Why are there so many exercises in bodybuilder workouts?

Question

I did Starting Strength for 4 months and saw good results. I've changed to a novice bodybuilder workout, and noticed that the rep/set range has increased from 3x5 to 4x10, which makes sense for hypertrophy gains.

What I don't understand is how and why you need to do so many different exercises per body part..And I've seen this in many bodybuilder routines... E.g. on SS, you only did 15 reps of bench press, but on a typical chest day you might have to do bench, incline bench, flys...

1. How can you be expected to do flys property, when you have just done so many reps of bench + incline bench? How can you be expected to work your biceps or another small muscle group effectively when you have just complete one isolation exercise?

2. Why do you need to do flys, lateral raises etc when you already do sooo many compound movements such as shoulder presses or bench presses.

Answer 1

I don't know as much about the biological makeup of muscles as I should, so my answer is going to be based on the results I and many other fitness fanatics have had from doing workouts similar to the ones you have described.

"How can you be expected to do (exercise A) properly when you have just exhausted the     
muscle group from (exercise B)?"

Simple - if you cannot correctly perform exercise A because you are exhausted, decrease the weight. It doesn't matter how much weight you use as long as you - 1. have good form 2. are pushing yourself to your desired limit.

From my personal experience, my chest days generally consist of multiple different bench press exercises, with some flys and some serratus work. By the end of the workout I have done about 5 different exercises. The reason I can still do flys properly after I have exhausted my chest from bench press is because I use the proper weight to maintain good form during the exercise.

"Why do isolation workouts after doing compound workouts?"

I don't know quite as much about this question other than what seems like common sense. The answer is really in the question. Compound workouts are great for hitting multiple different muscles but in order to increase mass and definition you have to isolate different parts of those muscles which aren't necessarily worked by the compound exercises. Bench press does not work your outer chest muscles nearly as much as isolating them with flys. Still using chest as an example, your chest will not look proportional or very good in general if you only did flat bench press. Incline bench works the top of your chest while decline works the bottom.

This is all directly relatable to other muscle groups as well and does not just apply to chest workouts.

In my opinion and I think most people would agree, bodybuilding is about appearance - vascularity, definition, symmetry, striations, mass etc. Strength training is simply about getting stronger. The two are very different so don't be surprised that BB requires isolation workouts as well as compound workouts.

Answer 2

Starting strength is an excellent beginner strength training program. However, bodybuilding programs are more focused on muscle hypertrophy than strength.

Though they are obviously related, strength and hypertrophy are different. Strength training involves lower reps and longer rest periods than hypertrophy training.

Why so many different exercises? There is some recent research showing that different exercises can activate different parts of a muscle. For example, a squeeze press provides greater activation of the clavicular head of the pec than a db fly.

That could be a reason. I'll link if I can find the study.