Elbow-To-Knee
- Target muscle
- Obliques, Rectus Abdominis
- Synergist muscles
- Gluteus Maximus, Iliopsoas, Quadriceps
- Equipment
- Body weight
- Body part
- Waist
- Type
- Strength
The elbow-to-knee is a bodyweight core exercise that primarily works the obliques and rectus abdominis through a cross-body twisting crunch. As you bring one elbow toward the opposite knee, the glutes, hip flexors (iliopsoas), and quads assist by drawing the leg up. It's a beginner-friendly move for building rotational ab strength with no equipment.
How to do the Elbow-To-Knee
- 1Lie on your back with your knees bent, feet flat on the floor, and your hands lightly behind your head with elbows pointing out to the sides.
- 2Brace your core by gently pulling your navel toward your spine, and press your lower back into the floor.
- 3Curl your head and shoulders off the floor while lifting one knee up toward your chest.
- 4Rotate your torso to bring the opposite elbow across your body toward the raised knee until they meet or nearly touch.
- 5Pause briefly at the top and squeeze your obliques without yanking on your neck.
- 6Lower your shoulders and leg back to the starting position under control.
- 7Repeat on the other side, alternating elbow to opposite knee for your target reps.
- 8Finish your final rep, then relax your head, neck, and legs back to the floor.
Form tips
- Drive the rotation from your waist and obliques, not from your arms — your hands only cradle your head, they don't pull it.
- Move at a controlled tempo and exhale as you crunch up to deepen the contraction in your abs.
- Keep your lower back lightly pressed into the floor throughout to keep tension on the core and protect your spine.
- Lift the opposite shoulder off the floor, not just the elbow, so the twist comes from your trunk rather than your shoulder joint.
Common mistakes
- Pulling on your head and neck with your hands, which strains the cervical spine instead of working the abs.
- Rushing the reps and using momentum, which swings you through the movement and removes tension from the obliques.
- Only reaching the elbow across without rotating the torso, so the twist stops short and the obliques barely engage.
- Letting the lower back arch off the floor, which shifts load away from the core and can stress the spine.
Frequently asked questions
What muscles does the elbow-to-knee work?
It primarily works the obliques and rectus abdominis, with the gluteus maximus, hip flexors (iliopsoas), and quadriceps assisting as you draw the knee up.
Is the elbow-to-knee good for beginners?
Yes. It's a bodyweight movement that needs no equipment and can be scaled by slowing the tempo or reducing range, making it a solid starting point for building core and oblique strength.
How many reps and sets should I do?
Aim for 2–4 sets of 10–20 reps per side, alternating sides. Focus on a controlled twist and full contraction rather than speed or high counts.
How is the elbow-to-knee different from a bicycle crunch?
Both bring the elbow to the opposite knee with a twist, but the bicycle crunch extends the other leg out straight and pedals continuously, while the elbow-to-knee can be done one side at a time with feet starting on the floor.
Where should I feel the elbow-to-knee?
You should feel it mainly in your obliques along the sides of your waist and across the front of your abs. If you feel it in your neck, your hands are likely pulling your head instead of your core doing the work.
