If you’re a runner, footballer, golfer, or just someone who keeps themselves active — your feet and ankles are working incredibly hard. And one of the most overlooked muscles in the lower body is a little thing called the flexor hallucis longus, or FHL. Not a name that rolls off the tongue, we know — but when it’s not happy, you’ll definitely know about it.

So, what is the FHL?

The flexor hallucis longus is a deep muscle that runs down the back of your lower leg, behind your ankle, and under your foot. Its main job is to flex your big toe and stabilise your foot during push-off — that moment when your foot leaves the ground whether you’re running, hiking, playing football, or even just walking up a hill. It’s also what helps you rise onto your toes and control your footing on uneven ground — and if you’ve ever tackled the cliff paths between Rozel and Bouley Bay, you’ll know that counts for a lot.

When the FHL gets overloaded or irritated, it can cause what we call FHL dysfunction — and it can really interfere with how you move.

Who tends to get it?

Anyone can develop FHL issues, but it’s particularly common in people whose activities involve repetitive push-off movements or lots of big toe flexion. We tend to see it in:

• Trail runners tackling Jersey’s coastal cliff paths — the uneven terrain and constant elevation changes put significant demand on the FHL
• Footballers — whether you’re deep in Muratti preparation or playing weekend league, those quick starts, stops, and direction changes really load this muscle
• Rugby players — from grassroots club rugby right through to the intensity of Siam Cup, explosive push-off and rapid changes of direction are FHL territory
• Golfers — yes, really — the push-off through the big toe is a significant part of the golf swing
• Cyclists and triathletes, particularly those building volume in training
• Anyone on their feet all day — from trades and hospitality to retail

What does it feel like?

• Deep aching pain at the back of the ankle or into the calf
• Soreness along the arch or underside of the foot
• Pain when pushing off through the big toe — particularly noticeable going uphill or accelerating
• Stiffness or a clicking sensation near the ankle
• A general feeling of tightness that just won’t shift

Left unaddressed, it can start to change the way you move — and that’s when other things begin to grumble too.

A few things you can try at home

If you’ve caught this early, these exercises are a good starting point:

🔵 Big toe flexion with a resistance band — Loop a band around your big toe, anchor it, and work through gentle flexion and extension. This isolates the FHL and starts to rebuild strength and control through your push-off.

🔵 Heel raises with a ball squeeze — Place a small ball between your heels and slowly rise onto your toes while squeezing. This fires up the deep stabilisers of the foot and ankle and encourages better alignment.

🔵 Calf release with a tennis ball — Sit on the floor, place a tennis ball under your calf, and slowly roll along the inner part of your lower leg to find tight spots. Releasing tension here takes pressure off the FHL as it travels through the ankle and foot.

That said — if your pain is worsening, or things aren’t improving after a couple of weeks, it’s worth getting it properly assessed by one of our excellent physiotherapists.

How we can help at the JSSC

This is something we see regularly in our clinic, particularly in Jersey’s wonderfully active population. Whether you’re in the thick of Siam Cup training, counting down to Muratti, or simply trying to keep up with your weekly cliff path run — our approach is always to understand the full picture. Not just where it hurts, but why it’s happening.

We’ll carry out a thorough assessment to identify contributing factors, whether that’s load management, biomechanics, footwear, or muscle imbalance. From there, treatment might include hands-on manual therapy to reduce tension and improve mobility, a tailored strengthening programme, dry needling to the deep calf where the FHL runs, and — where relevant — a running or movement analysis to look at how your whole body is loading through that foot.

The good news? FHL dysfunction responds really well to the right treatment. The sooner it’s picked up, the quicker we can get you back to what you love — whether that’s the cliff paths, the pitch, or the fairway.

Don’t let niggling foot or ankle pain become a bigger problem. If something doesn’t feel right, come and see us — we’re here to help. 💙