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Isokinetic hamstring/quadriceps strength ratio: influence from joint angular velocity, gravity correction and

P Aagaard1, E B Simonsen, M Trolle

  • 1Team Danmark Testcenter, Department of Exercise Physiology TTA-2001, Rigshospitalet, University Hospital Copenhagen, Denmark.

Acta Physiologica Scandinavica
|August 1, 1995
PubMed
Summary

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Gravity correction is crucial for accurately measuring hamstring/quadriceps strength ratios (H/Q ratio) across different speeds. Fast knee extension shows a balanced strength relationship, highlighting hamstring functional capacity for knee stability.

Area of Science:

  • Biomechanics
  • Human Movement Science
  • Sports Medicine

Background:

  • The hamstring/quadriceps strength ratio (H/Q ratio) is a key indicator of muscle balance around the knee.
  • Understanding how joint angular velocity and gravity affect H/Q ratios is essential for accurate assessment.
  • Previous research has not fully elucidated the impact of these factors on both conventional and functional H/Q ratios.

Purpose of the Study:

  • To investigate isokinetic peak- and angle-specific hamstring/quadriceps strength ratios (H/Q ratio) during concentric and eccentric contractions.
  • To examine the influence of joint angular velocity and gravity correction on these ratios.
  • To define and analyze 'functional' H/Q ratios representing knee extension and flexion.

Main Methods:

  • Isokinetic peak and 50-degree moments were measured at 30, 120, and 240 degrees/second.

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  • Conventional H/Q ratios were calculated for concentric and eccentric contractions.
  • Functional H/Q ratios (Hecc/Qcon for extension, Hcon/Qecc for flexion) were computed, with and without gravity correction.

    • Main Results:

    • Gravity-corrected conventional H/Q ratios remained consistent across speeds and contraction modes (0.47-0.56).
    • Non-corrected H/Q ratios increased with concentric contraction velocity (0.58 to 0.74 at 240 degrees/second).
    • At 240 degrees/second, functional ratios showed Hecc/Qcon of 1.05 (peak) and 0.89 (50 degrees), and Hcon/Qecc of 0.27 (peak) and 0.28 (50 degrees).

    Conclusions:

    • Gravity correction significantly influences the observed H/Q ratio changes with varying extension velocities.
    • A near 1:1 hamstring/quadriceps strength ratio for fast knee extension suggests substantial hamstring contribution to knee stability.
    • These findings emphasize the importance of considering gravity correction and angular velocity in H/Q ratio assessments for functional insights.