Upper extremity coordination strategies depending on task demand during a basic daily activity

Forearm Posture Affects the Corticospinal Excitability of Intrinsic and Extrinsic Hand Muscles in Dominant and Nondominant Sides

Different forearm postures can modulate corticospinal excitability. However, there is no consensus on whether handedness plays a role in such a mechanism. This study investigated the effects of 3 forearm postures (pronation, neutral, and supination) on the corticospinal excitability of muscles from the dominant and nondominant upper limbs. Surface electromyography was recorded from the abductor digiti minimi, flexor pollicis brevis, and flexor carpi radialis from both sides of 12 right-handed volunteers. Transcranial magnetic stimulation pulses were applied to each muscle's hotspot in both cerebral hemispheres. Motor-evoked potential peak-to-peak amplitude and latency and resting motor threshold were measured. The data were evaluated by analysis of variance. The level of significance was set at 5%. The resting motor threshold was similar for the 3 muscles and both sides. Motor-evoked potential peak-to-peak amplitude from flexor pollicis brevis was lower during supination, and the dominant upper limb latency was longer. The flexor carpi radialis presented lower motor-evoked potential peak-to-peak amplitudes for neutral and shorter latencies during supination. Abductor digiti minimi seemed not to be affected by posture or side. Different muscles from dominant and nondominant sides may undergo corticospinal modulation, even distally localized from a particular joint and under rest.

Exploration of outcome measures for assessing orthotic intervention in upper extremity peripheral nerve injuries: 2 case reports

In upper extremity peripheral nerve injuries, orthotic intervention has been used as a valuable device to restore function. However, there is lacking evidence to support it. The purpose of this study was to explore the application of body function's outcome measures for orthotic intervention evaluation in patients with peripheral nerve injury. Two participants sustaining a peripheral nerve injury who underwent orthotic intervention were assessed: subject 1 was a 25-year-old man with ulnar and median nerve injury presenting with a composite claw; subject 2, a 28-year-old man with radial nerve injury presenting with a dropped wrist. Strength, range of motion, and electromyography were measured in 2 conditions: wearing the orthosis and without it. The Jamar, Pinch Gauge, a 3D motion capture system (Optitrack-NaturalPoint), and surface electromyography (Trigno Wireless System, Delsys) were the chosen instruments. Both subjects presented differences in grip and pinch strength. In both tasks, subject 1 reached higher wrist extension while wearing the orthosis. Subject 2 reached higher wrist extension and radial deviation while wearing the orthosis. There were marked differences in both tasks for subject 2, especially the maintenance of wrist extension when wearing the orthosis. Electromyographic assessment showed higher root-mean-square values for all muscles, in both tasks for subject 1. For subject 2, a higher root-mean-square value was found for flexor carpi ulnaris during the execution of task 1 wearing the orthosis. Outcome measures of body function can quantify the impact of orthotic intervention in patients sustaining peripheral nerve injury, and therefore, they are feasible for evaluating it.

Exploring the EMG transient: the muscular activation sequences used as novel time-domain features for hand gestures classification

Introduction

Muscular activation sequences have been shown to be suitable time-domain features for classification of motion gestures. However, their clinical application in myoelectric prosthesis control was never investigated so far. The aim of the paper is to evaluate the robustness of these features extracted from the EMG signal in transient state, on the forearm, for classifying common hand tasks.

Methods

The signal associated to four hand gestures and the rest condition were acquired from ten healthy people and two persons with trans-radial amputation. A feature extraction algorithm allowed for encoding the EMG signals into muscular activation sequences, which were used to train four commonly used classifiers, namely Linear Discriminant Analysis (LDA), Support Vector Machine (SVM), Non-linear Logistic Regression (NLR) and Artificial Neural Network (ANN). The offline performances were assessed with the entire sample of recruited people. The online performances were assessed with the amputee subjects. Moreover, a comparison of the proposed method with approaches based on the signal envelope in the transient state and in the steady state was conducted.

Results

The highest performance were obtained with the NLR classifier. Using the sequences, the offline classification accuracy was higher than 93% for healthy and amputee subjects and always higher than the approach with the signal envelope in transient state. As regards the comparison with the steady state, the performances obtained with the proposed method are slightly lower (<4%), but the classification occurred at least 200 ms earlier. In the online application, the motion completion rate reached up to 85% of the total classification attempts, with a motion selection time that never exceeded 218 ms.

