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Phys. Ther. Korea 2023; 30(3): 174-183

Published online August 20, 2023

https://doi.org/10.12674/ptk.2023.30.3.174

© Korean Research Society of Physical Therapy

Test–retest Reliability and Concurrent Validity of a Headphone and Necklace Posture Correction System Developed for Office Workers

Gyu-hyun Han1 , PT, BPT, Chung-hwi Yi2 , PT, PhD, Seo-hyun Kim1 , PT, BPT, Su-bin Kim1 , PT, BPT, One-bin 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: Chung-hwi Yi
E-mail: pteagle@yonsei.ac.kr
https://orcid.org/0000-0003-2554-8083

Received: May 25, 2023; Revised: July 25, 2023; Accepted: July 26, 2023

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: Office workers experience neck or back pain due to poor posture, such as flexed head and forward head posture, during long-term sedentary work. Posture correction is used to reduce pain caused by poor posture and ensures proper alignment of the body. Several assistive devices have been developed to assist in maintaining an ideal posture; however, there are limitations in practical use due to vast size, unproven long-term effects or inconsistency of maintaining posture alignment. We developed a headphone and necklace posture correction system (HANPCS) for posture correction using an inertial measurement unit (IMU) sensor that provides visual or auditory feedback. Objects: To demonstrate the test-retest reliability and concurrent validity of neck and upper trunk flexion measurements using a HANPCS, compared with a three-dimensional motion analysis system (3DMAS).
Methods: Twenty-nine participants were included in this study. The HANPCS was applied to each participant. The angle for each action was measured simultaneously using the HANPCS and 3DMAS. The data were analyzed using the intraclass correlation coefficient (ICC) = [3,3] with 95% confidence intervals (CIs).
Results: The angular measurements of the HANPCS for neck and upper trunk flexions showed high intra- (ICC = 0.954–0.971) and inter-day (ICC = 0.865–0.937) values, standard error of measurement (SEM) values (1.05°–2.04°), and minimal detectable change (MDC) values (2.92°–5.65°). Also, the angular measurements between the HANPCS and 3DMAS had excellent ICC values (> 0.90) for all sessions, which indicates high concurrent validity.
Conclusion: Our study demonstrates that the HANPCS is as accurate in measuring angle as the gold standard, 3DMAS. Therefore, the HANPCS is reliable and valid because of its angular measurement reliability and validity.

Keywords: Neck, Pain, Posture, Spine, Work

Article

Original Article

Phys. Ther. Korea 2023; 30(3): 174-183

Published online August 20, 2023 https://doi.org/10.12674/ptk.2023.30.3.174

Copyright © Korean Research Society of Physical Therapy.

Test–retest Reliability and Concurrent Validity of a Headphone and Necklace Posture Correction System Developed for Office Workers

Gyu-hyun Han1 , PT, BPT, Chung-hwi Yi2 , PT, PhD, Seo-hyun Kim1 , PT, BPT, Su-bin Kim1 , PT, BPT, One-bin 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:Chung-hwi Yi
E-mail: pteagle@yonsei.ac.kr
https://orcid.org/0000-0003-2554-8083

Received: May 25, 2023; Revised: July 25, 2023; Accepted: July 26, 2023

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: Office workers experience neck or back pain due to poor posture, such as flexed head and forward head posture, during long-term sedentary work. Posture correction is used to reduce pain caused by poor posture and ensures proper alignment of the body. Several assistive devices have been developed to assist in maintaining an ideal posture; however, there are limitations in practical use due to vast size, unproven long-term effects or inconsistency of maintaining posture alignment. We developed a headphone and necklace posture correction system (HANPCS) for posture correction using an inertial measurement unit (IMU) sensor that provides visual or auditory feedback. Objects: To demonstrate the test-retest reliability and concurrent validity of neck and upper trunk flexion measurements using a HANPCS, compared with a three-dimensional motion analysis system (3DMAS).
Methods: Twenty-nine participants were included in this study. The HANPCS was applied to each participant. The angle for each action was measured simultaneously using the HANPCS and 3DMAS. The data were analyzed using the intraclass correlation coefficient (ICC) = [3,3] with 95% confidence intervals (CIs).
Results: The angular measurements of the HANPCS for neck and upper trunk flexions showed high intra- (ICC = 0.954–0.971) and inter-day (ICC = 0.865–0.937) values, standard error of measurement (SEM) values (1.05°–2.04°), and minimal detectable change (MDC) values (2.92°–5.65°). Also, the angular measurements between the HANPCS and 3DMAS had excellent ICC values (> 0.90) for all sessions, which indicates high concurrent validity.
Conclusion: Our study demonstrates that the HANPCS is as accurate in measuring angle as the gold standard, 3DMAS. Therefore, the HANPCS is reliable and valid because of its angular measurement reliability and validity.

