Most people are unsure what to do when an exercise hurts. Stop? Push through? Call the clinic? This guide is the same one we hand to patients at Forza Physiotherapy, written by our team with help from our physiotherapy intern. It explains what pain during rehab usually means, gives you a simple traffic light system for deciding what to do next, and shows you how to handle a flare-up without losing the progress you have made. The printable handout is at the end.

Pain is a signal, not necessarily damage

It is natural to be apprehensive when something hurts. Here is the good news: pain is a signal, and it is not always a sign that tissue is being damaged. Healing tissue is sensitive. A sore knee six weeks after surgery or a shoulder that complains during a stretch is often reporting on load, not on harm.

How you interpret that signal matters. Thoughts like "I'll never get better", "pain must mean I'm causing tissue damage" or "I shouldn't move because I'm hurt" are common, and they are counterproductive. Research shows those thoughts do not only affect mood. They can increase pain receptor sensitivity and make the brain's pain alarm system more vigilant, so the same movement feels worse. Catastrophizing is a real obstacle to musculoskeletal rehab, and one you can work on.

Movement is medicine

Rehab is not just what happens in the clinic. Your sessions with us are the blueprint: we assess, treat, and set the plan. The prescribed exercises you do at home are the building blocks. Understanding your pain, rebuilding trust in your body, and practising the right movements at the right time is what gets you back to the things you want to do.

The traffic light system

The traffic light system is a way to read your body's response to an activity and decide what to do next. Five steps:

1. Rate your baseline pain out of 10, before you start.

2. Pick one to three activities you want to do more of. Daily tasks, the gym, a sport.

3. Create a harm check (explained below).

4. Do the activity.

5. Reassess, then follow the protocol for the colour you land on.

Green light: the load is being tolerated

• No change in your range of motion, strength or function.

• Pain stays in the 4 to 7 out of 10 range during the activity and settles afterwards; it does not get worse once you stop.

• Pain returns to your baseline within 30 minutes if you are 4 to 8 weeks from onset, within 2 hours at 8 to 16 weeks, and within 24 hours beyond 16 weeks.

What to do: keep going and gradually rebuild. Add about 1 to 5 percent more activity each session.

Yellow light: too much, too fast

• No change in range, strength or function.

• Pain climbs 3 or more points above your baseline and stays there for 2 hours (4 to 8 weeks from onset), 24 hours (8 to 16 weeks) or 48 hours (16 weeks and beyond).

What to do: continue the activity, but use the flare-up toolbox. Short-term relief: ice for 30 minutes, three to four times a day, and pain medication as needed. Bigger-picture fixes: modify the activity, rest a little more or shorten the session, avoid adding anything new, spread your activity across the week rather than stacking it, and keep your thinking positive.

Red light: stop and get reassessed

• A major loss of range, strength or function.

• Severe pain, 7 out of 10 or more, that stops you continuing.

• Pain that lasts for days or weeks.

What to do: stop the activity and contact us so we can reassess and adjust your plan.

The harm check

Pain is easy to misread, and it has many possible triggers. A harm check gives you your bearings. It is a movement, or a short sequence of movements, that you can perform confidently from the start of your rehab, chosen with your physiotherapist to match the area you are working on. When you suspect you have done too much, run your harm check. If your movement, strength and function are still there, you have a clearer picture of what is actually going on, and you can move forward with confidence rather than fear.

Handling flare-ups

A yellow light does not mean stop. It means hold steady: keep doing your current activities, but do not introduce new ones or progress the intensity or duration until things settle. Distributing activity across the week is the single most useful habit for keeping flare-ups from building.

Sudden spikes in load are the common cause. Large single-session jumps relative to what your body is used to have been linked with higher injury rates across many sports. One study followed 5,205 runners over 18 months and more than 588,000 individual runs. A single run more than 10 percent longer than the longest run of the previous month raised injury risk noticeably: smaller spikes raised it by about 64 percent, and major spikes, more than double the longest recent run, by about 128 percent (Frandsen and colleagues, 2025). The lesson for rehab is the same. Build up gradually.

Other things that help during a flare-up: pain medication where appropriate, compression and icing for inflammation, and relaxation strategies such as calming music, mindful breathing or imagining a pleasant place, which can take the edge off the dwelling on pain. And, as above, keep your thoughts and language positive. Negative thinking only amplifies sensitivity.

Download the handout

The printable version of this guide, Move with Confidence: Pain, Healing and Your Home Exercises, is free to download and keep on your fridge or your phone. Download the handout (PDF)

Source for the traffic light system: A World of Hurt: A Guide to Classifying Pain (2016), musculoskeletal-pain.com.

Not sure which colour you are on?

That is what we are here for. Book an assessment with the Forza team online at forzaphysiotherapy.janeapp.com or call us at (604) 359-2919, and we will build your harm check and your plan with you. This article is general education and is not a substitute for an assessment by a registered physiotherapist.