Discussion

Muscular activation sequences are suitable alternatives to the time-domain features commonly used in classification problems belonging to the sole EMG transient state and could be potentially exploited in control strategies of myoelectric prosthesis hands.

Effect of age on upper limb, neck, and trunk kinematics during activities of daily living

Motion analysis during activities of daily living has been conducted in numerous studies. However, information is lacking regarding age-related differences that affect clinical assessment and treatment goals. This study aimed to examine the effect of age on kinematics during activities of daily living. Three-dimensional motions of the shoulder, elbow, neck, and trunk of 12 younger adults (age, 29.8 ± 5.4 years; 7 men and 5 women) and 10 older adults (age, 69.5 ± 4.9 years; 6 men and 4 women) were measured during the acts of reaching for a table, bringing a glass to the mouth for drinking, wiping the buttocks, tying shoelaces, washing hair, washing the axilla, reaching for a high shelf, and reaching for the floor. The ranges of motion and sequential joint angles were compared between age groups by using discrete analysis and statistical parametric mapping, respectively. The ranges of motion of all joint angles in older and younger adults were comparable in the drinking, washing hair, washing the axilla, and reaching for the floor tasks. Statistical parametric mapping indicated that older adults had significantly poorer neck extension than did younger adults during the drinking (67-92% cycle time) and tying shoelaces (64-95% cycle time) tasks. Kinematics were mostly maintained in healthy older adults during activities of daily living. However, reduced motions were confirmed later during some tasks. The results indicated that existing knowledge combined with the current findings, which take age into account, could be used in clinical settings to assess the kinematics of activities of daily living and set treatment goals.

Motion Capture Technologies for Ergonomics: A Systematic Literature Review

Muscular skeletal disorder is a difficult challenge faced by the working population. Motion capture (MoCap) is used for recording the movement of people for clinical, ergonomic and rehabilitation solutions. However, knowledge barriers about these MoCap systems have made them difficult to use for many people. Despite this, no state-of-the-art literature review on MoCap systems for human clinical, rehabilitation and ergonomic analysis has been conducted. A medical diagnosis using AI applies machine learning algorithms and motion capture technologies to analyze patient data, enhancing diagnostic accuracy, enabling early disease detection and facilitating personalized treatment plans. It revolutionizes healthcare by harnessing the power of data-driven insights for improved patient outcomes and efficient clinical decision-making. The current review aimed to investigate: (i) the most used MoCap systems for clinical use, ergonomics and rehabilitation, (ii) their application and (iii) the target population. We used preferred reporting items for systematic reviews and meta-analysis guidelines for the review. Google Scholar, PubMed, Scopus and Web of Science were used to search for relevant published articles. The articles obtained were scrutinized by reading the abstracts and titles to determine their inclusion eligibility. Accordingly, articles with insufficient or irrelevant information were excluded from the screening. The search included studies published between 2013 and 2023 (including additional criteria). A total of 40 articles were eligible for review. The selected articles were further categorized in terms of the types of MoCap used, their application and the domain of the experiments. This review will serve as a guide for researchers and organizational management.

Does thermoplastics' thickness influence joint stabilization and movement coordination? An inferential study of wrist orthoses

BACKGROUND

Given the existence of multiple low-temperature thermoplastics, clinicians fabricating can readily modify an orthoses' thickness, weight and flexibility, among other properties. However, there is limited evidence on the impact of such different materials on upper extremities' biomechanics.

OBJECTIVE

Our study aimed to investigate differences in joint stabilization and movement coordination provided by upper extremity orthotics fabricated with low-temperature thermoplastics of different thicknesses.

STUDY DESIGN

Inferential, cross-sectional study.

METHOD

We conducted a kinematic analysis of a standardized task through a three-dimensional motion capture system. Ten participants (5 female) performed the same task under three circumstances: 1) wearing a volar wrist immobilization orthosis, made with a 3.2-mm thick low-temperature thermoplastic; 2) using the same orthotic fabricated with a 1.6-mm thick material; and (3) without orthoses. We divided the standardized task into five logical phases for data analysis, obtaining the active range of motion of the shoulder, elbow, forearm, and wrist joints as the primary outcome. Secondary outcomes included movement smoothness and coordination, measured by the number of motor units, time, and distance travelled by the upper extremity.

RESULTS

Despite changes in thermoplastic thickness, both orthotics significantly restricted the wrist motion during task performance (F(2,16) = 14.32, P < .01, and η2p = 0.797), with no difference between the 2 devices and no significant changes to proximal joints' active range of motion. Although orthoses use increased the time required for task performance (F(2,16) = 23.05, P < .01, and η2p = 0.742), no significant differences in movement smoothness or coordination were noted.

