Alternative to Reduced Stresses on the Upper Extremity in a Standing Workstation

2021 ◽  
pp. 001872082110573
Author(s):  
Ilseok Lee ◽  
Jiwon Choi ◽  
Sang Hyeon Kang ◽  
Sangeun Jin
Keyword(s):  
Muscle Activation ◽  
Elbow Flexion ◽  
Upper Body ◽  
Wrist Extension ◽  
Activation Level ◽  
Anterior Deltoid ◽  
The Many ◽  
The Cost ◽  
Extensor Carpi Radialis ◽  
Forearm Muscle

Objective This study evaluated a standing armrest to provide more acceptable ergonomic guidelines that may reduce the cost of standing computer workstations. Background Of the many advantages of standing workstations, there have been no efforts to minimize the biomechanical cost, such as larger wrist extension and greater forearm muscle activity than sitting. Method Sixteen participants were asked to perform a typing task under a combination of the following factors: (1) desk shape (rectangular and concave); (2) desk height (0, +5, -5 cm from 90° elbow flexion); and (3) monitor height (0, −10 cm from the eyes). During the trials, the trunk kinematics, muscle activation levels, and CoP were recorded. Results Both arms were further away from the upper body under the concave and +5 desk height than under the normal condition, but significant decreases in the extensor carpi radialis (8.6%), anterior deltoid (28.8%), and L4 paraspinals (5.5%) were observed. Similarly, the wrist extension angle decreased by 10.5° (42%) under this condition, but the posture required a 2.2° (19%) increase in wrist adduction angle. The CoP irregularity was greater under the concave workstation, indicating more complex motion. Conclusion A higher and concave desk can provide an armrest effect while engaged in a standing workstation by reducing the wrist extension and related muscle activation level, but at the cost of a larger wrist adduction angle. Application Providing a standing armrest (+5 cm height and concave desk) could reduce the stresses on the upper extremities, but a split keyboard should be considered to minimize wrist adduction.

scholarly journals Influence of Ball Impact Location on Racquet Kinematics, Forearm Muscle Activation and Shot Accuracy during the Forehand Groundstrokes in Tennis

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 89
Author(s):  
Masahiro Ikenaga ◽  
Nobue Okuma ◽  
Hiroki Nishiyama ◽  
Shinichiro Chiba ◽  
Katsutoshi Nishino ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Muscular Activity ◽  
Side Impact ◽  
Ball Impact ◽  
Tennis Players ◽  
Impact Location ◽  
Flexor Muscles ◽  
Flight Parameters ◽  
Extensor Carpi Radialis ◽  
Forearm Muscle

We aimed to clarify the effect of ball–racquet impact locations on the dynamic behavior of tennis racquet, the accuracy of shots and muscle activation of the forearm. Eight male intermediate tennis players performed ten forehand groundstrokes. A motion capture system was used to measure the motions of racquet, ball and human body at 2000 Hz, and electromyography (EMG) activities of wrist extensor and flexor muscles were measured simultaneously. The flight parameters of the ball were measured by ballistic measurement equipment. All shots were divided into tertiles based on ball impact location along the lateral axis of tennis racquet. We found that the off-center, upper-side impact induces a larger muscular activity in extensor carpi radialis. Passive radial deviation of the wrist occurring immediately after ball impact may account for this. Furthermore, the off-center, upper-side impact could be associated with a missed shot having a lower, outward ball launch angle.

scholarly journals Pronator Quadratus to Extensor Carpi Radialis Brevis Nerve Transfer in C5–C7 or C5–C8 Brachial Plexus Injuries for Independent Wrist Extension

2020 ◽  
Vol 53 (01) ◽  
pp. 036-041
Author(s):  
Anil Bhatia ◽  
Mahmoud Salama
Keyword(s):  
Brachial Plexus ◽  
Nerve Transfer ◽  
Elbow Flexion ◽  
Shoulder Abduction ◽  
Wrist Extension ◽  
Pronator Quadratus ◽  
Motor Branch ◽  
Nerve Surgery ◽  
Extensor Carpi Radialis

