We are going to do Swiss ball jackknifes today. To perform a jackknife you get in the push-up position with your legs extended and your shoelaces on the ball. Then tighten your abs up and pull the ball toward you chest. Keep your back nice and flat. Then, roll it back to the start position.

PERFORM PER ROUND:

• 25 sec  – Jackknife
• 15 sec – REST
• 25 sec  – Jackknife
• 15 sec – REST

Rest 1 Minute between rounds

NUMBER OF ROUNDS:

• Beginner – 2
• Intermediate – 4
• Advanced – 6

Your Gymboss Interval Timer will easily time this workout.