CONCLUSION

Our results indicate that wrist orthoses fabricated with a 1.6-mm thick low-temperature thermoplastic can provide joint stabilization similar to a device made from a 3.2-mm thickness material, suggesting thinner thermoplastics' efficacy to stabilize joints in the absence of contractures or preexisting chronic conditions.

Exploring the efficacy of a set of smart devices for postural awareness for workers in an industrial context – A protocol for a single-subject experimental design (Preprint)

BACKGROUND

In manufacturing industries, tasks requiring poor posture, high repetition, and long duration commonly induce fatigue and lead to an increased risk of work-related musculoskeletal disorders. Smart devices assessing biomechanics and providing feedback to the worker for correction may be a successful way to increase postural awareness, reducing fatigue, and work-related musculoskeletal disorders. However, evidence in industrial settings is lacking.

OBJECTIVE

This study protocol aims to explore the efficacy of a set of smart devices to detect malposture and increase postural awareness, reducing fatigue, and musculoskeletal disorders.

METHODS

A longitudinal single-subject experimental design following the ABAB sequence will be developed in a manufacturing industry real context with 5 workers. A repetitive task of screw tightening of 5 screws in a standing position into a piece placed horizontally was selected. Workers will be assessed in 4 moments per shift (10 minutes after the beginning of the shift, 10 minutes before and after the break, and 10 minutes before the end of the shift) in 5 nonconsecutive days. The primary outcomes are fatigue, assessed by electromyography, and musculoskeletal symptoms assessed by the Nordic Musculoskeletal Questionnaire. Secondary outcomes include perceived effort (Borg perceived exertion scale); range of motion of the main joints in the upper body, speed, acceleration, and deceleration assessed by motion analysis; risk stratification of range of motion; and cycle duration in minutes. Structured visual analysis techniques will be conducted to observe the effects of the intervention. Results for each variable of interest will be compared among the different time points of the work shift and longitudinally considering each assessment day as a time point.

RESULTS

Enrollment for the study will start in April 2023. Results are expected to be available still in the first semester of 2023. It is expected that the use of the smart system will reduce malposture, fatigue, and consequently, work-related musculoskeletal pain and disorders.

CONCLUSIONS

This proposed study will explore a strategy to increase postural awareness in industrial manufacturing workers who do repetitive tasks, using smart wearables that provide real-time feedback about biomechanics. Results would showcase a novel approach for improving self-awareness of risk for work-related musculoskeletal disorders for these workers providing an evidence base support for the use of such devices.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/43637.

Upper limb joint coordination preserves hand kinematics after a traumatic brachial plexus injury

Background

Traumatic brachial plexus injury (TBPI) causes a sensorimotor deficit in upper limb (UL) movements.

Objective

Our aim was to investigate the arm–forearm coordination of both the injured and uninjured UL of TBPI subjects.

Methods

TBPI participants (n = 13) and controls (n = 10) matched in age, gender, and anthropometric characteristics were recruited. Kinematics from the shoulder, elbow, wrist, and index finger markers were collected, while upstanding participants transported a cup to their mouth and returned the UL to a starting position. The UL coordination was measured through the relative phase (RP) between arm and forearm phase angles and analyzed as a function of the hand kinematics.

Results

For all participants, the hand transport had a shorter time to peak velocity (p &lt; 0.01) compared to the return. Also, for the control and the uninjured TBPI UL, the RP showed a coordination pattern that favored forearm movements in the peak velocity of the transport phase (p &lt; 0.001). TBPI participants' injured UL showed a longer movement duration in comparison to controls (p &lt; 0.05), but no differences in peak velocity, time to peak velocity, and trajectory length, indicating preserved hand kinematics. The RP of the injured UL revealed altered coordination in favor of arm movements compared to controls and the uninjured UL (p &lt; 0.001). Finally, TBPI participants' uninjured UL showed altered control of arm and forearm phase angles during the deceleration of hand movements compared to controls (p &lt; 0.05).

Conclusion

These results suggest that UL coordination is reorganized after a TBPI so as to preserve hand kinematics.

Shoulder structure and function: The impact of osteoarthritis and rehabilitation strategies

STUDY DESIGN

Invited review.

BACKGROUND

Shoulder osteoarthritis can result in significant functional deficits. To improve diagnosis and treatment, we must better understand the impact of osteoarthritis on shoulder biomechanics and the known mechanical benefits of currently available treatments.

