International Journal of Occupational Safety and
Ergonomics

ISSN: 1080-3548 (Print) 2376-9130 (Online) Journal homepage: http://www.tandfonline.com/loi/tose20

The influence of a dynamic elastic garment on
musculoskeletal and respiratory wellness incomputer users
Michael Decker, Kellie A. Gomas, Steven J. Narvy & C. Thomas Vangsness
To cite this article: Michael Decker, Kellie A. Gomas, Steven J. Narvy & C. Thomas Vangsness(2016): The influence of a dynamic elastic garment on musculoskeletal and respiratory
wellness in computer users, International Journal of Occupational Safety and Ergonomics, DOI:
10.1080/10803548.2016.1182321
To link to this article: http://dx.doi.org/10.1080/10803548.2016.1182321

Accepted author version posted online: 18
May 2016.
Published online: 27 May 2016.
Submit your article to this journal

Article views: 9

View related articles

View Crossmark data

Full Terms & Conditions of access and use can be found at
http://www.tandfonline.com/action/journalInformation?journalCode=tose20

International Journal of Occupational Safety and Ergonomics (JOSE), 2016
http://dx.doi.org/10.1080/10803548.2016.1182321

The influence of a dynamic elastic garment on musculoskeletal
and respiratory wellness in computer users
Michael Deckera , Kellie A. Gomasb , Steven J. Narvyc and C. Thomas Vangsnessc∗
a University of Denver, USA; b Postonix Physical Therapy, USA; c University of Southern California, USA

Background. Evidence is growing that computer users are at increased risk of developing musculoskeletal disorders, particularly those involving the upper extremity, with significant financial cost and lost productivity. Objective. The purpose ofthis study was to determine the short-term eﬀects of wearing a dynamic elastic garment (Posture Shirt! ; AlignMed, USA)on musculoskeletal wellness and health in the computer workplace. Methods. Ninety-six computer users were evaluated.
The Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire was completed. A functional assessment of posture,lung function, and grip strength was performed after wearing the Posture Shirt! for 4 weeks. A training log was kept totrack usage of the garment, as well as weekly sensations of fatigue, productivity, and energy level. Results. After 4 weeks,
there was statistically significant improvement in forward shoulder and head posture, thoracic kyphosis, and grip strength.
Improvements in spirometry measures did not meet statistical significance. Postural fatigue and muscular fatigue decreased
by 21% and 29%, respectively, and energy level and productivity increased by 20% and 13%, respectively. Conclusion. This
prospective study demonstrated positive short-term impact of the Posture Shirt! on both subjective and objective measuresof posture, lung function, grip strength, fatigue, and productivity.
Keywords: feedback; posture; workplace ergonomics

1. Introduction
Computer use today is all but ubiquitous and spans virtually all age groups. Department of Education data [1]note that 97% of high school students, 91% of elementary
students, and 80% of kindergarten students are computer
users. In the workplace, 49% of working adults used a computer at work in 1997; by 2003, this number had grown to56%, and it is even higher today.[2]Because computer use is so prevalent, even relatively
small risks associated with computer use can have important public health and financial implications. Evidenceis growing that computer users are at increased risk ofdeveloping musculoskeletal disorders (MSDs), particularly
those involving the upper extremity,[2–5] which continue
to be a substantial economic burden with significant impact
on workplace productivity. According to the US Bureau ofLabor Statistics,[6] e.g., MSDs accounted for 32% of the
injuries and illnesses requiring days away from work in
2004. The median number of days away from work was 7days for all cases in this study. In addition, more than onequarter of the working population is aﬀected by low backpain each year, with a lifetime prevalence of 60–80%, anda significant impact on productivity.[7,8]The role of posture in reducing the burden of workrelated musculoskeletal disease has also been a topic ofmuch research. In particular, improper posture can produce low energy levels and exert significant stress on the*Corresponding author. Email: vangsness@usc.edu© 2016 Central Institute for Labour Protection – National Research Institute (CIOP-PIB)

