Muscle Load Simulation (Kymograph App)

An interactive kymograph simulator that demonstrates the physiological effects of Preload and Afterload on skeletal muscle contraction.

This tool is designed to mimic a traditional physiology lab experiment, drawing muscle contraction curves (twitches) on a rotating digital drum, while allowing for easy visual comparison of different weight loads.

🎮 How to Use

The application is split into two main tabs to isolate the variables being tested.

1. Effect of Preload (Length-Tension Relationship)

Preload stretches the muscle before it contracts. This simulates hanging a weight on the muscle while it is relaxed, altering the initial overlap of actin and myosin filaments.

• Set the Load: Use the slider to select a weight from 0g to 80g.
• Trigger Stimulus: Click to fire the electrical stimulus and record the contraction.
• Observe: * At 0g, you see the baseline contraction.
  • As you increase the weight to 20g and 30g, the amplitude increases. This represents the muscle reaching its optimal length (optimal actin-myosin overlap).
  • As you increase the weight beyond 30g (e.g., 60g, 80g), the amplitude decreases rapidly because the muscle is overstretched, preventing cross-bridge formation.

2. Effect of Afterload (Force-Velocity / Isotonic Contraction)

Afterload is the load the muscle must lift during contraction. The muscle does not stretch before contracting; it simply tries to lift a weight resting on a platform.

• Set the Load: Use the slider to select a weight from 0g to 80g.
• Trigger Stimulus: Click to fire the stimulus.
• Observe:
  • At 0g, you see the identical baseline contraction.
  • As you increase the weight, the Latent Period increases. This happens because the muscle must spend more time in the isometric phase, building up enough internal tension to overcome the weight before it can actually begin to shorten.
  • The Amplitude decreases steadily as the weight gets heavier, representing the decreased ability of the muscle to lift heavier loads.

🧹 Clearing the Drum

Use the Clear Drum button on either tab to wipe the history and start fresh. Older traces are purposefully "dulled" in opacity to allow the newest, brightest trace to stand out.