Intra-Rater Reliability of Trunk Muscle Strength Measurement in the Lying Position by a Hand-Held Dynamometer

Introduction: The purpose of this study was to validate the within-day and between-day intra-rater reliability measurements of belt-fixed trunk muscle strength measurements using a hand-held dynamometer (HHD) using intra-class correlation coefficients.

Materials and Methods: Forty healthy adult males without chronic low back pain were selected. Trunk muscle strength was measured using belt-fixed HHD in supine and prone positions on the bed. The average value and the relative trunk muscle strength were measured and verified for the within-day and between-day intra-rater reliability measurements.

Results: The ICCs of the absolute strength value were 0.87-0.97. The ICCs of the relative strength value in the between-day intra-rater reliability measurements ranged from 0.68 to 0.74. The high reliability of trunk muscle strength measurement with HHD using belt fixation in the lying position was obtained.

Conclusions: It was believed that HHD could be used as a low-cost and portable method for measuring trunk muscle strength in the clinical and research settings. However, the relative muscle strength measurement considering the effect of weight was slightly less reliable.

Key words: Reproducibility of Results; Abdominal muscles; Back muscles.