The peroneal muscles are not as well known as some of our other lower body superstar muscles, but they are vital for healthy gait mechanics, especially on uneven surfaces. Improper body alignment or wearing unsound footwear may not only create discomfort or injury to the peroneals, but to other muscles and joints also, near and far from feet and ankles. Before buying summer sandals, take a moment to consider the potential hazards in the shoe department and how flip flops can cause foot pain.

The peroneal muscles are vital for healthy gait.

The peroneus longus and brevis originate from outside of the fibula. The tendon of the stealthy peroneus longus passes below the 5th metatarsal, crosses the sole of the foot and inserts under the 1st metatarsal and cuneiform bones. This is a key component in the pulley/lever system of the foot; creating stabilization of the great toe during movement, balance, and especially walking gait.  In 1954, podiatrist John Hicks was the first to compare the marvelous arch mechanism of the human foot to a ‘windlass,’ a term taken from sailing and heavy equipment design.  Windlass describes a powerful winch where a cord is wound around a cylinder to lift a heavy load.  In the human foot, this effect is demonstrated when the plantar fascia (the ‘cord’) pulls from the calcaneus and toes dorsiflex, especially the big toe; where it coils around the metatarsal heads (‘cylinder’) to pull the “load” (you).

During the dorsiflexion of the big toe, the peroneus longus stabilizes gait. However, when wearing flip-flops, the big toe actually plantar flexes in order to grab the flip-flop and prevent it from slipping off the foot!   This partial destruction of nature’s amazing “windlass effect” is only one way flip-flops foster dysfunctional motor patterns in muscles of the foot, particularly in the peroneus longus, while hindering the plantar fascia from doing its job. This disruption of proper mechanics also renders the arch of the foot far less effective, allowing the “load” to move precariously above. This literally takes some ‘spring’ out of your step.  While high heels are known to cause postural dysfunction and injury, flip-flops may be the more stealthy ‘arch rivals.’

When irrational shoe selection must prevail for a special day, try to practice moderation and some self-care. Here is a great Yoga Tune Up® video demonstrating one way to improve mobility and strength in ankle and foot stabilizers, giving that extra care to your amazing ‘windlass’ soles:

Watch our free Quickfix video for feet and ankles

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Diane Marra

Diane Marra is an Exercise Physiologist and Biomechanics specialist with more than 20 years’ experience teaching in universities, hospitals, corporate and community settings. Diane holds a Master’s Degree in Kinesiology from California State University and numerous fitness certifications. Her scientific research, conducted for the US Army Medical Department and California State University, has been presented at international conferences and published in clinical journals. Today, Diane is creating new programs as the corporate Wellness Manager for a global manufacturing company and still teaches part-time for SUNY Buffalo State College. Since personally overcoming multiple injuries and chronic pain, Diane has a passion for helping ‘regular folks’ who sit too much, manage pain conditions, seek post-injury recovery, and/or simply want to be stronger. Current credentials include: National Strength & Conditioning Association (NSCA™-CPT), American College of Sports Medicine/ ExeRxcise is Medicine® ​Level 1, Yoga Tune Up® and TRX™ Diane is currently developing a new course for her SUNY Graduate students about Workplace Ergonomics and Selfcare, offers private training sessions and occasional workshops in the Buffalo-Niagara area while continuing to do free-lance research/ writing for Medical and Fitness publications.

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I am going to take the approach of changing my shoes to different ones will be healthier for my feet. I can’t give up my flip flops but I will rethink which ones to wear and not wear any longer. It’s not just about stretching but strengthening the foot and calf muscle but also to include is the Therapy balls for rolling out the foot and calf.

Ashley Everhart

Yes! So true! Usually when I introduce the idea of minimalist shoes flip flops are the default response people jump to. Thank you for sharing!

Janine Watson

So now I understand much better your comments from the Santa Rosa workshop. I won’t toss the flip flops but promise to only wear them for brief periods of time, not walking to the yoga studio!!

Donna Burch

Thanks miss Diane!
Oh, I do love my flip flops… I threw out many shoes while suffering from plantar fasciitis a few years ago.
I found Olo Kai flip flops which actually have arch support. Have you seen these? I wonder if they are just as bad. Can’t wait to see you in Santa Rosa!!!

Jessie Dwiggins

Fascinating! I know my feet feel terrible after long stretches of walking in flip flops, but I didn’t know why. It makes perfect sense now, the big toe stays dorsiflexion while the remaining toes extend slightly, creating and unreliable foot pattern. Beyond that, I imagine it creates roll to the outside of the foot without the big toes as an anchor. I can see the misalignment “cause and effects” traveling all the way up the body. Dang, I really like flip flops.

Katy Haldiman, MS, RN

Since learning about the importance of the feet and proper gait to overall health, I’ve been working on strengthening and stretching of my feet. I wear Happy Feet socks to stretch the toes and I’m slowly replacing my footwear in favor of minimalist and barefoot shoes. Rolling my feet on YTU balls is also a part of my routine. Great article!

Sue Kilpatrick

Wow!! This makes me want to clear out my closet. I have seen the effects first had with my flip-flop loving daughter and her bunion surgeries. Even with all that we have gone through, this is the best description of the cause I have read. Thank you!

Camille Corrivault-Gascon

Je ne savais pas l’impact que cela pouvait avoir de porter des flip flop, c’est vraiment intéressant de comprendre la mécanique de notre pied et de comprendre la raison pourquoi il n’est pas bon d’en porter. Il est important de magasiner des soulier ou sandales adéquate pour une meilleur santé de nos pieds et bien sure de notre corps entier.


Flip-flops are so convenient and so close to natural / barefoot, but now that I understand the mechanics and the disfunction that occurs, I will practise some self-care and limit my time spent in them. Thanks for the good info.

Diane M

Hi Elizabeth, I honestly have not researched what adaptations the body makes (if any) for those who live in tropical cultures and exclusively wear backless floppy sandals for decades along with barefoot time. e.g. Picturing Southeast Asia, etc. Barefoot is best obviously for the neurological system to help the body function properly. Katie Bowman is an excellent writer and a Kinesioogy specialist. She recommends regular “Water Shoes” for daily wear. They have ventilation, zero/limited positive heels, and are NOT backless therefore allowing normal gait mechanics to occur (in her book “Alignment Matters”). According to Bowman, neurologists recommend water shoes for… Read more »

Elizabeth Bond

Wow. As a native Floridian who wears flip-flops year round (sometimes even with socks in the winter) you have just changed my world. I always thought that my feet were healthier because they weren’t in shoes, but I never thought about the Big Toe plantar flexing to grip the sandal. I have been confusing my feet for all of my life. I prefer being barefoot most of the time, but this preference has lead to me stepping on 4 bees in just one month! What shoes would you suggest for someone that doesn’t like their feet to feel enclosed and… Read more »

Scott Simons

Very very interesting. I flip-flopped my way through India for four months last year, I wish I had read this before going. I love flip flops, however after reading this blog, I will rethink which sandals I buy. I was not aware that the peroneus longus and brevis were so key for a balanced gait. I will definitely focus on making sure my big toe dorsi flexes as much as possible next time I walk in my sandals.