.1%, 88.9%, and 91.7%. Analogue values for time to recovery from the last dose were 11.1%, 63.9%, 83.3%, 86.1%, 86.1%, 88.9%, 88.9%, and 91.7%. The proportion of patients who still had TOFratio=0 in the assessment performed at min 15 did not differ significantly between these 2 methods (P=0.088). Both TOF-Scan and TOF-Cuff showed a false-negative result in patients with clinical symptoms of preterm recovery; the numerical difference favored TOF-Cuff (1.6% vs 2.1%) but without statistical significance (P=0.2235). CONCLUSIONS When measurement on the limb is not possible, TOF-Scan on the eyelid can be an alternative for TOF-Cuff on the upper arm, if the time to relaxation is multiplied by at least 8, which is enough for 90% of patients.

Motor learning in multijoint virtual arm movements with novel kinematics.

Humans move their hands toward precise positions, a skill supported by the coordination of multiple joint movements, even in the presence of inherent redundancy. However, it remains unclear how the central nervous system learns the relationship between redundant joint movements and hand positions when starting from scratch. To address this question, a virtual-arm reaching task was performed in which participants were required to move a cursor corresponding to the hand of a virtual arm to a target. The joint angles of the virtual arm were determined by the heights of the participants' fingers. The results demonstrated that the participants moved the cursor to the target straighter and faster in the late phase than they did in the initial phase of learning. This improvement was accompanied by a reduction in the amount of angular changes in the virtual limb joint, predominantly characterized by an increased reliance on the virtual shoulder joint as opposed to the virtual wrist joint. These findings suggest that the central nervous system selects a combination of multijoint movements that minimize motor effort while learning novel upper-limb kinematics.

Effectiveness of upper arm and breathing exercises to improve inflammatory markers in severe COVID-19 patients.

Studies have suggested associations between inflammatory markers with the severity of coronavirus disease 2019 (COVID-19). Therefore, exercises that could reduce the level of inflammatory markers might be beneficial. The aim of this study was to determine the effect of upper arm and breathing exercises on inflammatory markers such as ferritin, lactate dehydrogenase (LDH), and C-reactive protein (CRP) in severe COVID-19 patients. A quasi-experimental with pre-test and post-test control group design was conducted among severe COVID-19 aged 18-70 years old, with or without comorbidities. Baseline data of inflammatory markers (ferritin, LDH, and CRP) were measured before the exercises and repeated post-exercise. The upper arm and breathing exercises were performed for ten days, twice a day (morning and evening) for ten minutes. A paired Student t-test was used to assess the changes in the inflammatory markers' levels. Our data indicated that levels of ferritin and CRP were not significantly different between pre- and post-exercise. However, the level of LDH decreased significantly from 481.35 U/L to 331.80 U/L (p=0.001). This study highlights that pulmonary rehabilitation exercises might be beneficial to enhance the recovery process in severe COVID-19 patients.

Non-invasive spinal cord electrical stimulation for arm and hand function in chronic tetraplegia: a safety and efficacy trial.

Cervical spinal cord injury (SCI) leads to permanent impairment of arm and hand functions. Here we conducted a prospective, single-arm, multicenter, open-label, non-significant risk trial that evaluated the safety and efficacy of ARCEX Therapy to improve arm and hand functions in people with chronic SCI. ARCEX Therapy involves the delivery of externally applied electrical stimulation over the cervical spinal cord during structured rehabilitation. The primary endpoints were safety and efficacy as measured by whether the majority of participants exhibited significant improvement in both strength and functional performance in response to ARCEX Therapy compared to the end of an equivalent period of rehabilitation alone. Sixty participants completed the protocol. No serious adverse events related to ARCEX Therapy were reported, and the primary effectiveness endpoint was met. Seventy-two percent of participants demonstrated improvements greater than the minimally important difference criteria for both strength and functional domains. Secondary endpoint analysis revealed significant improvements in fingertip pinch force, hand prehension and strength, upper extremity motor and sensory abilities and self-reported increases in quality of life. These results demonstrate the safety and efficacy of ARCEX Therapy to improve hand and arm functions in people living with cervical SCI. ClinicalTrials.gov identifier: NCT04697472 .

The use of accelerometer bracelets to evaluate arm motor function over a stroke rehabilitation period - an explorative observational study.

