LEARNING OUTCOMES
After completing this enduring educational activity, the learner will be better able to:
- Discuss the association between work characteristics and conditions of the work environment and shoulder pain.
- Describe inappropriate telecommuting environments being associated with an increase in the prevalence of shoulder pain.
- Suggest ways to improve the telecommuting environment to prevent shoulder pain.
Musculoskeletal disorders are a major health problem among office workers, with an estimated prevalence of more than 50% reported in the 2000s.1–3 Among musculoskeletal disorders, shoulder pain is a major health complaint in 30% of office workers.1–3 Shoulder pain decreases the physical and mental quality of life and is associated with depression and sleep disorders.4,5 Furthermore, workers with shoulder pain may have difficulty concentrating, take more breaks, and be absent from work long-term, which reduces labor productivity.6–8
Shoulder pain among office workers is associated with the work characteristics and conditions of the work environment. Inappropriate work environment characteristics include nonadjustable desks, glare, and reflections on the screen. Working conditions include rest-pause duration and the number of working hours per day using a computer.9–11 Inappropriate characteristics of the work environment may lead to inappropriate posture, causing shoulder pain.9,11
In offices, employers have attempted to prevent musculoskeletal disorders by taking measures to enhance the working environment characteristics, such as ensuring appropriate brightness in the room; appropriate selection and placement of personal computers, keyboards, and mice for workers; use of chairs with adjustable height and tilt; and use of height-adjustable desks with an appropriately large workspace and enough foot space.12 Previous studies have reported that 67.8% of companies took measures against these work environments, and more than 50% of their workers considered the work environment in their offices to be appropriate.13
However, telecommuting environments are inadequate because the surveys conducted during the COVID-19 pandemic revealed that more than 50% of telecommuters did not have a work desk or chair, and more than 60% of telecommuters did not have a work room or space.14,15 Telecommuting was rapidly promoted to prevent the spread of the COVID-19 pandemic from the beginning of 2020, and many companies have introduced telecommuting without preparing a proper telecommuting system. Moreover, many workers do not have the time to prepare for telecommuting environments. Although the Japanese government issued guidelines on preparing appropriate telecommuting environments in February 2018 before the COVID-19 pandemic, more than 50% of companies did not know the guidelines in October 2020, and workers did not have sufficient knowledge about the telecommuting environment.16
Inappropriate telecommuting environments have been shown to be associated with lower back pain.17 However, the association between telecommuting environments and shoulder pain among telecommuters remains unclear. This study aimed to investigate the association between telecommuting environments and shoulder pain.
METHODS
Study Design and Participants
This Internet-monitored, cross-sectional study was conducted in Japan during the third wave of COVID-19 from December 22 to 26, 2020. The study protocol has been reported in a previous article.18 Of 33,302 participants in the survey, 27,036 were surveyed excluding those who provided fraudulent answers. Of the remaining 27,036 participants, manual workers and those who telecommuted three or fewer days per week were excluded, and the remaining 2537 were included in the final analysis. Therefore, we analyzed participants who mainly performed desk work or worked in the hospitality industry and telecommuted at least 4 days per week. This study was approved by the Ethics Committee of the Ethics Committee of the University of Occupational and Environmental Health, Japan (approval no. R2-079 and R3-006). All participants provided informed consent.
Assessment of Shoulder Pain
We assessed the presence of shoulder pain using two questions. First, we asked all participants “In the past 2 weeks, have you experienced any shoulder pain or lower back pain?” If the participant answered yes, we asked them an additional question, “What was the average degree of shoulder pain you have experienced during the past 2 weeks?” We used a numerical rating scale to rate pain and defined a score of three or higher as the presence of pain (pain intensity was rated on a scale of 0 to 10: with a rating of zero indicating no pain at all and 10 indicating the strongest pain experienced). A numerical rating scale is one of the major assessment methods of musculoskeletal pain and is used in studies whose outcomes are pain or clinical practice.19
Assessment of Telecommuting Environments
Few questions about the telecommuting environment are similar to the questions we used in our previous study.17 The telecommuting environment was assessed based on the response to the following eight questions: “Do you have a place or room where you can concentrate on your work?,” “Do you have enough light on the desk for you to work?,” “Do you have enough workspace on your desk?,” “Do you have enough foot space under your desk to stretch your legs?,” “Are the temperature and humidity in your workroom comfortable?,” “Do you use an office desk or chair? (including a children’s study desk),” “Do you use a non-office desk or chair? (dining table or sofa),” and “Do you use a low table or kotatsu (common Japanese traditional heating appliance and a heating low table covered with a blanket) to work?” Participants answered “yes” or “no” to each question.
