Movement of the Week: Hamstring Curl-In on Physioball

Movement of the Week: Hamstring Curl-In on Physio Ball

Rebuild Phase

You used to have lower back pain. Now you don't.

Now you want to build a stronger, more resilient spine with the hope of reducing your risk of pain or injury in the future.

The goal here is to teach your hamstrings to stabilize your pelvis under load, a pattern that shows up every time you sprint or step off a curb.

The hamstring curl-in on a physio-ball is one of my favorite movements to help with that process.

Why This Movement, Why Now

By the time you reach this phase, you can produce force in controlled conditions. You've done the work. Your hamstrings and lower back are stronger.

But strength in isolation isn't the same as coordination under competing demands.

Sprinting asks the hamstrings to do several things at once; stabilize the pelvis, control knee extension during swing, produce propulsive force. Most of what came before asked for one job at a time.

The stability ball curl-in doesn't replicate sprinting. But it's a good movement to work on managing dual demands at low stakes. Your hamstrings have to hold hip extension and produce knee flexion at the same time.

That matters for your spine. When the hamstrings hold hip extension, they keep the pelvis from tipping forward, which is what keeps your lower back from arching under load. Lose the hip extension while you're busy curling, and the pelvis tips. For anyone whose back doesn't like extension, that's the pattern that causes problems.

So this movement is really asking a question: can your hamstrings protect the spine while they're also busy doing something else? In real-world tasks, they never get to do just one job. This is where you start learning to manage both.

It also tells us something. If you can't maintain position here, slowly, on a ball, that's useful information about readiness for faster, heavier work.

This is a waypoint, not an endpoint. It doesn't train the high-velocity eccentric capacity that protects against sprint-related hamstring injuries. That work still needs to follow. But this is where that road starts.

A Note on Readiness

This movement isn't a basic dead-bug or bird-dog. It's one of the movements not everyone gets to and that's okay.

Before you attempt the curl-in, you should be able to hold a bridge with your heels on the ball, hips up, without your back arching or your hips dropping. If that's not solid yet, keep working on holding a bridge in this position. The bridge hold is building the same capacity, just at a lower demand.

If the bridge is fine but your hamstrings cramp or give out during the curl, that's usually a sign they're doing more than their share, the glutes aren't contributing enough to the hip extension task. A few weeks of floor bridges can build the cooperation this movement requires.

The curl-in will be there when you're ready.

The Movement

Lie on your back with your heels on a physio ball, legs straight. Press your heels into the ball and lift your hips until your body forms a straight line from shoulders to heels.

Bend your knees and curl the ball toward you, keeping your hips up. The challenge is not letting your low back arch as the ball rolls in.

Pause at the top, extend back out slowly. That's one rep.