By Matthew Dilnot, DPM
Dr. Dilnot is a Consultant Podiatrist at the Melbourne Foot Clinic, Melbourne, Victoria, Australia; Clinical Supervisor at LaTrobe University, Bundoora, Victoria, Australia; and a Director at Equus Medical Products, Eltham, also in Melbourne. He discloses that he is a distributor of foot-strengthening products.
LER: In modern foot care, foot strengthening is not commonly used as a treatment method. Why not?
MD: Strangely, this might be because the foot is hidden or encased in a shoe—the very thing that possibly leads to a deficit in foot strength in the first place. This does not necessarily mean I advocate that we all go barefoot or wear minimalist footwear. But we need to keep an open mind about how shoes affect muscle function and redistribute forces. As podiatrists, we often see the foot working as a unit, not an intricate collection of joints surrounded by equally intricate muscles and tendons. But seeing the foot as a single unit might limit our awareness of how foot-strength deficits in one area can shift pressure and forces to another, which then affects the foot as a whole. Ironically, then, running shoes may now be designed to supplement the deficits that shoes might have caused in the first place.
Also, podiatrists have become comfortable with the use of foot orthoses, but we might not use foot strengthening regularly because we are unsure how effective it can be and whether it can change the course of injury and deformity. Foot strengthening usually requires home exercises, which depend on the patient being compliant to be effective. We want to be confident that what we are doing offers a return on investment in time. Podiatrists have not been traditionally trained and do not have the culture within the profession to implement these programs with confidence.
I remember that, when I was attending podiatry school almost 30 years ago, we were just coming out of an era when the small muscles of the foot were still considered by many to be largely vestigial, difficult to activate, and mostly unimportant. Back then, strengthening programs were considered pointless for most conditions of the foot and practiced only by fringe practitioners; hallux valgus was considered by many to be merely a cosmetic problem; and there was little awareness of the importance of big-toe strength in balance.20 In fact, hallux valgus surgery was often assigned to trainee orthopedic surgeons as their first bone operation, mainly because results were considered unimportant.23 The proximal phalanx of the great toe was often removed in that procedure—leaving behind a toe that was largely useless.
Decades earlier, however, we had some great surgeons and podiatrists championing the importance of foot strength. In 1954, chiropodist M. D. England advocated delaying footwear for as long as possible in children to build foot strength and prevent problems in adulthood.24
LER: Can a line be drawn between foot-muscle strength and hallux valgus?
MD: Hallux valgus has been a problem among humans for thousands of years, but recently we’ve seen a significant increase in the rate of valgus deformity in countries where a transition is being made, beginning at a young age, from barefoot or straw shoes to western-style footwear.25 It’s commonly quoted that the rate of hallux valgus among barefoot populations is approximately 3% (although this varies considerably across populations). What we see, however, is that, in some populations, the rate has skyrocketed to approximately 30% when people transition to western-style footwear.25 We are yet to learn what is causing this increase, but I think there is a strong possibility that it is, at least in part, the result of a reduction in foot-strength development in children that, quite possibly, might enhance their risk of hallux valgus and clawing of the lesser toes in adult life.
LER: Can foot strengthening be applied to managing plantar fasciitis?
MD: Treatment of plantar fasciitis invariably includes calf stretching.26 The presumption is that, in all cases of plantar fasciitis, there is limited flexibility of the calf. Indeed, reduced ankle range is common, but is not present in all cases.27 We should try to ascertain, patient by patient, why plantar fasciitis has developed. In addition, there is also routine prescription of a foot orthosis to reduce load on the plantar fascia.28
But something is missing in this paradigm: evaluation of foot strength as a potential component of care. Although plantar fasciitis is commonly associated with a lack of ankle range (which does possibly contribute to plantar fasciitis), there are still cases that occur in a state of hypermobility, not hypomobility, of the ankle—in which case calf stretching is highly unlikely to provide resolution. In fact, calf stretching has been shown in some studies to be ineffective in people with restricted ankle ranges as well.26
Many practitioners don’t take the time to assess range of motion, or disregard their findings if they do, and follow a formula for every case in hopes that a uniform approach might work for all. Some of my patients who have a hypermobile ankle are stretching 3 to 5 times a day and are not seeing improvement. For them, stretching is inappropriate: They already have enough range—probably too much range!
Research from the University of Sydney has shown that the strength of the ankle evertor (peroneal muscles) and toe flexors is significantly reduced in people with plantar fasciitis.27 This research builds on a growing body of evidence regarding plantar fasciitis and reduced foot strength.29-31 Granted, this is early work, but I think we are on the cusp of a new appreciation of strength in the foot—not only in the way we assess it but also in the ways we implement treatment and combine that treatment with other forms of care, such as treatment of patellofemoral joint syndrome.32
Let me add that extraordinary new findings being reported on how strength is used and applied go well beyond the foot, of course, to the entire body. We have seen impressive work in the shoulder, thanks to which we’ve realized that many smaller muscles around this joint can have an extraordinary effect on reducing impingement.33 Regarding back pain, patients with seemingly devastating degeneration become symptom-free or improve substantially with strength training.34
LER: Earlier, Dr. Mickle discussed her work on using muscle strengthening to address toe deformities. To conclude our discussion, what’s your perspective on this strategy?