Assessment of the Participants’ Characteristics and Other Covariates
Socioeconomic, lifestyle, psychological, and work-related factors were examined. Socioeconomic factors included age, sex, body mass index (BMI), educational background (junior high school, high school, vocational school, junior college or technical college, university or graduate school), and equivalent income (household income divided by the number of consumption units in the household). Lifestyle factors included smoking status (current smoking status), alcohol consumption (two or more days a week), physical activity (walking or equivalent physical activity for one or more hours a day for two or more days per week), and exercise (30 or more minutes for two or more days per week). Mental factors included the number of days of experiencing mental health problems in the past 30 days. Work-related factors included job type (mainly desk work and work involving communicating with people), working time (hours/week), and company size (number of total employees at the company).
Statistical Analysis
Age, BMI, and number of days experiencing mental health problems in the past 30 days were presented as continuous variables with means and standard deviations. The other variables are presented as categorical variables with numbers and percentages.
A multilevel logistic regression analysis nested by the city of residence, with shoulder pain as the dependent variable and assessment of telecommuting environment as the independent variable, was performed. Age, sex, BMI, educational background, equivalent income, smoking status, alcohol consumption, physical activity, exercise, job type, working time (hours/week), company size, and the number of days of experiencing mental health problems during the past 30 days were used as covariates to adjust for potential confounders. All statistical analyses were performed using the Stata (Stata Statistics software: Release 16; StataCorp LLC, College Station, TX). Statistical significance was set at P < 0.05.
RESULTS
The characteristics of the participants are summarized in Table 1. The prevalence of shoulder pain among the study participants was 52.5%. Women had a higher percentage of shoulder pain than men. The group with shoulder pain had more days of mental health problems than did the group without shoulder pain.
TABLE 1 -
Participant Characteristics
|
Without Shoulder Pain (n = 1205) |
With Shoulder Pain (n = 1332) |
| Age (y), mean (SD) |
50.2 (10.0) |
48.8 (10.0) |
| Sex (men) |
765 (63.5%) |
652 (48.9%) |
| BMI, mean (SD) |
22.5 (3.6) |
22.5 (3.8) |
| Educational background |
|
|
| Junior high school |
12 (1.0%) |
10 (0.8%) |
| High school |
202 (16.8%) |
227 (17.0%) |
| Vocational school |
147 (12.2%) |
159 (11.9%) |
| Junior college/technical college |
100 (8.3%) |
174 (13.1%) |
| University |
633 (52.5%) |
654 (49.1%) |
| Graduate school |
111 (9.2%) |
108 (8.1%) |
| Equivalent income (¥10,000) |
|
|
| <261 |
442 (36.7%) |
453 (34.0%) |
| 261–475 |
345 (28.6%) |
456 (34.2%) |
| >475 |
418 (34.7%) |
423 (31.8%) |
| Lifestyle |
|
|
| Smoking status (yes) |
316 (26.2%) |
318 (23.9%) |
| Alcohol consumption (yes) |
534 (44.3%) |
579 (43.5%) |
| Physical activity (yes) |
435 (36.1%) |
462 (34.7%) |
| Exercise (yes) |
354 (29.4%) |
355 (26.7%) |
| Job type |
|
|
| Mainly desk work |
973 (80.7%) |
1069 (80.3%) |
| Mainly work involving communicating with people |
232 (19.3%) |
263 (19.7%) |
| Working time (h/wk) |
|
|
| <40 |
848 (70.4%) |
897 (67.3%) |
| 40–48 |
164 (13.6%) |
166 (12.5%) |
| 49–60 |
127 (10.5%) |
191 (14.3%) |
| >60 |
66 (5.5%) |
78 (5.9%) |
| Company size (person) |
|
|
| <10 |
717 (59.5%) |
742 (55.7%) |
| 10–99 |
93 (7.7%) |
121 (9.1%) |
| 100–999 |
133 (11.0%) |
169 (12.7%) |
| >1000 |
262 (21.7%) |
300 (22.5%) |
| The number of days of experiencing mental health problems in the past 30 days, mean (SD) |
2.5 (6.4) |
5.6 (8.8) |
The telecommuting environments of the participants are summarized in Table 2. For all survey items, group with shoulder pain had a higher percentage of inappropriate telecommuting environments than the group without shoulder pain.