BACKGROUND: Assessments of arm motor function are usually based on clinical examinations or self-reported rating scales. Wrist-worn accelerometers can be a good complement to measure movement patterns after stroke. Currently there is limited knowledge of how accelerometry correlate to clinically used scales. The purpose of this study was therefore to evaluate the relationship between intermittent measurements of wrist-worn accelerometers and the patient's progression of arm motor function assessed by routine clinical outcome measures during a rehabilitation period. METHODS: Patients enrolled in in-hospital rehabilitation following a stroke were invited. Included patients were asked to wear wrist accelerometers for 24 h at the start (T1) and end (T2) of their rehabilitation period. On both occasions arm motor function was assessed by the modified Motor Assessment Scale (M_MAS) and the Motor Activity Log (MAL). The recorded accelerometry was compared to M_MAS and MAL. RESULTS: 20 patients were included, of which 18 completed all measurements and were therefore included in the final analysis. The resulting Spearman's rank correlation coefficient showed a strong positive correlation between measured wrist acceleration in the affected arm and M-MAS and MAL values at T1, 0.94 (p < 0.05) for M_MAS and 0.74 (p < 0.05) for the MAL values, and a slightly weaker positive correlation at T2, 0.57 (p < 0.05) for M_MAS and 0.46 - 0.45 (p = 0.06) for the MAL values. However, no correlation was seen for the difference between the two sessions. CONCLUSIONS: The results confirm that the wrist acceleration can differentiate between the affected and non-affected arm, and that there is a positive correlation between accelerometry and clinical measures. Many of the patients did not change their M-MAS or MAL scores during the rehabilitation period, which may explain why no correlation was seen for the difference between measurements during the rehabilitation period. Further studies should include continuous accelerometry throughout the rehabilitation period to reduce the impact of day-to-day variability.

Mapping Method of Human Arm Motion Based on Surface Electromyography Signals.

This paper investigates a method for precise mapping of human arm movements using sEMG signals. A multi-channel approach captures the sEMG signals, which, combined with the accurately calculated joint angles from an Inertial Measurement Unit, allows for action recognition and mapping through deep learning algorithms. Firstly, signal acquisition and processing were carried out, which involved acquiring data from various movements (hand gestures, single-degree-of-freedom joint movements, and continuous joint actions) and sensor placement. Then, interference signals were filtered out through filters, and the signals were preprocessed using normalization and moving averages to obtain sEMG signals with obvious features. Additionally, this paper constructs a hybrid network model, combining Convolutional Neural Networks and Artificial Neural Networks, and employs a multi-feature fusion algorithm to enhance the accuracy of gesture recognition. Furthermore, a nonlinear fitting between sEMG signals and joint angles was established based on a backpropagation neural network, incorporating momentum term and adaptive learning rate adjustments. Finally, based on the gesture recognition and joint angle prediction model, prosthetic arm control experiments were conducted, achieving highly accurate arm movement prediction and execution. This paper not only validates the potential application of sEMG signals in the precise control of robotic arms but also lays a solid foundation for the development of more intuitive and responsive prostheses and assistive devices.

Young Girl with Right Arm Cramps while Writing.

A 15-year-old girl arrived with her father. She reported experiencing discomfort and cramps in her right arm while writing for the past 3 months. Her father had observed a palpable lump medially in her right mid-arm. She mentioned variations in the size of the lump on occasion. She denied experiencing any notable pain in the lump.

The anterior cingulate cortex is involved in intero-exteroceptive integration for spatial image transformation of the self-body.

Spatial image transformation of the self-body is a fundamental function of visual perspective-taking. Recent research underscores the significance of intero-exteroceptive information integration to construct representations of our embodied self. This raises the intriguing hypothesis that interoceptive processing might be involved in the spatial image transformation of the self-body. To test this hypothesis, the present study used functional magnetic resonance imaging to measure brain activity during an arm laterality judgment (ALJ) task. In this task, participants were tasked with discerning whether the outstretched arm of a human figure, viewed from the front or back, was the right or left hand. The reaction times for the ALJ task proved longer when the stimulus presented orientations of 0°, 90°, and 270° relative to the upright orientation, and when the front view was presented rather than the back view. Reflecting the increased reaction time, increased brain activity was manifested in a cluster centered on the dorsal anterior cingulate cortex (ACC), suggesting that the activation reflects the involvement of an embodied simulation in ALJ. Furthermore, this cluster of brain activity exhibited overlap with regions where the difference in activation between the front and back views positively correlated with the participants' interoceptive sensitivity, as assessed through the heartbeat discrimination task, within the pregenual ACC. These results suggest that the ACC plays an important role in integrating intero-exteroceptive cues to spatially transform the image of our self-body.

