Exercise

KNEE TUCK

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AbsHip flexors
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Workout Center

The knee tuck is a dynamic core exercise performed in a plank position with your feet resting on sliding discs or another low-friction surface. As you draw both knees toward your chest and extend back out, the movement challenges the rectus abdominis, hip flexors, and shoulder stabilizers at the same time. Because the hands stay planted while the lower body moves, it also demands real shoulder and scapular stability. Unlike a static plank, the sliding action keeps continuous tension on the core through the entire set, making it an effective finisher for core training.

Muscles Targeted

  • Primary: Rectus abdominis, hip flexors (iliopsoas)
  • Secondary: Obliques, transverse abdominis
  • Tertiary: Shoulders, chest, quadriceps (as stabilizers)

Starting Position

Set up in a high plank with your hands directly under your shoulders and arms fully extended. Place the balls of your feet on sliding discs, gliding pads, or a folded towel on a hard floor, with your body forming a straight line from head to heels. Engage your core and keep your hips level with your shoulders before initiating the first rep.

Execution Steps

  1. Brace your core by pulling your belly button toward your spine before you move
  2. Slide both feet forward simultaneously, bending your knees and hips to draw them toward your chest
  3. Keep your hips level as your knees travel forward - avoid letting them pike upward
  4. Pause briefly when your knees reach their furthest point of flexion under your torso
  5. Slide your feet back to the starting plank position under control, resisting the urge to let them shoot out
  6. Repeat for the desired number of reps while maintaining a rigid plank throughout

Form Cues

  • Keep your hands planted and shoulders stacked directly over your wrists throughout the set
  • Avoid raising your hips into a pike position - use core control, not hip-flexor momentum, to drive the knees in
  • Keep your neck neutral by looking at the floor slightly ahead of your hands
  • Move at a controlled tempo on both the tuck and the extension - don't let the discs fly
  • Exhale as you draw the knees in, inhale as you extend back out

Common Mistakes

  • Piking the hips: Raising the hips as the knees come in shifts work away from the abs and turns the movement into a hip-flexor exercise. Keep hips level with your shoulders.
  • Sagging through the lower back: Letting the hips drop or the lower back arch increases spinal stress. Keep the core braced throughout.
  • Rushing the reps: Moving too fast trades control for momentum and cuts the time under tension. Slow the tempo down.
  • Letting the feet fly out: Losing control on the extension phase reduces the eccentric stimulus and can strain the hip flexors. Extend with the same control as the tuck.
  • Placing the hands too far forward: This adds shoulder strain and makes plank stability harder. Stack the wrists directly under the shoulders.

Variations

  • Single-leg knee tuck: Alternate one leg at a time to increase the core stability demand and address side-to-side imbalances
  • Stability ball knee tuck: Feet on a stability ball instead of sliders, requiring more balance control
  • Pike-to-tuck combo: Alternate tucking the knees with a full pike (hips up, legs straight) for added difficulty
  • TRX knee tuck: Feet suspended in TRX straps, adding an unstable, hanging component to the exercise
  • Cross-body knee tuck: Draw one knee diagonally toward the opposite elbow to add oblique emphasis

Tips for Progression

  • Add reps gradually: Build from 8-10 reps to 15-20 reps before adding a harder variation
  • Slow the tempo: Add a 2-3 second pause at full tuck to increase time under tension
  • Progress to single-leg or stability ball versions once the standard version feels controlled
  • Add sets: Increase from 2-3 sets to 4-5 sets as your core endurance improves

Training Notes

Program knee tucks 2-3 times per week as part of a core circuit or as a finisher after your main lifts. Work in the 10-15 rep range for 3-4 sets, resting 30-45 seconds between sets since the movement is core-focused rather than heavily loaded. It pairs well with anti-extension work like planks and anti-rotation work like Pallof presses for balanced core development.

Exercise Details

Body Parts
Abs, Hip flexors
Category
Workout Center

Frequently Asked Questions

How often should I do the KNEE TUCK?

Because the KNEE TUCK works abs, hip flexors, two to three sessions a week is a sensible range for most people. It is a compound movement, so it pulls in several muscle groups at once and needs a full day of recovery before you hit the same pattern again. If you train it harder, do it less often.

Is the KNEE TUCK suitable for beginners?

The KNEE TUCK sits at an intermediate level for most lifters. Start light, nail the technique, and only add load once the pattern feels automatic. New to lifting? A coach can check your setup in a single session.

What should I do if the KNEE TUCK causes pain?

Stop the set right away. A working burn in abs is fine, but sharp or pinching pain is a signal, not a challenge. Reset your sliding discs setup, drop the weight, and if the pain comes back, talk to a physio or certified trainer before your next session.

How much weight should I use for the KNEE TUCK?

Pick a load you can move with clean form for every planned rep, where only the last one or two feel genuinely hard. Since this is a pulling movement, let your back and arms drive the work rather than yanking with momentum. When form holds across all sets, nudge the load up a little.

Can I modify the KNEE TUCK?

Plenty of options exist. You can swap the sliding discs for something similar, shorten the range of motion while you learn the groove, or change your stance to shift the emphasis around abs, hip flexors. Splitting a compound lift into its parts is a fair way to build the pattern. Adjust to fit your body, not the other way round.