• Good advice for aches, pains & injuries

“Windows of Opportunity” in Rehab

The importance of WOO in recovery from injury and chronic pain (using frozen shoulder as an major example)

Paul Ingrahamupdated

Photo of an open window, looking out onto a view almost entirely of the ocean, except for a few plants in the foreground. It’s bright outside and dark inside. The window has a vintage frame and many panes.

A “window of opportunity” (WOO) is a period of pain relief and/or boosted confidence that makes it easier to do normal activities and therapeutic exercises. This is a popular concept in physical therapy and rehab.

I’ll use frozen shoulder as an example to illustrate this general principle — which is relevant to almost any issue — because the WOO might be an especially important idea in frozen shoulder rehab, especially in cases that seem to involve neurological inhibition of movement.

What’s so great about a WOO? It facilitates activity and exercise

Pain relief is inherently valuable to people, of course, but there’s a huge bonus prize: it helps get you moving again.

To appreciate why a WOO might matter, it’s important to understand not only that exercise is medicine, but really good medicine. Its benefits are both more substantial, easier to achieve, and more lasting than most people realize.1 Anything that makes it easier to move and exercise, even briefly, is really quite valuable.

Frozen shoulder can be an extremely difficult condition to treat. There isn’t anything like an actual cure for the toughest cases. The same is true for countless other common, “simple” musculoskeletal conditions — they are so difficult that the marketplace is cluttered with promises to desperate patients. Mitigation and coping is often the best you can do, but that’s critical with a condition like frozen shoulder, where you have to do your best to use whatever range of motion you possibly can — to minimize the nearly inevitable losses.

WOOs for functionally frozen shoulders

Most of the best conservative treatment options for frozen shoulder — or at least the least-lame options — are either about creating or using windows of opportunity. While this is broadly true of rehab for many other conditions, it’s especially relevant to frozen shoulder because of the possible role of “functional freezing” — that is, if the limitation in movement is caused by neurological inhibition, rather than a physical stuckness. It’s unclear how much this happens, but it’s relatively easy to figure out if you know what you are looking for: see The Role of “Spasm” in Frozen Shoulder.

A WOO is mainly useful to the extent that freezing is caused by excessive neurological inhibition. A brain that is incorrectly convinced that it has to limit shoulder movement might be more easily persuaded/reassured if you do rehab exercise while the pain is blunted.

But WOO might even be useful for frozen shoulder involving contracture. These patients also need to do whatever they can to maintain shoulder range, and there are surely better and worse times to do that. Reduced pain is a good example of a better time!

Is WOO woo-woo?

Let’s check the bullshit detector before we go any further. While there’s probably plenty of legitimacy in the idea of a window of opportunity, wisely applied, the notoriously skeptical physical therapist blogger Adam Meakins argues that the idea of a window of opportunity is often just a thin, self-serving justification for using ineffective methods, “more for the therapists’ benefit rather than the patients’.”2

I completely agree. I see it all the time.

Ineffective therapies can still often produce transient, trivial pain relief because almost anything can.3 In some cases, such minor benefits might be encouraging and motivating enough to constitute a meaningful opportunity to advance recovery. For instance, someone might be more willing to do some exercise, or get an extra morale boost while wrestling with their nicotine addiction.

In many cases, the WOO is just not enough — too brief, too minor — and it’s just a weak excuse for a treatment that has little else to recommend it.

But not in all cases, I suspect. It is also low-hanging fruit, logical, practical, and obviously more applicable to some conditions and cases than others. For instance…

What’s in a WOO? What makes a better WOO? Examples

Mostly, a fine WOO is made from anything that has a somewhat reliable and robust pain-relief or “reassuring” effect — more substantive than just a placebo. Although a placebo can also generate a bit of WOO, we’re looking for something a little more substantive. A little topical analgesic on an ankle sprain, for instance, can relieve more pain than a placebo (that’s how we know it works, by definition).4 Even though it’s not a really potent pain relief effect, it’s still measurably stronger than a blast of optimism — which means it can create a better opportunity to wiggle the ankle a little more (simple pain-free mobilizations in the early stages, more systematic joint mobility drills later).

Important: the idea isn’t to create an opportunity to over-do it — that’s a different WOO, which some athletes seek out. The idea is just to facilitate normal rehab stuff.

