Abstract
Study Design
Case series (longitudinal).
Introduction
Only few reports concerning the efficacy of commonly used strategies for preventing
upper limb occupational disorders associated with prolonged typing exist.
Purpose of the Study
We aimed to investigate whether the duration of typing and the use of 2 strategies
(hand rest and wrist support) changes muscle physiological response and therefore
the electromyography records.
Methods
We enrolled 25 volunteers, who were unfamiliar with the task and did not have musculoskeletal
disorders. The subjects underwent 3 prolonged typing protocols to investigate the
efficacy of the 2 adopted strategies in reducing the trapezius, biceps brachii, and
extensor digitorum communis fatigue.
Results
Typing for 1 hour induced muscular fatigue (60%-67% of the subjects). The extensor
digitorum communis muscle exhibited the highest percentage of fatigue (72%-84%) after
1 and 4 hours of typing (1 hour, P = .04; 4 hours, P = .02). Fatigue levels in this muscle were significantly reduced (24%) with the use
of pause typing (4 hours, P = .045), whereas biceps brachii muscle fatigue was reduced (32%) only with the use
of wrist supports (P = .02, after 4 hours). Trapezius muscle fatigue was unaffected by the tested occupational
strategies (1 hour, P = .62; 4 hours, P = .85).
Discussion
Despite presenting an overall tendency for fatigue detected during the application
of the protocols, the assessed muscles exhibited different behavior patterns, depending
on both the preventive strategy applied and the muscle mechanical role during the
task.
Conclusion
Hand rest and wrist support can successfully reduce muscle fatigue in specific upper
limb muscles during prolonged typing, leading to a muscle-selective reduction in the
occurrence of fatigue and thus provide direct evidence that they may prevent work-related
musculoskeletal disorders.
Level of Evidence
N/A
Keywords
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Journal of Hand TherapyAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- A prospective study of computer users: I. Study design and incidence of musculoskeletal symptoms and disorders.Am J Ind Med. 2002; 41: 221-235
- Effects of neutral posture on muscle tension during computer use.Int J Occup Saf Ergon. 2001; 7: 61-78
- Upper extremity function: what's posture got to do with it?.J Hand Ther. 2015; 28: 106-113
- Upper extremity kinematic and kinetic adaptations during a fatiguing repetitive task.Ergonomics. 2015; 19: 1-8
- Muscular exercise and fatigue.Sport Med. 1985; 2: 120-132
- Investigation of applied forces in alphanumeric keyboard work.Am Ind Hyg Assoc J. 1994; 55: 30-35
- Muscle fatigue: what, why and how it influences muscle function.J Physiol. 2008; 586(Pt 1): 11-23
- Muscular endurance and electromyographic fatigue in myofascial shoulder pain.Arch Phys Med Rehabil. 1984; 65: 522-525
- Examining the low, high and range measures of muscle activity amplitudes in symptomatic and asymptomatic computer users performing typing and mousing tasks.Eur J Appl Physiol. 2009; 106: 243-251
- Postural load during VDU work: a comparison between various work postures.Ergonomics. 1997; 40: 1255-1268
- A study of forearm muscle activity and wrist kinematics in symptomatic office workers performing mouse-clicking tasks with different precision and speed demands.J Electromyogr Kinesiol. 2011; 21: 59-66
- Low-amplitude trapezius activity in work and leisure and the relation to shoulder and neck pain.J Appl Physiol. 2006; 100: 1142-1149
- Surface EMG of shoulder and back muscles and posture analysis in secretaries typing at visual display units.Int Arch Occup Environ Health. 1999; 72: 387-394
- Central nervous adaptations following 1 wk of wrist and hand immobilization.J Appl Physiol. 2008; 105: 139-151
- Method for evaluation of muscle fatigue and endurance from electromyographic fatigue curves.Am J Phys Med. 1968; 47: 125-135
- Rank-ordered regulation of motor units.Muscle Nerve. 1996; 19: 563-573
- Electromyographical indication of muscular fatigue in occupational field studies.Int J Ind Ergon. 2000; 25: 645-660
- Effects of postural and visual stressors on myofascial trigger point development and motor unit rotation during computer work.J Electromyogr Kinesiol. 2011; 21: 41-48
- The use of occupation-based assessments and intervention in the hand therapy setting – A survey.J Hand Ther. 2015; 28: 300-305
- Effects of wrist rest and forearm support on muscle activity.Percept Mot Ski. 2006; 103: 873-878
- Individual differences in typing: pause length.Percept Mot Ski. 2006; 103: 946
