 In terms of, I guess you could say, rep ranges and different exercises and growth rates. If everything is, I guess, dependent on how your body responds to it, how do you find what's optimal to you until you've literally done every rep range of every exercise? Because there's no way to really tell. I don't know if it's possible to find what's optimal because it's going to be a moving target. Age is going to affect it as you get older. There's going to be changes depending on how you do the exercise. Interestingly, the repetition range is something that people do have more of a general response to. There are going to be some on average. Most people will respond well to a variety of repetitions. Some people do respond a little bit better to lower or higher repetitions, but most people over a long enough period of time, the repetition range that is effective is pretty broad. In fact, interesting things that have been coming out over the past decade or so, there have been studies that have compared the effects on muscular strength and size with different loads and repetition ranges, including one that just came out recently. They found that regardless of whether or not a person uses a very heavy weight and lower repetitions or a shorter rest, sorry, set duration, or if they use a lighter weight and a longer set duration or higher repetitions, the end results are the same. Now that's on average. If you take a study and you divide two groups up and you compare, you might have some people on either side, again, due to individual variability, that are going to do a little better with one or the other. Now, if you wanted to determine this over a long period of time, what I tend to see with people, if they tend to do better with lower repetitions, is a pattern where they will have difficulty getting past some number, but if you increase the weight slightly when they get to that number, they're able to match it. Going the other way, an indication that somebody might do a little bit better with a higher repetition range, is if they get to their upper rep count and then when you add weight, they have difficulty getting any repetition. Sometimes you have to increase the reps more before you add the weight. So it's, again, something that would need to be experimented with. You can't just do a test and say, well, this person is going to respond better to lower or higher. Actually, you can't do a test in the gym. There's some research suggesting a relationship between ideal repetition range and the genotype for angiotensin converting enzyme, but unless you're going to go and get gene tests and have that looked at, look at basically patterns in exercise performance. If you're aiming for, say, 6 to 10 and you're constantly stuck at 7 or 8, try adding a little bit weight. If you can consistently increase the weight while still hitting that 7 or 8, then you might do well with that. On the other hand, if you get to 10, you add a little bit weight and then your reps drop significantly the next time. You just have a hard time with weight increases. Go back to the previous weight, wait until you get more repetitions before adding a little bit weight. And this tends to work better with people who do a little bit better with higher repetitions. But in general, the majority of people, it doesn't seem to make as much of a difference. Again, you're going to have some people either way. They're going to do a little better, a little worse with higher or lower. But a broad range seems to be effective.