Because of its ability to target the entire core, the Swiss-ball crunch should be a staple in your workout. The exercise primarily works the rectus abdominis, or six-pack muscles, and the transverse abdominis. But when performed properly, it also calls on muscles that stabilize the hips and lower back. Problem is, many men position themselves incorrectly on the ball and don't fully engage the transverse abdominis, which is a band of muscle that pulls the abdominal wall inward to protect you and helps activate other muscles. Pull your belly button in toward your spine and hold it there throughout the move so you keep the transverse abdominis contracted.
Once you've mastered the move, you can add resistance with a medicine ball held at arm's length toward the ceiling or a weight plate held behind your head. Perform three sets of eight to 12 repetitions, resting for 60 seconds between sets, once or twice a week.
1. Sit on a Swiss ball with your feet flat on the floor, shoulder-width apart. Walk your feet forward as you lie back on the ball. Stop when the ball is under your hips, lower back, and middle back, knees bent 90 degrees.
2. Your lower back should feel like it's curved around the ball. Keep your head in line with your upper body. Place your hands behind your ears and draw in your abs.
3. Raise your chest up and slightly forward in a crunching motion. Do not pull on your neck to initiate the crunch. You've reached the end of your range of motion when the middle of your back loses contact with the ball. Pause, then slowly return to the starting position.