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I love doing jackknives. It’s one of those “old school” exercises where you can feel those muscles working like it should, especially if you go all out and try to get deep down on the floor.
I’ve had some great success with this exercise, so I wanted to share some tips on how to do it right.
Jackknives Muscles Worked?
The primary muscles that will be worked with an exercise like this are the pecs and shoulders. The upper arms, back and abs also need to engage in order to maintain proper form throughout the movement and not allow yourself to overextend.
Jackknives Exercise Benefits?
You will be able to see a lot of strength and muscle gains if you keep up with this exercise. That is, as long as you do it right!
The jackknife is an old school version of the sit-up. It’s a hard exercise meant to engage your abdominal, shoulders and back muscles.
How To Do It?
Set up for jackknives exercise by lying on the floor with your back touching the ground. Place both hands at the sides of your head, palm down on the floor.
Keep your legs straight out in front of you with your toes pointed to the ceiling.
Next, push up through your arms and shoulders until you are sitting upright. You will keep one leg extended while pulling it under yourself without hardly bending the knee.
Then reach across your body towards that foot with either hand until you grab onto it with an “X” grip (much like when shooting a basketball).
Keep looking forward throughout this movement so that you don’t strain your neck muscles. Now pull that leg in towards yourself all while pushing away from the ground using only your shoulders and arms.
At this point you are still in the upright position with one leg extended straight out in front of you while holding on to your foot.
You will now want to lean towards that side until your shoulder touches the ground.
From here, sit up once more and then bring your opposite knee in under yourself to meet with its counterpart hand all while keeping that extended leg straight throughout the entire exercise.
When finished, push back up into a seated position with all your weight resting upon your shoulders.
Add These to Your Workout and Watch That Six Pack Grow
The jackknife is exactly what it sounds like: performing a sit-up by pulling one leg in at a time rather than pushing them both together.
Because you only pull one limb at a time, this is not considered an effective core exercise, but exercising your core is important, nonetheless.
You can sit up as far as you wish, but the goal is to go as deep as your flexibility allows.
Much like a butterfly stretch, this exercise can be performed every day stretching the pectoral muscles and building strength for an increased range of motion.
Jackknives Variations?
There are variations to this same exercise where you will lean towards one side instead of pulling your knee in. This works the obliques very heavily while keeping the primary muscle groups engaged.
If you want to make it more intense, use some ankle weights or hold light dumbbells with both hands. Resting on just your shoulders is significantly harder than resting on your elbows because it keeps your body off the ground but requires full compression from top to bottom.
Jackknives Exercise Alternatives?
Jackknives are very old school way to work the abdominals and shoulders. These days, more advanced exercises have been created that can be done simply by laying down flat on your back.
For example, you could place both feet together above your hips as if doing a bridge. Then lower both legs down to either side by bending from the hips while reaching with your knees as far as possible.
Stop when you feel a stretch in your sides or obliques and then repeat for up to ten reps per set.
This exercise will not only strengthen your abs but also engage other muscle groups such as the hips, glutes and hamstrings.
It’s one of those workouts that gets a lot of things stronger at once rather than just one thing.
Another ab exercise that works the abs is an exercise that can be performed by lying down flat with your arms at your side and feet extended straight up into the air.
You will then use both hands to reach across yourself towards your opposite foot for ten reps before switching sides.
Like most airplane motions, this one really focuses on the lower oblique muscles more so than the upper portion.
There are also “Upright” versions of this same movement. You will sit on a bench with both legs bent underneath to keep them out of swinging distance.
You will lean back onto the bench slightly and perform the same motion. As if reaching for an opposite leg instead of an opposite hand as in other variations.
Give This Jackknives Workout A Try
I think most people would benefit by doing Jackknives every day for a few weeks. Followed by another abdominal exercise like planks or hanging leg raises. This is definitely an old school move, so it’s time you give it a try if you haven’t already.