PURPOSE

The purpose of this paper is to present up-to-date data on the effects of osteoarthritis and rehabilitation on the biomechanical parameters contributing to shoulder function. With this goal, we also reviewed the anatomy and the ranges of motion of the shoulder.

METHODS

A search of electronic databases was conducted. All study designs were included to inform this qualitative, narrative literature review.

RESULTS

This review describes the biomechanics of the shoulder, the impact of osteoarthritis on shoulder function, and the treatment of shoulder osteoarthritis with an emphasis on rehabilitation.

CONCLUSIONS

The shoulder is important for the completion of activities of daily living, and osteoarthritis of the shoulder can significantly reduce shoulder motion and arm function. Although shoulder rehabilitation is an integral treatment modality to improve pain and function in shoulder osteoarthritis, few high-quality studies have investigated the effects and benefits of shoulder physical and occupational therapies. To advance the fields of therapy and rehabilitation, future studies investigating the effects of therapy intensity, therapy duration, and the relative benefits of therapy subtypes on shoulder biomechanics and function are necessary.

Effect of virtual reality on motor coordination in children with cerebral palsy: a systematic review and meta-analysis of randomized controlled trials

Background

Improving motor coordination is an important prerequisite for the functional development of children with cerebral palsy (CP). Virtual reality (VR) may be efficient, interactive, adjustable and motivating physiotherapy choice for children with deficient coordination. This review aimed to identify, evaluate and formulate all the evidence concerning the efficacy of VR on motor coordination in children with CP and to compare the Physiotherapy Evidence Database (PEDro) with Cochrane Risk of Bias (RoB).

Main text

Five databases (PubMed, Cochrane Central Register of Controlled Trials, Web of Science, Science Direct and google scholar) were systemically searched from inception up to 1st January 2019. Studies included VR intervention for children with cerebral palsy with motor incoordination. Studies methodological quality was assessed by Cochrane RoB and PEDro scale. Nineteen studies met the prespecified eligibility criteria. There was a large effect size (SMD 0.75) on fine motor coordination. However, there was a non-significant, small beneficial effect (SMD 0.15) on gross motor coordination. The association between the overall Cochrane RoB and PEDro scores was fair (r = 0.28, P value 0.248). There was a slight agreement between overall and moderate categories PEDro scores and Cochrane RoB (κ = 0.02) and κ = 0.10), respectively. However, high and low categories were moderately agreed with Cochrane RoB (κ = 0.43) and (κ = 0.46).

Conclusion

VR seems to be effective for improving fine motor coordination with questionable effect on gross motor coordination. PEDro scale is fairly correlated with Cochrane RoB, so development and validation of a more compatible quality assessment tools specific to physiotherapy trials are needed.

Motor Ability Evaluation of the Upper Extremity with Point-To-Point Training Movement Based on End-Effector Robot-Assisted Training System

Assessment is critical during the procedure of stroke rehabilitation. However, traditional assessment methods are time-consuming, laborious, and dependent on the skillfulness of the therapist. Moreover, they cannot distinguish whether the improvement comes from the abnormal compensation or the improvement of upper extremity motor function. To make up for the shortcomings of the traditional methods, this study proposes a novel assessment system, which consisted of a rehabilitation robot and motion capture (MoCAP) system. A 9-degree-of-freedom (DOF) kinematic model is established, which consists of the shoulder girdle, shoulder, elbow, and wrist joints. And seven assessment indices are selected for this assessment system, including a range of motion (ROM), shoulder girdle compensation (SGC), trunk compensation (TC), aiming angle (AA), motion error (ME), motion length ratio (MLR), and useful force (UF). For AA, ME, and MLR, all describe the motor ability of the upper extremity, and a linear model was proposed to map these three indices into one index, called motor control ability (MCA). Then, this system can quantitatively evaluate human upper extremity motor function from joint space kinematics, Cartesian space kinematics, and dynamics. Three healthy participants were invited to verify the effectiveness of this system. The preliminary results show that all participants' handedness performs a little better than the nonhandedness. And the performance of the participants and the change of all the upper limb joints can be directly watched from the trajectory of the hand and joint angles' curve. Therefore, this assessment system can evaluate the human upper limb motor function well. Future studies are planned to recruit elderly volunteers or stroke patients to further verify the effectiveness of this system.