spine over time. The ensuing postural kyphosis can impact
physical and respiratory function, neurologic problems,and back pain.[9] Several observational epidemiologic
studies have linked postural variables to musculoskeletal
outcomes. Hünting et al. [10] found greater reporting ofneck, shoulder, and arm discomfort in patients with greater
head rotation angle and inclination, and also noted thatthe ability to work with hands and forearms supported
was associated with decreased discomfort. Starr et al. [11]found that back discomfort was reported statistically significantly more frequently in computer users who had adownward monitor viewing angle. Sauter et al. [12] noted
less frequent arm discomfort in patients with lower keyboard height relative to the elbows. Faucett and Rempel[13] found head rotation and keyboard height above elbow
height to be significantly associated with upper torso pain
and stiﬀness severity. Marcus et al. [14] found a similarlink between keyboard height and greater risk of neck andshoulder outcomes.
Accordingly, stretching, strengthening, postural education, and ergonomic oﬃce equipment have all been
employed to help reduce posture-related complications ofprolonged computer use in the oﬃce setting. However,these eﬀorts may fall short in promoting optimal working posture. Biofeedback, a method which uses sensory
cues to help train the mind to control bodily functions,has been proposed as a potential solution. The Posture2

M. Decker et al.

Shirt! (AlignMed Inc., USA) is a commercially available, dynamic, elastic upper-extremity ergonomic garment
designed to harness biofeedback to improve workplace
function to stimulate muscles and induce joint alignment.
The purpose of this study was to determine the shortterm eﬀects of wearing the Posture Shirt! : on objectivefunctional assessments of head and shoulder posture, respiratory function, and manual strength; and as subjective
perception of fatigue, energy level, and productivity in theworkplace.
2. Methods
2.1. Recruitment of volunteers
Our pool of study participants consisted of employees ofa large municipal utility provider whose primary work
duty involved computer usage at a desk-based sedentaryjob. Interested employees were screened by questionnaire
for major health problems such as significant respiratory
dysfunction which could confound testing variables. Of
the 100 subjects who expressed interest in participation,
four were excluded for having pre-existing major respiratory illness. Ninety-six volunteer computer users consented
to participate and were evaluated prospectively. Participants were assigned a subject number which was usedduring the course of the study to protect their confidentiality and anonymity. Prior to beginning the study, theDisabilities of the Arm, Shoulder and Hand (DASH) outcome questionnaire [15] was administered to all study
subjects to characterize any baseline upper-extremity dysfunction. The DASH questionnaire consists of a 30-item
disability/symptom scale, which is scored from 0 = no disability to 100 = severe disability, and assesses the ability
to perform activities of daily living as well as recreational
activities. The DASH work module (which assesses a
person’s ability to use their usual work technique, any limitations due to upper-extremity pain, ability to do work as
well as he/she wishes, and ability to spend usual amountof time doing work) and the DASH sports module (assessing these same characteristics as they pertain to sporting
activities) were also assessed.
2.2. Functional assessments
A functional assessment of posture, lung function, and grip
strength was performed on study subjects before and after
a 4-week period of wearing the Posture Shirt! . During
the study period, subjects performed their standard occupational duties (i.e., desk-based computer usage). The metrics
assessed are described in the following.
2.2.1. Forward shoulder posture
Forward shoulder posture was measured with a doublesquare measurement device which consists of a 40.6cm combination square with a second level added in an

inverted position.[16,17] The participant stood next to awall with their buttocks or back touching the wall. The
double square was positioned over the shoulder with one
square flush against the wall. The second square wasadjusted until it touched the tip of the acromioclavicular
joint. The measurement between the wall and the participant’s right shoulder was recorded in a relaxed normal
posture.
2.2.2. Forward head posture and thoracic kyphosis
Forward head and thoracic postural parameters were measured while the participant was sitting in a relaxed normal
posture.[18] Reflective, anatomical markers were positioned on the spinous process of the seventh cervicalvertebra, on the spinous process of the seventh thoracic
vertebra, and on the acromioclavicular joint. A digital picture was taken of the participant and the angle of forward
head posture was defined as the line drawn from the tragus of the ear to the seventh cervical vertebra subtended
to the horizontal. Thoracic posture was calculated as theangle between this horizontal line and the line drawn fromthe seventh cervical spinous process to the seventh thoracic
spinous process.
2.2.3.

