Captain's Chair Knee Raise: how to do it right
In short: Knee raise on the captain's chair, a lower-abs isolation loaded in the shortened position, with peak tension when your knees come up toward your chest.
How to do it, step by step
- 1Set your forearms on the pads, back pressed against the backrest, shoulders low and active.
- 2Start with legs straight or slightly bent, pelvis neutral, no swinging.
- 3Bring your knees up toward your chest then curl your pelvis upward to lift your butt off the backrest.
- 4Squeeze your abs hard for 1 second in the top position, when the pelvis is tilted.
- 5Lower slowly over 2 to 3 seconds under control, without letting go all at once.
The mistake to avoid
Don't just lift your thighs. Curl your pelvis upward.
Other common mistakes
- Only raising the knees without curling the pelvis, which shifts all the work onto the psoas: think of lifting your butt off the backrest at the end of the rise.
- Swinging to launch your legs, which steals the tension from the abs: slow down and start from a stable position.
- Dropping back down in a free-fall, which cancels the eccentric phase: control the return over 2 to 3 seconds.
- Skipping the squeeze at the top when that's where the peak tension is: take a real 1-second contraction.
Muscles worked
- Main:
- Abs
The rectus abdominis, especially its lower portion below the navel, does most of the work through the curling of the pelvis. The iliopsoas takes a big part in hip flexion but you should limit its role. The obliques stabilize the trunk and prevent side-to-side swinging.
What to replace it with
Same muscle, same part of the movement: these exercises do the same job.
- Cable Crunch ›
- Machine Crunch ›
- Cable Oblique Crunch ›
- Weighted Dumbbell Russian Twist ›
- Kettlebell Russian Twist ›
Frequently asked questions
How do I do this exercise?
Set your forearms on the pads, back pressed against the backrest, shoulders low and active. Start with legs straight or slightly bent, pelvis neutral, no swinging. Bring your knees up toward your chest then curl your pelvis to lift your butt off the backrest, squeeze hard for 1 second at the top, then lower slowly.
How high should I raise my knees?
What matters isn't the height of the knees but the pelvic tilt at the end of the rise. Lift your butt off the backrest and bring your pubic bone toward your sternum: that's where the rectus abdominis works. If you just raise your thighs without curling, you're mostly working the psoas. Aim for the full range you control, without squirming.
I don't feel anything in my abs, is that normal?
If you mostly feel your hips or thighs, you're just raising your knees without curling your pelvis. Reduce the low range and focus on the last third: lift your butt off the backrest and make your thighs touch your belly through the tilt. Squeeze hard for 1 second at the top, that's where the rectus abdominis gets recruited.
How fast should I do the movement?
Rise in a controlled way, squeeze for 1 second at the top when the pelvis is tilted, then lower slowly over 2 to 3 seconds. Above all, don't let your legs drop in a free-fall, it's the braked descent that keeps the tension on your abs.
How should I breathe?
Breathe in with legs low, breathe out gradually during the rise and breathe out fully at the top to accentuate the contraction and the pelvic tilt. Keep your belly drawn in and your trunk braced the whole time to lock your back against the backrest.