26 July 2026

Rolling Jackknife in the Pool

The rolling jackknife exercise blends a classic ab movement with a little tweak that challenges your body in new ways. This is one of those exercises that takes full advantage of buoyancy, allowing you to practice movements that are difficult to perform on land. To get started, you will need a pool noodle tucked under your arms for support. If that is not enough, put on an aqua belt for added support.

Video: Rolling Jackknife Exercise in the Pool

This video demonstrates the rolling jackknife exercise from multiple angles and highlights relevant muscles. If you don't see any video below, please disable your ad-blocker!

Rolling Jackknife is a one continuous exercise, but because it combines two separate movements, it's easier to learn by breaking it down step by step. We'll begin with the jackknife, then look at the side rolls, and finally put the two movements together in a safe and controlled way. At the end, I'll also show you another exercise that pairs nicely with the rolling jackknife.

The Jackknife Movement

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Jackknife is a popular abdominal exercise that involves bringing your knees and chest together while lying, and then slowly extending your body. The key is to bend with force and control the movement as you extend. A common mistake is pushing down on the noodle with your arms to lift your torso. Although this makes the movement easier, it shifts some of the work away from the abs. Instead, rest your hands on the noodle and let your abs do the lifting.

Side to Side Roll

2

The second part of the rolling jackknife, the side roll, adds another challenge and engages more muscles on both sides of your body. It involves gently rotating your body from side to side while maintaining your floating position on the noodle. The trick is to rotate your entire body, except your head, without rushing the movement or using your arms. Rolling too far on the side can put you in the wrong position, so keep it simple and within a comfortable range.

Side Roll With Jackknife

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Performing a jackknife while rolling is what gives this exercise a unique challenge compared to a simple jackknife movement. It forces your core to work harder to maintain your position while engaging your obliques in the background. The main focus is still the bending motion of the legs and torso, while rotating smoothly. A common mistake is rotating only the lower body, which is not only unsafe but also puts other muscles to work instead of your core. Your entire body should move together as one and stay nicely aligned throughout the movement.

What You Should Feel

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When performed correctly, the rolling jackknife should feel like you've done a set of crunches, only with a deeper core engagement. While the effort is spread across your waist area, your abdominal muscles will feel most of the burn, while your obliques stay quietly engaged. If your arms become tired, that means you're using them instead of your core. Likewise, if your neck begins to feel sore, it's worth checking your body alignment. Keeping your body properly aligned allows your core to do the work while the rest of your body remains relaxed and neutral.

Related Exercises

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Try the side crunches to mix up your rolling jackknife routine. This exercise is similar, but it only involves bending your knees and torso once, after rolling on both sides. The engagement is also similar, except the continuous bending in the rolling jackknife keeps your abs under constant tension. Give both exercises a go to find out which suits your routine better.