TABLE 2 -
Telecommuting Environments of Participants
|
Without Shoulder Pain (n = 1205) |
With Shoulder Pain (n = 1332) |
| Telecommuting environment characteristics |
|
|
| Do you have a place or room where you can concentrate on your work? (no) |
194 (16.1%) |
263 (19.7%) |
| Do you have enough light on the desk for you to work? (no) |
133 (11.0%) |
228 (17.1%) |
| Do you have enough space on your desk to work? (no) |
279 (23.2%) |
366 (27.5%) |
| Do you have enough foot space under your desk to stretch your legs? (no) |
190 (15.8%) |
283 (21.2%) |
| Are the temperature and humidity in your workroom comfortable? (no) |
238 (19.8%) |
367 (27.6%) |
| Do you use an office desk or chair? (including a children’s study desk) (no) |
525 (43.6%) |
604 (45.3%) |
| Do you use a non-office desk or chair? (eg, dining room table, sofa) (yes) |
475 (39.4%) |
528 (39.6%) |
| Do you use a low table or kotatsu to work? (yes) |
297 (24.6%) |
373 (28.0%) |
The association between shoulder pain and telecommuting environments is summarized in Table 3. The responses for the questions “Do you have enough light on the desk for you to work (no)” (odds ratio [OR], 1.39; 95% confidence interval [CI], 1.09–1.78; P = 0.008), “Do you have enough foot space under your desk to stretch your legs (no)” (OR, 1.27; 95% CI, 1.02–1.58; P = 0.029), and “Are the temperature and humidity in your workroom comfortable (no)” (OR, 1.41; 95% CI, 1.16–1.72; P = 0.001) were significantly associated with shoulder pain in models 1 and 2 (model 1 was adjusted for sex and age, and model 2 was adjusted for other potential confounders). The response for the question “Do you have enough space on your desk to work (no)” (OR, 1.28; 95% CI, 1.07–1.53; P = 0.008) was significantly associated with shoulder pain in only model 1.
TABLE 3 -
The Association Between Telecommuting Environments and Shoulder Pain
|
Model 1†
|
Model 2‡
|
| OR |
95% CI |
P
|
OR |
95% CI |
P
|
| Telecommuting environments |
|
|
|
|
|
|
|
|
| Do you have a place or room where you can concentrate on your work? (no) |
1.24 |
1.01 |
1.52 |
0.044 |
1.09 |
0.88 |
1.36 |
0.418 |
| Do you have enough light on the desk for you to work? (no) |
1.63 |
1.30 |
2.06 |
<0.001 |
1.39 |
1.09 |
1.78 |
0.008 |
| Do you have enough space on your desk to work? (no) |
1.28 |
1.07 |
1.53 |
0.008 |
1.12 |
0.92 |
1.35 |
0.256 |
| Do you have enough foot space under your desk to stretch your legs? (no) |
1.48 |
1.20 |
1.82 |
<0.001 |
1.27 |
1.02 |
1.58 |
0.029 |
| Are the temperature and humidity in your workroom comfortable? (no) |
1.55 |
1.29 |
1.87 |
<0.001 |
1.41 |
1.16 |
1.72 |
0.001 |
| Do you use an office desk or chair? (including a children’s study desk) (no) |
1.00 |
0.85 |
1.17 |
0.984 |
0.96 |
0.81 |
1.14 |
0.633 |
| Do you use a non-office desk or chair? (eg, dining room table, sofa) (yes) |
0.95 |
0.80 |
1.11 |
0.500 |
0.95 |
0.80 |
1.12 |
0.550 |
| Do you use a low table or kotatsu to work? (yes) |
1.14 |
0.96 |
1.37 |
0.141 |
1.14 |
0.95 |
1.37 |
0.168 |
†Model 1: adjusted for age, sex.
‡Model 2: adjusted for age, sex, body mass index, educational background, equivalent income, smoking status, alcohol consumption, physical activity, exercise, job type, working time, company size, and the number of days experiencing mental health problems in the past 30 days.
