Education · Upper legs

Knee flexion

Target Hamstrings  ·  Equipment Body weight  ·  Level Beginner  ·  Reps 4

Knee flexion is a beginner-level education movement targeting the hamstrings, written in Posecode, a small open-source language that LLMs like ChatGPT, Claude, and Gemini can write to describe human movement as text. Every joint angle below is hard-clamped to a safe range of motion.

How to do it

1. Flex2.5s · ease-in-out Bend the right knee, heel toward the glutes: the knee's single plane
2. Extend2.5s · ease-in-out Lower the shin back to standing

The .posecode source

This is the exact text an LLM writes to produce the animation above: phases and joint angles, not 3D transforms.

posecode stretch "Knee flexion (ROM demo)"
  rig humanoid
  pose start = standing

  step "Flex" 2.5s ease-in-out:
    knee_right: flex 130
    cue "Bend the right knee, heel toward the glutes: the knee's single plane"

  step "Extend" 2.5s ease-in-out:
    knee_right: flex 0
    cue "Lower the shin back to standing"

  repeat 4

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