A physical therapist says this is the muscle you probably aren’t training but should be

If you walk or run, you want to keep this muscle strong

Woman sits on treatment table while man looks at and gently holds her foot
(Image credit: SDI Productions / Getty Images)

If you want to avoid ankle issues and foot injuries, particularly if you're a runner, then there is one muscle that you need to concentrate on strengthening.

"The posterior tibialis is a small but important muscle that supports and controls the arch of the foot when you are walking or running," physical therapist and certified personal trainer Dr Kaylee Kuzma told me. "If this muscle is weak it will cause overpronation of the foot, or a flat foot. This can lead to a number of different issues including plantar fasciitis of the foot, shin splints, and even hip and knee pain can occur because of the additional stress that will be placed on these joints."

In a recent Instagram Reel, Kuzma demonstrates a series of movements to strengthen the posterior tibialis, including foot doming, an exercise that strengthens the intrinsic smaller muscles in your feet that support the arches of the foot. This can help improve foot muscle activation, reduce the risk of injury and boost balance.

  • 1. Heel raises with ball between your heels
  • 2. Foot doming with band under big toe
  • 3. Resisted ankle inversion
  • 4. Single-leg Romanian deadlift with band under big toe

Why you should strengthen the smaller muscles in your feet

The foot has larger muscles known as global movers, which are responsible for movements like walking and running. The smaller muscles are known as intrinsic muscles and are found at the bottom of the foot.

These muscles are much smaller and deeper, and they work together to stabilize the different joints in the feet and provide a stable base for the larger muscles to function efficiently.

Sometimes known as the foot core, there are four layers to these deeper small muscles in the bottom of the foot. When these muscles don’t work properly, you can be more prone to injury.

"It is important to perform specific exercises for this muscle, especially if you are a runner," says Kuzma.

Maddy Biddulph

Maddy Biddulph is a freelance journalist specializing in fitness, health and wellbeing content. With 26 years in consumer media, she has worked as a writer and editor for some of the bestselling newspapers, magazines and websites in the US and UK. 

She is also a qualified L3 personal trainer and weight loss advisor, and helps women over 40 navigate menopause by improving their physical and mental strength. At Maddy Biddulph Personal Training, she runs one-to-one and small group training for menopausal women who want to get fit to ease symptoms and feel like themselves again.