A Systematic Review of EMG Applications for the Characterization of Forearm and Hand Muscle Activity during Activities of Daily Living: Results, Challenges, and Open Issues

The role of the hand is crucial for the performance of activities of daily living, thereby ensuring a full and autonomous life. Its motion is controlled by a complex musculoskeletal system of approximately 38 muscles. Therefore, measuring and interpreting the muscle activation signals that drive hand motion is of great importance in many scientific domains, such as neuroscience, rehabilitation, physiotherapy, robotics, prosthetics, and biomechanics. Electromyography (EMG) can be used to carry out the neuromuscular characterization, but it is cumbersome because of the complexity of the musculoskeletal system of the forearm and hand. This paper reviews the main studies in which EMG has been applied to characterize the muscle activity of the forearm and hand during activities of daily living, with special attention to muscle synergies, which are thought to be used by the nervous system to simplify the control of the numerous muscles by actuating them in task-relevant subgroups. The state of the art of the current results are presented, which may help to guide and foster progress in many scientific domains. Furthermore, the most important challenges and open issues are identified in order to achieve a better understanding of human hand behavior, improve rehabilitation protocols, more intuitive control of prostheses, and more realistic biomechanical models.

The immediate effect of thumb orthoses on upper extremity's movement: A kinematic analysis of five unique devices

BACKGROUND

Thumb orthoses are a standard treatment modality, with substantial evidence to support its usage for multiple conditions affecting the upper extremity. Despite commonly prescribed, little is known about the immediate impact of such devices on the upper extremity, including potential modifications on motor patterns.

RESEARCH QUESTION

We aimed to determine the changes in the upper limb kinematics during the usage of thumb orthotics, comparing differences in orthotic design, length, and fabrication materials.

METHODS

In this cross-sectional study, subjects performed a standardized reaching task and the placing subtest of the Minnesota Manual Dexterity Test (MMDT) while wearing five unique thumb orthoses. Besides the active range of motion of the shoulder, elbow, wrist and hand joints, movement smoothness (Number of Movement Units-NMU), speed, and motion control strategies were analyzed through eight Qualisys Oqus 300 cameras (Qualisys AB, Göteborg, Sweden).

FINDINGS

Ten non-disabled, university students participated in this study. Despite differences in fabrication materials, all orthotics reduced thumb's abduction (13.3° to 4.3°), and metacarpophalangeal flexion (11.5° to 4.2°). Although orthotics impacted movement smoothness and hand function during its usage, forearm-based devices further increased the NMUs and the time required for the MMDT performance (Control: NMU = 4.8, MMDT = 58.1; Long Orthotics: NMU = 6.6, MMDT = 78.2), while short, flexible orthoses provided thumb stabilization without significant impact on upper extremity movement strategies.

SIGNIFICANCE

Although joint stabilization was similar among orthotics fabricated with rigid and flexible materials, the improved hand dexterity observed during the use of flexible devices suggests an advantage of flexible orthotics for enhanced stability and hand function. These results can assist healthcare professionals during the selection and prescription of thumb orthotics, providing information not only on the range of motion but other sensorimotor aspects involved in upper extremity movement patterns that may be affected by orthotics usage.

Does Object Height Affect the Dart Throwing Motion Angle during Seated Activities of Daily Living?

Complex wrist motions are needed to complete various daily activities. Analyzing the multidimensional motion of the wrist is crucial for understanding our functional movement. Several studies have shown that numerous activities of daily livings (ADLs) are performed using an oblique plane of wrist motion from radial-extension to ulnar-flexion, named the Dart Throwing Motion (DTM) plane. To the best of our knowledge, the DTM plane angle performed during ADLs has not been compared between different heights (e.g. table, shoulder and head height), as is common when performing day-to-day tasks. In this study, we compared DTM plane angles when performing different ADLs at three different heights and examined the relationship between DTM plane angles and limb position. We found that height had a significant effect on the DTM plane angles - the mean DTM plane angle was greater at the lower level compared to the mid and higher levels. A significant effect of shoulder orientation on mean DTM plane angles was shown in the sagittal and coronal planes. Our findings support the importance of training daily tasks at different heights during rehabilitation following wrist injuries, in order to explore a large range of DTM angles, to accommodate needs of common ADLs.

Vibration as an adjunct to exercise: its impact on shoulder muscle activation

PURPOSE

There is an interest within elite sport in understanding the impact of a vibrating platform as an adjunct to exercise in the training and rehabilitation of throwing athletes. However, there has been no comprehensive evaluation of its impact on the rotator cuff muscles or its effect on the timing of shoulder muscle recruitment more globally.

