An electromyographic analysis of two handwriting grasp patterns

A Scoping Review of Grasp and Handwriting Performance in School-Age Children

OBJECTIVE

Handwriting is a critical functional skill that impacts academic participation and progress. Occupational therapists address components of grasp in their handwriting intervention as it is commonly assumed that grasp affects legibility, fluency, and endurance, yet research studies examining this relationship are limited.

METHOD

We used scoping review methodology to map existing research on grasp and handwriting performance in school-age children and to identify gaps in the literature.

RESULTS

Thirteen articles met search criteria and were categorized by grasp patterns and handwriting performance, and grasp force and handwriting performance. Findings suggest an inefficient grasp can lead to decreased handwriting legibility and fatigue. The current literature is inconclusive and several gaps were identified.

CONCLUSION

Additional studies should address research gaps through inclusion of children with special needs and interventions including lengthier handwriting tasks representative of a typical school day.

Evaluating the impact of writing surface and configuration on muscle activation level during a handwriting task: An exploratory study

BACKGROUND: Tablets are ubiquitous in workplaces and schools. However, there have been limited studies investigating the effect tablets have on the body during digital writing activities. OBJECTIVE: This study investigated the biomechanical impact of writing interface design (paper, whiteboard, and tablet) and orientation (horizontal, 45°, and vertical) on tablet users. METHODS: Fourteen adults (7 male, 7 female) participated in a study during which they performed simple writing tasks. Surface electromyography (sEMG) sensors were used to measure upper extremity muscle activation. RESULTS: Results indicate that the effects of writing surface type were most pronounced in forearm muscle activation. Specifically, in the extensor carpi radialis (ECR), where muscle activity was lower on the tablet PC surface. The effects of writing configuration were prominent in the shoulder and forearm. The activation of the flexor carpi ulnaris (FCU) and trapezius muscles was significantly lower in the 45° configuration. An exception to the efficacy of this configuration was the anterior deltoid muscle, which exhibited the lowest muscle activity in the horizontal orientation. CONCLUSIONS: Tablet surface and the 45° configuration resulted in the lowest muscle activation levels. Future studies should include longer experiment duration to investigate the effects of continuous writing.

Development of an Ergonomic Writing Assistive Device for Finger Pain Reduction in the Elderly

The decreased muscle mass and increased prevalence of musculoskeletal diseases in the elderly means that this population often experiences difficulty with writing. Although various commercial writing assistive devices exist to reduce pain and improve writing efficiency, low satisfaction with their design prevents them from being widely adopted. In this study, we developed a new ergonomic writing assistive device that overcomes these shortcomings and reduces finger pain. Twenty elderly people with normal writing skills participated in a performance evaluation of our designed device. We used two commercial writing assistive devices and the developed writing assistive device to write a given experimental sentence three times each for each device. For each device, finger-related muscles activity and finger pressure were measured during the experiment, and satisfaction level was evaluated using the modified QUEST 2.0 after the experiment. As a result, the activity in abductor pollicis brevis (18.16%) and first dorsal interosseous muscle (14.17%) was significantly higher when using the NDWAD (newly developed writing assistive device) than when using commercialized WADs (writing assistive devices) (p < 0.05). Finger pressure in the thumb (0.59 N), index finger (1.09 N), and middle finger (0.46 N) was significantly lower when using NDWAD than when using WADs (p < 0.05). The satisfaction level of NDWAD (4.47) was higher than that of WADs. Therefore, we confirmed that our design reduced finger pressure and improved user satisfaction. Consequently, the NDWAD developed in this study can be used as a writing aid not only for the elderly, but also for patients with writing disabilities.

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 relationship between muscle activation and handwriting quality with non-native grip styles

PURPOSE

This study aimed to explore the differences in muscle activity, handwriting legibility, and consistency when using the 4 primary handwriting grip styles: dynamic quadrupod (DQ), dynamic tripod, lateral quadrupod (LQ) and lateral tripod.

STUDY DESIGN AND METHODS

Thirty-four 18-22-year-old participants completed a handwriting legibility test on paper as well as consistency and metrics tests using both surface electromyography and a digital writing tablet. Electromyography was used to measure the activity of 6 muscles associated with handwriting, and the tablet measured stroke duration, length, velocity, and pen pressure. Subjects used each grip style with all protocols and scores were normalized to their native grip. Significance was set at P < .05.