Lung volume measurements

Forced expiratory volume in 1 s (FEV1 ) was measured witha spirometer [19] while sitting in a relaxed normal posture.
The participant inhaled a full, deep breath and then placed
the spirometer in his/her mouth and exhaled as forcefully
as possible for 6 s. Three trials were performed with 1 minof rest in between each forced expiratory maneuver. The
largest value was recorded and analyzed.
2.2.4. Hand grip strength measurements
Hand grip strength was measured with a hand-helddynamometer.[20] Participants were tested in the seatedposition with the elbow at a right angle and the dynamometer held in the hand with the wrist in a neutral position. The
participant then squeezed as hard as possible for three separate 3-s trials interspersed with 5-s inter-trial rest intervals.
The largest value was recorded and analyzed.
2.3. Garment usage log
Participants were given a log to track the daily amountof time they spent wearing the dynamic elastic garment
at work. Visual analog scales (VAS) were also given as
a part of the training log to track weekly sensations of subjective postural fatigue; neck, shoulder, and arm fatigue;
productivity; and energy level.
2.4. Statistical analysis
Participant characteristics were described as the meanand standard deviation for continuous outcomes and as a

3

SD

Activities
Work module
Sports module

86
85
37

9.90
5.59
12.50

11.59
12.01
18.22

Note: DASH = Disabilities of the Arm,
Shoulder and Hand.

[3, 5][3, 9][0.4, 1]
[5, 18][ − 2, 6][ − 1, 5]
5
6
1
12
4
2
81 < 0.001 < 0.001
79 < 0.001 < 0.001
79 < 0.001 < 0.001
79
0.001 < 0.001
88
0.371 < 0.001
88
0.172 < 0.001
277.3
14.7 − 9.16
46.1
5.2 − 5.24
247.4
5.4 − 3.83
79.0
24.2 − 3.36
462.5 126.0
0.91
3.05
0.71 − 1.40
93
93
93
93
93
93
81 < 0.001
90
0.030
90
0.351
92 < 0.001
92
0.162
92
0.040
− 8.92− 2.180.95− 4.92− 1.41− 2.08
19.7
6.0
5.3
23.5
119.3
0.69
275.9
44.5
245.0
76.4
467.4
3.07
96
96
96
96
96
96
20.8
6.0
5.8
22.5
128.2
0.72

Mdn
p
SD
Mdn
Mdn

SD

N

Mdn

SD

t

df

p

N

No shirt
Immediate eﬀect
Shirt
No shirt

Note: p adj include total hours as a covariate. CI = confidence interval; FEV1 = forced expiratory volume in 1 s; FVC = forced vital capacity.

M

96
96
96
96
96
96

N

Forward shoulder
Forward headThoracic kyphosis
Grip strength
FVC
FEV1

DASH subscore

N

DASH questionnaire items.

MetricTable 1.

Table 2. Outcomes for participants at each measurement point.

3.2. Eﬀects of the Posture Shirt!
Table 2 presents the outcomes for participants at eachmeasurement point. At baseline, there was a statisticallysignificant improvement in FEV1 (p = 0.040), forward
shoulder posture (p < 0.001), strength (p < 0.001), andforward head posture (p = 0.030) between measurements
taken with and without the shirt.
After 4 weeks, there was a significant diﬀerence in all
outcomes except for the spirometry measures of forced
vital capacity (FVC) and FEV1 , as reflected in Figures 1–5.
Percent change was highest for grip strength (12%). After
adjusting for total reported hours of usage, all changes were
statistically significant (p < 0.001). Although not statistically significant, the 3.8% improvement in FEV1 after 4
weeks did yield a magnitude of 5 L/min improvement, andmay be functionally significant.

t3.1. Demographics
Ninety-six participants were included in this study. Ages
ranged from 21 to 61 years (M = 44.7 ± 8.4 years).
Of these, 62 were females (64.6%) and the remainder
was male. Three participants reported a history of mild
asthma; one patient had been prescribed medication, andthe remaining two patients had no prescribed medications.
One participant dropped out of the study, and there wassome minor missing data on one other subject due tovacation during the study period.
At the beginning of the study period, participants hada mean DASH activity score of 9.9 ± 11.6, consistent
with no baseline upper-extremity dysfunction. The DASH
subscore breakdown is presented in Table 1.

