Bicycle Crunch

The bicycle crunch is one of the most effective bodyweight exercises for the obliques because it combines spinal flexion with rotation, the exact job your obliques are built to do. As you alternate bringing each elbow toward the opposite knee while pedaling your legs, you create constant tension through the entire midsection without any equipment. It's beginner-friendly, scalable, and travels anywhere. Done well, it builds rotational core strength and trunk control that carries over to running, lifting, and sport. Done sloppily, it becomes a neck-yanking leg flail. This guide shows you how to make every rep count.

How to do the bicycle crunch

1. Lie flat on your back with your lower spine pressed into the floor and your hands resting lightly behind your ears, fingertips touching but not laced (laced fingers tempt you to pull on your neck).
2. Lift both feet off the floor and bend your knees to roughly 90 degrees, raising your shoulder blades slightly off the mat to engage the abs before you begin.
3. Rotate your torso to bring your left elbow toward your right knee while simultaneously extending your left leg out long, keeping it a few inches off the floor.
4. Drive the rotation from your ribcage and obliques, twisting the shoulder across rather than just flapping the elbow toward the knee.
5. Reverse smoothly to the other side, bringing your right elbow toward your left knee as your right leg extends, like a controlled pedaling motion.
6. Exhale as you crunch and rotate, inhale as you transition, and keep your lower back glued to the floor throughout the set.
7. Continue alternating for the prescribed reps per side, keeping the tempo deliberate rather than rushed.

Muscles worked

The primary muscle is the obliques, the internal and external obliques that run along the sides of your trunk and are responsible for rotating and side-bending the torso. Every time you twist an elbow across to the opposite knee, the obliques contract hard to produce that rotation, which is exactly why the bicycle crunch out-targets a standard crunch for the sides of your waist. The secondary muscle is the abs (rectus abdominis), the front sheet of the core that handles the spinal flexion as you curl your shoulders up off the floor and hold them elevated. The hip flexors also assist by drawing each knee in, while the deep transverse abdominis works isometrically to stabilize your spine.

Benefits

• Trains the obliques through rotation, building the twisting strength that straight crunches miss
• Requires zero equipment and minimal space, so it works at home, in a hotel, or anywhere
• Hits the obliques and abs simultaneously for efficient, time-saving core work
• Improves trunk control and anti-rotation stability that carries over to running and lifting
• Easily scaled for beginners by bending the legs more or slowing the tempo

Common mistakes

• Yanking the neck: Keep hands light behind the ears and lead with your ribcage, not your hands, so your neck stays neutral.
• Just touching elbow to knee: Rotate the whole torso so the shoulder travels across the body, otherwise the obliques barely fire.
• Racing through reps: Speed turns it into momentum-driven flailing, so slow down and feel each side contract.
• Letting the lower back arch up: Press your lumbar spine into the floor the entire set to protect it and keep tension on the abs.
• Dropping the shoulder blades between reps: Keep your shoulders curled off the mat throughout so the abs never get a rest.
• Extending the leg too low: If your back lifts off the floor, keep the extending leg higher until your core can control it.

Form tips

• Lead each rep with your ribcage rotating toward the opposite knee, not with your elbow pulling forward.
• Keep your hands cradling your head with light contact only, never pulling on your neck.
• Press your lower back firmly into the floor to keep tension on the obliques and protect your spine.
• Slow the tempo so you can feel the oblique on each side squeeze at the top of the rotation.
• Raise the angle of the extended leg if your lower back starts to lift, then lower it as you get stronger.

Sets & reps

A great starting point is the FORMA seed of 3 sets of 15 to 20 reps per side with about 45 seconds of rest between sets. For building muscular endurance and definition, stay in that 15 to 20 per side range and prioritize controlled, full rotations over speed. For more strength-focused core work, slow the tempo dramatically (a 2 to 3 second pause at each elbow-to-knee position) and do 3 to 4 sets of 10 to 12 per side. Beginners can start with 2 sets of 10 per side and build up. Because it's bodyweight, progress by adding reps, slowing tempo, or extending the legs lower rather than adding load.

Frequently asked questions