An Analysis of Intrapitch Variation in Joint and Segment Velocities With Throwing Arm Kinetics in High School and Professional Baseball Pitchers.

BACKGROUND: Improper sequencing order of maximal joint and segment velocities has been identified as an important predictor for both throwing arm kinetics and ball velocity. PURPOSE: To investigate the intrapitcher variation of maximal segment velocities and the relationship to throwing arm kinetics and ball velocity in high school (HS) and professional (PRO) pitchers. STUDY DESIGN: Descriptive laboratory study. METHODS: HS (n = 59) and PRO (n = 338) pitchers, instructed to throw 8 to 12 fastball pitches, were evaluated with 3-dimensional motion capture (480 Hz). Maximal joint and segment velocities were calculated for each pitch, and the standard deviation of the maxima was calculated per pitcher. These standard deviations were used to classify pitchers as "low variance" or "high variance" for each segmental velocity subgroup, "overall low variance" or "overall high variance" based on cumulative segment velocity variation, or "population," with any pitcher eligible to be included in multiple subcategories. Maximal velocities and throwing arm kinetics were compared among the various subgroups. RESULTS: The HS low-variance shoulder internal rotation velocity subgroup (4949 ± 642 deg/s) had significantly lower maximal shoulder internal rotation velocity compared with HS population (5774 ± 1057 deg/s) (P < .001); similar findings were observed for PROs (5269 ± 835 vs 5824 ± 1076 deg/s; P < .001), as well as lower shoulder superior force compared with the PRO population (14.8% ± 8.8% vs 17.8% ± 8.8% body weight; P = .001). The PRO low-variance lead knee extension velocity subgroup had significantly lower maximal lead knee extension velocity (216 ± 135 vs 258 ± 125 deg/s; P = .001) and shoulder distractive force (111.5% ± 14.4% vs 115.6% ± 15.9% body weight; P = .003) compared with the PRO population. The PRO overall low-variance subgroup had significantly lower shoulder distractive force (111.8% ± 14.1% vs 119.6% ± 15.5% body weight; P = .008) and elbow anterior force (40.6% ± 5.0% vs 43.6% ± 6.2% body weight; P = .008) compared with the PRO overall high-variance subgroup. CONCLUSION: HS and PRO pitchers with low variance for joint and segment velocities achieved significantly lower maximal velocities in the subgroup of interest, while preserving ball velocity. PRO pitchers with overall low variance among multiple maximal joint and segment velocities demonstrated decreased shoulder distractive and elbow anterior force. CLINICAL RELEVANCE: PRO pitchers with low intrapitch variation in maximal joint and segment velocities may be viewed as kinetically conservative throwers. These pitchers with similarly maintained mechanics between pitches may have an increasingly regimented form that preserves kinetic forces about the throwing arm. The opposite may be true for PRO pitchers with increased variability in segmental velocities during their pitching motion, as they showed increased throwing arm kinetics including shoulder distractive and elbow anterior force compared with the overall low-variance group, theoretically increasing their risk of injury.

The SPECTRAL Perfusion Arm Clamping dAtaset (SPECTRALPACA) for video-rate functional imaging of the skin.

Spectral imaging has the potential to become a key technique in interventional medicine as it unveils much richer optical information compared to conventional RBG (red, green, and blue)-based imaging. Thus allowing for high-resolution functional tissue analysis in real time. Its higher information density particularly shows promise for the development of powerful perfusion monitoring methods for clinical use. However, even though in vivo validation of such methods is crucial for their clinical translation, the biomedical field suffers from a lack of publicly available datasets for this purpose. Closing this gap, we generated the SPECTRAL Perfusion Arm Clamping dAtaset (SPECTRALPACA). It comprises ten spectral videos (∼20 Hz, approx. 20,000 frames each) systematically recorded of the hands of ten healthy human participants in different functional states. We paired each spectral video with concisely tracked regions of interest, and corresponding diffuse reflectance measurements recorded with a spectrometer. Providing the first openly accessible in human spectral video dataset for perfusion monitoring, our work facilitates the development and validation of new functional imaging methods.

The impact of high-intensity arm crank exercise on reaction time in wheelchair fencers: gender differences and mechanical predictors.

