Why Big Toe Strength Matters: FHL Training

A Smarter Way to Reduce Calf, Shin and Plantar Fascia Pain

At Sydney Physio Clinic we regularly see runners with ongoing calf tightness, shin soreness, or stubborn plantar fascia pain that never fully settles. Historically, the focus has been directed towards stretching, foam rolling, or treating the painful area itself. While these can help short term, they do not always address one of the key contributors to efficient running mechanics — big toe strength. This is where targeted FHL training can make a meaningful difference.

FHL training focuses on strengthening the flexor hallucis longus, a deep muscle that bends the big toe and plays a vital role in how the foot functions during walking and running.

What is the FHL and why is it important?

The flexor hallucis longus runs from the back of the lower leg, passes behind the ankle, and attaches to the base of the big toe. During the push-off phase of running, the FHL helps press the big toe firmly into the ground. This contributes to:

• Forward propulsion
• Stability through the arch of the foot
• Efficient transfer of force from the calf to the ground

When the FHL is weak or lacks endurance, the foot often becomes less stable at push-off. As a result, other tissues must compensate which over time, may increase strain and overload in other areas.

How FHL training can help reduce calf pain

The calf muscles and the FHL work together during push-off. If the big toe cannot contribute enough force, the calf complex often works harder to generate forward movement. This can lead to persistent tightness or overload, especially during higher mileage or speed work.

By including FHL training in a strengthening program, runners can share the workload more evenly between the foot and calf. This improved load distribution may help reduce repeated strain on the calf muscles over time.

The link between FHL training and shin pain

Shin pain in runners is often associated with changes in how forces travel through the lower leg. Poor foot control and inefficient push-off can alter loading patterns, increasing stress along the tibia.

FHL training helps improve the foot’s ability to create a stable and effective lever during propulsion. When the foot functions more efficiently, forces can be transferred more smoothly up the leg, potentially reducing excessive stress through the shin.

FHL training and plantar fascia support

The plantar fascia works with the muscles of the foot to support the arch and manage load during running. Strong big toe flexors assist this system by helping stiffen the forefoot as you push off.

If the FHL is “underperforming” the plantar fascia may take on more repetitive loading. FHL training can improve the strength and endurance of the big-toe flexors, supporting better arch control and potentially reducing irritation of the plantar fascia over time.

Why specific FHL training matters

Many runners have tried general foot exercises like towel scrunches. While these may provide modest gains they usually do not provide enough resistance to build any meaningful strength in athletes. Like any muscle, the FHL needs progressive loading to adapt.

This is where a structured approach using a tool like HeelHero can be helpful. HeelHero allows you to apply consistent, graded resistance through the big toe, making FHL training more effective and easier to progress.

How to start FHL training with HeelHero

Begin with low to moderate effort. You should feel the work under the big toe and along the inside of the arch, rather than cramping through all the toes.

Big toe press holds
Press your big toe down into HeelHero and hold for 20–30 seconds. Keep the other toes relaxed. Repeat 4–6 times.

Slow controlled presses
Press down through the big toe for 2–3 seconds, pause, then slowly release. Aim for 3 sets of 8–12 repetitions.

Standing progression
As strength improves, perform the press while standing tall and gently lifting your heel slightly, maintaining pressure through the big toe. Moving from double leg to single leg raising as you progress. 

Ideally complete FHL training exercises around 3 times per week. As with all strengthening, progress gradually and allow time for your tissues to adapt.

Building stronger foundations for running

FHL training is not a quick fix, but it can be a powerful addition to a runner’s rehab or performance program. When the big toe contributes effectively at push-off, the calf does not have to do all the work, the foot becomes more stable, and running mechanics often feel smoother and more efficient.

If you are experiencing recurring calf, shin, or plantar fascia pain, adding structured FHL training with a progressive tool like HeelHero may help improve your foot strength and overall running resilience.

This information is general in nature and does not replace individual assessment. If pain persists, we recommend booking an appointment with one of our team at Sydney Physio Clinic for a more personalised plan.