267.2
43.8
245.4
73.6
459.5
3.01

3. Resultsdf

4-week changep adj% change (weeks 1–4)

percentage for categorical variables. The distribution ofcontinuous outcomes was examined for normality. Intentto-treat analyses were performed using a paired t test to
determine the immediate eﬀect of wearing the shirt at pretest, as well as the change after 4 weeks of shirt usage.
Linear regression models were then performed to adjust for
the eﬀect of total hours reported across 4 weeks to determine the eﬀect of adherence on change. VAS scores werereported for all 4 weeks and linear trends across time were
examined. For all statistical analysis, an α level of 0.05 wasused.

95% CI

International Journal of Occupational Safety and Ergonomics (JOSE)

4

M. Decker et al.

Figure 1. Forward shoulder posture.
Note: Post: WS = post-test without Posture Shirt® ; Pre:
PS = pre-test with Posture Shirt® ; Pre: WS = pre-test without
Posture Shirt® .

Figure 2. Forward head posture.
Note: Post: WS = post-test without Posture Shirt® ; Pre:
PS = pre-test with Posture Shirt® ; Pre: WS = pre-test without
Posture Shirt® .

Figure 4. Forced expiratory volume in 1 s (%).
Note: FEV1 = forced expiratory volume in 1 s;
Post = post-test; Pre = pre-test.

Figure 5. Grip strength.
Note: Post: WS = post-test without Posture Shirt® ; Pre:
PS = pre-test with Posture Shirt® ; Pre: WS = pre-test without
Posture Shirt® .

Table 3. Hours of wearing the Posture Shirt! .

Figure 3. Thoracic kyphosis.
Note: Post: WS = post-test without Posture Shirt® ; Pre:
PS = pre-test with Posture Shirt® ; Pre: WS = pre-test without
Posture Shirt® .

3.3. Participant compliance
The number of hours per week participants wore the Posture Shirt! is reported in Table 3. Compliance data wereavailable for 80 participants in week 1 and for 79 participants in weeks 2–4. Hours worn increased from weeks 1 to
2, with most people reporting wearing the Posture Shirt!
for 20 h during week 1 and for 40 h during week 2. The
hours of average usage were similar for weeks 2–4.

25th
75th
percentile percentile

Week

N

1
2
3
4
Total (weeks
1–4)
M per week

80 21.1
79 38.1
79 36.6
79 37.5
80 131.9

8.1 2010.6 40
12.6 40
12.5 40
35.3 136.0

18
32
32
32
117.5

22
48.5
46
50
156

80

8.4

29.4

39

Mdn

33.1

SD

M

34.0

3.4. VAS scores
Table 4 presents the VAS measures across 4 weeks.
There was a significant linear decline in subjective measures of postural fatigue (p = 0.011) and muscular fatigue(p < 0.001). There were statistically significant increases
in energy level (p < 0.001) and improvement in productivity (p = 0.006).

5International Journal of Occupational Safety and Ergonomics (JOSE)
Table 4.

VAS and DASH questionnaire scores across 4 weeks.
Week 1

Week 2

Week 3

Week 4

Metric (VAS)

N

M

SD

N

M

SD

N

M

SD

N

M

SD

Postural fatigue
Muscular fatigue
Energy level
Productivity

78
78
78
78

0.33
0.34
0.53
0.59

0.22
0.22
0.18
0.16

77
77
77
77

0.33
0.33
0.57
0.62

0.19
0.19
0.18
0.16

77
77
77
77

0.28
0.28
0.62
0.63

0.18
0.17
0.18
0.17

77
77
77
77

0.26
0.24
0.64
0.66

0.20
0.18
0.19
0.18

Note: DASH = Disabilities of the Arm, Shoulder and Hand; VAS = visual analog scale.

