There are 7 categories of work-outs that I use, each with a variety of exercises that satisfies that category's requirements. If you know you have a Category C work-out scheduled, you still have a selection to choose from. Depending on the time of year, I plan my training by how many A, B, C, D, E, F, and G components will make up the work-out. To replicate the racing form, I try and break down the racing stride and work each segment. Going to a track meet and only racing at 100M, 200M, 400M, 400IH, and a relay should be a tea party compared to work-outs.
Flexibility is implied as a critical aspect to any work-out program.
It is so important, that if somebody held a gun to your head and told you to chose between exercising and stretching, stretching is more important selection. But there are a number of work-out protocols that will satisfy the strength requirements. I like to repeat the entire circuit routine three times. Using the circuit training technique, you work one muscle group, then go on to a different muscle group, providing some rest to the muscle group just worked. But because there is minimal interval between the different exercises, the heart muscle gets a continuous work-out.