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Phys. Ther. Korea 2023; 30(3): 221-229
Published online August 20, 2023
https://doi.org/10.12674/ptk.2023.30.3.221
© Korean Research Society of Physical Therapy
Effects of a Posture Correction Feedback System on Upper Body Posture, Muscle Activity, and Fatigue During Computer Typing
Subin Kim1 
, PT, BPT, Chunghwi Yi2 , PT, PhD, Seohyun Kim1 , PT, BPT, Gyuhyun Han1 , PT, BPT, Onebin Lim3 , PT, PhD
1Department of Physical Therapy, The Graduate School, Yonsei University, 2Department of Physical Therapy, College of Software and Digital Healthcare Convergence, Yonsei University, Wonju, 3Department of Physical Therapy, Mokpo Science University, Mokpo, Korea
Correspondence to: Chunghwi Yi
E-mail: pteagle@yonsei.ac.kr
https://orcid.org/0000-0003-2554-8083
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background: In modern society, the use of computers accounts for a large proportion of our daily lives. Although substantial research is being actively conducted on musculoskeletal diseases resulting from computer use, there has been a recent surge in interest in improving the working environment for prevention. Objects: This study aimed to examine the effects of posture correction feedback (PCF) on changes in neck posture and muscle activation during computer typing.
Methods: The participants performed a computer typing task in two sessions, each lasting 16 minutes. The participant’s dominant side was photographed and analyzed using ImageJ software to verify neck posture. Surface electromyography (EMG) was used to confirm the participant’s cervical erector spinae (CES) and upper trapezius muscle activities. The EMG signal was analyzed using the percentage of reference voluntary contraction and amplitude probability distribution function (APDF). In the second session, visual and auditory feedback for posture correction was provided if the neck was flexed by more than 15° in the initial position during computer typing. A 20-minute rest period was provided between the two sessions.
Results: The neck angle (p = 0.014), CES muscle activity (p = 0.008), and APDF (p = 0.015) showed significant differences depending on the presence of the PCF. Furthermore, significant differences were observed regarding the CES muscle activity (p = 0.001) and APDF (p = 0.002) over time.
Conclusion: Our study showed that the feedback system can correct poor posture and reduces unnecessary muscle activation during computer work. The improved neck posture and reduced CES muscle activity observed in this study suggest that neck pain can be prevented. Based on these results, we suggest that the PCF system can be used to prevent neck pain.
Keywords: Ergonomics, Muscle fatigue, Musculoskeletal diseases, Neck pain, Posture, Working conditions
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Original Article
Phys. Ther. Korea 2023; 30(3): 221-229
Published online August 20, 2023 https://doi.org/10.12674/ptk.2023.30.3.221
Copyright © Korean Research Society of Physical Therapy.
Effects of a Posture Correction Feedback System on Upper Body Posture, Muscle Activity, and Fatigue During Computer Typing
Subin Kim1 , PT, BPT, Chunghwi Yi2 , PT, PhD, Seohyun Kim1 , PT, BPT, Gyuhyun Han1 , PT, BPT, Onebin Lim3 , PT, PhD
1Department of Physical Therapy, The Graduate School, Yonsei University, 2Department of Physical Therapy, College of Software and Digital Healthcare Convergence, Yonsei University, Wonju, 3Department of Physical Therapy, Mokpo Science University, Mokpo, Korea
Correspondence to:Chunghwi Yi
E-mail: pteagle@yonsei.ac.kr
https://orcid.org/0000-0003-2554-8083
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Background: In modern society, the use of computers accounts for a large proportion of our daily lives. Although substantial research is being actively conducted on musculoskeletal diseases resulting from computer use, there has been a recent surge in interest in improving the working environment for prevention. Objects: This study aimed to examine the effects of posture correction feedback (PCF) on changes in neck posture and muscle activation during computer typing.
Methods: The participants performed a computer typing task in two sessions, each lasting 16 minutes. The participant’s dominant side was photographed and analyzed using ImageJ software to verify neck posture. Surface electromyography (EMG) was used to confirm the participant’s cervical erector spinae (CES) and upper trapezius muscle activities. The EMG signal was analyzed using the percentage of reference voluntary contraction and amplitude probability distribution function (APDF). In the second session, visual and auditory feedback for posture correction was provided if the neck was flexed by more than 15° in the initial position during computer typing. A 20-minute rest period was provided between the two sessions.
Results: The neck angle (p = 0.014), CES muscle activity (p = 0.008), and APDF (p = 0.015) showed significant differences depending on the presence of the PCF. Furthermore, significant differences were observed regarding the CES muscle activity (p = 0.001) and APDF (p = 0.002) over time.
Conclusion: Our study showed that the feedback system can correct poor posture and reduces unnecessary muscle activation during computer work. The improved neck posture and reduced CES muscle activity observed in this study suggest that neck pain can be prevented. Based on these results, we suggest that the PCF system can be used to prevent neck pain.
Keywords: Ergonomics, Muscle fatigue, Musculoskeletal diseases, Neck pain, Posture, Working conditions
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Table 1 . Participant demographics (N = 20).
Variable Value Age (y) 22.9 ± 3.5 Height (cm) 168.3 ± 7.8 Weight (kg) 64.7 ± 10.9 Neck disability index 2.1 ± 1.6 Values are presented as mean ± standard deviation..
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Table 2 . Mean ± standard deviation of the neck angle (°) (N = 20).
0 min 5 min 10 min 15 min Feedback p-value (F) Time p-value (F) Nonfeedback 34.72 ± 6.67 33.32 ± 6.84 33.79 ± 6.89 33.19 ± 7.88 0.014* (7.401) 0.512 (0.799) Feedback 36.86 ± 6.76 36.58 ± 7.08 37.00 ± 7.42 37.81 ± 7.84 Values are presented as mean ± standard deviation. *p < 0.05..
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Table 3 . Mean ± standard deviation of the neck and upper trunk muscle activity (%RVC) (N = 20).
0 min 5 min 10 min 15 min Feedback p-value (F) Time p-value (F) CES Nonfeedback 45.99 ± 25.01 51.12 ± 32.66 53.81 ± 36.67 52.87 ± 29.07 0.008** (5.535) 0.001** (14.39) Feedback 39.05 ± 20.20 41.96 ± 29.54 43.43 ± 29.16 43.33 ± 27.56 UT Nonfeedback 18.54 ± 18.47 25.10 ± 28.61 28.27 ± 33.08 26.26 ± 23.12 0.116 (2.72) 0.098 (2.46) Feedback 18.24 ± 20.41 19.76 ± 24.97 20.66 ± 23.16 19.93 ± 21.94 Values are presented as mean ± standard deviation. %RVC, percentage of reference voluntary contraction; CES, cervical erector spinae; UT, upper trapezius. **p < 0.01..