Jack Knife Exercise: Tips, Techniques, Correct Form and Benefits

The jack knife has been around longer than many people realize. It’s been a mainstay of gymnastics workouts since the turn of the last century, and remains a popular exercise option to this day.

The jack knife is a core-strengthening exercise that involves lying face-up on the floor, pulling your legs up towards your chest and then rotating your body so you can touch the ground with your feet. It's a challenging movement that works several different muscle groups at once and provides a host of benefits.

In other words, it’s a powerful exercise that suits nearly everyone and should be part of your core-strengthening protocol.

What Is a Jack Knife Exercise, Exactly?

The jack-knife is an abdominal exercise designed to work the abdominal muscles, principally the lower abs. There are many variations of this exercise that allow people with different levels of fitness and experience to work their abdominal muscles.

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Here are some tips on how to do the jack knife properly:

1. Lie down with your stomach on the floor or on a mat and stretch your arms straight out above your head. Keep your legs straight and together.

2. Slowly raise your legs and arms to touch each other above you while keeping your back in a neutral position. Hold it for three seconds and then return back to the starting position slowly.

3. Repeat it at least 12 times, working up to 3 sets of 12 repetitions as you get stronger.

If this is too difficult for you, you can start by just raising your legs without stretching them up towards the ceiling. You can also try doing it with bent legs instead of straight ones, or from a kneeling position instead of lying flat on the floor or mat.

While doing jack knife exercises, be careful not to overdo them because they can cause injuries such as muscle strains and spasms in the lower back area which can be painful and take time to heal.

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Benefits:

There are plenty of reasons to give this exercise a try:

• They're great for abs: If you want stronger abs and a six pack, this might be the exercise for you. As one of the best ab exercises out there, they'll help you develop strong muscles that'll keep you looking fit.

• They're good for posture: It leverages your lower back and abdominal muscles to help improve your posture. Over time, this can make you taller, more confident, and even less prone to injury.

• They improve flexibility: This requires you to lift both your upper body and legs off the ground at once—and it's no easy task! But if you practice them regularly, these movements will help increase the flexibility of your torso in general.

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What muscles does the jack knife exercises target?

The jack knife exercise is a great way to work your core, but you'll also be engaging other muscle groups depending on the variation you choose.

Your transverse abdominis (aka "deep abs") and rectus abdominis (aka "six-pack muscles") are the two main abdominal muscles that are targeted as well. But your obliques, glutes, and lower back will get a little action too!

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Takeaway

Consistency is important for any workout plan. The more you love the exercise you do, the easier it becomes to stick with your routine.

Jack knife exercise is a simple yet challenging exercise that you can use to build core strength and improve your posture.

What's more, the jackknife is an exercise that nearly everyone can do without experiencing significant pain or injury.

So step away from those crunches and planks, which have earned their place as staples in many fitness programs. Try adding this to your routine today and see how it feels.