Take Heed, the Iron Guru speaks:

“Do no more sets and reps than you would on any other muscle group, etc. Add weight by holding a plate behind your head. Let’s take first things first, get rid of all the fat you can before you start your abdominal program. Otherwise, you will be disappointed because abdominal exercises do not reduce fat. Only fast training where heart and lungs are involved will have any effect on your metabolic rate. Another aspect, of which no one is aware, is that abdominal work should never be done by a beginner in weight training. Any abdominal exercises involve the Solar Plexus. This area sometimes known as the “second brain”. Here can be found a great network of nerves and blood vessels that join and congregate. Abdominal work is such a shock to the nervous system that I could take any undeveloped beginner in my gym and add abdominal work and it would stop all muscular gains. Even stars like Larry Scott and Don Howorth rarely work their abdominals because of the shock to the arms which they are so proud of.

It should be understood that full sit-ups and leg raises are not abdominal exercises. These movements work the Psoas Major and Psoas Minor group. The Quadratius Lumborum are also utilized. The Psoas Muscles connect the upper femur bones of the leg to the lower lumbar region of the spine. This large muscle pulls the upper body to a sitting position, or pulls the legs up, as in the leg raise. You are also employing the Sartorius in the leg raise. The stomach muscles of Rectus Abdominus attach to the pelvic basin and the junction of these points. To illustrate, lie flat on your back, roll your shoulders and head foreword. At the same time raise your pelvis upwards and back towards your chest. This movement is basically the only function of the abdominals. To isolate the Psoas Muscles so that you don’t inadvertently pull with them, spread your knees and pull your heels towards your buttocks. Now, in this frog position place your hands behind your neck and perform 1/4 sit-ups. Cramp the rectus at the top of the movement by performing one burn.”

– Vince Gironda