But here’s a weirder WOO: the odd effect of vibration on stretching, a weird little body hack. Many people can suddenly stretch further — significantly increased range of motion — right after their muscles are shaken (not stirred).567 And it lasts! Increasing flexibility is substantially or entirely about building up neurological tolerance of stretch, so the experience of stretching quite a bit further than usual is easy for the nervous system to remember — “Oh, I learned I can stretch that far without tearing anything. Righto then, I’ll keep going that far!” This is an interesting but exotic example, based on a phenomenon that not many people know about (or need, frankly — flexibility is overrated).

So, in a sense, a WOO is created not just by any effective treatment, but almost anything that makes patients feel better in any meaningful way. That sounds great, but there’s a dark side to it as well: there are shockingly few effective treatments for chronically painful conditions. Back pain, for instance, is one of the most notoriously untreatable conditions in all of medicine89 — which means that finding good WOO-generators for back pain patients is quite a challenge.

But the best quality of the WOO is that it doesn’t actually have to create a lasting benefit to be meaningful. In fact, it’s transient almost by definition — it’s a window of opportunity, not a hangar-bay-door of opportunity. And this is why WOO can be both used and overused as a justification for treatments like massage or chiropractic adjustment, which have notoriously ephemeral benefits for most patients, most of the time.

This has been a short excerpt from my frozen shoulder book. If you want to know more, there’s a substantial free introduction, and a couple of other excerpts available:

About Paul Ingraham

Headshot of Paul Ingraham, short hair, neat beard, suit jacket.

I am a science writer in Vancouver, Canada. I was a Registered Massage Therapist for a decade and the assistant editor of for several years. I’ve had many injuries as a runner and ultimate player, and I’ve been a chronic pain patient myself since 2015. Full bio. See you on Facebook or Twitter.

Related Reading

What’s new in this article?

Mar 18, 2020 — More context and detail, extensive editing, some new citations and examples — a significant overall upgrade the week after publication.

March — Publication.

March — Publication.


  1. It has been said that exercise is the closest thing there is to a miracle cure. “All the evidence suggests small amounts of regular exercise (five times a week for 30 minutes each time for adults) brings dramatic benefits,” we “age well” when we are active (Gopinath): less anxiety (Schuch), prevention of dementia (Smith) and a laundry list of other diseases (Pedersen), and as little as just 10 minutes per week might push back death itself (Zhao).

    But why is it so awesome? Exertion mobilizes extensive networks of biological resources that are relatively dormant while we’re watching Netflix. It’s biologically “normalizing,” pushing systems to work the way they are supposed to work. Exercise cannot normalize everything, but it does stimulate an incredibly broad spectrum of biological function — way more than any medicine, supplement, or superfood.

  2. [Internet]. Meakins A. Closing the window of opportunity …; 2016 October 12 [cited 18 Oct 31].
  3. Cook C. Immediate effects from manual therapy: much ado about nothing? J Man Manip Ther. 2011 Feb;19(1):3–4. PubMed #22294847ra ❐ PainSci #53461 ❐

    This short but technical article makes a simple, important point: we’ve seen a lot of less-than-awesome research showing that essentially any treatment can probably provide statistically significant immediate benefits (because pain is readily modulated by novel sensory input), but “the limited effect size for many … raises concerns about their clinical significance” and “may not provide substantial value during long-term, progressive, clinical decision making.”

    What we need to further flesh out is which set of interventions that lead to immediate effects that are designed to define a clinical outcome, actually lead to long-term clinical benefits. What we don’t need is a litany of further studies that assume clinical importance because immediate effects occurred directly after the administration of a manual therapy intervention; we've got that covered.

  4. Altman R, Barkin RL. Topical therapy for osteoarthritis: clinical and pharmacologic perspectives. Postgrad Med J. 2009 Mar;121(2):139–47. PubMed #19332972 ❐


    Nonsteroidal anti-inflammatory drugs (NSAIDs) have shown efficacy in patients with osteoarthritis (OA) pain but are also associated with a dose-dependent risk of gastrointestinal, cardiovascular, hematologic, hepatic, and renal adverse events (AEs). Topical NSAIDs were developed to provide analgesia similar to their oral counterparts with less systemic exposure and fewer serious AEs. Topical NSAIDs have long been available in Europe for the management of OA, and guidelines of the European League Against Rheumatism and the Osteoarthritis Research Society International specify that topical NSAIDs are preferred over oral NSAIDs for patients with knee or hand OA of mild-to-moderate severity, few affected joints, and/or a history of sensitivity to oral NSAIDs.