METHODS

Twenty healthy participants were recruited with EMG recorded from 15 shoulder girdle muscles. Isometric shoulder flexion at 25% maximal voluntary contraction was performed in three testing scenarios [no vibration; whole body vibration (WBV); and arm vibration (AV)]. A press up and triceps dips with and without vibration were also performed. Muscular recruitment was assessed pre- and post-vibration exposure as participants initiated forward flexion.

RESULTS

Activation of the anterior deltoid (p = 0.002), serratus anterior (p = 0.004), and rotator cuff muscles (p = 0.004-0.022) occurred significantly earlier following exposure to vibration. Significantly greater activation was seen in the anterior, middle and posterior deltoid, upper, middle and lower trapezius, serratus anterior, teres major, latissimus dorsi, supraspinatus, and infraspinatus when the isometric contraction was performed with either WBV and/or AV (p =  < 0.001-0.040). Similarly, increased activation was also demonstrated during the press up and triceps dips when performed with vibration.

CONCLUSION

The use of vibration as an adjunct to exercise provokes a near global increase in shoulder muscle activation level. Furthermore, exposure to vibration alters muscular recruitment improving readiness for movement. This has potential implications within elite sport for both training and game preparation; however, further longitudinal work is required.

Assessment of hand function during activities of daily living using motion tracking cameras: A systematic review

The human hand is the most frequently used body part in activities of daily living. With its complex anatomical structure and the small size compared to the body, assessing the functional capability is highly challenging. The aim of this review was to provide a systematic overview on currently available 3D motion analysis based on skin markers for the assessment of hand function during activities of daily living. It is focused on methodology rather than results. A systematic review according to the PRISMA guidelines was performed. The systematic search yielded 1349 discrete articles. Of 147 articles included on basis of title, 123 were excluded after abstract review, and 24 were included in the full-text analysis with 13 key articles. There is still limited knowledge about hand and finger kinematics during activities of daily living. A standardization of the task is required in order to overcome the nonrepetitive nature and high variability of upper limb motion and ensure repeatability of task performance. To yield a progress in the analysis of human hand movements, an assessment of human kinematics including fingers, wrist, and thumb and an identification of relevant parameters that characterize a healthy motion pattern during functional tasks are needed.

Patterns of muscle coordination during dynamic glenohumeral joint elevation: An EMG study

The shoulder relies heavily on coordinated muscle activity for normal function owing to its limited osseous constraint. However, previous studies have failed to examine the sophisticated interrelationship between all muscles. It is essential for these normal relationships to be defined as a basis for understanding pathology. Therefore, the primary aim of the study was to investigate shoulder inter-muscular coordination during different planes of shoulder elevation. Twenty healthy subjects were included. Electromyography was recorded from 14 shoulder girdle muscles as subjects performed shoulder flexion, scapula plane elevation, abduction and extension. Cross-correlation was used to examine the coordination between different muscles and muscle groups. Significantly higher coordination existed between the rotator cuff and deltoid muscle groups during the initial (Pearson Correlation Coefficient (PCC) = 0.79) and final (PCC = 0.74) stages of shoulder elevation compared to the mid-range (PCC = 0.34) (p = 0.020–0.035). Coordination between the deltoid and a functional adducting group comprising the latissimus dorsi and teres major was particularly high (PCC = 0.89) during early shoulder elevation. The destabilising force of the deltoid, during the initial stage of shoulder elevation, is balanced by the coordinated activity of the rotator cuff, latissimus dorsi and teres major. Stability requirements are lower during the mid-range of elevation. At the end-range of movement the demand for muscular stability again increases and higher coordination is seen between the deltoid and rotator cuff muscle groups. It is proposed that by appreciating the sophistication of normal shoulder function targeted evidence-based rehabilitation strategies for conditions such as subacromial impingement syndrome or shoulder instability can be developed.

Quantitative assessment of upper extremities motor function in multiple sclerosis

BACKGROUND

Upper extremity (UE) motor function deficits are commonly noted in multiple sclerosis (MS) patients and assessing it is challenging because of the lack of consensus regarding its definition. Instrumented biomechanical analysis of upper extremity movements can quantify coordination with different spatiotemporal measures and facilitate disability rating in MS patients.

OBJECTIVE

To identify objective quantitative parameters for more accurate evaluation of UE disability and relate it to existing clinical scores.

METHODS

Thirty-four MS patients and 24 healthy controls (CG) performed a finger-to-nose test as fast as possible and, in addition, clinical evaluation kinematic parameters of UE were measured by using inertial sensors.

