Sequence - What stage of the workout should I train my abdominals?

The continuing dominant paradigm is that the abs should be trained last in the workout. But what if they're the weakest body part? Doesn't seem to matter to some "experts." What if they're the number one training focus for performance? Again it doesn't seem to matter - they're placed last. Why? The repetitive answer I get to this is, "They cause fatigue of stabilizers and it would be dangerous to do things like squats after doing abs."

Where's the evidence, empirical or research? Again, that doesn't seem to matter. Nobody does abdominals first! What a load of trash! The excuses support the paradigm, nothing more. I train abdominals first when they're priority for whatever reason, and only put them at the end of the workout when I don't want to dilute substrate or emotional energy prior to maximal strength workout. In other words, I wouldn't want a total body fatigue draining the neuromuscular system, thus reducing the potential load. So there's an occasional reason to place ab training last in your workout, but has nothing to do with preventing injuries!

Periodization - How should I periodize my abdominal training?

Generally speaking I like to commence a training career, year or block, with the mastering of control/stability sub-quality (See below), and then over time phase along the sub quality continuum to my end goal. This is simply moving from left to right along the strength sub-qualities continuum. If the sub-quality I want to peak on is from earlier along the continuum, I return to it.

Control Stability > General Strength/Hypertrophy > Maximal Strength > Speed Strength > Strength Endurance

Muscle Group Division - Is there more than one abdominal muscle?

I break the abdominal down into six muscle groups or functions. This may not be technically correct in the strictest sense, it's just a simple and effective approach to ensuring exposure to every @part@ of the abs and other trunk stabilizers.

1. "Lower" abdominal e.g. hip flexion

2. "Upper" abdominal e.g. trunk flexion

3. Lateral flexion e.g. side bends

4. Rotation e.g. twists

5. Co-contraction of abdominal and gluteal

6. Integration of total trunk stability

Muscle Sub-Group Allocation - Which of the 6 sub-groups do I train on which days? If you're training with a day or more rest between sessions, you can afford to do all six sub-groups within one training session. You don't have to, but you can. If you're training two or more days in a row with no day off, then I recommend you don't train all six in the one session. I might allocate abdominal sub-groups in the following way in a four day split:

A - Lower Abs, Lateral flexion, co-contraction

B - Upper Abs, rotation

C - Lower Abs, lateral flexion, co-contraction Integration

D - Upper abs, rotation