The purpose of this blog is to discuss the common misconceptions about pain in rehab, examine the evidence around the topic, and provide general guidelines for use.
Should Rehab Be Pain-Free?
The most common reason for a referral to physical therapy is pain (Liu & Fletcher 2006). Therefore, it would be expected for physical therapy to decrease pain. However, does this mean that physical therapy itself should be pain-free?
There are two main questions that must be addressed:
- How does allowing pain during rehab impact outcomes?
- How much pain should be allowed during rehab?
How Does Allowing Pain During Rehab Impact Outcomes?
According to most published research, it appears that allowing some level of pain during rehab does not worsen long-term pain and may have positive effects on quality of life and strength. Some specific diagnoses this has been studied in include achilles tendinopathy, patellar tendinopathy, knee and hip replacements, subacromial shoulder pain, patellofemoral pain syndrome, knee osteoarthritis, generalized hip and knee pain, and acute hamstring strains.
Tendinopathy
Tendinopathies are one of the most studied conditions as it relates to the impact of allowing pain during exercise. Alfredson et al 1998 performed the initial study examining this concept in patients with Achilles tendinopathy, allowing pain during eccentric exercises unless it became disabling. The researchers found better pain scores and greater eccentric plantar flexor strength after 12 weeks for the exercise group compared to after 24 weeks for the surgical group.
A multitude of other studies in patients with Achilles tendinopathy have produced similar outcomes with minimal-to-no differences in pain scores and moderate-to-no improvement in strength/performance after allowing pain versus not during the exercises at multiple follow ups ranging from 3 weeks to 1 year after initiation of the exercise program. There were, however, worse outcomes when allowing pain in patients with insertional tendon pain (32% satisfactory results) compared to mid-portion tendinosis (89% satisfactory results). (Norregaard et al 2007, Silbernagel et al 2001 & 2007, Fahlström et al 2003).
Similar outcomes (no significant differences between groups) have also been shown in patients with patellar tendinopathy by Frohm et al 2007.
Post Surgery
Research into this specific topic after total knee and total hip replacements is unfortunately limited. For total hip replacements, a systematic review by Konnyu et al 2023 found no significant differences between different rehabilitation programs. For total knee replacements, another systematic review by Konnyu et al 2023 found that the majority of studies showed no difference between rehab programs for pain, stiffness, range of motion, strength, mobility, and patient satisfaction.
While not included in the systematic review by Konnyu and colleagues, Bandholm et al 2014 attempted to measure any increases in pain during different intensities of knee extensions after total knee replacements. They showed that pain increased from a 2.7/10 at rest up to a 4.3/10 during an 8 repetition max and up to a 5.3/10 during a set to muscular failure before returning to baseline pain levels within one minute. While muscle hypertrophy can be improved training with low loads, improvements in muscular strength is maximized with >60% 1RM loads which Bandholm et al demonstrated to be safe after total knee replacements.
Subacromial Pain Syndrome
For subacromial pain syndrome, there have been multiple studies comparing a higher load shoulder exercise program in which some amount of pain is allowed to a lower load exercise program in which no pain is allowed. For example, one study showed that a higher load, increased pain-allowed group had similar pain outcomes and greater strength compared to a lower load, no increased pain-allowed group after 12 weeks (Maenhout et al 2013). Another study showed better pain and function in the painful group than the control group (Holmgren et al 2012). Other studies showed no difference in pain or function between allowing pain during exercises versus not (Littlewood et al 2016, Hallgren et al 2014).
Patellofemoral Pain
Patellofemoral pain syndrome (PFPS) has less associated research. Thomee 1997 compared eccentric to isometric training with both groups instructed that 2/10 pain is “safe”, 5/10 pain is “acceptable”, and pain above 5/10 is “high risk”, with acknowledgement that pain should subside by the next morning. The researcher found significant decreases in pain and improvement in functional tests for both groups but no significant differences between them.
Smith et al 2016 published a case report that involved educating a patient with PFPS about the flaws associated with tissue-based pathology models of pain while providing a home exercise program consisting of a painful exercise twice a day. The patient reported being 80% better at discharge after 19 weeks.
