The fourth human movement is the trunk rotation. It is far superior to the countless ab machines in gyms across the country as well as those silly ab devices on info-mercials. The term "trunk" represents the entire abdominal region and hip structure including the lower back and glute (butt) muscles.
Typical ab exercises only stimulate the rectus abdominus, or the magical "6-pack". Well, there is more to optimal human movement than a 6-pack, whether it's muscle or beer.
Performing crunches on the floor, swiss balls, or ab machines focuses excessively on the front stomach muscles due to the limited range of crunches. A quick look at the abdominal musculature illustrates the need for comprehensive training.
- rectus abdominus - "6-pack"; flexes the trunk; moves the torso towards the pelvis
- transversus abdominus - forms the abdominal wall; provides trunk stability; maintains internal abdominal pressure; protects the internal organs
- external oblique - located on each side of the rectus abdominus; right ext. oblique performs a left rotation; left ext. oblique performs a right rotation
- internal oblique - inside of the hip bones; left int. oblique performs a left rotation; right int. oblique performs a right rotation
Unfortunately, items 2, 3, and 4 are often neglected during the typical floor crunch or ab machine workout. Therefore, part 2 will detail specific trunk movements to train these four areas, and as a bonus, stimulate the lower back and glute muscles.
Make it a great day!