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. 2023 Jan 16:11:e14672.
doi: 10.7717/peerj.14672. eCollection 2023.

Inter-rater and intra-rater reliability of isotonic exercise monitoring device for measuring active knee extension

Chonnanid Limsakul  1 , Kiattisak Sengchuai  2 , Rakkrit Duangsoithong  2 , Nattha Jindapetch  2 , Jermphiphut Jaruenpunyasak  3
Affiliations

Inter-rater and intra-rater reliability of isotonic exercise monitoring device for measuring active knee extension

Chonnanid Limsakul et al. PeerJ. .

Abstract

Background: The goal of this study was to assess the reliability of electromyography and range of motion measurements obtained using a knee exercise monitoring system. This device was developed to collect data on knee exercise activities.

Methods: Twenty healthy individuals performed isotonic quadriceps exercises in this study. The vastus medialis surface electromyography (sEMG) and range of motion (ROM) of the knee were recorded during the exercise using the isotonic knee exercise monitoring device, the Mobi6-6b, and a video camera system. Each subject underwent a second measuring session at least 24 h after the first session. To determine reliability, the intraclass correlation coefficients (ICCs) and standard error of measurement (SEM) at the 95% confidence interval were calculated, and a Bland-Altman analysis was performed.

Results: For inter-rater reliability, the ICCs of the mean absolute value (MAV) and root mean square (RMS) of sEMG were 0.73 (0.49, 0.86) and 0.79 (0.61, 0.89), respectively. ROM had an ICC of 0.93 (0.02, 0.98). The intra-rater reliability of the MAV of the sEMG was 0.89 (0.71, 0.96) and the intra-rater reliability of RMS of the sEMG was 0.88 (0.70, 0.95). The ROM between days had an intra-rater reliability of 0.82 (0.54, 0.93). The Bland-Altman analysis demonstrated no systematic bias in the MAV and RMS of sEMG, but revealed a small, systematic bias in ROM (-0.8311 degrees).

Conclusion: For sEMG and range of motion measures, the isotonic knee exercise monitoring equipment revealed moderate to excellent inter- and intra-rater agreement. However, the confidence interval of ROM inter-rater reliability was quite large, indicating a small agreement bias; hence, the isotonic knee exercise monitor may not be suitable for measuring ROM. This isotonic knee exercise monitor could detect and collect information on a patient's exercise activity for the benefit of healthcare providers.

Keywords: Inter-rater reliability; Intra-rater reliability; Isotonic exercise device; Knee extension; Knee rehabilitation; Range of motion; Surface electromyography.

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Conflict of interest statement

The authors have no conflicts of interest to declare.

Figures

Figure 1
Figure 1. Isotonic exercise monitoring device and its peripheral equipment: (A) sandbag, (B) isotonic exercise monitoring device, (C) triaxial accelerometer channel for knee angle measurement, (D) sEMG channel, (E) graphic user interface (GUI).
Figure 2
Figure 2. Experimental settings of the: (A) Con-Trex’s lever arm, (B) isotonic exercise monitoring device, (C) Con-Trex device, (D) anterior superior iliac spines, (E1 and E2) electrode placement (E1: 80% of the distance between (D) and (F), E2: 20 mm next to E1).
Figure 3
Figure 3. Feature extraction process of sEMG in: (A) the isotonic exercise monitoring device and (B) the Mobi6-6b device.
Figure 4
Figure 4. ROM calculation process in: (A) the isotonic exercise monitoring device and (B) the computer vision method.
Figure 5
Figure 5. Example of knee joint angle calculation using the trigonometry rules in Eq. (5) where θ is the angle of the knee joint.
Figure 6
Figure 6. The Bland–Altman plot of the inter-rater agreement of MAV between the isotonic exercise monitoring device and the Mobi6-6b (n = 40).
Figure 7
Figure 7. The Bland–Altman plot of inter-rater agreement of RMS values between the isotonic exercise monitoring device and the Mobi6-6b (n = 40).
Figure 8
Figure 8. The Bland–Altman plot of inter-rater agreement of ROM values between the isotonic exercise monitoring device and the computer vision method (n = 40).
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