4. Discussion
Postural dysfunction in the workplace is a major concern
with the potential for significant morbidity and loss ofwork time and work productivity. This pilot study demonstrates statistically significant objective improvements inshort-term head and shoulder posture, kyphosis, and grip
strength, decreases in postural and muscle fatigue, andimprovements in subjective energy level and productivity in municipal computer users. These results warrant
longer-term follow up with a larger sample.
Upper-extremity MSDs result from many factors,
including physical, psychosocial, and personal factors.[21]Of these, physical factors may be the most easily modifiable, but still represent a complex interplay of muscular physiology. Sitting-related load on the cervical spine
is aﬀected by posture, e.g., and may be an important
contributor to neck pain in oﬃce workers performing
computer-based tasks.[22,23] Flexed head and neck postures have been associated with increased gravitationalload and cervical extensor muscle activity, which may contribute to the higher prevalence of neck pain in individuals
with this postural alignment.[24,25] Conversely, correction
towards a more upright posture tends to decrease cervicalextensor activity and to increase activation of deep flexor
muscles.[26,27] In addition, the overall sitting posture
may influence this dynamic balance of muscle activation.
More slumped sitting postures involving cervico-thoracic
flexion are associated with greater cervical extensor muscle activity, while more upright sitting postures that
reduce forward head translation and cervical flexion
appear to reduce the level of cervical extensor activity.
[26,28,29]
Current practices in occupational MSD management
to address this multifactorial problem are varied, andinclude workplace interventions such as ergonomics training and workstation readjustment, clinical interventions
such as physical therapy, and disability management programs. Several recent systematic reviews [30–33] havenoted a mixed or insuﬃcient level of evidence for theeﬀect of occupational interventions on upper-extremity
MSDs, and have failed to show any single-dimensionalor multi-dimensional strategy that has been consistently
eﬀective across occupational settings.
‘Smart garments’ designed to help promote biofeedback to maintain proper posture have been proposed as anovel solution for upper-extremity MSDs. Data for suchdevices are sparse in the literature, however. Wong andWong [34] developed a garment consisting of three sensor
modules, a digital data acquisition and feedback system,and the actual garment itself. Five study subjects (M age
25.2 years) were evaluated in the garment after 4-day trials of wearing the garment for 2 h during daily activities.
Statistically significant improvement in the lumbar curvein the sagittal plane was noted. Similarly, Lou et al. [9,35]
designed a smart garment consisting of a harness and two
data-sensor loggers and evaluated this in four subjects whowore the garment 3 h/day for 4 consecutive days. A statistically significant improvement in kyphotic angle was noted.
However, both of these studies have much smaller numbers of participants and present much more short-term datacompared with the present study of 96 users with 4-weekfollow-up.
The Posture Shirt! is diﬀerent from the previously
described garments, in that it has no built-in electronicmechanism. Rather, the garment is designed to envelop
portions of the torso, iliac crests, and upper arms and utilize anatomically-placed elastomeric fabric panels (known
as Neuro-Bands! ) to stimulate biofeedback. Specifically,
the varying tensions within the Neuro-Bands! provide
conscious and unconscious postural cues to help restorealignment of the spine, neck, and shoulder girdle.
As such, the present prospective study demonstrated
a positive short-term impact of the Posture Shirt! on
objective measures of head and shoulder posture, thoracic
kyphosis, lung function, and grip strength. In addition,subjective improvements in fatigue, posture, energy, andproductivity were demonstrated.
One main limitation of this pilot study is the lackof a control group; there may be a component of aplacebo eﬀect and a selection bias of those wishing toparticipate in the study. In addition, the short period of
follow-up and garment usage provide only pilot data forshort-term outcomes among municipal computer users;
long-term improvements in the measured parameters
cannot be inferred from the present study. Nonetheless,even short-term reductions in workplace fatigue can berelevant clinically and economically. In addition, although
improvements in lung function did not meet statisticalsignificance by the end of the study period, these improvements may be relevant clinically and in the workplace.

6

M. Decker et al.

Moreover, this study did not undergo the scrutiny ofan Institutional Review Board (IRB) process. One year
was spent holding numerous meetings with city administrators and attorneys regarding the safety of the dynamic
elastic garment, the ability of study participants to conduct
their normal duties without going over hours while fulfilling study testing, and other logistical concerns. Ultimately,
the administrators and attorneys were satisfied with the
non-invasive nature of the study garment, and the repeatedmeasures design without a control group as described wasdeemed to be most eﬃcient within this structured work
environment. As such, the decision was made to proceedwithin a tight window of employee use to uniquely collect these data without formal IRB approval of the study
protocol.
5. Conclusion
This dynamic elastic garment had a statistically significant short-term improvement in both subjective and objective measures of workplace ergonomics among municipal
computer users. Occupational application of the Posture
Shirt! during prolonged sitting and computer work may
improve posture, physiologic lung function, and subjective
employee productivity and fatigue.
Disclosure statement
No potential conflict of interest was reported by the author(s).