RESULTS

Females had a lower range in legibility scores than males by 3.5% ± 1.7% (p = .046, d = 0.713), but grip style did not impact legibility. The upper trapezius (UT) was more active in the lateral tripod and LQ grips compared to DQ by 16.8% ± 5.2% and by 13.8% ± 5.2%, (p = .007, p = .012, respectively, partial η2 = 0.188). The stroke duration was greater in the LQ grip style than dynamic tripod and DQ grip styles (p = .008, p = .023, respectively; partial η2 = 0.123).

CONCLUSIONS

Lateral grip styles involve more whole-arm, stabilizing movements while dynamic grip styles require fine dexterous movements. Furthermore, females are likely to be able to employ any grip with minimal effect on legibility. For a patient needing guidance in rehabilitation, understanding the differences in grips could aid selection of the optimum grip style to employ based on their muscular control deficits.

Can upper limb taping or exercises improve hand function, writing speed and self-perception of performance in adolescent school children?

BACKGROUND

The majority of students spend time in writing, which is a prime performance measure in examinations. Enhancement in handwriting should benefit students to attain better academic performance.

OBJECTIVE

To assess the effectiveness of taping and exercises on hand function, writing speed, self-perception of writing and to compare these techniques.

METHODS

A randomized control trial was conducted using cluster sampling in adolescent children across four schools in an urban city. A 4-week intervention study was conducted on 123 students divided into taping, exercise and control groups. Outcome measures were grip strength, pinch strength, 12-min writing speed test and the Writer Self-Perception Scale (WSPS). For intra-group analysis, a paired t-test was used for parametric values and the Wilcoxon signed rank test was used for non-parametric values. For inter-group analysis, one-way analysis of variance (ANOVA) for parametric values and the Kruskal-Wallis test for non-parametric values was used.

RESULTS

The taping group showed a significant improvement in grip strength (1.79 kg; p = 0.00), pinch strength [1.67 lb (757.4 g); p = 0.00] and writing speed (39.77 words/12 min; p = 0.00). The exercise group showed significant improvement in grip strength (2.09 kg; p = 0.00), pinch strength (1.28 lb; p = 0.00), writing speed (28.38 words/12 min; p = 0.00). In the control group, there was a significant increase in pinch strength (1.023 lb; p = 0.01) and writing speed (12.94 words/12 min; p = 0.02). Inter-group analysis showed significant difference in writing speed (p = 0.002) and grip strength (p = 0.00). There was no significant difference in perception (p = 0.071).

CONCLUSION

Taping and exercise are equally effective for enhancement of hand function, writing speed and self-perception in adolescent school children.

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.

Surface EMG-based Sketching Recognition Using Two Analysis Windows and Gene Expression Programming

Sketching is one of the most important processes in the conceptual stage of design. Previous studies have relied largely on the analyses of sketching process and outcomes; whereas surface electromyographic (sEMG) signals associated with sketching have received little attention. In this study, we propose a method in which 11 basic one-stroke sketching shapes are identified from the sEMG signals generated by the forearm and upper arm muscles from 4 subjects. Time domain features such as integrated electromyography, root mean square and mean absolute value were extracted with analysis windows of two length conditions for pattern recognition. After reducing data dimensionality using principal component analysis, the shapes were classified using Gene Expression Programming (GEP). The performance of the GEP classifier was compared to the Back Propagation neural network (BPNN) and the Elman neural network (ENN). Feature extraction with the short analysis window (250 ms with a 250 ms increment) improved the recognition rate by around 6.4% averagely compared with the long analysis window (2500 ms with a 2500 ms increment). The average recognition rate for the eleven basic one-stroke sketching patterns achieved by the GEP classifier was 96.26% in the training set and 95.62% in the test set, which was superior to the performance of the BPNN and ENN classifiers. The results show that the GEP classifier is able to perform well with either length of the analysis window. Thus, the proposed GEP model show promise for recognizing sketching based on sEMG signals.

Biomechanical analyses of prolonged handwriting in subjects with and without perceived discomfort

Since wrist-joint position affects finger muscle length and grip strength, we studied its biomechanical relevance in prolonged handwriting. We recruited participants from young adults, aged 18-24, and separated them into control (n=22) and in-pain (n=18) groups, based whether or not they experience pain while handwriting. The participants then performed a writing task for 30 min on a computerized system which measured their wrist-joint angle and documented their handwriting kinematics. The in-pain group perceived more soreness and had a less-extended wrist joint, longer on-paper time, and slower stroke velocity compared to control group. There was no significant difference in handwriting speed and quality between the two groups. The wrist extension angle significantly correlated with perceived soreness. Ergonomic and biomechanical analyses provide important information about the handwriting process. Knowledge of pen tip movement kinematics and wrist-joint position can help occupational therapists plan treatment for individuals with handwriting induced pain.