To achieve high performance, wheelchair fencing (WF) athletes are required to exhibit good physiological and timing indicators. The main aims of this study were to assess the relationship between the results of the repeated sprint ability (RSA) test and reaction time (RT) in WF, and to evaluate changes in RT after repeated high-intensity sprints in the group of an international-level WF athletes. This experimental study involved 18 athletes (aged 34.6 ± 7.70) from the Paralympic WF team. To establish the impact of fatigue on psychomotor capacity, the participants undergo a series of tests. At the beginning of the study, first reaction time (RT1) was measured. Afterwards, the RSA test was performed using the arm crank ergometer to evaluate the participants' repeated sprint ability. Immediately after RSA, the second reaction time (RT2) was measured. Statistical analysis revealed moderate correlations between the RT2 and total work, decrease of work (DW), highest peak power, mean peak power, and highest peak power/kg, but these correlations were not statistically significant (p > 0.05). All fencers achieved a significantly shorter average RT2 (p < 0.005) after the RSA test (0.383 ± 0.035 s) than before the test (0.391 ± 0.038 s). Additionally, RT2 was significantly shorter than RT1 in the women's group (p < 0.001). Moreover, males had significantly greater values of repeated sprint ability parameters: highest work, total work, decrease of work and highest peak power (p < 0.05) than females. To conclude, repeated high-intensity arm crank exercise has a positive impact on simple postexercise cognitive tasks in WF fencers, especially in women, and leads to a decrease in RT. The RSA parameters can be predictors of changes in RT in men and women wheelchair fencers.

Kinematic descriptors of arm reaching movement are sensitive to hemisphere-specific immediate neuromodulatory effects of transcranial direct current stimulation post stroke.

Transcranial direct current stimulation (tDCS) exerts beneficial effects on motor recovery after stroke, presumably by enhancement of adaptive neural plasticity. However, patients with extensive damage may experience null or deleterious effects with the predominant application mode of anodal (excitatory) stimulation of the damaged hemisphere. In such cases, excitatory stimulation of the non-damaged hemisphere might be considered. Here we asked whether tDCS exerts a measurable effect on movement quality of the hemiparetic upper limb, following just a single treatment session. Such effect may inform on the hemisphere that should be excited. Using a single-blinded crossover experimental design, stroke patients and healthy control subjects were assessed before and after anodal, cathodal and sham tDCS, each provided during a single session of reaching training (repeated point-to-point hand movement on an electronic tablet). Group comparisons of endpoint kinematics at baseline-number of peaks in the speed profile (NoP; smoothness), hand-path deviations from the straight line (SLD; accuracy) and movement time (MT; speed)-disclosed greater NoP, larger SLD and longer MT in the stroke group. NoP and MT revealed an advantage for anodal compared to sham stimulation of the lesioned hemisphere. NoP and MT improvements under anodal stimulation of the non-lesioned hemisphere correlated positively with the severity of hemiparesis. Damage to specific cortical regions and white-matter tracts was associated with lower kinematic gains from tDCS. The study shows that simple descriptors of movement kinematics of the hemiparetic upper limb are sensitive enough to demonstrate gain from neuromodulation by tDCS, following just a single session of reaching training. Moreover, the results show that tDCS-related gain is affected by the severity of baseline motor impairment, and by lesion topography.

3D octopus kinematics of complex postures: Translation to long, thin, soft devices and their potential for clinical use.

INTRO/BACKGROUND: Octopuses are capable of complex arm movements. Unfortunately, experimental barriers and lack of a robust analysis method made it difficult to quantify the three-dimensional (3D) kinematics of soft, flexible bodies, such as the octopus arm. This information is not only crucial for understanding the posture of the animal's arm but also for the development of similarly designed soft, flexible devices. OBJ/GOAL: The primary goal of this work was to create a method to comprehensively quantify complex, 3D postures of octopus (Octopus Bimaculoides) arms in a manner that is conducive and translatable to octopus arm-inspired devices for health monitoring and rehabilitation. METHODS: In this study, 3D underwater motion capture was used to collect kinematic data on both live octopuses and disembodied arms that still had neural activity. A new method was developed to define how arm curvature and regional segments were oriented relative to each other in 3D. This included identification of the bend within a segment along with the computation of the relative orientation between segments, thus permitting the complete quantification of complex arm motions. RESULTS: By comparing vector-based and radius of curvature-based approaches to magnitude of curvature, it was clear that the vector-based approach was less dependent on the length of a segment and that its reported ranges of motion were translatable for outcome measures associated with clinical use. The new approach for the relative orientation of each segment of the octopus arm resulted in the capability of describing the octopus arm in many unique postures, such as straight, simple bending, and complex bending as it utilized the three rotational angles. OUTCOME/IMPACT: This method and its application to octopus arms will yield new information that can be used to better communicate and track not only octopus arm movements but in the development of complex, segmented, soft-bodied devices that can be used in health monitoring and rehabilitation.

