Original article
Test-Retest Reliability of Isokinetic Knee Extension and Flexion

https://doi.org/10.1016/j.apmr.2007.02.006Get rights and content

Abstract

Sole G, Hamrén J, Milosavljevic S, Nicholson H, Sullivan SJ. Test-retest reliability of isokinetic knee extension and flexion.

Objective

To assess reliability of isokinetic peak torque and work for knee flexion and extension.

Design

Single-group test-retest.

Setting

University laboratory.

Participants

Eleven men and 7 women (mean age, 21y).

Interventions

Not applicable.

Main Outcome Measure

Peak torque and work for concentric and eccentric knee extension and flexion were recorded at 60°/s for 3 trials on 2 occasions. Intraclass correlation coefficient model 3,1 (ICC3,1), standard error (SE) of measurements, and smallest real differences were calculated for the maximum and for the mean peak torque and work of the 3 repetitions.

Results

Relative reliability was “very high” for peak torque and work (ICC range, >.90). The SE measurements ranged between 5% and 10% of the initial values for both peak torque and work. The smallest change that indicates a real improvement for a single subject (smallest real differences) ranged from 12% to 25% for peak torque and work variables and from 25% to 30% for the peak torque ratios.

Conclusions

Isokinetic concentric and eccentric knee extensor and flexor strength variables are reliable when measured by the same examiner in asymptomatic subjects.

Section snippets

Methods

Subjects were included in the study if they participated in elite, subelite, or recreational running-related sports at least twice weekly and, at the time of testing, were participating fully in their planned sports training and/or competition. Exclusion criteria included having sustained a lower limb, pelvic, or back injury in the past 6 months that prevented them from participating in their training for more than 1 week, or if they had any neurologic or systemic disease affecting a lower

Results

Twenty healthy subjects (13 men, 7 women) volunteered for this study. Two men (aged 22y and 35y) did not attend the second session because of a soccer-related injury and a work commitment, respectively, and were excluded from the study. The mean age ± SD for the 11 men was 20±1 years and for the women it was 22±3 years. The mean body mass index ± SD for the men was 23.0±2.5kg/m2 and for the women was 22.3±2.6kg/m2. Two of the men were experienced in resistance training but none of the subjects

Discussion

Our subjects formed a heterogeneous group with regard to sex, experience with strength testing and training, and sports backgrounds and were a reflection of patients most commonly seen by clinicians at the community level. The men were generally stronger than the women, as is apparent from the Bland-Altman plots (see fig 1). No other systematic differences existed between the sexes, however, thus we pooled the reliability statistics for the men and the women.

Correlations from .50 to .69 have

Conclusions

With the Kin-Com 500H isokinetic dynamometer, the relative reliability for all knee flexion and extension variables at a velocity of 60°/s was very high and was high for the He:Qc, but low for the Hc:Qc. In uninjured subjects, the smallest change that can indicate a real improvement (smallest real difference) ranges from 13 to 34Nm (15%−23%) for peak torque and from 14 to 23J (12%−25%) for work variables. The peak torque ratios are less sensitive in detecting a real change, with the smallest

References (33)

  • E. Domholdt

    Rehabilitation research: principles and applications

    (2005)
  • U.B. Flansbjer et al.

    What change in isokinetic knee muscle strength can be detected in men and women with hemiparesis after stroke?

    Clin Rehabil

    (2005)
  • J.M. Bland et al.

    Measurement error and correlation coefficients

    BMJ

    (1996)
  • L.G. Portney et al.

    Foundations of clinical research: applications to practice

    (2000)
  • H. Beckerman et al.

    Smallest real difference, a link between reproducibility and responsiveness

    Qual Life Res

    (2001)
  • J.L. Keating et al.

    Unpredictable error in dynamometry measurements: a quantitative analysis of the literature

    Isokinet Exerc Sci

    (1998)
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    Supported by the Physiotherapy Research Trust, School of Physiotherapy, University of Otago (research grant-in-aid).

    No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated.

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