    In contrast, the guidelines of the American Pain Society and American College of Rheumatology have in the past recommended topical methyl salicylate and topical capsaicin, but not topical NSAIDs. This reflects the fact that the American guidelines were written several years before the first topical NSAID was approved for use in the United States. Neither salicylates nor capsaicin have shown significant efficacy in the treatment of OA.

    In October 2007, diclofenac sodium 1% gel (Voltaren Gel) became the first topical NSAID for OA therapy approved in the United States following a long history of use internationally. Topical diclofenac sodium 1% gel delivers effective diclofenac concentrations in the affected joint with limited systemic exposure. Clinical trial data suggest that diclofenac sodium 1% gel provides clinically meaningful analgesia in OA patients with a low incidence of systemic AEs.

    This review discusses the pharmacology, clinical efficacy, and safety profiles of diclofenac sodium 1% gel, salicylates, and capsaicin for the management of hand and knee OA.

  5. Issurin VB, Liebermann DG, Tenenbaum G. Effect of vibratory stimulation training on maximal force and flexibility. J Sports Sci. 1994 Dec;12(6):561–6. PubMed #7853452 ❐

    In this 1994 experiment, as described by Sands et al, gymnasts “used a vibrating ring suspended by a cable, in which the foot of the subject was placed while they stretched forward over the raised leg, targeting the hamstrings. The resulting increase in ROM was astonishing. These researchers demonstrated that vibration could enhance flexibility.” The results were replicated by Sands et al in 2006, and Kinser et al in 2008.

  6. Sands WA, McNeal JR, Stone MH, Russell EM, Jemni M. Flexibility enhancement with vibration: Acute and long-term. Med Sci Sports Exerc. 2006 Apr;38(4):720–5. PubMed #16679989 ❐

    This experiment replicated the results of an intriguing 1994 experiment by Issurin et al. Ten highly trained gymnasts did forward splits with or without vibration. They stretched to the point of discomfort for 4 minutes, alternating between each leg, 10 seconds of stretching at a time. Flexibility immediately after stretching with vibration was dramatically greater; the long-term results were less striking.

  7. Kinser AM, Ramsey MW, O’Bryant HS, et al. Vibration and stretching effects on flexibility and explosive strength in young gymnasts. Med Sci Sports Exerc. 2008 Jan;40(1):133–40. PubMed #18091012 ❐

    Replicates the findings of both Issurin and Sands — “simultaneous vibration and stretching may greatly increase flexibility, while not altering explosive strength.”

  8. Machado LA, Kamper SJ, Herbert RD, Maher CG, McAuley JH. Analgesic effects of treatments for non-specific low back pain: a meta-analysis of placebo-controlled randomized trials. Rheumatology (Oxford). 2009 May;48(5):520–7. PubMed #19109315 ❐ PainSci #54670 ❐

    This is a meticulous, sensible, and readable analysis of the very best studies of back pain treatments that have ever been done: the greatest hits of back pain science. There is a great deal of back pain science to review, but authors Machado, Kamper, Herbert, Maher and McCauley found that shockingly little of it was worth their while: just 34 acceptable studies out of a 1031 candidates, and even among those “trial quality was highly variable.” Their conclusions are derived from only the best sort of scientific experiments: not just the gold-standard of randomized and placebo-controlled tests, but carefully choosing only the “right” kind of placebos (several kinds of placebos were grounds for disqualification, because of their known potential to skew the results). They do a good job of explaining exactly how and why they picked the studies they did, and pre-emptively defending it from a couple common concerns. The results were sad and predictable, robust evidence of absence: “The average effects of treatments … are not much greater than those of placebos.”

  9. Vincent K, Maigne JY, Fischhoff C, Lanlo O, Dagenais S. Systematic review of manual therapies for nonspecific neck pain. Joint Bone Spine. 2013 Oct;80(5):508–15. PubMed #23165183 ❐

    The authors of this review conclude from 18 “high quality” trials that manual therapies “contribute usefully” to the treatment of back pain. And yet none of them was clearly any better than any other therapy, either alone or in combination. In other words, none of them really work.

    So why would they “contribute usefully”? What does that even mean? Without saying it outright, they probably mean that they think trivial benefits create windows of opportunity! And that’s not unreasonable speculation — but such weak methods would only open small windows.