- Electromyographical assessment on muscular fatigue–an elaboration upon repetitive typing activity.J Electromyogr Kinesiol. 2004; 14: 661-669
- Fatigue development in the finger flexor muscle differs between keyboard and mouse use.Eur J Appl Physiol. 2014; 114: 2469-2482
- Gender differences in skeletal muscle fatigability are related to contraction type and EMG spectral compression.J Appl Physiol. 2003; 94: 2263-2272
- Gender differences in workers with identical repetitive industrial tasks: Exposure and musculoskeletal disorders.Int Arch Occup Environ Health. 2008; 81: 939-947
- Development of recommendations for SEMG sensors and sensor placement procedures.J Electromyogr Kinesiol. 2000; 10: 361-374
- Electromyographic activity during typewriter and keyboard use.Ergonomics. 1994; 37: 477-484
- Escalas de Borg e OMNI na prescrição de exercício em cicloergômetro.Rev Bras Cineantropometria e Desempenho Hum. 2011; 13: 117-123
- Can continuous physical training counteract aging effect on myoelectric fatigue? A surface electromyography study application.Arch Phys Med Rehabil. 2003; 84: 513-517
- Do patient-reported outcome measures capture functioning aspects and environmental factors important to individuals with injuries or disorders of the hand?.J Hand Ther. 2013; 26: 332-342
- Comparison of different estimators of electromyographic spectral shifts during work when applied on short test contractions.Med Biol Eng Comput. 1991; 29: 511-516
- Inflammation and the pathophysiology of work-related musculoskeletal disorders.Brain Behav Immun. 2006; 20: 423-429
- Precision of measurements of physical workload during standardised manual handling. Part I: surface electromyography of m. trapezius, m. infraspinatus and the forearm extensors.J Electromyogr Kinesiol. 2004; 14: 443-454
- Influence of arm and wrist support on forearm and back muscle activity in computer keyboard operation.Appl Erg. 2009; 40: 286-291
- Carpal tunnel syndrome and the use of computer mouse and keyboard: a systematic review.BMC Musculoskelet Disord. 2008; 9: 134
- Effects of computer mouse design and task on carpal tunnel pressure.Ergonomics. 1999; 42: 1350-1360
- Occupational upper extremity disorders in the federal workforce. Prevalence, health care expenditures, and patterns of work disability.J Occup Environ Med. 1998; 40: 546-555
- The influence of body posture, arm movement, and work stress on trapezius activity during computer work.Eur J Appl Physiol. 2007; 101: 445-456
- The effects of different pause types on neck and shoulder EMG activity during VDU work.Ergonomics. 1989; 32: 527-537
- The integration of electromyography (SEMG) at the workstation: assessment, treatment, and prevention of repetitive strain injury (RSI).Appl Psychophysiol Biofeedback. 2003; 28: 167-182
NIOSH. Musculoskeletal Disorders and Workplace Factors. NIOSH Publication No. 97–141.
- Does elevating and tilting the input device support surface affect typing force and postural exposures of the wrist?.Work. 2011; 39: 187-193
- Work-related Musculoskeletal Disorder (WRMSDs) Statistics.Great Britain, 2015 (Available at:)
JHT Read for Credit
Quiz: #523
Record your answers on the Return Answer Form found on the tear-out coupon at the back of this issue or to complete online and use a credit card, go to JHTReadforCredit.com. There is only one best answer for each question.
- #1.The study design was
- a.RCTs
- b.qualitative
- c.a retrospective cohort
- d.a longitudinal case series
- a.
- #2.The proposed intervention was a combination of
- a.ultrasound and deep friction massage
- b.splinting and resistive exercise
- c.wrist support and rest
- d.rest from function and TENS
- a.
- #3.The subject population was
- a.all normal volunteers
- b.all patients with chronic fatigue syndrome
- c.50% normal and 50% actual patients
- d.professional soccer players
- a.
- #4.The muscle exhibiting the most fatigue was the
- a.EIP
- b.EDC
- c.ECRB
- d.ECRL
- a.
- #5.The proposed intervention demonstrated positive effects
- a.false
- b.true
- a.
When submitting to the HTCC for re-certification, please batch your JHT RFC certificates in groups of 3 or more to get full credit.
Article info
Publication history
Published online: February 21, 2017
Accepted:
November 20,
2016
Received in revised form:
November 8,
2016
Received:
May 11,
2016
Footnotes
This research was supported by the following grants: Pará Amazon Research Support Foundation (FAPESPA) number 180/2012; CAPES/COFECUBE research grant number 819-14, and Coordination for the Improvement of Higher Education Personnel (CAPES).
Identification
Copyright
© 2016 Hanley & Belfus, an imprint of Elsevier Inc. All rights reserved.