RESULTS

Generally, a higher disability score was associated with an increase of several temporal parameters, like slower task performance. The time taken to touch their nose was longer when the task was fulfilled with eyes closed. Time to peak angular velocity significantly changed in MS patients (EDSS > 5.0). The inter-joint coordination significantly decreases in MS patients (EDSS 3.0-5.5). Spatial parameters indicated that maximal ROM changes were in elbow flexion.

CONCLUSIONS

Our findings have revealed that spatiotemporal parameters are related to the UE motor function and MS disability level. Moreover, they facilitate clinical rating by supporting clinical decisions with quantitative data.

Identification of forearm skin zones with similar muscle activation patterns during activities of daily living

Background

A deeper knowledge of the activity of the forearm muscles during activities of daily living (ADL) could help to better understand the role of those muscles and allow clinicians to treat motor dysfunctions more effectively and thus improve patients’ ability to perform activities of daily living.

Methods

In this work, we recorded sEMG activity from 30 spots distributed over the skin of the whole forearm of six subjects during the performance of 21 representative simulated ADL from the Sollerman Hand Function Test. Functional principal component analysis and hierarchical cluster analysis (HCA) were used to identify forearm spots with similar muscle activation patterns.

Results

The best classification of spots with similar activity in simulated ADL consisted in seven muscular-anatomically coherent groups: (1) wrist flexion and ulnar deviation; (2) wrist flexion and radial deviation; (3) digit flexion; (4) thumb extension and abduction/adduction; (5) finger extension; (6) wrist extension and ulnar deviation; and (7) wrist extension and radial deviation.

Conclusion

The number of sEMG sensors could be reduced from 30 to 7 without losing any relevant information, using them as representative spots of the muscular activity of the forearm in simulated ADL. This may help to assess muscle function in rehabilitation while also simplifying the complexity of prosthesis control.

Influência da órtese estática de punho na atividade muscular e amplitude de movimento de ombro e cotovelo durante uma tarefa funcional: estudo biomecânico

RESUMO As órteses são recursos terapêuticos indicados para proteger, corrigir deformidades ou auxiliar em certas funções; porém, seu uso pode acarretar compensações proximais no ombro. O objetivo deste estudo é avaliar a influência da órtese estática dorsal do punho, em 30° de extensão na biomecânica do ombro e cotovelo, em 25 voluntários assintomáticos durante uma tarefa funcional. Os dados da amplitude de movimento e ativação muscular foram adquiridos de forma sincronizada e simultânea durante parte do teste funcional Elui, que simula alimentação, dividida em alcance, deslocamento e liberação, de uma jarra, nas condições sem e com órtese. Para possibilitar a comparação entre os diferentes sujeitos e músculos, os dados foram analisados pela integral do sinal EMG de cada músculo e, para análise cinemática, foram construídos sistemas de coordenadas de marcadores pré-definidos. Os sinais captados foram filtrados e processados por um software personalizado, e utilizou-se o teste t para amostras pareadas - software SPSS, p<0,05. Notou-se um aumento significativo da ativação dos músculos deltoide anterior e peitoral maior na fase de alcance, e trapézio superior, deltoide anterior e posterior na fase de liberação com a órtese. A cinemática mostrou aumento significativo na amplitude de movimento na abdução do ombro, flexão do cotovelo e pronação do antebraço na fase de deslocamento, e dos movimentos extensão do ombro e flexão do cotovelo na fase de liberação. Nossos achados sugerem que o uso da órtese estática do punho durante a execução de uma tarefa pode acarretar compensações, com predomínio da ativação dos músculos mais proximais do membro superior.

Use of optical motion capture for the analysis of normative upper body kinematics during functional upper limb tasks: A systematic review

Quantifying three-dimensional upper body kinematics can be a valuable method for assessing upper limb function. Considering that kinematic model characteristics, performed tasks, and reported outcomes are not consistently standardized and exhibit significant variability across studies, the purpose of this review was to evaluate the literature investigating upper body kinematics in non-disabled individuals via optical motion capture. Specific objectives were to report on the kinematic model characteristics, performed functional tasks, and kinematic outcomes, and to assess whether kinematic protocols were assessed for validity and reliability. Five databases were searched. Studies using anatomical and/or cluster marker sets, along with optical motion capture, and presenting normative data on upper body kinematics were eligible for review. Information extracted included model characteristics, performed functional tasks, kinematic outcomes, and validity or reliability testing. 804 publication records were screened and 20 reviewed based on the selection criteria. Thirteen studies described their kinematic protocols adequately for reproducibility, and 8 studies followed International Society of Biomechanics standards for quantifying upper body kinematics. Six studies assessed their protocols for validity or reliability. While a substantial number of studies have adequately reported their protocols, more systematic work is needed to evaluate the validity and reliability of existing protocols.

