Jackknife
Plane of Motion
Sagittal
Muscle Focus
Spinal Flexors
Rectus Abdominis, External Obliques, Internal Obliques
Brings the hips overhead and maintains the c-curve overhead.
Co-contracts with the hip extensors when shooting the legs up to the ceiling.
Controls the body in the roll down back to the mat.
Spinal Extensors
Erector Spinae, Semispinalis, Deep Posterior Spinal Group
Works with the spinal flexors to maintain the body in a c-curve overhead.
Work with the hip extensors when reaching the legs to the ceiling.
Work with spinal flexors and hip extensors on the roll back down to the mat.
Hip Flexors
Iliopsoas, Rectus Femoris, Sartorius, Tensor Fasciae Latae, Pectineus
Keeps the legs off the floor in the beginning.
Assists with the spinal flexors to begin the rollover.
Hip Extensors
Gluteus Maximus, Hamstrings
Keeps the legs from dropping to the chest when overhead.
Shoots the legs up to the ceiling.
Other Muscles at Play
Anterior spinal stabilizer provides lumbo-pelvis stabilization and support on the spine.
Hip adductors keep the legs glued together throughout the exercise.
Knee extensors keep the legs straight.
Plantar flexors keep the feet pointed.
Shoulder extensors provide an anchor point into the floor to create stability.
Objectives
Strengthen the back extensors and hip extensors.
Improve flexibility and control over the lower back muscles.
Increase the flexibility and strength of the hamstrings and hip extensors further.
Improve flexibility through the posterior chain.
Increase the co-contraction of the deeper core with the hip extensors for stability, balance and coordination.
Focus on breathing to synchronize the movement.