Date of Award

2004

Document Type

Scholarly Project

Degree Name

Master of Physical Therapy (MPT)

Department

Physical Therapy

First Advisor

Susan H.N. Jeno

Keywords

Muscles -- physiology; Torque

Abstract

Muscle testing using a stationary dynamometer has given therapists a more objective method of assessing a patient's strength. However, few studies have been performed as to the effects that dynamometer placement has on force production.

The purpose of this randomized, repeated measure study was to determine whether there was a significant difference in reliability between torque measurements with dynamometer placement at two well-defined points on the forearm. The differences in torque values from the two points of application (distal wrist crease and the midpoint of the forearm) were also compared to assess for differences between these values.

Thirty-two healthy subjects (23 female and 9 males) were tested in this study. For inclusion in this study, the subjects had to be between 18 and 30 years of age and must have had no prior history of wrist, elbow, or shoulder pathology.

The test protocol consisted of measuring and marking the patient's right forearm at both the distal wrist crease (DW) and the midpoint (MP) of the forearm. Following the measurement, the subject was placed in a rigid chair with the right arm placed into 90° of elbow flexion and 0° of shoulder abduction. Instructions were given once the patient was in this test position. The patient was asked to perform a maximal isometric contraction against the dynamometer for 5 seconds during each of the 6 trials. Three of these trials were performed at each test location (DW and MP) for a total of 6 trials. The subject received a 30 second rest between each trial.

The results of the study showed that both the DW and the MP of the forearm produced highly reliable results; r = .99 and r = .98, respectively. There was, however, a significant difference when the torque (ft-lbs) and the pounds of force were compared between the two application points. The mean torque value for the DW was 36.80 ± 17.09 ft-lbs, while the mean torque value for the midpoint was 22.94 ± 8.86 ft-lbs. The mean pounds of force production at the DW was 40.72 ± 17.16 pounds of force, while the mean pounds of force production at the MP was 51.07 ± 18.22 pounds of force.

When testing elbow flexor strength with a stationary dynamometer, reliable results can be expected as long as the dynamometer is placed at the same point on the limb for each trial. The significant difference noted between both the DW and the MP in terms of torque values and pounds of force production indicates that consistent dynamometer placement is essential for reliable results. If a subject is tested at different points of the forearm when assessing elbow flexor strength, reliable results may be compromised since different amounts of torque and pounds of force are produced at different points of the forearm. The dynamometer must be placed at the same point during each trial to ensure reliability.

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