Lesson: Muscle Spindles

Lesson: Muscle Spindles — Your Silent Partners (or Opponents) in Every Lock

What Are Muscle Spindles?

Muscle spindles are tiny sensory receptors located within skeletal muscles, specifically in the intrafusal muscle fibers.

Their job? To detect changes in muscle length & the rate of that change.

They’re part of the proprioceptive system, helping your body:

• Maintain posture

• Adjust movement in real time

• Protect muscles from overstretching

How Do They Work?

1. You stretch a muscle suddenly

2. Muscle spindles fire

3. A reflex loop through the spinal cord causes the same muscle to contract

4. This is known as the myotatic reflex (or stretch reflex)

Think of a knee-jerk reflex: the tap stretches the tendon, which stretches the quad → reflexively kicks.

Martial Arts Application

When you apply a lock (like an armbar or S-lock), you often:

• Stretch a muscle rapidly (e.g., the biceps or wrist extensors)

• If done poorly or too quickly, this can cause reflexive resistance — the muscle tightens to fight the stretch

But here’s the key:

If you slow the stretch slightly or distract with a skin twist or cutaneous input, you can bypass the spindle’s activation.

That means less resistance, smoother lock, & more control.

Bonus: Why Combining with Cutaneous Nerve Stimulation Works

When you stimulate skin receptors at the same time:

• You create competing sensory input

• The brain has to prioritize signals

• Muscle spindles may be ignored or delayed → you get your technique in before reflex resistance kicks in

In Tuite Strategy:

• Avoid sudden yanks — instead, use controlled, progressive tension

• Combine skin twist + joint angle + stretch

• Target muscle-tendon junctions, where spindles are densest

By taking advantage of scientific principles and anatomy, we can make our technique better!

Understand the Science. Master the Art! 🐼