In the early months, I struggled. I had just discovered this website and was beginning to read the articles. Everything written in them was new information to me. So, when I started, I didn't know what I was doing. If your still interested, here's what I remember doing. 2 sets of crunches and 2 sets of reverse crunches, each set on about 1 minute rest (I didn't time it). I completed sets until complete failure. Eventually I added sit-ups. I do not remember how long I went before I added sit-ups.
During the same period, I was also beginning to work on my back and lower and upper body. I was also going to taekwondo 2 times a week. All of this proved too much for me. I grew tired and did not look forward to working out. I did not wake up healthy, happy, and full of energy. Instead, I was exhausted, grumpy, and my knees, hips, and back were aching, so I stopped working out. I continued, however, to go to taekwondo class. As I read more of the articles, though, I began to question the quality of my instruction, and whether I was fit enough to learn a martial art. I have since quit, and I'm really glad I did.
Over time, I read and re-read all of the articles, Kurz's "Science of Sports Training," and Tudor Bompa's "Periodization for Sports" (see the Athlete's Bookshelf link in any of the articles).
With all of that in mind, I created a new workout plan. Here's what it looks like currently as far as my abdominal workout is concerned. I work out in 3-week cycles: low, medium, and high intensity. Week 1 (2 workouts): 2 sets of crunches until slight discomfort (slight burn or sense of weakness); 1 set of sit-ups. I perform a predetermined number of sit-ups, which equals the number of sit-ups I performed in the last workout of the previous week. If I begin to feel a slight burn or sense of weakness before that point, however, I stop. Rest interval = 1 minute.
Week 2 (3 workouts): Crunches: Same deal except I go until I experience a greater sense of burn and/or weakness. Sit-ups: same number as in Week 1 plus an additional predetermined number. If I feel too much burn or weakness or if the quality of the sit-up begins to decline, I will stop, but I've never gotten to that point. Rest interval is the same as in Week 1.
Week 3 (3 workouts): Crunches: Same deal except I go until failure (i.e., the quality of my repetition begins to suffer or I can no longer breath in a controlled manner). Sit-ups: Same deal, except I add another predetermined number of repetitions. Every 6th week, in the last workout for the week, I skip the crunches and do 1 set of as many quality sit-ups as I can.
I like this workout because (1) I've progressed; (2) it fits my time constraints, and my physical and mental energy level; and (3) it is both rigid and flexible enough that it prevents me from overworking my body, which I am prone to do. Eventually, this workout will change. At some point, I'll be adding weights and twists and perhaps dropping a set of crunches or adding another set of sit-ups.