Reliability of clinical pressure-pain algometric measurements obtained on consecutive days.

BACKGROUND AND PURPOSE

Algometers have been used to measure muscle and other soft tissue tenderness. The purpose of this study was to investigate (1) "normal" pressure-pain threshold (PPT) in the biceps brachii muscle, (2) the reliability of repeated measurements of PPT in subjects without pain over 3 consecutive days, (3) the reliability of measurements of PPT between examiners, and (4) the number of measurements required to obtain a best estimate of PPT.

SUBJECTS

Thirty-five subjects participated in the study.

METHODS

Pain-pressure threshold of the biceps brachii muscle was measured using a Fischer algometer. Three test trials were done on each subject on each of 3 days by each of two examiners. Intraclass correlation coefficients (ICCs) and graphical methods were used to analyze the results.

RESULTS

The ICCs revealed almost perfect reliability for measurements of PPT within and across 3 days and substantial reliability between examiners. The best estimate of PPT was obtained using the mean of the second and third trials each day. Graphical methods demonstrated that agreement between examiners was greatest at low mean pain thresholds. There was no effect for order of examiner.

CONCLUSION AND DISCUSSION

The PPT is a reliable measure, and repeated algometry does not change pain threshold in healthy muscle over 3 consecutive days. The PPT can be used to evaluate the development and decline of experimentally induced muscle tenderness. Reliability is enhanced when all measurements are taken by one examiner.