Funding
This study was funded by AlignMed, Inc., in which Dr Vangsness
holds a small ownership stake.

References[1] National Center for Education Statistics. Rates of computer and internet use by children in nursery schooland students in kindergarten through twelfth grade: 2003.
[Internet]. Washington (DC): US Department of Education [cited 2014 Jan 3]. Available from: http://nces.ed.gov/
pubs2005/2005111rev.pdf.
[2] US Census Bureau. Computer use in the United States, 1997
[Internet]. Washington (DC): US Department of Commerce[cited 2014 Jan 3]. Available from: https://www.census.gov/
prod/99pubs/p20-522.pdf.
[3] Gerr F, Marcus M, Monteilh C. Epidemiology of musculoskeletal disorders among computer users: lessons learned
from the role of posture and keyboard use. J Electromyogr
Kinesiol. 2004;14:25–31. doi:10.1016/j.jelekin.2003.09.014.
[4] Gerr F, Monteilh CP, Marcus M. Keyboard use and musculoskeletal outcomes among computer users. J Occup
Rehabil. 2006;16(3):259–271. doi:10.1007/s10926-006-90
37-0.
[5] Tittiranonda P, Burastero S, Rempel D. Risk factors formusculoskeletal disorders among computer users. Occup
Med. 1999;14:17–38.
[6] Bureau of Labor Statistics. Lost-work time injuries and illnesses: characteristics and resulting days away from work,
2004. [Internet]. Washington (DC): US in [2] Departmentof Labor [cited 2014 Jan 5]. Available from: http://www.
bls.gov/news.release/archives/osh2_12132005.pdf.
[7] Lee P, Helewa A, Goldsmith CH, et al. Low back pain:
prevalence and risk factors in an industrial setting. J
Rheumatol. 2001;28(2):346–351.
[8] Lis AM, Black KM, Korn H, et al. Association between
sitting and occupational LBP. Eur Spine J. 2007;16(2):283–
298. doi:10.1007/s00586-006-0143-7.
[9] Lou E, Lam GC, Hill DL, et al. Development of asmart garment to reduce kyphosis during daily living. Med
Biol Eng Comput. 2012;50(11):1147–1154. doi:10.1007/
s11517-011-0847-7.
[10] Hünting W, Läubli T, Grandjean E. Postural and visual loads
at VDT workplaces. I. Constrained postures. Ergonomics.
1981;24(12):917–931. doi:10.1080/00140138108924914.
[11] Starr SJ, Shute S, Thompson CR. Relating posture to discomfort in VDT use. J Occup Med. 1985;27:269–271.
[12] Sauter SL, Schleifer LM, Knutson SJ. Work posture, workstation design, and musculoskeletal discomfort in a VDTdata entry task. Hum Factors. 1991;33:151–167.
[13] Faucett J, Rempel D. VDT-related musculoskeletal symptoms: interactions between work posture and psychosocial work factors. Am J Ind Med. 1994;26:597–612.
doi:10.1002/ajim.4700260503.
[14] Marcus M, Gerr F, Monteilh C, et al. A prospective study ofcomputer users: II. Postural risk factors for musculoskeletal
symptoms and disorders. Am J Indust Med. 2002;41:236–
249. doi:10.1002/ajim.10067.
[15] De Smet L. The DASH questionnaire and score in theevaluation of hand and wrist disorders. ActaOrthop Belg.
2008;74(5):575–578.
[16] Kluemper M, Uhl TL, Hazelrigg H. Eﬀect of stretching andstrengthening shoulder muscles on forward shoulder posture in competitive swimmers. J Sport Rehabil. 2006;15(1):58–70.
[17] Peterson DE, Blankenship KR, Robb JB, et al. Investigation of the validity and reliability of four objective techniques for measuring forward shoulder posture. J
Orthop Sports Phys Ther. 1997;25(1):34–42. doi:10.2519/
jospt.1997.25.1.34.
[18] Greenfield B, Catlin PA, Coats PW, et al. Posture inpatients with shoulder overuse injuries and healthy individuals. J Orthop Sports Phys Ther. 1995;21(5):287–295.
doi:10.2519/jospt.1995.21.5.287.
[19] NIOSH spirometry guidelines. Center for Disease Control and Prevention; 2005 [cited 2014 Jan 4]. Available from: http://www.cdc.gov/niosh/docs/2004-154c/pdfs/
2004-154c.pdf.
[20] Kelln BM, McKeon PO, Gontkof LM, et al. Hand-helddynamometry: reliability of lower extremity muscle testingin healthy, physically active, young adults. J Sports Rehabil.
2008;17(2):160–170.
[21] Mahmud N, Kenny DT, Md Zein R, et al. The eﬀects
of oﬃce ergonomic training on musculoskeletal complaints, sickness absence, and psychological well-being:a cluster randomized control trial. Asia Pac J Public
Health. 2015;27(2):NP1652–1668. doi:10.1177/10105395
11419199.
[22] Choi H. Quantitative assessment of co-contraction in cervical musculature. Med Eng Phys. 2003;25(2):133–140.
doi:10.1016/S1350-4533(02)00151-0.
[23] Côté P, van der Velde G, Cassidy JD, et al. The burden and determinants of neck pain in workers: results ofthe bone and joint decade 2000–2010 task force on neckpain and its associated disorders. Spine (Phila Pa 1976).
2008;33(Supp4):S60–S74. doi:10.1097/BRS.0b013e3181
643ee4.