Abstract Background Patients with lesions affecting C7 and C8 roots (in addition to C56) demonstrate loss of independent wrist dorsiflexion in addition to loss of shoulder abduction and elbow flexion. Traditionally, this deficit has been addressed using tendon transfers after useful function at the shoulder and elbow has been restored by primary nerve surgery. Confidence with nerve transfer techniques has prompted attempts to replace this method by incorporating procedures for wrist dorsiflexion in the primary operation itself. Aim The objective of this study was to report the results of pronator quadratus motor branch transfers to the extensor carpi radialis brevis motor branch to reconstruct wrist extension in C5–C8 root lesions of the brachial plexus. Patients and Methods Twenty-three patients, average age 30 years, with C5–8 root injuries underwent operations an average of 4.7 months after their accident. Extrinsic extension of the fingers and thumb was weak or absent in two cases while the remaining 18 patients could open their hand actively. The patients lacked independent wrist extension when they were examined with the fingers flexed as the compensatory action of the extrinsic finger extensors was removed. The average follow-up was 21 months postoperative with the minimal follow-up period was at least 12 months. Results Successful reinnervations of the extensor carpi radialis brevis (ECRB) were demonstrated in all patients. In 17 patients, wrist extension scored M4, and in 3 patients it scored M3. Conclusions The pronator quadratus (PQ) to ECRB nerve transfer in C5–C7 or C5–C8 brachial plexus injuries for independent wrist extension reconstruction gives consistently good results with minimal donor morbidity.

scholarly journals Muscle Activation in Traditional and Experimental Barbell Bench Press Exercise: A Potential New Tool for Fitness Maintenance

Sports ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 224
Author(s):  
Andrea Melani ◽  
Giuliana Gobbi ◽  
Daniela Galli ◽  
Cecilia Carubbi ◽  
Elena Masselli ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Professional Training ◽  
Muscle Activation ◽  
Bench Press ◽  
Biceps Brachii ◽  
Elbow Flexion ◽  
Upper Body ◽  
Triceps Brachii ◽  
Extended Position ◽  
Lower Load

Background: The bench press exercise (BP) is commonly practiced in both recreational and professional training. The weight is lowered from a position where the elbows are at a 90° angle at the start and <90° at the end of eccentric phase, and then returned to the elbows extended position. In order to focus the exercise more on the triceps brachii (TB) rather than the pectoralis major (PM), the inter-handle distance (IHD) is decreased diminishing the involvement of the PM in favor of the TB. Purpose: To improve performance of the exercise by reducing force dissociation and transmitting 100% of the external load to the muscle tissue we propose a prototype of the barbell with a bar on which two sleeves are capable of sliding. The dynamic modifications of the IHD keep the elbow flexion angle constant at 90°. Results: Analysis of the inter-handle distance (IHD) signals of the upper body muscles showed a marked increase in muscle activity using the experimental barbell for the PM (19.5%) and for the biceps brachii (173%). Conclusions: The experimental barbell increased the muscle activity typical of the bench press exercise, obtaining the same training induction with a lower load and consequently preventing articular stress.

scholarly journals Muscle Activity in Upper-Body Single-Joint Resistance Exercises with Elastic Resistance Bands vs. Free Weights

2018 ◽  
Vol 61 (1) ◽  
pp. 5-13 ◽  
Author(s):  
Ronny Bergquist ◽  
Vegard Moe Iversen ◽  
Paul J Mork ◽  
Marius Steiro Fimland
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Upper Body ◽  
Elastic Resistance ◽  
Activation Level ◽  
Joint Resistance ◽  
Resistance Exercises ◽  
Resistance Bands ◽  
Feasible Alternative ◽  
Body Resistance

Abstract Elastic resistance bands require little space, are light and portable, but their efficacy has not yet been established for several resistance exercises. The main objective of this study was to compare the muscle activation levels induced by elastic resistance bands versus conventional resistance training equipment (dumbbells) in the upper-body resistance exercises flyes and reverse flyes. The level of muscle activation was measured with surface electromyography in 29 men and women in a cross-over design where resistance loadings with elastic resistance bands and dumbbells were matched using 10-repetition maximum loadings. Elastic resistance bands induced slightly lower muscle activity in the muscles most people aim to activate during flyes and reverse flies, namely pectoralis major and deltoideus posterior, respectively. However, elastic resistance bands increased the muscle activation level substantially in perceived ancillary muscles, that is deltoideus anterior in flyes, and deltoideus medius and trapezius descendens in reverse flyes, possibly due to elastic bands being a more unstable resistance modality. Overall, the results show that elastic resistance bands can be considered a feasible alternative to dumbbells in flyes and reverse flyes.