Keywords: Neck, Pain, Posture, Spine, Work

Fig 1.

Figure 1.Headphone and necklace posture correction system (HANPCS) software program. ‘Fixed Angle’ means the angle threshold value, and if the angle of the sensor exceeds this value, feedback can be given. If the time is set in the ‘Trigger Delay’, feedback can be given after the set time after the angle of sensor exceeds Fixed Angle. The duration of the auditory feedback from the headphones can be set in ‘Sound Times.’ The computer screen is shut down for the set time, if the time is set in ‘Block Screen.’
Physical Therapy Korea 2023; 30: 174-183https://doi.org/10.12674/ptk.2023.30.3.174

Fig 2.

Figure 2.Process of the movement. (A) Starting position, (B) neck flexion, (C) upper trunk flexion.
Physical Therapy Korea 2023; 30: 174-183https://doi.org/10.12674/ptk.2023.30.3.174

Fig 3.

Figure 3.Sensor and marker placement.
Physical Therapy Korea 2023; 30: 174-183https://doi.org/10.12674/ptk.2023.30.3.174

Fig 4.

Figure 4.Scatterplot using HANPCS and 3DMAS. (A) Neck flexion and (B) upper trunk flexion. HANPCS, headphone and necklace posture correction system; 3DMAS, three-dimensional motion analysis system.
Physical Therapy Korea 2023; 30: 174-183https://doi.org/10.12674/ptk.2023.30.3.174

Fig 5.

Figure 5.Bland–Altman plot using HANPCS and 3DMAS. (A) Neck flexion in session 1, (B) upper trunk flexion in session 1, (C) neck flexion in session 2, (D) upper trunk flexion in session 2, (E) neck flexion in session 3, and (F) upper trunk flexion in session 3. HANPCS, headphone and necklace posture correction system; 3DMAS, three-dimensional motion analysis system; SD, standard deviation.
Physical Therapy Korea 2023; 30: 174-183https://doi.org/10.12674/ptk.2023.30.3.174

Table 1 . Participant demographics (N = 29).

VariableMale (n = 18)Female (n = 11)
Age (y)23.1 ± 2.822.6 ± 3.0
Height (cm)174.4 ± 4.9160.5 ± 5.3
Weight (kg)75.6 ± 4.957.9 ± 10.5
Body mass index (kg/m2)24.9 ± 3.622.4 ± 3.5

Values are presented as mean ± standard deviation..


Table 2 . Neck flexion and upper trunk flexion for each session using HANPCS and 3DMAS.

VariableSession 1Session 2Session 3
HANPCS
Neck flexion (˚)52.6 ± 8.252.2 ± 8.052.2 ± 8.1
Upper trunk flexion (˚)30.4 ± 4.930.7 ± 4.929.7 ± 4.7
3DMAS
Neck flexion (˚)53.6 ± 8.553.6 ± 8.352.8 ± 7.9
Upper trunk flexion (˚)31.6 ± 4.932.3 ± 4.930.5 ± 5.1

Values are presented as mean ± standard deviation. HANPCS, headphone and necklace posture correction system; 3DMAS, three-dimensional motion analysis system..


Table 3 . Reliability of the flexion angle measurement.

VariableIntra-day reliabilityInter-day reliability


ICC (95% CI)SEMMDC (95% CI)ICC (95% CI)SEMMDC (95% CI)
HANPCS
Neck flexion (˚)0.971 (0.939–0.987)1.373.790.937 (0.865–0.970)2.045.65
Upper trunk flexion (˚)0.954 (0.902–0.978)1.052.920.865 (0.713–0.937)1.764.87
3DMAS
Neck flexion (˚)0.981 (0.960–0.991)1.153.180.946 (0.884–0.974)1.905.20
Upper trunk flexion (˚)0.970 (0.937–0.986)0.842.320.923 (0.835–0.964)1.383.82

HANPCS, headphone and necklace posture correction system; 3DMAS, three-dimensional motion analysis system; ICC, intraclass correlation coefficient; CI, confidence interval; SEM, standard error of measurement; MDC, minimal detectable change..


Table 4 . Validity of the flexion angle measurement.

VariableSession 1Session 2Session 3



ICC (95% CI)ICC (95% CI)ICC (95% CI)
Neck flexion (˚)0.993 (0.984–0.997)0.994 (0.987–0.997)0.990 (0.979–0.995)
Upper trunk flexion (˚)0.985 (0.967–0.993)0.954 (0.902–0.978)0.960 (0.915–0.981)

ICC, intraclass correlation coefficient; CI, confidence interval..