Muscle Activation and Inertial Motion Data for Noninvasive Classification of Activities of Daily Living

OBJECTIVE

Remote monitoring of physical activity using body-worn sensors provides an objective alternative to current functional assessment tools. The purpose of this study was to assess the feasibility of classifying categories of activities of daily living from the functional arm activity behavioral observation system (FAABOS) using muscle activation and motion data.

METHODS

Ten nondisabled, healthy adults were fitted with a Myo armband on the upper forearm. This multimodal commercial sensor device features surface electromyography (sEMG) sensors, an accelerometer, and a rate gyroscope. Participants performed 17 different activities of daily living, which belonged to one of four functional groups according to the FAABOS. Signal magnitude area (SMA) and mean values were extracted from the acceleration and angular rate of change data; root mean square (RMS) was computed for the sEMG data. A nearest neighbors machine learning algorithm was then applied to predict the FAABOS task category using these raw data as inputs.

RESULTS

Mean acceleration, SMA of acceleration, mean angular rate of change, and RMS of sEMG were significantly different across the four FAABOS categories ( in all cases). A classifier using mean acceleration, mean angular rate of change, and sEMG data was able to predict task category with 89.2% accuracy.

CONCLUSION

The results demonstrate the feasibility of using a combination of sEMG and motion data to noninvasively classify types of activities of daily living.

SIGNIFICANCE

This approach may be useful for quantifying daily activity performance in ambient settings as a more ecologically valid measure of function in healthy and disease-affected individuals.

Electromyographic Activity of the Upper Limb in Three Hand Function Tests

Objective/Background

Occupational therapists usually assess hand function through standardised tests, however, there is no consensus on how the scores assigned to hand dexterity can accurately measure hand function required for daily activities and few studies evaluate the movement patterns of the upper limbs during hand function tests. This study aimed to evaluate the differences in muscle activation patterns during the performance of three hand dexterity tests.

Methods

Twenty university students underwent a surface electromyographic (sEMG) assessment of eight upper limb muscles during the performance of the box and blocks test (BEST), nine-hole peg test (9HPT), and functional dexterity test (FDT). The description and comparison of each muscle activity during the test performance, gender differences, and the correlation between individual muscles’ sEMG activity were analysed through appropriate statistics.

Results

Increased activity of proximal muscles was found during the performance of BEST (p < .001). While a higher activation of the distal muscles occurred during the FDT and 9HPT performance, no differences were found between them. Comparisons of the sEMG activity revealed a significant increase in the muscle activation among women (p = .05). Strong and positive correlations (r > .5; p < .05) were observed between proximal and distal sEMG activities, suggesting a coordinate pattern of muscle activation during hand function tests.

Conclusion

The results suggested the existence of differences in the muscle activation pattern during the performance of hand function evaluations. Occupational therapists should be aware of unique muscle requirements and its impact on the results of dexterity tests during hand function evaluation.

Control of a wrist joint motion simulator: A phantom study

The presence of muscle redundancy and co-activation of agonist-antagonist pairs in vivo makes the optimization of the load distribution between muscles in physiologic joint simulators vital. This optimization is usually achieved by employing different control strategies based on position and/or force feedback. A muscle activated physiologic wrist simulator was developed to test and iteratively refine such control strategies on a functional replica of a human arm. Motions of the wrist were recreated by applying tensile loads using electromechanical actuators. Load cells were used to monitor the force applied by each muscle and an optical motion capture system was used to track joint angles of the wrist in real-time. Four control strategies were evaluated based on their kinematic error, repeatability and ability to vary co-contraction. With kinematic errors of less than 1.5°, the ability to vary co-contraction, and without the need for predefined antagonistic forces or muscle force ratios, novel control strategies - hybrid control and cascade control - were preferred over standard control strategies - position control and force control. Muscle forces obtained from hybrid and cascade control corresponded well with in vivo EMG data and muscle force data from other wrist simulators in the literature. The decoupling of the wrist axes combined with the robustness of the control strategies resulted in complex motions, like dart thrower׳s motion and circumduction, being accurate and repeatable. Thus, two novel strategies with repeatable kinematics and physiologically relevant muscle forces are introduced for the control of joint simulators.