From the minimalist footwear movement to barefoot training, one of the greatest benefits of getting out of the orthotics and motion-controlled shoes is the activation of the plantar intrinsic foot muscles.
As the health and fitness industry begins to embrace the many benefits of intrinsic foot strength, researchers are starting to question which foot exercises may be the most beneficial for strengthening the plantar foot. Which foot exercises could we consider to be evidence-based?
Abductor Hallucis Strength
If we considered the intrinsic foot musculature, the most important or most influential intrinsic muscle would have to be the abductor hallucis.
Originating on the plantar medial aspect of the calcaneus and inserting into the base of the proximal phalynx of the great toe, this plantar intrinsic muscle:
– abducts the hallux
– creates an inversion moment to the subtalar joint
– supports or lifts the navicular bone
– stimulates the Deep Front fascial line
– drives co-activation of the deep lateral rotators
I always talk about the short foot exercise as the most effective exercise to target this muscle, but a recent 2013 study by Kim et al. questions the benefit of short foot – and actually explores the benefit of perhaps another exercise. The exercise in question is referred to as toe-spread.
In the study Kim et al. demonstrated through EMG analysis that when performing the toe spread exercise there was almost 45% greater muscle recruitment of the abductor hallucis.
So does this mean that toe spread trumps short foot when it comes to intrinsic muscle exercises? Not necessarily!
Kim et al. found that the ability to perform a toe-spread exercise was limited in those subjects with a bunion due to the altered position of the abductor hallucis tendon. It is important to note that those subjects with a bunion were able to perform short foot and achieve abductor hallucis activation.
This is important to note as many of our clients, patients and athletes may have a bunion deformity and we need to choose the most appropriate exercise to target their foot type and abductor hallucis alignment. It should be noted that in subjects with a bunion, the abductor hallucis can still function as a subtalar joint invertor and supporter of the navicular bone.
Integrating Intrinsic Strengthening
Whether you decide to have your clients and patients do short foot or toe spread, the programming should be the same. I use intrinsic strengthening as the foundation to all my patient rehab and foot strengthening programs. From plantar fasciitis to post-ankle sprain, all patients can benefit from activating the plantar foot.
Step 1 – Activation
When activating a muscle you will want to focus on isometric contractions as these have the greatest motor unit recruitment. Begin by hold short foot or toe spread for 10 seconds. Relax. Repeat 5 – 8 times.
Step 2 – Isolated Strengthening
After waking up the abductor hallucis now you can focus on building strength and endurance in this muscle. Perform 10 – 15 repetitions per side for 3 sets. Your client or athlete may begin to feel the abductor hallucis fatigue or cramp. If this happens do not push through the cramp as it can easily become a planar fasciitis-type pain. Myofascially release the bottom of the foot before proceeding.
Step 3 – Integrated Strengthening
Finally, because our feet and core are so deeply integrated you want to begin to integrate abductor strengthening with deep lateral rotator strength. Throughout the repetitions focus on the deep hip and pelvic floor engagement. To increase the activation of the deep hip and pelvic floor I encourage my clients to before their foot exercises on a single leg.
For some examples of barefoot single leg exercises incorporating short foot please click HERE
Are you barefoot strong?
Kim et al. Comparison of muscle activities of the abductor hallucis and adductor hallucis between the short foot and toe-spread out exercise in subjects with mild hallux valgus. J
Back Musc Rehab, 2013. 26: 163-168.