Suspension Knee Tuck
Also known as: trx knee tuck
- Primary muscleAbs
- EquipmentBodyweight
- DifficultyAdvanced
- TypeCore · Core flexion
- Secondary muscles
- Hip Flexors
- Body part
- Core
- Position
- Lying
- Laterality
- Bilateral (both sides together)
- Category
- Strength
Track this exercise in SetGrip — no account needed
Feet suspended in straps instead of resting on a ball or bench, the plank-to-tuck movement has no stable contact point at all - the straps swing in every direction and the trunk must cancel it. That constant correction is the point, and why this rates advanced next to the Stability Ball Knee Tuck it otherwise mirrors.
How to do the Suspension Knee Tuck
- Hang from a pull-up bar with your arms fully extended and your palms facing away from you.
- Engage your core and lift your knees up towards your chest, curling your pelvis towards your ribcage.
- Pause for a moment at the top, then slowly lower your knees back down to the starting position.
- Repeat for the desired number of repetitions.
Tip: Breathe out as you crunch and let the last bit of air leave the lungs at the top of each rep.
Muscles worked
Primary
Abs · Core
The rectus abdominis shortens to bend the spine forward, and each rep should end with the upper abs fully contracted and the ribs pulled down.
Secondary
- Hip Flexors — The hip flexors take over if your feet are anchored and you come up too high; keep the range short to leave them out.
Common mistakes
- Pulling on the neck — hands behind the head should support, not yank; keep the elbows wide and the chin about a fist away from the chest.
- Sitting all the way up — a crunch is a curl of the ribs toward the pelvis, not a sit-up; the lower back should stay on the floor the whole time.
- Cranking out fast reps — momentum does the work if you bounce; lift to a squeeze, hold for a count and lower slowly.
- Never adding load — once bodyweight reps get easy, hold a plate on the chest or use a cable rather than doing sets of 50.
Sets, reps and where it fits
| Goal | Sets × reps | Rest |
|---|---|---|
| Strength | 3 × 8–12 | 60 s |
| Endurance | 2–3 × 15–25 | 45 s |
Crunches close out a session after the heavy work, or they can fill the rest periods between sets of a lift that does not need much bracing. Pair a cable crunch with a cable side bend on the same stack.
Variations and alternatives
Similar exercises
Without bodyweight
Frequently asked questions
What muscles does the Suspension Knee Tuck work?
The Suspension Knee Tuck primarily works the abs. It also involves the hip flexors, which assist the movement and stabilise the joints.
Is the Suspension Knee Tuck good for beginners?
Not as a starting point. The Suspension Knee Tuck is rated advanced because it demands strength, mobility or coordination that takes time to build. Beginners should work up to it through the easier variations listed on this page.
What can I do instead of the Suspension Knee Tuck?
If you cannot do the Suspension Knee Tuck, try the Cable Reverse Crunch, the Foam Roller Knee Tuck or the Decline Crunch. Each of them trains the abs through a similar movement, so you can swap them in without changing the rest of the workout.
How many sets and reps should I do?
It depends on your goal. For the Suspension Knee Tuck, a sensible starting point is strength: 3 × 8–12 with 60 s rest; endurance: 2–3 × 15–25 with 45 s rest. Train it at the end of a session or pair it with a lower-body lift as active rest.
Track the Suspension Knee Tuck in SetGrip
All 1,100+ exercises with animations are in the app. No account, no sign-up — your data stays on your iPhone. Works with Apple Watch.
More exercises
Exercise data and animations are licensed ExerciseDB content used in SetGrip. This page is for general information and is not medical or coaching advice.