Treating Plantar Fasciitis With Foot Strengthening vs. Stretching: Different Takes on the Same Study
Posted on September 25 2014
I recently read an article on the New York Times Well Blog about a study in the Scandinavian Journal of Medicine & Science in Sports. The study, by Michael Rathleff and colleagues, compared strengthening vs. stretching exercises to treat plantar fasciitis (PF). In a nutshell, the Times article reported that the study found strengthening exercises to provide superior improvement after 3 months compared to stretching, but that with additional time the stretching group responded equally well compared to the strengthening group. So the basic conclusion might be interpreted as being that both interventions improved symptoms over the long term, but that foot strengthening exercises improve PF symptoms more rapidly.
Having experienced a long-term (though fairly low-grade) case of plantar fasciitis myself a few years ago, I’m always curious when I see reports of potentially effective treatment protocols for the condition. As such, I though I’d dig a bit more into this study.
The full text is not available for free (I received a copy from the author), but the lead author wrote up a nice summary of what they did on RunningPhysio.com. Basically, they took 48 patients with diagnosed plantar fasciitis and randomized them into either a plantar-specific stretching regimen or a high load strength training regimen for the foot (all subjects also received gel heel inserts).
Here’s the description of the stretching regimen (via Michael Rathleff on RunningPhysio):
“Patients were instructed to perform this exercise whilst sitting by crossing the affected leg over the contralateral leg (Figure 1). Then, while using the hand on the affected side, they were instructed to place the fingers across the base of the toes on the bottom of the foot (distal to the metatarsophalangeal joints) and pull the toes back toward the shin until they felt a stretch in the arch of the foot. They were instructed to palpate the plantar fascia during stretching to ensure tension in the plantar fascia. As in Digiovanni, patients were instructed to perform the stretch 10 times, for 10 seconds, three times per day .”
The above-described plantar fascia stretching regimen was used in a previous study (DiGiovanni et al., 2003) and was found to provide superior results to an Achilles tendon stretching regimen.
“High-load strength training consisted of unilateral heel-raises with a towel inserted under the toes to further activate the windlass-mechanism (Figure 2). The towel was individualised, ensuring that the patients had their toes maximally dorsal flexed at the top of the heel-rise. The patients were instructed to perform the exercises every second day for three months. Every heel-rise consisted of a three second concentric phase (going up) and a three second eccentric phase (coming down) with a 2 second isometric phase (pause at the top of the exercise). The high-load strength training was slowly progressed throughout the trial as previously reported by Kongsgaard et al. . They started at 12 repetition maximum (RM) for three sets. After two weeks, they increased the load by using a backpack with books and reduced the number of repetitions to 10RM, simultaneously increasing the number of sets to four. After four weeks, they were instructed to perform 8RM and perform five sets. They were instructed to keep adding books to the backpack as they became stronger.”
And here is the summary of study outcomes that the lead study author wrote on RunningPhysio:
We used the Foot Function Index as our primary outcome after three months but also did follow-ups after 1,6 and 12 months. At our 3 months follow-up we saw that patients randomised to high load strength training had a 29 points lower Foot Function Index. This is far greater than the minimal relevant difference and suggests a superior effect of high-load strength training compared to plantar specific stretching. An important aspect is that we saw no difference between groups at 6 and 12 months indicating no superior long-term effect. However, if you ask patients to choose between two treatments that have similar long-term effect but one will give you a quicker reduction in pain, I am certain that all patients would choose the treatment, which provides them with the quickest reduction in pain.
This all sounds great – if you have plantar fasciitis and want to improve your symptoms, a foot strengthening routine like the one used in this study could provide relief more quickly than a stretching routine. There is some logic behind this finding as eccentric loading is commonly used to treat tendon injuries such as in Achilles tendinopathy. The idea is that if you strengthen the tissue, it becomes better capable of handling the loads placed on it.
As with any academic study, it’s always important to be open minded and critical. Such is the nature of science. Podiatrist Craig Payne recently wrote a critique of this study on his site Run Research Junkie, and it makes for interesting reading. He points out that the results are consistent with the approach he advocates for treating plantar fasciitis, and outlines a number of positives about the study. But he also points out a number of concerns. Of these, I’m only going to comment on one here, and that is the lack of a control group that did not receive either intervention (or the gel heel inserts).
As Craig points out in his critique it is not atypical for plantar fasciitis to simply improve on its own with time (sometimes an extended period of time). For example, I experienced symptoms with my case of PF for over a year, and though I did seek treatment I have no idea if my case resolved due to a specific intervention (e.g., I did a lot of calf foam rolling, Graston/ART, and some stretching) or if it simply resolved on its own (it actually improved during a summer when I was running a lot more miles than I had in quite awhile). Thus, without a control group in this study we can’t say for certain that stretching or strengthening exercises performed better than just letting the case of PF improve with time (it’s worth noting that studies looking at the effectiveness of stretching vs. controls for treating PF have given mixed results). Craig also points out that the intervention of the gel heel insert in both groups could have contributed to improvement, but again we cannot assess any influence of that compared to a group that did not receive a heel insert.
All we can really say with certainty from this study is that foot strengthening exercises provided quicker improvement in plantar fasciitis symptoms when compared to plantar stretching. It’s important to note that this does not preclude either of these interventions as potentially valuable tools in the treatment of plantar fasciitis. It’s also worth noting that plantar stretching is a commonly used/advocated approach to managing plantar fasciitis, so in that sense this study was comparing a new protocol to one that is commonly used. As such, the fact that strengthening led to quicker improvement in symptoms is a valuable finding. But I do agree with Craig in that the lack of a control group makes it difficult to discern the benefit of either protocol relative to doing nothing at all. A logical follow-up study would therefore be to compare foot strengthening exercises to a sham treatment or no treatment at all.
All of the above being said, the logic behind the strengthening approach does make sense to me and is, as mentioned, consistent with treatment protocols for some forms of tendinopathy. If my PF decided to return at some point it’s a treatment I would consider, but I would like to know a bit more about how it performs relative to a control.