Letter to the Editor

PEDIATRICS ◽  
1994 ◽  
Vol 93 (1) ◽  
pp. 151-152
Author(s):  
Caroline Breese Hall ◽  
Harold S. Margolis
Keyword(s):  
Public Health ◽  
Private Practice ◽  
Clinton Administration ◽  
Health Issues ◽  
Childhood Immunization ◽  
Letter To The Editor ◽  
The Many ◽  
The Cost

We appreciate the concerned letter of Dr Jacobs and his thoughtful questions arising both from his knowledge of the recommendations and public health issues, as well as those of private practice. The cost of vaccines is an issue with which we must all be concerned. By highlighting the importance of childhood immunization the Clinton administration has engendered interest and, thus, optimism that efforts toward reducing the cost will be successful. However, we should remember that the many excellent studies that have analyzed the reasons why children are not being vaccinated have shown that cost is not the major factor, but access, difficulties, and obstacles, real and perceived, to obtaining immunizations are.

scholarly journals Differential muscle function between muscle synergists: long and lateral heads of the triceps in jumping and landing goats (Capra hircus)

2008 ◽  
Vol 105 (4) ◽  
pp. 1262-1273 ◽  
Author(s):  
Andrew M. Carroll ◽  
David V. Lee ◽  
Andrew A. Biewener
Keyword(s):  
Muscle Function ◽  
High Speed ◽  
Muscle Activation ◽  
Reaction Force ◽  
Elbow Flexion ◽  
Capra Hircus ◽  
Triceps Brachii ◽  
Joint Work ◽  
Long Head ◽  
Lateral Head

We investigate how the biarticular long head and monoarticular lateral head of the triceps brachii function in goats ( Capra hircus) during jumping and landing. Elbow moment and work were measured from high-speed video and ground reaction force (GRF) recordings. Muscle activation and strain were measured via electromyography and sonomicrometry, and muscle stress was estimated from elbow moment and by partitioning stress based on its relative strain rate. Elbow joint and muscle function were compared among three types of limb usage: jump take-off (lead limb), the step prior to jump take-off (lag limb), and landing. We predicted that the strain and work patterns in the monoarticular lateral head would follow the kinematics and work of the elbow more closely than would those of the biarticular long head. In general this prediction was supported. For instance, the lateral head stretched (5 ± 2%; mean ± SE) in the lead and lag limbs to absorb work during elbow flexion and joint work absorption, while the long head shortened (−7 ± 1%) to produce work. During elbow extension, both muscles shortened by similar amounts (−10 ± 2% long; −13 ± 4% lateral) in the lead limb to produce work. Both triceps heads functioned similarly in landing, stretching (13 ± 3% in the long head and 19 ± 5% in the lateral) to absorb energy. In general, the long head functioned to produce power at the shoulder and elbow, while the lateral head functioned to resist elbow flexion and absorb work, demonstrating that functional diversification can arise between mono- and biarticular muscle agonists operating at the same joint.

scholarly journals Behnke_Armbruster_Strobel - The needs of the many - Influence of personality on third-party judgments of utilitarian rule violations

2020 ◽  
Author(s):  
Alexander Behnke ◽  
Diana Armbruster ◽  
Anja Strobel
Keyword(s):  
Emotional Responses ◽  
Minority Rights ◽  
Third Party ◽  
Online Study ◽  
The Third ◽  
Moral Decisions ◽  
The Many ◽  
Personality Features ◽  
The Cost ◽  
Sense Of Justice

Safeguarding the rights of minorities is crucial for just societies. However, there are conceivable situations were minority rights might seriously impede the rights of the majority. Favoring the minority in such cases constitutes a violation of utilitarian principles. To investigate the emotional, cognitive, and punitive responses of observers of such utilitarian rule transgressions, we conducted an online study with 1004 participants. Two moral scenarios (vaccine policy and epidemic) were rephrased in the third-party perspective. In both scenarios the protagonist opted against the utilitarian option which resulted in more fatalities in total, but avoided harm to a minority. The scenarios varied in whether the minority would have been harmed accidentally or deliberate. The majority of participants chose not to punish the scenarios’ protagonists at all. However, 30.5% judged that protecting the minority over the interests of the majority when only accidental harm would have occurred (vaccine policy) was worthy of punishment. In comparison, only 11.5% opted to punish a protagonist whose decision avoided deliberate harm to a minority at the cost of the majority (epidemic). Emotional responses and appropriateness ratings paralleled these results. Furthermore, complex personality × situation interactions revealed the influence of personality features, i.e., psychopathy, empathy, altruism, authoritarianism, need for cognition and faith in intuition, on participants’ responses. The results further underscore the need to consider the interaction of situational features and inter-individual differences in moral decisions and sense of justice.

scholarly journals SURVEY TECHNIQUES/PROCEDURES AND DATA PROCESSING FOR MONITORING NEARSHORE SEDIMENT TRANSPORT

1982 ◽  
Vol 1 (18) ◽  
pp. 97
Author(s):  
J. Zacks
Keyword(s):  
Sediment Transport ◽  
Surf Zone ◽  
Survey Techniques ◽  
The Past ◽  
Bed Elevation ◽  
Innovative Methods ◽  
Survey Error ◽  
Nearshore Sediment Transport ◽  
The Many ◽  
The Cost