MD: Acknowledging the valuable research that’s been done, the foot nevertheless appears to have missed the full attention it deserves in regard to strengthening. It’s time to explore the importance of foot strengthening using everything we have learned from various disciplines to evaluate this body part more objectively. We’re just beginning to develop a tool set for more appropriately evaluating foot strength, delivering effective programs of care, and measuring the results of foot strengthening.
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- Saragiotto BT, Yamato TP, Hespanhol Junior LC, Rainbow MJ, Davis IS, Lopes AD. What are the main risk factors for running-related injuries? Sports Med. 2014;44:1153-1163.
- van Gent RN, Siem D, van Middelkoop M, van Os AG, Bierma-Zeinstra SM, Koes BW. Incidence and determinants of lower extremity running injuries in long distance runners: a systematic review. Br J Sports Med. 2007;41:469-480.
- Herbert RD, de Noronha M. Stretching to pre-vent or reduce muscle soreness after exercise. Cochrane Database Syst Rev. 2007;CD004577. www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD004577.pub2/full. Accessed August 11, 2018.
- Pereles D, Roth A, Thompson D, Darby JS, Tho mpson MS. A large, randomized, prospective study of the impact of a pre-run stretch on the risk of in-jury in teenage and older runners. (Report) Indianapolis, IN: USA Track & Field; 2007. http://www.usatf.org/stretchStudy/StretchStudyReport.pdf. Accessed August 11, 2018.
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- Burne SG, Khan KM, Boudville PB, et al. Risk factors associated with exertional medial tibial pain: a 12 month prospective clinical study. Br J Sports Med. 2004;38:441-445.
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- McClinton S, Collazo C, Vincent E, Vardaxis V. Impaired foot plantar flexor muscle performance in individuals with plantar heel pain and association with foot orthosis use. J Orthop Sports Phys Ther. 2016;46:681-688.
- Mickle KJ, Caputi P, Potter J, Steele JR. Efficacy of a progressive resistance exercise program to increase toe flexor strength in older people. Clin Biomech (Bristol, Avon). 2016;40:14-19.
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- Tsuzuku S, Kajioka T, Sakakibara H, Shimaoka K. Slow movement resistance training using body weight improves muscle mass in the elderly: A randomized controlled trial. Scand J Med Sci Sports. 2018;28:1339-1344.
- Endo M, Ashton-Miller JA, Alexander NB. Effects of age and gender on toe flexor muscle strength. J Gerontol A Biol Sci Med Sci. 2002;57:M392-M397.
- Menz HB, Zammit GV, Munteanu SE, Scott G. Plantarflexion strength of the toes: age and gender differences and evaluation of a clinical screening test. Foot Ankle Int. 2006;27:1103-1108.
- Mickle KJ, Angin S, Crofts G, Nester CJ. Effects of age on strength and morphology of toe flexor muscles. J Orthop Sports Phys Ther. 2016;46:1065-1070.
- Mickle KJ, Munro BJ, Lord SR, Menz HB, Steele JR. ISB Clinical Biomechanics Award 2009: toe weakness and deformity increase the risk of falls in older people. Clin Biomech (Bristol, Avon). 2009;24:787-791.
- Mickle KJ, Nester CJ. Morphology of the toe flexor muscles in older adults with toe deformities. Arthritis Care Res (Hoboken). 2018;70:902-907.
- Jung DY, Koh EK, Kwon OY. Effect of foot orthoses and short-foot exercise on the cross-sectional area of the abductor hallucis muscle in subjects with pes planus: A randomized controlled trial. J Back Musculoskelet Rehabil. 2011;24:225-231.
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- Radford JA, Landorf KB, Buchbinder R, Cook C. Effectiveness of calf muscle stretching for the short-term treatment of plantar heel pain: a randomised trial. BMC Musculoskelet Disord. 2007;8:36.
- Sullivan J, Burns J, Adams R, Pappas E, Crosbie J. Musculoskeletal and activity-related factors associated with plantar heel pain. Foot Ankle Int. 2015;36:37-45.
- Rasenberg N, Riel H, Rathleff MS, Bierma-Zeinstra SM, van Middelkoop M. Efficacy of foot orthoses for the treatment of plantar heel pain: a systematic review and meta-analysis. Br J Sports Med. 2018;52:1040-1046.
- Allen RH, Gross MT. Toe flexors strength and passive extension range of motion of the first metatarsophalangeal joint in individuals with plantar fasciitis. J Orthop Sports Phys Ther. 2003;33:468-478.
- Chang R, Kent-Braun JA, and Hamill J. Use of MRI for volume estimation of tibialis posterior and plantar intrinsic foot muscles in healthy and chronic plantar fasciitis limbs. Clin Biomech (Bristol, Avon). 2012;27:500-505.
- Cheung RT, Sze LK, Mok NW, Ng GY. Intrinsic foot muscle volume in experienced runners with and without chronic plantar fasciitis. J Science Med Sport. 2016;19:713-715.
- Mølgaard CM, Rathleff MS, Andreasen J, et al. Foot exercises and foot orthoses are more effective than knee focused exercises in individuals with patellofemoral pain. J Science Med Sport. 2018;21:10-15.
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