BOSU Myotatic Crunch
What Is the BOSU Myotatic Crunch?
BOSU Myotatic Crunch is an isolation exercise that primarily targets the core, with the obliques and hip flexors assisting. It is an intermediate-level movement performed lying back over the dome of a BOSU Balance Trainer with the arms held straight overhead, starting each rep with the torso arched back over the dome so the abdominals begin in a stretched position.
The name comes from the myotatic reflex, the stretch reflex that makes a muscle contract when it is lengthened. The idea is to lower slowly into the stretch and then turn out of it smoothly into the crunch. In practice, two things set it apart from a regular BOSU Crunch. The extended start lets the abdominals work through a longer range than a crunch that begins with the torso resting along the dome, and the overhead arms move the weight of the upper body further from the waist, which makes the same body weight harder to lift.
The rectus abdominis does most of the work as the ribs curl toward the pelvis, while the external obliques help flex the trunk and keep it from tipping sideways on the dome. The hip flexors take a larger share as the torso rises, which is why the rep stops when the arms point at the ceiling rather than continuing to a full sit-up. The shoulders work lightly to hold the arms in line with the ears throughout.
The exercise suits clients who can already do slow, controlled crunches and want a harder body-weight option before adding load. It fits at the end of a session as core accessory work, done with a slow lowering phase rather than for speed. Anyone who cannot yet control a floor Crunch or a BOSU Crunch with the arms crossed should build those first, and people whose lower back dislikes arching can train the core with the Dead Bug instead.
Muscles Worked
- Rectus Abdominis
- Primary
- External Oblique
- High
- Rectus Femoris
- Medium
- Deltoid
- Low
- Sartorius
- Low
- Serratus Anterior
- Minimal
Instructions
- Place the BOSU on the floor with the dome facing up.
- Sit on the front edge of the dome, then lie back so your lower and middle back rest over the top of it and your hips stay low near the floor.
- Bend your knees and plant your feet flat on the floor, about hip-width apart.
- Extend your arms straight overhead with your hands together and your upper arms beside your ears.
- Slowly lower your upper back and arms back over the dome for 3 to 4 seconds until you feel a stretch across your abdominals, keeping your shoulders off the floor.
- Pause in the stretch for 1 to 2 seconds.
- Exhale and curl up, bringing your ribs toward your pelvis while your arms stay in line with your ears.
- Stop when your arms point straight up at the ceiling, with both feet still flat on the floor.
- Inhale and lower slowly back into the stretch, then repeat for the desired number of reps.
Common Mistakes
Dome in the wrong spot
With the dome under the shoulder blades the stretch disappears and the neck takes over, and with it under the hips the lower back ends up holding the arch, so set it under the lower and middle back.
Forcing the stretch
Dropping far back into a hard arch pinches the lower back, so lower only as far as feels like a comfortable stretch across the abdominals.
Swinging the arms forward
Throwing the arms toward the knees to start the rep turns it into momentum, so keep the upper arms beside the ears and let the torso carry them.
Bouncing out of the bottom
Dropping quickly into the stretch and rebounding out of it takes tension off the abdominals, so lower slowly and pause briefly before curling up.
Coming up too far
Sitting all the way upright hands the work to the hip flexors and lets the abdominals rest, so stop when the arms point at the ceiling.
Feet lifting off the floor
When the feet rise, the hip flexors are hauling the torso up, which is a sign to shorten the stretch or bring the hands closer to the head.
Injuries
BOSU Myotatic Crunch is a medium risk exercise when performed with proper technique. The load is only body weight, but each rep begins with the lower back arched over the dome and the arms extended overhead, which lengthens the lever the abdominals have to lift. The most common complaints are a pinching feeling in the lower back from forcing the stretch too far, neck strain from pulling the head forward, and hip flexor tightness when the torso comes up too high.
Set the dome under the lower and middle back before the first rep, lower into the stretch slowly, and stop at a point you can hold comfortably with the shoulders still off the floor. Keep the upper arms beside the ears so the head moves with the torso instead of leading it, keep both feet flat on the floor, and finish the rep when the arms point at the ceiling.
To make it easier, lean back less at the bottom, bring the hands in toward the forehead to shorten the lever, or go back to a BOSU Crunch with the arms crossed over the chest. A floor Crunch or the Dead Bug trains the abdominals without the arched start. To progress, slow the lowering phase further, then hold a light weight plate or dumbbell in both hands overhead.
Stop if you feel sharp or pinching pain in the lower back, pain or tingling that travels into a leg, neck pain that does not ease when you relax the head, or dizziness when lying back. People with pain that worsens when they arch or bend the lower back, a known stress fracture of the spine, or a current disc injury should get clearance from a clinician before doing this exercise.
- Primary Focus
- Core
- Equipment
- Balance trainer
- Modality
- Strength
- Difficulty
- Intermediate
Alternative Exercises
Frequently Asked Questions
- Q: What does "myotatic" mean?
Myotatic refers to the stretch reflex, the automatic contraction a muscle makes when it is stretched. The exercise is built around starting each rep with the abdominals lengthened over the dome, so the practical result is a longer range of motion than a standard crunch.
- Q: How is it different from a BOSU Crunch?
A BOSU Crunch starts with the torso resting along the dome and the arms crossed over the chest. The myotatic version starts with the back arched over the dome and the arms straight overhead, so it covers more range and the longer lever makes each rep harder.
- Q: How far back should I lean?
Lower until you feel a comfortable stretch across the front of your stomach, with your shoulders still off the floor. If your lower back pinches or your hips lift off the dome, you have gone too far.
- Q: What tempo should I use?
Lower into the stretch over 3 to 4 seconds, pause for 1 to 2 seconds, then curl up over about 2 seconds. The slow lowering and the pause are what keep the reps honest, so do not bounce out of the bottom.
- Q: How do I make it harder?
Once you can do 10 to 15 slow reps with good form, hold a light weight plate or dumbbell in both hands overhead. Because the weight sits at the end of a long lever, start lighter than you would for a crunch with the weight on your chest.
- Q: Can I do it with lower back pain?
Only if arching back over the dome feels comfortable. Many back problems, especially ones that hurt when you lean backward, are aggravated by that position, so switch to a bracing exercise such as the Dead Bug and check with a clinician if the pain persists.