Choosing an appropriate training split requires knowledge of your own recovery abilities and training tolerance. It can be kind of tricky to get that down as starting out in weight lifting usually involves just copying what other, more successful lifters are doing. In the beginning, everybody grows and it’s not until you’ve been around for a while that you recognize that the same old thing doesn’t work or that what will work really well for somebody else may not provide satisfactory results for you.
One of the paradigms that has proven to be very useful in finding appropriate frequencies volumes and intensities for individuals is the concept of fast and slow gainers. To start, let me say that this is a very broad classification and it’s certainly not set in stone. This is by no means a concrete binary. But if we allow ourselves the ability to paint with a broad brush, we can generally rank how sensitive somebody is to any given training stress. It turns out that we can make really good decisions about how to structure their training by better balancing stress and recovery and that is essential for continued growth.

Fast gainers, very broadly, are explosive athletes and those who are predisposed to gaining muscle very quickly. You’re going to see heavier and bigger framed lifters progressed faster from a given dose of training stress because they start out lifting heavier absolute loads. You’re going to see explosive athletes respond better because every effort they put out is a much higher intensity than their non-explosive counterparts; from the get-go, every effort they put out will pack a bigger wallop. This is related to how we program for advanced lifters; being very strong means that every rep carries a bigger total systemic stress and that means that advanced lifters typically can’t train as hard, as often, with as much volume and that they generally benefit for more frequent deloads.
Low-frequency programs fit very well for a prototypical fast gainer. Not only can they get strong with less total work within a week but they actually might benefit from it. If somebody who is predisposed to growing very quickly from a training stress gets overeager and starts packing too many workouts into a short time frame, they’re going to run into a recovery wall and it won’t be until they notice themselves actually getting weaker from work out to work out that it might dawn on them that they need to dial it back.
We can see examples of these types of programs in action, as they typically get recommended by some of the best lifters around (who are, of course, fast gainers themselves). Brian Carroll’s 1020 life is a fantastic book on scheduling a simple sustainable long-term plan for powerlifting growth but his training Is relatively low frequency and low volume AND he recommends a deload every third week. The Lilliebridge method take this one step further by alternating heavy squat and deadlift days every single week. What that means is that anyone following the program is only going to deadlift heavy and squat heavy twice per month.
Now this goes a long way to solving problems for those who tend to overeach too easily as the best thing a talented athlete can do is get out of their own way. However, for somebody who doesn’t grow so quickly, more frequent sessions are going to be required and efforts will have to be more substantial in each one. That’s where programming for slow gainers comes in.
Slow gainers are going to be people who don’t respond to a single dose of training quite as well. Identifying that can be tricky; you might be inclined to think anybody who isn’t a fast gainer must automatically be a slow gainer. Real slow gainers are going to be very resistant to growth from training relative to the rest of the population. They will be outliers, exceptions to the rule, just like the fast gainers. Most of you are going to fall somewhere in the middle (remember, this isn’t a clear binary).
Just because you don’t respond as well as the best 0.1 % doesn’t mean that you should go get yourself a flag that says “hardgainer” so you can wave it around the squat rack during every training session. It just means your training is going to have to bias away from what typically works for them.
We broadly put people in the slow-gainer category who are uncoordinated, have smaller frames, aren’t very aggressive and whose hormones are not optimized for growth: females, under weight lifters, the elderly population, etc. In very very broad terms, these populations will be better with higher training frequency, higher percentages and pushing the envelope a little bit more on each working set. To parapharase Josh Bryant,
“Just like the slow kid has to hit the books harder, slow gainers have to train more often”.
The benefit of being a hardgainer is that you don’t have to worry so much about over-reaching but, rather, detraining. In general, those who fall into this category are going to be better off with more total work done and won’t suffer the ill effects of frequent heavy sessions to the same degree as their fast gainer counterparts.
Identifying which camp you fall into is going to come down to figuring out what causes you to plateau. If overreaching has typically been a problem for you and you find that when you take your foot off the gas and allow yourself to recover big things happen, then you’re probably in fast gainer territory. I would generally recommend a lower frequency 1-2 times per week program with a pretty firm throttle on your RPEs, keeping them in the 7 to 8 range.
If, on the other hand, you haven’t been a savage in the gym, if you’ve been running programs that feature each lift one time per week and have been getting in and out in around an hour, failure to grow may very well be a result of simply not doing enough work. Remember, it’s up to you to titrate your training to find what gets the best outcome so if what you’re doing now isn’t cutting it, you have a choice of training more or training less.
Everybody has the ability to dramatically increase their strength and muscularity. The difference between fast and slow gainers isn’t their potential for succes, but rather what they can get away with in thier training. Don’t fall into the trap of thinking that, just because there’s slightly more work required for you to get the same outcome as somebody else, that it’s the same as being a lost cause so you might as well not even bother. That’s a loser mentality. If anything, you should see as empowering the fact that you have the ability to train smarter and can beat the other guy on grit alone when they are coasting on their God-given talent. You need at least one of the two if you want to succeed: if you’re lacking in both grit AND talent, then I recommend you hedge your expectations.