The Traffic Light System: How to Decide What’s Safe to Train

Written By Kevin Do

One of the biggest mistakes people make during rehab or training is guessing how hard to push or avoiding movement altogether out of fear.

At FLŌ Physical Therapy & Performance, we use simple, repeatable frameworks to help you train with confidence, build capacity, and avoid setbacks.

Below are the three tools we use with every client.

Pain doesn’t automatically mean damage.
But not all pain should be ignored either.

The Traffic Light System helps you make smart decisions during exercise—without overthinking every rep.

🟢 Green Light — Safe to Move

  • Little to no pain during the movement

  • No pain within the range you’re using

  • You feel muscle fatigue or a “burn,” not joint pain

  • Movement feels productive and controlled

  • Any soreness returns to baseline within 24–48 hours

What this means:
✅ Keep training. This is where most progress happens.

🟡 Yellow Light — Proceed with Caution

  • Mild discomfort (generally <3/10)

  • Symptoms are present but do not worsen during the exercise

  • Discomfort stays consistent across reps

  • Soreness resolves within 24–48 hours

What this means:
⚠️ You can continue, but consider reducing range, load, or volume.
When in doubt, default back to Green Light movements.

🔴 Red Light — Stop or Modify for Now

  • Sharp, catching, or intense pain

  • Pain increases as you continue moving

  • You feel protective, hesitant, or guarded

  • Symptoms linger or worsen beyond 48 hours

What this means:
🛑 Stop that specific movement. Modify or remove it temporarily—not forever.

Red light doesn’t mean you’re broken.
It means we need a different entry point.

Kevin Do
Next

RPE: How Hard Should Exercise Feel?