Same-session and between-day intra-rater reliability of hand-held dynamometer measurements of isometric shoulder extensor strength

Abstract

[Purpose] The purpose of present study was to establish the same-session and between-day intra-rater reliability of measurements of extensor strength in the maximum abducted position (MABP) using hand-held dynamometer (HHD). [Subjects] Thirteen healthy volunteers (10 male, 3 female; mean ± SD: age 19.8 ± 0.8 y) participated in the study. [Methods] Participants in the prone position with maximum abduction of shoulder were instructed to hold the contraction against the ground reaction force, and peak isometric force was recorded using the HHD on the floor. Participants performed maximum isometric contractions lasting 3 s, with 3 trials in one session. Between-day measurements were performed in 2 sessions separated by a 1-week interval. Intra-rater reliability was determined using intraclass correlation coefficients (ICC). Systematic errors were assessed using Bland-Altman analysis for between-day data. [Results] ICC values for same-session data and between-day data were found to be “almost perfect”. Systematic errors not existed and only random error existed. [Conclusion] The measurement method used in this study can easily control for experimental conditions and allow precise measurement because the lack of stabilization and the impact of tester strength are removed. Thus, extensor strength in MABP measurement is beneficial for muscle strength assessment.

Intra- and inter-rater reliability of isometric shoulder extensor and internal rotator strength measurements performed using a hand-held dynamometer

“…The results of the present study also showed high intra-rater reliability that was considered ‘almost perfect’. Therefore, consistent with previous studies3 ) , use of the mean of 3 trials is recommended for this measurement method. Regarding the intra-rater measurement error for for extensor strength, Awatani et al3 ) reported that the ICC 1, 2 for between-day data was ≤6.2 N, and using data from the same study, the SEM% was calculated to be 6.7%.…”

“…Therefore, consistent with previous studies3 ) , use of the mean of 3 trials is recommended for this measurement method. Regarding the intra-rater measurement error for for extensor strength, Awatani et al3 ) reported that the ICC 1, 2 for between-day data was ≤6.2 N, and using data from the same study, the SEM% was calculated to be 6.7%. The coefficients of variation (CVs) of the SEM and SEM% were the same8 ) , and the common analytical goal for the CV is ≤10%9 ) .…”

“…In the case of both measurements, the participants lay in the prone position with their toes, abdomen, chest, and mentum touching the ground. The shoulder in which extensor strength was to be measured in the MABP was positioned with maximum shoulder abduction, with the elbow extended and the forearm in a neutral position3 ) . The shoulder to be measured in internal rotator strength in ABERP was positioned with 90° shoulder abduction and 90° external rotation, with the elbow 90° flexion and the forearm in a neutral position.…”

“…The opposite shoulder in the case of both measurements was positioned in contact with the side of the body. For both measurements, the HHD was placed on a firm carpet and against the heads of the metacarpal bones on the palm side, and it was held in place with a hand to prevent any improper movement during measurement3 ) . Participants were instructed to hold the contraction against the ground reaction force, and the peak isometric force was recorded using the HHD on the floor.…”

“…Awatani et al3 ) reported high intra-rater reliability in the measurement of extensor strength in the MABP. However, thier study did not investigate inter-rater reliability in the measurement of extensor strength in the MABP.…”