Pain During Rehab: Is It OK, and How Much Is Too Much?

Some discomfort during rehab is common, and tolerable pain doesn't worsen outcomes.

"Is it OK to feel pain during rehab?" It's one of the most common, and most uncomfortable, questions in rehabilitation, and the answer probably isn't as black and white as you'd like.

Pain during rehab can be normal and expected, especially when we're loading tissues that are sensitive, healing or recently injured (such as after surgery or a muscle strain). The short version: yes, pain during rehab can be OK, once red flags are ruled out. Below, we'll look at what the research says and outline practical guidelines that have worked well clinically.

Early research on pain during rehab

One of the earliest studies on this question was conducted by Thomeé (1997). Forty women with patellofemoral pain syndrome were divided into two rehab groups, one doing isometric exercises and the other eccentric exercises. Both groups were allowed to exercise into pain using a pain-monitoring model, rated on the familiar 0–10 scale:

• 0–2/10: safe
• 3–5/10: acceptable
• Above 5/10: high risk / unacceptable

Participants were told to adjust their exercises if pain increased the following day. The result: both groups had less pain and better function, even though they exercised with pain.

Painful vs. pain-free rehab: is one better?

Several studies have directly compared pain-free rehab with rehab performed up to a pain threshold:

• Hamstring strains: a randomized controlled trial found no difference in time to recovery between pain-free rehab and rehab allowed up to 4/10 pain, but the pain-threshold group maintained better strength and flexibility throughout recovery.
• Achilles tendinopathy: patients allowed to continue painful activities (like running and jumping) using Thomeé's pain-monitoring model showed no difference in pain or function compared with those who avoided painful activity.
• Shoulder pain (subacromial pain syndrome): patients allowed to load the shoulder using a pain-monitoring model reported better pain and function than those following a non-loading program.
• Systematic review (Smith et al., 2017): exercising into pain showed short-term benefits for pain, with no meaningful difference in medium- or long-term outcomes compared with pain-free exercise.

How much pain actually occurs during rehab?

Other studies have looked at pain responses during rehab without directly comparing pain-free and painful exercise:

• After total knee replacement: pain increased with higher loads, but only exceeded daily-activity pain levels when exercises were taken close to fatigue. On average, pain returned to baseline within 2 minutes after exercise.
• After total hip replacement: over a 10-week progressive strengthening program, resting pain stayed low and exercise pain averaged only about 1.5/10 higher. Pain decreased over time despite increasing loads. About a third of patients had a clinically meaningful pain increase (more than 2/10) during about one-sixth of their sessions, and no adverse events were reported.

What does this all mean?

Rehab requires loading tissues that may still be sensitive or healing. Some pain with loading is often unavoidable if we want to restore function and return to meaningful activity. The research consistently shows that:

• Pain during rehab is common
• Pain rarely reaches harmful levels
• Allowing tolerable pain doesn't worsen outcomes
• In some cases, it may help maintain strength, confidence and activity levels

The key message isn't "push through anything," but rather: it's OK to feel symptoms, within reason. This fits with broader pain science showing that pain and tissue damage don't always correlate directly (see what chronic pain is).

A practical pain guideline that works clinically

A more flexible version of Thomeé's pain-monitoring model has worked well in practice:

• Pain during exercise should be tolerable (as defined by you)
• Pain should settle with rest
• Pain should be at baseline or better the next day

If any of these conditions aren't met, modify the exercise or activity (load, volume, speed or range of motion). This approach applies only after red flags and serious pathology have been ruled out, which a physical therapist can screen for. From there, a PT can help scale and progress activity safely over time.

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the takeaway

Once red flags are ruled out, some pain during rehab is normal and doesn't worsen outcomes. Keep pain tolerable, make sure it settles with rest and is back to baseline by the next day, and adjust the exercise if it isn't. Rehab should build confidence, not fear.

Frequently asked questions

Is it normal to have pain during rehab?

Yes. Pain is common when loading sensitive or healing tissues, rarely reaches harmful levels, and allowing tolerable pain doesn't worsen outcomes, once red flags have been ruled out.

How much pain is OK during rehab exercises?

A practical guide: pain should be tolerable, settle with rest and be at baseline or better the next day. Thomeé's original model rated 0–2/10 as safe, 3–5/10 as acceptable and above 5/10 as high risk.

Is painful exercise better than pain-free exercise?

A 2017 systematic review found a small short-term benefit for exercising into pain and no meaningful difference in the medium or long term, so pain need not be a barrier.

What should I do if pain is worse the next day?

Modify the exercise by adjusting load, volume, speed or range of motion, and check in with your physical therapist.

References

Thomeé R. A comprehensive treatment approach for patellofemoral pain syndrome in young women. Phys Ther. 1997;77(12):1690-1703. doi:10.1093/ptj/77.12.1690

Smith BE, Hendrick P, Smith TO, et al. Should exercises be painful in the management of chronic musculoskeletal pain? A systematic review and meta-analysis. Br J Sports Med. 2017;51(23):1679-1687. doi:10.1136/bjsports-2016-097383