Elsevier

Journal of Hand Therapy

Volume 22, Issue 4, October–December 2009, Pages 320-327
Journal of Hand Therapy

Scientific/Clinical Article
The Concurrent Validity of a Hand-held versus a Stationary Dynamometer in Testing Isometric Shoulder Strength

https://doi.org/10.1016/j.jht.2009.04.008Get rights and content

Abstract

Study design

Clinical Measurement-Validity.

Introduction

Validity of the JTech PowerTrack II hand-held dynamometer (JTech; JTech Medical, Salt Lake City, UT) for measuring shoulder strength has yet to be established.

Purpose of the Study

To examine the concurrent validity of isometric strength scores obtained with the JTech PowerTrack II, and on a stationary dynamometer, the LIDO WorkSET (LIDO; LoredanBiomedical, West Sacramento, CA).

Methods

Thirty-eight subjects performed three maximal efforts of shoulder flexion, abduction, and external rotation on a single occasion on the two dynamometers. Two testers were randomly assigned to administer the tests.

Results

Pearson correlations between the scores on the two dynamometers (r.0.81) indicated a good concurrent validity. Correlations were similar when the results were subdivided by tester or gender.

Conclusions

This study suggests that either the JTech PowerTrack II or LIDOWorkSET provide comparable scores for shoulder strength. Although not interchangeable because of the differences in units of measurement, the relative conclusions about strength should be similar, regardless of which instrument is used.

Level of Evidence

Not applicable.

Section snippets

Subjects

Thirty-eight men (n = 21) and women (n = 17), recruited through convenience sampling, voluntarily participated in the study. Eleven subjects were needed to have more than 80% power to detect a Pearson product coefficient of 0.70. With 38 subjects, the power was 99%. Inclusion criteria were 1) age 18 years and above; and 2) no wrist pain or pathology. Wrist pathology was an exclusion criterion due to the need for the shoulder strength to be transmitted by gripping the shoulder test device on the

Results

All patients completed the test protocol without difficulty. The mean isometric maximal strength obtained with the LIDO and the JTech for men and women and for subjects with or without shoulder symptoms are shown in Table 1. In all three muscle groups tested (flexors, abductors, and external rotators), men were stronger than the women (p < 0.001) with each dynamometer.

Correlations between the two dynamometer were high in all three shoulder muscle groups with Pearson coefficients (r) ranging from

Discussion

This study demonstrated a high correlation between scores obtained for isometric shoulder strength in men or women, with no or mild shoulder symptoms, using the LIDO SD and the JTech hand-held dynamometer. This is in agreement with the correlation established between static strength scores obtained with the HHD and SD when measuring strength of the knee24 and elbow.25 Correlations between scores obtained on a HHD and the LIDO during isometric elbow flexion and extension ranged from 0.72 to

Conclusion

The JTech computerized hand-held dynamometer provided isometric shoulder strength scores that are closely related to those obtained on the LIDO when testing shoulder abductors, flexors, and external rotators in the scapular plane. Both instruments can provide valid measures of isometric shoulder strength. Although scores between the instruments cannot be interchanged because of differences in units of measurements, determination of impairment levels should be related regardless of which

Quiz: Article # 138

Record your answers on the Return Answer Form found on the tear-out coupon at the back of this issue. There is only one best answer for each question.

  • #1.

    The purpose of the study was to test the

    • a.

      reliability of the JTech Power Track II in measuring shoulder strength

    • b.

      validity of the JTech Power Track II in measuring isotonic shoulder strength

    • c.

      validity of a hand held dynamometer in measuring isometric shoulder strength

    • d.

      specificity of the JTech Power Track II in measuring shoulder external rotation

  • #2.

    The

References (25)

  • R.W. Bohannon

    Test-retest reliability of hand-held dynamometry during a single session of strength assessment

    Phys Ther

    (1986)
  • R.W. Bohannon

    Intertester reliability of hand-held dynamometry: a concise summary of published research

    Percept Mot Skills

    (1999)
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    Funded by a New Investigator Award, Canadian Institute of Health Research. Joy C. MacDermid was funded by a New Investigator Award.

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