Six pack abs with the knife exercise –

Marcelo Correa (/)

Called a switchblade, the sit-up gained its name for making the movement that mimics the performance of the tool. “It demands a lot from the obliques, transversus and rectus abdominis”, explains trainer Chico Salgado, from Rio de Janeiro. That is, he draws the buds of his belly. “But it also works the posterior thighs”, he adds. As strength is needed in the core – a set of muscles that supports and protects the center of the body –, the exercise is recommended for those who already have an intermediate level of physical conditioning. “Difficulty increases as we add reps into sets or do all the reps on one side then the other.”

Carol teaches

Lying on your back, one of your knees bent and the arm on the same side extended above your head – the other is glued to your torso. Raise, at the same time, the arm that was behind and the opposite leg, until the tips of the toes and hands meet in the center of the body, making the total contraction of the abdomen. The shoulder blades must come off the ground.

Chico suggests 10 to 15 repetitions for intermediates and 25 to 30 for advanced ones.