International Journal of Occupational Safety and Ergonomics (JOSE)[24] Yip CH, Chiu TT, Poon AT. The relationship between headposture and severity and disability of patients with neck
pain. Man Ther. 2008;13(2):148–154. doi:10.1016/j.math.
2006.11.002.
[25] Straker L, Skoss R, Burnett A, et al. Eﬀect of visual display height on modelled upper and lower cervical gravitational moment, muscle capacity, and relative strain.
Ergonomics. 2009;52(2):204–221. doi:10.1080/00140130
802331609.
[26] Caneiro JP, O’Sullivan P, Burnett A, et al. The influence of diﬀerent sitting postures on head/neck posture andmuscle activity. Man Ther. 2010;15(1):54–60. doi:10.1016/
j.math.2009.06.002.
[27] Falla D, O’Leary S, Fagan A, et al. Recruitment of the deep
cervical flexor muscles during a postural-correction exercise performed in sitting. Man Ther. 2007;12(2):139–143.
doi:10.1016/j.math.2006.06.003.
[28] Edmondston SJ, Sharp M, Symes A, et al. Changes
in mechanical load and extensor muscle activity in thecervico-thoracic spine induced by sitting posture modification. Ergonomics. 2011;54(2):179–186. doi:10.1080/00140
139.2010.544765.
[29] Harms-Ringdahl K, Ekholm J, Schüldt K, et al. Loadmoments and myoelectric activity when the cervicalspine is held in full flexion and extension. Ergonomics.
1986;29(12):1539–1552. doi:10.1080/00140138608967267.

7[30] Kennedy CA, Amick BC 3rd, Dennerlein JT, et al. Systematic review of the role of occupational health andsafety interventions in the prevention of upper extremity musculoskeletal symptoms, signs, disorders, injuries,
claims and lost time. J Occup Rehabil. 2010;20(2):127–162.
doi:10.1007/s10926-009-9211-2.
[31] Boocock MG, McNair PJ, Larmer PJ, et al. Interventions
for the prevention and management of neck/upper extremity musculoskeletal conditions: a systematic review. Occup
Environ Med. 2007;64(5):291–303. doi:10.1136/oem.2005.
025593.
[32] Brewer S, Van Eerd D, Amick BC 3rd, et al. Workplace interventions to prevent musculoskeletal and visual
symptoms and disorders among computer users: a systematic review. J Occup Rehabil. 2006;16(3):317–350.
doi:10.1007/s10926-006-9031-6.
[33] Hoe VC, Urquhart DM, Kelsall HL, et al. Ergonomic design
and training for preventing work-related musculoskeletal
disorders of the upper limb and neck in adults. Cochrane
Database Syst Rev. 2012;8:CD008570.
[34] Wong WY, Wong MS. Smart garment for trunk posture monitoring: a preliminary study. Scoliosis. 2008;3:7.
doi:10.1186/1748-7161-3-7.
[35] Lou E, Moreau MJ, Hill DL, et al. Smart garment to help
children improve posture. Conf Proc IEEE Eng Med Biol
Soc. 2006;1:5374–5377.