The cost of many coastal projects is often increased by the expensive beach repair and maintenance required to remedy the destabilising effects of structures on the adjoining coastline. Physical and/or mathematical models have been developed for use in planning these projects in order to predict and quantify the effects of marine sediment transport on the coastal topography. Such models need to be calibrated against prototype data and one method of gauging volumetric sediment movement is by successive bathymetric/ topographic profiting surveys which are performed seasonally and annually. Since large quantities of sediment are related to small changes in bed elevation it is clear that this profiling needs to be done with the utmost precision* The areas most affected extend from the beach through the surf zone to water depths of about 25 metres. The surf zone in particular is a dynamic and hostile area which falls outside the traditional activities of both the hydrographic and land surveyors. Consequently innovative methods, deficient in sound survey principle and practice, have often been pursued in this area without any attempt being made to assess the tolerance on the data. This paper attempts to show that it is possible to produce reliable and verifiable results to the required accuracy by using conventional survey equipment and techniques, also by taking the necessary precautions against the many possible sources of survey error. The procedures and techniques described have evolved from NRIO's involvement over the past decade in major projects at Richards Bay, Durban, Koeberg and in False Bay. The results of a recent verification investigation are fully reported in this paper.

scholarly journals Monoclonal Antibody Therapy and Long-term Outcomes in Multiple Sclerosis – The Challenge of Treatment Optimisation

2018 ◽  
Vol 13 (2) ◽  
pp. 78
Author(s):  
Antonio Scalfari ◽  
Paolo A Muraro ◽  
◽  
Keyword(s):  
Multiple Sclerosis ◽  
Monoclonal Antibody ◽  
Antibody Therapy ◽  
Careful Consideration ◽  
Therapeutic Landscape ◽  
Treatment Optimisation ◽  
Frequent Administration ◽  
Therapeutic Opportunity ◽  
The Many ◽  
The Cost

The therapeutic landscape of multiple sclerosis (MS) has been transformed by the advent of several new monoclonal antibody (MAb) therapies that can potentially lead to full stabilisation of detectable disease activity. Natalizumab, alemtuzumab and ocrelizumab are currently licensed MAbs for the treatment of MS. Daclizumab was licensed for the treatment of MS, although it has been recently withdrawn from the market by the manufacturer. Most patients are initially managed with first-line treatments, and, if disease breakthrough occurs, are escalated to a stronger compound, yet the available evidence indicates an early window of therapeutic opportunity for MAbs to exert most of their efficacy. It is important to balance the superior efficacy of MAbs compared with injectable treatments against more serious side effects, although these are well recognised and can be monitored where indicated and treated. In particular, the risk of progressive multifocal leucoencephalopathy with natalizumab can be managed by screening potential patients for the John Cunningham virus. The MAbs also have the benefit of convenience to patients compared with daily or weekly treatments since they are given via less frequent administration. The cost of these treatments, compared with other therapies, may be an important issue in many countries where healthcare budgets are under pressure. The complex decision of choosing the best treatment for an individual should be made jointly between the doctor and the patient after careful consideration of the many factors to be weighed.

Reflexive Response of Neck Muscle to Sudden Perturbation after Prolonged Smartphone Use

2021 ◽  
Vol 65 (1) ◽  
pp. 1250-1253
Author(s):  
Eunjee Kim ◽  
Donghyun Song ◽  
Dasom Park ◽  
Hyorim Kim ◽  
Gwanseob Shin
Keyword(s):  
Cervical Spine ◽  
Muscle Activation ◽  
Neck Muscle ◽  
Spinal Stability ◽  
Delayed Onset ◽  
Activation Level ◽  
Before And After ◽  
Smartphone Use ◽  
Head Stability ◽  
Passive Stretch

Prolonged smartphone use induces passive stretch of neck tissues and muscle fatigue, affecting spinal stability and pain. It is necessary to evaluate the effect of smartphone use on the reflexive response to detect the changes in neck tissues and head stability. A laboratory experiment (n=10) was conducted to investigate the reflexive response of neck muscle to perturbation after 30 minutes of smartphone use. Neck extensor muscle activation and its activation timing to perturbation were investigated before and after smartphone use. Head angle and muscle activation level were collected during smartphone use. During smartphone use, muscle activation gradually increased. After smartphone use, neck muscles showed a higher activation level and significantly delayed onset to perturbation. Smartphone use changed the reflexive response of the neck muscle. Further study is needed to investigate the association between smartphone use and neuromuscular changes to the tissues of the cervical spine.

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