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Isokinetics: which value is better to report?
  1. L D Mendonça,
  2. G M Amaral,
  3. H V R Marinho,
  4. A A Silva,
  5. S T Fonseca
  1. Laboratory of Prevention and Rehabilitation of Sports Injuries (LAPREV), Federal University of Minas Gerais, Belo Horizonte, Brazil

Abstract

Background Isokinetic tests are golden pattern for muscular performance evaluation. Nevertheless, there isn't any uniformity when reporting and analysing results, many authors have taken the peak torque value as major variable to be discussed.

Objective To verify correlations between values reported in ‘Comprehensive Evaluation’ generated by the Biodex System III pro and to determine the main values related to the total variance.

Design Data base analysis.

Setting Results from knee isokinetic evaluations in volleyball and football male players realised in LAPREV.

Participants 117 ‘Comprehensive Evaluation’, only the reports for dominant limb at 60°/s were used.

‘Comprehensive Evaluation’ reports generated 19 different values. Factorial analysis with Varimax Rotation (KMO=0.687; Bartlett's Test of Sphericity p=0.000) grouped all values in four main factors, named respectively:

  • Muscle Strengthening (eigenvalue=7391)

  • Performance Rise (eigenvalue=3073)

  • Muscle Length (eigenvalue=1858)

  • Performance Decay (eigenvalue=1223)

‘Total Work’ value showed bigger loading (0.949), this result represents its major contribution to total variance. This value represents the Muscle Strengthening Factor better than any other value. Furthermore, the ‘Peak Torque’ value was only the fourth value to contribute to this factor variance (0.889). The factor grouped 9 of 19 values, all of them related to work, torque and power. The Second Factor comprehended ‘Time to peak torque’ (0.904), ‘ROM’ (0.872) and ‘Acceleration time’ (0.576) values. The Muscle Length factor included ‘Peak Torque Angle’ (−0.912) and ‘Torque @25deg’ (0.798) values and the Fourth Factor comprised ‘Work Fatigue’ (0.838) and ‘Maximum work repetition#’ (−0.540) values.

Conclusion These preliminary results suggested that, during scientific investigation process, to report the appropriate variables is necessary to better define muscular performance. Peak torque should not be the better value to represent Muscle Strengthening and it's necessary to discuss which variable properly answers ours questions.

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