Bench Jackknife

Bench Jackknife Basics

Primary muscles worked: Rectus Abdominus

Synergist Muscles: Transversus Abdominus, Obliques

Mechanics: Isolation

Equipment: Flat Bench

How To Perform The Bench Jackknife

• Begin the bench jackknife, by laying with your back flat on a bench.
• Your butt should be on the edge of the bench so that your legs are suspended over the edge. Keep your legs and feet together.
• Place your arms up in the air with your hands side by side.
• Now, lift your legs straight up in the air toward the ceiling while simultaneously lifting your upper body off of the bench. You should attempt to reach your hands toward your toes.
• Perform the movement in a slow and controlled manner to ensure that you are getting proper activation of your muscles.
• Once you have reached the top position, hold it for a brief moment, and then lower your legs so that that are in line with the bench are your upper body is flat on the bench.

Bench Jackknife Tips

• Do not allow your legs to go lower than the line of the bench to ensure you do not create excess curvature of the spine.
• Also make sure that you do not raise your upper body by leading with your head. Leading with your head will cause you to activate muscles in your neck to help bring your body upward which can cause head and neck aches.
• Remember the goal is to work the abdominals not your neck.

Bench Jackknife and Sports Application

The bench jackknife is an excellent exercise for developing the lower abdominals of the core. The lower abdominals are often under trained in athlete's which leads to imbalances causing other muscles to overcompensate. Since the lower abdominals are so close in proximity to the legs, their development is highly critical in sports that require power transference from legs to the upper body. Throwing motions, rowing, and punching are just a few examples of the many examples of motions that require strong lower abdominals.