Can Strengthening The Abductor Hallucis Muscle Help Prevent Overuse Injuries?

We commonly overlook the abductor hallucis muscle in the foot and rarely does it even get recognition or discussion when it comes to any foot pathologies. However, recent literature has demonstrated its importance to the foot, especially to the medial longitudinal arch.1-4 Accordingly, let us examine the anatomy of the abductor hallucis and review how it may be more involved with the pathology we see on a day-to-day basis.

The abductor hallucis muscle originates at the posteromedial aspect of the calcaneus and inserts into the medial sesamoid of the hallux or proximal phalanx.5 The action of the abductor hallucis is to flex and supinate the first metatarsal, invert the calcaneus, externally rotate the tibia, and elevate the medial longitudinal arch.1 It also contributes to the stabilization and supination of the midtarsal joint against the pronating force of ground reaction during propulsion.6

Researchers have demonstrated that the abductor hallucis muscle supports the medial longitudinal arch and recommend strengthening foot intrinsics to prevent overuse injuries in those who present with excessive pronation. Fiolkowski and colleagues demonstrated with electromyography that the intrinsic pedal muscles play an important role in supporting the medial longitudinal arch and controlling pronation during static stance.2 Headlee and colleagues demonstrated that fatigue of the abductor hallucis muscle led to increased navicular drop.3 Fiolkowski and co-workers also confirmed this after witnessing an increased navicular drop by blocking the tibial nerve.2

The abductor hallucis muscle plays an important role in maintaining arch height as well as controlling excessive pronation. Strengthening this muscle can aid in treating and preventing overuse injuries. We should view it no differently than the posterior tibial muscle and tendon.

The question this poses is whether one should rely on external support such as an orthotic device to maintain or support the arch, or whether the focus should be on strengthening the intrinsic muscles of the feet, specifically the abductor hallucis. Jung and colleagues demonstrated that the short foot exercise is a useful exercise in increasing the strength of the abductor hallucis and medial longitudinal arch, more so than toe curls, which also provided a strength increase.4

Something else to consider is muscular tone, which is a measure of a muscle's resistance to stretching while in a passive, resting state. Muscular tone also describes the continuous, partial contraction of muscles while in a passive resting state. For example, when external force acts on a passive muscle, muscles will increase in tension due to the partial contraction, reflexively responding to avoid stretching.7 A weak gluteus medius muscle or thoracic and lumbar muscles can lead to poor posture.

Can we say the same for the abductor hallucis? If significant strength gains occur in the abductor hallucis, will increased muscle tone lead to a more stable structure of the arch? The above studies demonstrate increased support of the medial longitudinal arch during static stance. Knowing the abductor hallucis muscle abducts the hallux would lead one to think that by increasing the muscle’s tone, a reduction in a hallux valgus could result.

It is pretty clear the research demonstrates that strengthening the intrinsic musculature can influence foot structure. We still need to establish the degree of influence and whether this can have a positive effect on treating and preventing injuries.

References

1. Wong YS. Influence of the abductor hallucis muscle on the medial arch of
the foot: a kinematic and anatomical cadaver study. Foot Ankle Int. 2007; 28(5):617-20.

2. Fiolkowski P, Brunt D, Bishop M, Woo R, Horodyski M. Intrinsic pedal musculature support of the medial longitudinal arch: an electromyography study. J Foot Ankle Surg. 2003; 42(6):327-333.

3. Headlee DL, Leonard JL, Hart JM, Ingersoll CD, Hertel J. Fatigue of
the plantar intrinsic foot muscles increases navicular drop. J Electromyogr Kinesiol. 2008; 18(3):420-425.

4. Jung DY, Kim MH, Koh EK, et al. A comparison in the muscle activity of the abductor hallucis and the medial longitudinal arch angle during toe curl and short foot exercises. Physical Ther Sport. 2011; 12(1):30-35.

5. Kendall FP, McCreary EK, Provance PG, Rodgers MM, Romani WA. Muscles: Testing And Function, With Posture And Pain, fifth edition. Lippincott Williams & Wilkins, Philadelphia, 2005.

6. Mann R, Inman VT. Phasic activity of intrinsic muscles of the foot. J Bone Joint Surg (Am). 1964; 46:469-481.

7. Available at https://www.boundless.com/physiology/muscle-tissue/control-of-muscle-ten... .



Kevin A. Kirby DPMsays: April 24, 2014 at 11:33 am

While I agree that the abductor hallucis muscle may be “overlooked” by clinicians, possibly the reason that it is “overlooked” by most clinicians treating patients with pathologies caused by excessive subtalar joint (STJ) pronation moments and excessive medial longitudinal arch (MLA) flattening moments is because the abductor hallucis is such a tiny muscle compared to the other, much more powerful extrinsic muscles of the foot (i.e. posterior tibial, flexor hallucis longus and flexor digitorum longus) that have much greater potential to supinate the STJ and raise the MLA.

