I’m a trainer with a history of injury-prone knees—when I have five minutes spare I use this simple gym ball routine to help protect them

The hamstrings and glutes play an unsung role in protecting your knees.

That was the major lesson I took away from my physiotherapist after tearing both anterior cruciate ligaments on the soccer field—in separate incidents in my late 20s and early 30s.

Running down the back of the thighs, from the hips to the knees, the hamstrings help to stabilize the back of the knee joint to prevent hyperextension.

At the same time, they work as shock absorbers to protect the ligaments and cartilage, and they also help you decelerate at high speed.

Meanwhile, the glutes, which form a major part of the posterior chain system connected along the back of your body, help to stabilize the pelvis and keep your hips aligned to stop your knee caving inward under strain.

I’ve tried countless ways to strengthen these two muscle groups over the years, but there is one exercise that has stuck with me: gym ball hamstring curls.

Now, whenever I have a few minutes spare at the end of my workout, I'll add them into my core finisher to keep my knees protected and the surgeon's scalpel away.

How I use gym ball hamstring curls in my workouts

I like to include this exercise as part of a gym ball core and posterior-chain finisher at the end of my regular workouts to make the most of this piece of equipment.

I will start by doing the exercise using both feet for eight to 10 reps—to wake up the hamstrings and glutes.

Then I progress to the single-leg variety for two or three rounds of six to eight reps on each side, resting for 30 seconds between sets.

To even everything out, I will finish with one more round with my feet together for a final eight to 10 reps.

Things to know before doing gym ball hamstring curls

Whatever level you are at, take your time and really concentrate on the muscles you are targeting at the back of your thighs and glutes.

Because this exercise pinpoints the hamstrings in a way rarely achieved with multi-joint exercises like deadlifts or even single-leg deadlifts, it can feel quite intense.

Modify the movement as required—even holding a static glute bridge will effectively build strength as your hamstrings fight to resist the instability of the gym ball.

How to do the gym ball hamstring curl

Swiss Ball Hamstring Curl | Nuffield Health - YouTube

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Sets: 2-3 Reps: 8-10 Rest: 30-60sec

To begin, start with two to three sets of eight to 10 reps with your feet together and 30-60 seconds of rest between sets.

When you’re ready to progress the movement, perform two to three sets of six to eight reps on each side, with 30 seconds of rest between sets.

How to do it:

• Lie on your back with your heels resting on the top of a gym ball. Your feet should be hip-width apart and your knees bent at 90˚.
• Lift your hips while maintaining the bend in your knees.
• Press your hands into the floor to help maintain balance.
• Slowly extend your legs, rolling the ball away from you.
• Pause for one second, then bend your knees to bring your feet toward you, lifting your hips and rolling the ball toward you.
• Pause for one second, then begin the next rep.

Make it easier: Switch this move to a static glute bridge with your knees bent and hips raised for 30 seconds per set—your glutes and hamstrings will still have to work hard to maintain stability.

Make it harder: After a set with feet together, switch to a single-leg hamstring curl—keep one foot elevated while performing the movement with the other for six to eight reps, before swapping sides.

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