Optimal configurations for stiffness and compliance in human & robot arms.

Research in neurophysiology has shown that humans are able to adapt the mechanical stiffness at the hand in order to resist disturbances. This has served as inspiration for optimising stiffness in robot arms during manipulation tasks. Endpoint stiffness is modelled in Cartesian space, as though the hand were in independent rigid body. But an arm is a series of rigid bodies connected by articulated joints. The contribution of the joints and arm configuration to the endpoint stiffness has not yet been quantified. In this paper we use mathematical optimisation to find conditions for maximum stiffness and compliance with respect to an externally applied force. By doing so, we can retroactively explain observations made about humans using these mathematically optimal conditions. We then show how this optimisation can be applied to robotic task planning and control. Experiments on a humanoid robot show similar arm posture to that observed in humans. This suggests there is an underlying physical principle by which humans optimise stiffness. We can use this to derive natural control methods for robots.

Time-Dependent Changes of Extremity Volume and Tissue Alterations in Swollen Arms Caused by Taxanes.

Background: We aimed to determine the course of arm swelling caused by the use of taxanes and to identify valid predictors of persistent swelling. Methods and Results: A total of 15 patients with unilateral arm swelling that developed during the course, or within 3 months after termination, of postoperative taxane-based chemotherapy were included in the present study. The patients attended follow-up appointments every 3-6 months for 24 months after their initial visit. Their arm circumference was measured at each follow-up appointment, while ultrasonography of the skin and subcutaneous tissues was performed at the 0-, 6-, 12-, and 24-month follow-ups. Of the 15 patients, 12 (80%) saw their taxane-induced arm swelling resolved within a median of 12 months (range, 3-29 months) after their final taxane administration. Of the 12 patients whose swelling resolved, 9 did not use compression sleeves; however, their course of resolution did not differ from the other 3 patients who regularly used compression sleeves. In the three patients with persistent swelling, the excess subcutaneous thickness in the medial upper arm (median, 283%) was significantly greater than that in the patients whose swelling resolved (120%; p < 0.05) during their initial visits. Conclusions: Of the 15 patients included in the present study, 80% saw their taxane-induced arm swelling resolve within a median of 12 months after their final taxane administration, independent of the use of compression therapy. Persistent swelling may be predicted during the initial visit based on subcutaneous thickening of the medial upper arm.

Low Hand Grip Strength, Mid-Upper Arm Muscle Area, Calf Circumference, Serum Albumin Level, and Muscle Fiber Diameter as Risk Factors for Independent Walking Inability in Patients with Hip Fracture 6 Weeks after Bipolar Hemiarthroplasty Surgery.

Background: Bipolar hemiarthroplasty, one of the main treatment modalities for hip fracture, does not always promise the ability to walk independently after surgery. Patients with the same fracture characteristics and comorbidities, implants, and operators may also have different outcomes. Sarcopenia is thought to be one of the causes of the inability to walk independently after this operation; however, it has not been widely studied and is often overlooked. Methods: This study used a case-control design with 23 patients in the case group (patients unable to walk independently) and 23 patients in the control group (patients able to walk independently). Sampling was carried out consecutively according to the inclusion and exclusion criteria based on the medical records of patients with hip fractures after bipolar hemiarthroplasty at our hospital. In the preoperative period, hand grip strength (HGS), mid-upper arm muscle area (MUAMA), calf circumference (CC), serum albumin level, and total lymphocyte count were measured. A muscle biopsy was performed intraoperatively from the gluteus muscle with the amount of 200-350 mg. The patient's walking ability was assessed in the polyclinic using the Timed Up and Go test 6 weeks postoperatively. The statistical tests used were descriptive statistics, proportion comparison analysis with the chi-square test, and multiple logistic regression test. Results: Univariate analysis using chi-square test proved HGS, MUAMA, CC, serum albumin level, and muscle fiber diameter as risk factors for inability to walk independently 6 weeks after bipolar hemiarthroplasty (p = 0.003, p = 0.003, p = 0.006, p = 0.044, and p = 0.000, respectively). Logistic regression test proved 3 direct risk factors for the inability to walk independently 6 weeks after bipolar hemiarthroplasty, namely MUAMA, serum albumin level, and muscle fiber diameter, as the strongest predictive factor (adjusted odds ratio, 63.12). Conclusions: Low MUAMA, serum albumin levels, and muscle fiber diameter are direct risk factors for the inability to walk independently in hip fracture patients 6 weeks after bipolar hemiarthroplasty.

