Elbow-to-knee
beginner strength exercise · body weight · targets abs
- Body part
- waist
- Primary target
- abs
- Equipment
- body weight
- Difficulty
- beginner
The elbow-to-knee is an oblique-focused ab exercise performed lying with hands behind the head and one leg crossed over the other knee, then bringing the opposite elbow toward the crossed knee in a controlled crunch motion. The cross-body pattern engages the obliques alongside the rectus abdominis, producing efficient combined ab work. Most ab exercises engage the front abs primarily; cross-body movements like elbow-to-knee shift loading toward the obliques. For trainees seeking direct oblique work without weights or equipment, this exercise provides accessible training that compound exercises don't replicate. Where this earns its place is as accessory oblique work in core programs. Combined with planks, hollow holds, and front-ab exercises, elbow-to-knee variations complete the ab training spectrum. The cross-body coordination element also makes the exercise mentally engaging — preventing the boredom that pure repetition can produce.
Why train the Elbow-to-knee?
- Targets obliques through cross-body crunch pattern.
- Combines front-ab and oblique work in one exercise.
- Accessible to all fitness levels.
- Useful as accessory work in core training.
- Pairs naturally with rotational and isometric core exercises.
- Costs nothing and requires no equipment.
How to do the Elbow-to-knee: step by step
- 1Start by lying flat on your back with your knees bent and feet flat on the ground.
- 2Place your hands behind your head with your elbows pointing outwards.
- 3Engage your abs and lift your upper body off the ground, bringing your right elbow towards your left knee.
- 4At the same time, bring your left knee towards your right elbow, creating a twisting motion.
- 5Pause for a moment at the top, then slowly lower your upper body and extend your legs back to the starting position.
- 6Repeat the movement, this time bringing your left elbow towards your right knee and your right knee towards your left elbow.
- 7Continue alternating sides for the desired number of repetitions.
Muscles worked
Primary
abs
Secondary
obliques
Common mistakes to avoid
Pulling on the neck
Hands behind head are a guide. Let the obliques do the work.
Bouncing through reps
Slow controlled motion produces oblique engagement.
Cutting range
Bring elbow and knee close together. Partial reps reduce stimulus.
Letting the lower back arch off the floor
Press lower back into floor throughout.
Skipping the second side
Always do both sides equally.
Easier and harder variations
Easier
Reduce range or do shorter sets. Or perform with feet flat on floor instead of crossed leg.
Harder
Slow tempo. Or hold the contracted position 1-2 seconds. Or add ankle weights.
Alternative exercises
Bicycle crunch
Continuous alternating version. More dynamic.
Russian twist
Rotational core work.
Side plank
Isometric oblique work.
How to program the Elbow-to-knee into your training
Sets and reps: 3 sets of 12-20 reps per side. Frequency: 3-4 times per week. In core sessions: as accessory after main exercises.
Recovery and frequency
Minimal recovery cost. Daily training tolerable.
Frequently asked questions
How many reps?
12-20 per side.
How often?
3-4 times per week.
Will this give me obliques?
Builds the muscle. Visibility depends on body fat.
Elbow-to-knee vs bicycle crunch?
Bicycle crunch is continuous alternating; elbow-to-knee is more isolated per rep. Both work.
Should I add weight?
Eventually, yes — ankle weights or hand weights for serious oblique development.
Is this safe for back?
Generally yes when range stays controlled. Sharp pain warrants stopping.
Useful tools for this exercise
Build a workout with the Elbow-to-knee
Puna gives you guided bodyweight workouts you can do anywhere — no equipment, no gym, just structured progressions that build real strength.