Knee Osteoarthritis
Thorstensson et al 2005 looked at patients with moderate-to-severe knee osteoarthritis. The intervention group was instructed to perform weight bearing exercises at their most vigorous intensity possible with pain being “acceptable” as long as it wasn’t increased after 24 hours. Despite the control group doing no intervention, there was no difference between groups in pain, physical performance, or self-estimated function after 6 weeks, however the intervention group reported better quality of life. While vigorous exercise may not decrease pain from osteoarthritis, it has a multitude of other health benefits that likely warrants its performance with the knowledge it won’t worsen pain or function.
Hip and Knee Pain
Sandal et al 2016 used the same pain monitoring system as the original Thomee 1997 paper with people with 3+ months history of knee and hip pain. This study had patients perform an 8 week program emphasizing “core stability, postural function and orientation, lower limb muscle strength and functional tasks.” The patients performing the program had an average improvement of pain from 3.6/10 down to 2.6/10 by the end of 8 weeks.
A paper by Hickey et al 2020 found that allowing up to a 4/10 pain with a progressive strengthening and running protocol following an acute hamstring strain demonstrated no difference in return to play time, strength, or reinjury rates compared to not allowing any pain during the same rehab program.
How Much Pain Should Be Allowed During Rehab?
The original pain monitoring system of less than 5/10 pain during exercise (provided it decreased after stopping exercise, subsided by the next morning, and decreased over time) was created by one clinician based on their clinical experience. While it has never been directly compared to a different monitoring system, multiple variations of it have arisen in research such as “pain shouldn’t be disabling”, “daily pain and stiffness shouldn’t increase” and “pain is allowed up to 5/10.”
There is likely no universally perfect pain-monitoring system. Pain guidelines and monitoring should therefore be individualized and context-specific. A 5/10 pain will differ both from one person to another, as well as from day to day within one person. Therefore, rather than focusing on the specific pain number, it can be simplified to whether or not the pain is tolerable during exercise.
Now that we know some level of pain is acceptable in rehab, this opens up more possibilities of how exactly to go about the rehab process. The context of each individual’s situation will dictate how much pain is acceptable.
For a professional athlete at the apex of their season dealing with an acute hamstring strain, it may be deemed more worthwhile to play with acceptable pain as there is high financial and professional motivation to continue to play (whether they should or not may be debated).
For an attorney who is working 60 hours a week in a highly stressful job and is dealing with shoulder pain that is causing them intermittent discomfort throughout the day, they may prefer to remain pain-free with exercises.
For a sparsely active middle-aged adult with achilles tendinopathy whose only exercise is walking a mile with their friends 2x a week, it’s probably beneficial to continue to walk with their friends for both the social and physical benefits of that exercise rather than wait for the pain to completely dissipate before rejoining the walking group.
In post-operative patients, there is often more hesitation with pushing into pain. While there are two systematic reviews looking at total knee and total hip replacement patients and finding neutral-positive outcomes, this may not apply to all surgeries. In the context of post-operative ACL patients, pushing into progressively intolerable pain has the potential to produce continued swelling, quad inhibition, and decreased range of motion, as well as limit the knee’s tolerance to progress to the next stage of rehab.
Finally, in the context of a fracture, whether a traumatic fracture or a stress fracture, additional caution is warranted. After a traumatic fracture, whether managed operatively or non-operatively, continued pain at the fracture site should be avoided to abstain from overreaching the bone’s healing capacity during rehab. With stress fractures, you should aim to avoid any pain both during and after activity in the rehab process to allow the fracture to heal appropriately, as there are recurrence rates up to 21% in athletes and typically require significant activity restrictions.
Summary
In conclusion, allowing some pain during rehab does not seem to significantly alter long-term pain outcomes when compared to avoiding pain during rehab. Furthermore, allowing some pain in rehab might actually mildly improve other outcomes such as strength and quality of life. While rehab programs should always respect tissue healing timelines, the current body of literature seems to suggest that allowing a tolerable level of pain during rehab does not cause further damage to the tissues. As with most rehab related topics, more research is needed on acceptable levels and effects of pain during a rehab program in different conditions and populations. Ultimately, outside of specific conditions, some amount of pain is likely acceptable with rehab and exercise without fear of worsening the condition.
Want to learn more? Check out some of our other similar blogs:
Imaging Myths, How To Train Around Pain, Goldilocks Principle of Rehab
Thanks for reading!
