Reliability of the Passive Properties of the Calf Muscles in Healthy Subjects Assessed Using Isokinetic Device
Condition: Tendon Injuries; Muscle Tightness
MeSH terms: Tendon Injuries
Study type: Interventional

Summary: 
      The investigators designed this study to determine the test-retest reliability of the
      viscoelastic passive properties of the calf muscles assessed using isokinetic device in
      flexed and extended knee position. The second objective is to determine the clinical
      viability of the parameters using the coefficient of repeatability and to investigate the
      individual characteristics associated with increased calf stiffness or altered
      viscoelasticity
    

Detailed description: 
      Recordings using an isokinetic dynamometer make it possible to quantify the resisting force
      during passive muscle stretch for a constant speed movement in dorsal flexion (flexion) and
      its release in plantar flexion (extension). The surface electromyography (EMG) makes it
      possible to measure voluntary contraction and the movement is considered passive if the
      corrected and normalized EMG signal, using root-mean-square (RMS), is less than 10% RMS
      during the Maximal Voluntary Muscle Contraction (MVMC).

      Stiffness is calculated from the slope of the rise of the curve during the passive
      dorsiflexion phase of the joint. The elastic potential energy can be measured and corresponds
      to the area under the curve during elongation.

      During the plantar flexion return phase, there is a hysteresis phenomenon resulting in
      behavior that differs from the curve. This difference between the two curves corresponds to
      the behavior related to viscoelastic relaxation. Viscoelasticity has a thixotropic behavior,
      i.e. it varies over time, for example, with heating. These parameters have been studied
      together or separately to evaluate the effect of age or stretching on the passive mechanical
      properties of the calf.

      However, the test-retest reliability of the viscoelastic passive properties of the calf
      muscles assessed using isokinetic device has not been demonstrated.

      The investigators designed this study to determine the test-retest reliability of the
      viscoelastic passive properties of the calf muscles assessed using isokinetic device in
      flexed and extended knee position. The second objective is to determine the clinical
      viability of the parameters using the coefficient of repeatability and to investigate the
      individual characteristics associated with increased calf stiffness or altered
      viscoelasticity

      Muscle tension is expressed by the peak torque (Nm), recorded at neutral position (PT0°) and
      10° flexion (PT10°). Plantarflexor stiffness is determined as the slope of the torque-angle
      curve expressed as Nm·degree-1 during the linear region form 0-10° flexion (Slope0-10). A
      measure of elastic energy storage is calculated through the AUC of the torque-angle curve
      across the all range of motion. Hystérésis over time due to viscoelastic stress relaxation is
      calculated as the percent reduction in work absorption between the muscle stretching and
      releasing phases . The flexed-to-extended ratio is calculated as the ratio of flexed knee to
      extended knee and evaluated for PT0°, PT10° and Slope0-10 values , at 5 and 90°/sec
    

Intervention name(s): Test-Retest reproducibility
Intervention type(s): Diagnostic Test
Intervention description(s): Protocol is the same for extended or flexed knee. The testing apparatus was set up as described in the constructor owner's manual and subjects were positioned in the supine lying position. The After a 5 min rest period, the participant's ankle is passively stretched through slow loading cycles from 15° of ankle flexion to 35° of ankle extension. Oral instruction is given to the participants to stay relaxed and avoid any muscle contraction and movement of the leg throughout the passive stretching. To familiarize, participant have 3 repetitions of passive ankle flexion-extension at 5°.s-1, and after 2min rest, data are collected from one repetitions at 5°.s-1 in passive mode. The measurements are also performed at an angular rate of 90°.s-1, according to the same protocol. Data for maximal voluntary isokinetic contraction are collected from 3 maximal repetitions at 60°.s-1 in concentric mode and participant are encouraged by constant verbal stimulation.
Intervention model: Single Group Assignment
Intervention model description: One single group of 16 healthy volunteers
Masking: None (Open Label)
Primary purpose: Diagnostic