Strengthening the intrinsic muscles of the foot may help some patients with their symptoms. However, these small muscles can not possibly, by themselves, be expected to resist the severe deforming forces on the medial longitudinal arch in many of our patients who are obese, have equinus deformities and have flatter MLA heights. This one tiny muscle, the abductor hallucis, is simply too small to hold up the MLA by itself during weightbearing activities.

Instead of posing the question of “whether one should rely on external support such as an orthotic device to maintain or support the arch, or whether the focus should be on strengthening the intrinsic muscles of the feet, specifically the abductor hallucis," one should rather realize that there are many ways to treat excessive STJ pronation and MLA flattening including strengthening both the intrinsic and extrinsic muscles of the foot that cause STJ supination moments and MLA raising moments, stretching tight Achilles tendons, using pre-made and/or custom foot orthoses, low-Dye and high-Dye strapping of the foot and ankle, ankle bracing, anti-pronation shoes and boots, and even foot and lower extremity surgeries.

All of the above methods can be used together by the intelligent clinician to treat pronation-related pathologies in their patients in order to offer them the best available therapeutic options to make them pain-free and more active. However, simply focusing on the strengthening of one little intrinsic muscle of the foot to treat foot and lower extremity pathologies without first considering using all the other well-accepted and evidence-based treatments for pronation-related foot pathologies mentioned above just does not make good biomechanical sense.

Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine

Reply to this comment »
Jennifer Barlowsays: April 28, 2014 at 1:26 pm

I think as Dr. Campitelli stated, the "degree of influence" of strengthening the abductor hallucis is still to be determined. Looking at the work of Dr. Vladimir Janda, activating the abductor hallucis can have influence far beyond the sphere of this "tiny muscle," as it has been linked to co-activation of the pelvic floor and gluteal muscles. Certainly, the glutes can have an effect on foot posture.

Reply to this comment »
Blue says: April 29, 2014 at 2:02 pm

Dr. Campitelli,

Do variations in the total volume and disposition of muscle mass lying between the plantar fascia and the arch formed by the bones of the foot act to affect the tension in the fascia itself?

Kind regards,
Blue

Reply to this comment »
Craig Paynesays: May 1, 2014 at 9:20 am

Another case of cherry picking and the wishful thinking fallacy.

So many references ignored that contradict what you are claiming. Why?

How do you explain:
- Lynn et al (2012) - no change in arch height with abductor hallucis strengthening
- Lizis et al (2010) - no relationship between arch height and muscle power
- Shiro**** et al (2012) - strengthening of intrinsic muscles lead to a lower arch profile
- Ridge et al (2013) - transitioning to minimalist running did not change arch height
- Etheredge et al (2011) - no change in arch with minimalist running
- Williams et al (2012) - no increased activation of intrinsic muscles during barefoot running

Reply to this comment »
Nick Campitellisays: May 8, 2014 at 8:52 am

I appreciate everyone's comments as it must mean there is an interest for what I have to discuss.

Craig, as much as I would love to respond to your post, I do not quite understand what you have wrote. Are those your conclusions or the articles' conclusions? You only listed partial references and no titles so I do not have the time to comb through and review what you listed. I'd be glad to give my thoughts if you present more information. Many times, these studies present 6-8 weeks or so of a period of running and draw their conclusions from that. I'm sure you would agree that it takes longer then that to see a change physiologically in any muscle or soft tissue structure. I have data from a 6-month study that I hope to share soon that proves this. In regards to cherry picking, I guess I'm really not understanding what you mean? The definition of research is "the systematic investigation into and study of materials and sources in order to establish facts and reach new conclusions ... ". I am trying to reach conclusions based on the studies I have shown. Are you not doing the same thing? If so, then by your definition, I would have to say you're picking some cherries as well.

Kevin, here is a recent article that gives a more current and up to date way of looking at intrinsic muscles of the feet, especially the abductor hallucis:

McKeon PO, Hertel J, Bramble D, Davis I. The foot core system: a new paradigm
for understanding intrinsic foot muscle function. Br J Sports Med. 2014 Mar 21.

It establishes that the intrinsics of the feet are overlooked and play a role in stability and that our society too often looks to external support rather then strengthening the foot.

Thanks!

Nick Campitelli, DPM, FACFAS

Reply to this comment »

Post new comment

  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.

More information about formatting options

Image CAPTCHA
Enter the characters shown in the image.