Reliability of a Test for Assessment of Isometric Trunk Muscle Strength in Elderly Women

Abstract

Objective. The aim of this study was to analyze the reproducibility of a protocol using the maximal isometric strength test of the trunk in elderly women aged above 60 years, without low back pain. Methods. Twenty-one physically inactive elderly women, who had not engaged in any activity or exercise program in the past three months, participated in the cross-sectional study that consisted of two days of evaluations for the maximal isometric strength of the extensor and flexor muscles of the trunk, with a 48 h interval between the sessions. A platform with fixed seating was used, which allowed the fixation of the hip and lower limbs, with a load cell connected to a linear encoder. To verify the reliability of the test, the interclass correlation coefficient, variation coefficient, minimum detectable difference (MDD), standard error of measurement, and Bland–Altman graphs were calculated. Results. No statistical difference was observed between the first and second evaluation, which indicates that there was no learning effect. Interclass correlation coefficient values were classified as very high and high for extensor (0.98) and flexor (0.86) muscles, respectively, besides low variation (9% for both muscle groups) and acceptable values for minimum detectable difference (extensors = 51.1 N, flexors = 48.9 N). In addition, the Bland–Altman analysis revealed low bias and values within the limits of agreement. Conclusion. It is concluded that the test of maximum isometric strength of the trunk in healthy and trained elderly people presents high reliability. These values proved to be reliable if performed in at least two evaluation sessions, which confirms the hypothesis of the authors by the consistency of the measurement test.

Força do tronco de acordo com a idade e o nível de atividade física: as mulheres ativas mais velhas são tão fortes quanto as jovens inativas?

“…The maximum trunk strength test used to evaluate the sample has good reliability. This test's reproducibility was analyzed in previous research [19], and high and very high intraclass correlation coefficient and variation coefficient values were found for the trunk extensor and flexor muscles, respectively.…”

“…Then, a maximum isometric contraction in trunk flexion was performed. It is worth mentioning that the wooden seat used in the test was adjusted to the level of hips and lower limbs according to the individual's height, causing only the trunk muscles to be activated during the test protocol [18,19].…”

Practicable performance-based outcome measures of trunk muscle strength and their measurement properties: A systematic review and narrative synthesis

“…Eight studies assessed the intra-rater reliability of digital loading cells [36,40,41,48,49,51,54,62]. All reported sufficient intra-rater reliability for flexion, extension, and rotation against the COSMIN for good measurement properties where ICCs across all studies ranged from 0.75-1.00.…”

“…Sufficient inter-rater reliability of the strain gauge dynamometer (ICC > 0.80) was reported in one study, with overall, very low quality evidence (extremely serious ROB and small sample size (n = <50) [51]. Three studies evaluated the measurement error using the LOA and SEM, two with inadequate ROB [49,51] and one rated as adequate ROB [40]. As recommended by COSMIN, no overall grading was given due to lack of information regarding the MIC.…”

Validity and Reliability of Isometric-Bench for Knee Isometric Assessment

“…Muscle strength assessment is therefore a crucial point in both clinical and research settings, allowing the tracking of rehabilitation progress and exercise interventions to be designed accordingly. Assessing isometric muscle strength with custom-built load cells has been reported in the literature [13][14][15][16]. There are several off-the-shelf devices which assess muscle strength in both upper and lower limbs [17].…”