michael kors foto's|Michael Kors wallpaper images How to use a gym crunch machine. 3.1 Adjusting the Machine. 3.2 Proper Posture and Alignment. 3.3 Starting Position. 3.4 Movement and Technique. 3.5 Breathing and Tempo. 3.6 Common Mistakes to Avoid. 4. Targeted Muscle Groups. 4.1 Rectus Abdominis. 4.2 Obliques. 4.3 Transverse Abdominis. 5. Benefits of using a gym crunch machine. Subscribe