Investigation of the pressure value while performing biceps tenodesis for superior capsuler reconstruction.

BACKGROUND: To compare the histopathological results of biceps tenodesis (BT) performed with normal, low, and high pressures for superior capsule reconstruction (SCR) in rabbits with massive rotator cuff tears. MATERIALS AND METHODS: Thirty rabbits were divided into three groups. Rabbits 1-10 underwent SCR with BT at the same pressure (Group 1), value measured in the groove; 50% lower (Group 2); 50% higher (Group 3). After the 4-week follow-up, shoulder were en-bloc excised and histopathological evaluation was performed with modified Bonar's scale. Results were compared between the groups, statistically. RESULTS: Extracellular matrix were significantly lower in group 2 compared to the other groups (p < 0.05). Cellularity levels were significantly lower in group 2 compared to the other groups (p < 0.05). Group 2 had no difference between the sides (p > 0.05). Group 2 had lower vascularity levels compared to the other groups (p = 0.01). DICSUSSION: When the biceps tendon was in the bicipital groove and in a more mobile state with lower pressure exposure. BT performed with a tension that creates less pressure than the biceps in the groove is more successful in SCR.

Changes in Dynamic Mean Ankle Moment Arm in Unimpaired Walking Across Speeds, Ramps, and Stairs.

Understanding the natural biomechanics of walking at different speeds and activities is crucial to develop effective assistive devices for persons with lower-limb impairments. While continuous measures such as joint angle and moment are well-suited for biomimetic control of robotic systems, whole-stride summary metrics are useful for describing changes across behaviors and for designing and controlling passive and semi-active devices. Dynamic mean ankle moment arm (DMAMA) is a whole-stride measure representing the moment arm of the ground reaction impulse about the ankle joint-effectively, how "forefoot-dominated" or "hindfoot-dominated" a movement is. DMAMA was developed as a target and performance metric for semi-active devices that adjust once per stride. However, for implementation in this application, DMAMA must be characterized across various activities in unimpaired individuals. In our study, unimpaired participants walked at "slow," "normal," and "fast" self-selected speeds on level ground and at a normal self-selected speed while ascending and descending stairs and a 5-degree incline ramp. DMAMA measured from these activities displayed a borderline-significant negative sensitivity to walking speed, a significant positive sensitivity to ground incline, and a significant decrease when ascending stairs compared to descending. The data suggested a nonlinear relationship between DMAMA and walking speed; half of the participants had the highest average DMAMA at their "normal" speed. Our findings suggest that DMAMA varies substantially across activities, and thus, matching DMAMA could be a valuable metric to consider when designing biomimetic assistive lower-limb devices.

A machine-learning method isolating changes in wrist kinematics that identify age-related changes in arm movement.

Normal aging often results in an increase in physiological tremors and slowing of the movement of the hands, which can impair daily activities and quality of life. This study, using lightweight wearable non-invasive sensors, aimed to detect and identify age-related changes in wrist kinematics and response latency. Eighteen young (ages 18-20) and nine older (ages 49-57) adults performed two standard tasks with wearable inertial measurement units on their wrists. Frequency analysis revealed 5 kinematic variables distinguishing older from younger adults in a postural task, with best discrimination occurring in the 9-13 Hz range, agreeing with previously identified frequency range of age-related tremors, and achieving excellent classifier performance (0.86 AUROC score and 89% accuracy). In a second pronation-supination task, analysis of angular velocity in the roll axis identified a 71 ms delay in initiating arm movement in the older adults. This study demonstrates that an analysis of simple kinematic variables sampled at 100 Hz frequency with commercially available sensors is reliable, sensitive, and accurate at detecting age-related increases in physiological tremor and motor slowing. It remains to be seen if such sensitive methods may be accurate in distinguishing physiological tremors from tremors that occur in neurological diseases, such as Parkinson's Disease.