Common Tests Performed on Muscles Using SI-H Systems
Posted:
February 13, 2014

Length Change Tests (No Force Feedback Required) | ||||
Tests | Components | Test Description | Parameter Determined | Muscle Types |
Slack | SI-H Muscle Research System equipped with: Linear Motor and Motor Control Amplifier Position Commands from MDAC Software | Isometric Force Developed at Initial Length → Quick Release to New Length → Muscle Shortens with No Load →Force Increases as Muscle Slack Taken Up | Unloaded Shortening Velocity | Tetanized Skeletal Muscle Most Smooth Muscle All Skinned Muscles |
Constant Velocity Release | Isometric Force (Fo) Developed at Initial Length → Muscle Released at Constant Velocity → Constant Force (Fv) Eventually Reached | Force Characteristic of Release Velocity | ||
Stretch-Quick Release (QR) | Isometric Force Developed at Initial Length → Stretch → Quick Release of Muscle (1% to 10% Change in Muscle Length) → Change in Force | Rapid Crossbridge Attachment Rates | ||
Eccentric Contractions | Isometric Force Developed at Initial Length → Stretch Muscle → Release Muscle → Shortens to Same Length with Reduced Force | Effects of Excessive Sarcomere Strain | ||
Muscle Stiffness | Quick Stretch & Release (<1% Change in Muscle Length) → Increase in Length → Decrease in Force | Elasticity Constant | ||
Stretch/Release or Release/Stretch | Release or Stretch @ Various Times during either Contraction or Relaxation Phase of Single Twitch | Cardiac & Skeletal Twitch Muscles | ||
Vibration Protocols (No Force Feedback Required) | ||||
Tests | Components | Test Description | Parameter Determined | Muscle Types |
Vibration of Steadily Contracted Muscle | SI-H Muscle Research System equipped with: Linear Motor and Motor Control Amplifier Position Commands from MDAC Software | Isometric Force Developed at Initial Length → Vibrate (Release/Restretch Pulses) → Crossbridges Detach →Muscle Slack (No Force) → Stop Vibration → Return of Isometric Force | Crossbridge Detachment Rate | Tetanized Skeletal Muscle Most Smooth Muscle All Skinned Muscles |
Muscle Stiffness | Rapid Cyclic Length Changes →Decrease in Force → Unloaded Shortening of Muscle | Elasticity Constant | ||
Vibration of Twitch Muscles | Isometric Force during Twitch → Vibrate Muscle → Crossbridges Detach →Isometric Force Cancelled → Muscle Shortens | Unloaded Shortening Velocity | Cardiac & Skeletal Twitch Muscles | |
Constant Load Protocol (Force Feedback Required) | ||||
Tests | Components | Test Description | Parameter Determined | Muscle Types |
Isotonic Release | SI-H Muscle Research System equipped with: Linear Motor and Motor Control Amplifier Constant Load Module Commands from MDAC Software | Isometric Force (Fo) Developed at Initial Length → Isotonic Release to New Length & Force (Fv) → Shortening under Constant Load | Shortening Velocity Characteristic of Fv Force-Velocity Curves | Tetanized Skeletal Muscle Most Smooth Muscle All Skinned Muscles |
Afterload Protocols (Length Feedback Required) | ||||
Tests | Components | Test Description | Parameter Determined | Muscle Types |
Afterload Contractions | SI-H Muscle Research System equipped with: Linear Motor and Motor Control Amplifier Afterload Module Commands from MDAC Software | Isometric Force Developed at Initial Length → Motor Released → Muscle Shortens under Constant Load (isotonic contraction) → Maximum Muscle Activation Reached → Muscle Stretched to Original Length at a Constant Velocity. | Force Characteristic of Release Velocity Time to Reach Release Force after Muscle Deactivation | Cardiac & Skeletal Twitch Muscles |
Fixed-Length Protocols (No Force Feedback Required) | ||||
Tests | Components | Test Description | Parameter Determined | Muscle Types |
Isometric Twitch Analysis | SI-H Muscle Research System equipped with: Digital Micrometer (or Linear Motor and Motor Control Amplifier Position Commands from MDAC Software) | Muscle Held at Fixed Length →Stimulate → Record Muscle Twitch →Analyze Kinetics. | Contraction & Relaxation Velocities, Times, Forces | Cardiac & Skeletal Twitch Muscles |
Length-Tension Curves | Set Muscle Length (Above, Below, or Equal to Resting Length) → Stimulate →Record Twitch. | Passive & Active Tension as a Function of Muscle Length. | Cardiac & Skeletal Twitch Muscles | |
Tetanic Contraction Analysis | Muscle Held at Fixed Length →Stimulate at Different Frequencies →Record Muscle Response → Analyze Kinetics. | Contraction Velocities, Summation Frequencies, Fatigue Times, Forces | Tetanized Skeletal Muscles |