Common Tests Performed on Muscles Using SI-H Systems
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


See Selection