CI, confidence interval; OR, odds ratio.
DISCUSSION
This study showed that telecommuting environment characteristics, such as desk brightness, foot space, and comfortable temperature and humidity, were associated with shoulder pain.
Foot space and desk brightness are associated with shoulder pain because they influence posture, and sitting posture is reported to be associated with shoulder pain.9,11 The availability of sufficient foot space allows the worker to easily change posture and maintain a low load posture. If the desk brightness is inadequate, it is difficult to see the work surface and the worker must move closer to the work surface; therefore, the worker’s posture becomes poor. The Occupational Health Guidelines on Information Device Work at Office recommends that the work surface should be 300 lux or more in brightness.12
In addition, inappropriate room temperature and humidity were associated with shoulder pain. This study was conducted in winter. The average room temperature in Japanese living rooms during winter is low; therefore, cold exposure from inadequate heating systems could probably have caused shoulder pain.20 Cold exposure is reported to be associated with shoulder pain because repetitive work with cold exposure increases muscle fatigue.21–23 The appropriate temperature to prevent shoulder pain is unclear; however, it is good to maintain the room temperature at 18°C to 28°C according to the Ordinance on Health Standards in the Office.24
The use of office chairs and desks, kotatsu, and low tables was not associated with shoulder pain. However, in a previous study, the use of adjustable desks is reported to be associated with less shoulder pain.9 In addition, the Occupational Health Guidelines on Information Device Work at Office recommend that the desks can be adjusted height and the chair can be adjusted height or seat back leaning and have seat back and armrest.12 These may imply if the desk or chair has the function (adjustability, seat back, armrest) or not, not the type of the desk or chair, that is associated with shoulder pain. In this study, we did not ask participants about the function of the chair and desk, so we may not have been able to find any association between shoulder pain and the desk or chair.
This study suggested that maintaining a proper telecommuting environment is helpful for preventing shoulder pain. The problem with telecommuting is that it is difficult for employers to adequately manage workers’ health and safety, because employers cannot directly intervene in telecommuting environments as it is the most private environment for the workers. Therefore, employers should understand workers’ telecommuting environments and train them to independently maintain appropriate telecommuting environments. Employers can disseminate guidelines and utilize checklists to improve telecommuting environments.
This study has several limitations. First, this study is cross-sectional; therefore, reverse causality cannot be ruled out. However, it is unlikely that people with shoulder pain choose inappropriate telecommuting environments. Second, the participants subjectively answered questions on the status of their telecommuting environments. However, it was unlikely that the participants incorrectly answered that they used office chairs and desks, and had their own workrooms. Nevertheless, the objective evaluation of temperature, humidity, and illuminance requires an illuminance meter and a thermohygrometer. Therefore, it is difficult to objectively evaluate a questionnaire-based survey. Third, information on treatment, such as history of shoulder pain, use of nonsteroidal anti-inflammatory drugs and other medications, and history of surgery, was not known. Lastly, there may be a bias due to the assessment of pain retrospectively. In subjective assessment, participants may have answered that recent pain is more painful than old pain. Weaker pain may have been underestimated, because participants remember stronger pain more than weaker pain. However, we asked participants about only the recent past 2 weeks in this study. This bias unlikely occurred.
CONCLUSIONS
This study suggested that telecommuting environments were associated with shoulder pain in Japanese telecommuters. It is helpful for employers and workers to approach and maintain appropriate telecommuting environments to prevent shoulder pain.
ACKNOWLEDGMENTS
The current members of the CORoNaWork Project, in alphabetical order, are as follows: Dr Akira Ogami, Dr Ayako Hino, Dr Hajime Ando, Dr Hisashi Eguchi, Dr Keiji Muramatsu, Dr Koji Mori, Dr Kosuke Mafune, Dr Makoto Okawara, Dr Mami Kuwamura, Dr Mayumi Tsuji, Dr Ryutaro Matsugaki, Dr Seiichiro Tateishi, Dr Shinya Matsuda, Dr Tomohiro Ishimaru, Dr Tomohisa Nagata, Dr Yoshihisa Fujino (present chairperson of the study group), and Dr Yu Igarashi. All members are affiliated with the University of Occupational and Environmental Health, Japan.
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