Elbow to Knee
Elbow to knee is a standing bodyweight ab exercise where you drive one knee up while bringing the opposite elbow down to meet it, then alternate sides. The diagonal path works your abdominals and obliques together while your standing leg and core handle balance, so it doubles as light core stability work.
Why it works
Bringing an elbow toward the opposite knee is a rotational movement, and your obliques are built specifically to produce that kind of cross-body twist while your rectus abdominis handles the forward curl of the torso. Doing it standing on one leg at a time adds an extra layer: your deep core has to keep you upright and balanced while the rest of your abs are busy crunching, which is a demand a floor-based crunch never places on you.
Set up
- Stand tall with your feet hip-width apart and your hands lightly touching the sides of your head.
- Brace your core so your torso feels stable before you start moving.
- Pick a spot ahead of you to focus on for balance.
How to do it
- Lift your right knee up toward your chest.
- At the same time, rotate your torso and bring your left elbow down to meet the rising knee.
- Touch or nearly touch elbow to knee, then lower both back to the starting position.
- Repeat on the other side, lifting the left knee and rotating your right elbow toward it.
- Continue alternating sides at a controlled, steady pace for the set.
Form cues
- Rotate from your torso, not just by reaching with your arm.
- Keep your standing leg soft, not locked out.
- Exhale sharply on the crunch to engage your abs fully.
- Stay tall between reps instead of hunching forward.
Breathing: Exhale as your elbow and knee meet in the middle, inhale as you return to standing tall.
Common mistakes
Reaching the elbow toward the knee with the arm alone instead of rotating the torso.
Fix: Focus on twisting from your ribcage so your whole torso turns, letting the elbow follow naturally.
Rushing the reps so fast that balance breaks down and the range shortens.
Fix: Slow the tempo enough that each knee lift and rotation is controlled and full.
Letting the lower back arch between reps instead of staying braced.
Fix: Keep light tension in your core throughout the set rather than fully relaxing between reps.
How to program it
- 3 sets of 15 to 20 total reps (alternating sides) works well as a standing core finisher, since the bodyweight load and standing balance component keep it moderate rather than maximal.
- It fits naturally into a warm-up circuit or a metabolic finisher because it needs no equipment and gets your core and heart rate up together.
- A moderate frequency of 2 to 3 sessions a week suits it well; the standing, bodyweight nature keeps recovery demand low compared to loaded ab work.
Safety notes
- If balance is shaky, do the movement near a wall or a sturdy piece of furniture you can touch lightly for support.
- Keep the pace controlled if you have any lower back sensitivity; a fast, jerky rotation is where that tends to show up.
Exercise profile
- Force
- Pull
- Mechanics
- Compound
- Category
- Strength
Frequently asked questions
How many reps of elbow to knee should I do?
3 sets of 15 to 20 total reps, alternating sides each time, is a solid starting target for most people.
Can I do elbow to knee without any equipment?
Yes, it's a bodyweight standing exercise from the start; no equipment or floor space beyond where you're standing is needed.
Elbow to knee vs bicycle crunch, which is better for abs?
Both train the same diagonal oblique-and-abdominal pattern. Elbow to knee is done standing, so it adds a balance component and is gentler on the neck; the lying version (air bike in our library) lets you crunch harder since the floor supports your torso.
Why can't I feel my abs working during elbow to knee?
It usually means the reach is coming from the arm instead of a real torso rotation. Slow down and focus on twisting through your ribcage so the crunch actually happens in your abs.