Hypertrophy is the medical term for increasing the size of something without increasing the number of cells. Muscles can undergo hypertrophy but you cannot grow new muscles cells, just increase the size of the ones you've got.  This is important because the actual mix of various fiber types cannot be changed, contrary to popular belief.  One of the important functions of a good coach is to spot the type of fiber that an athlete has and direct him/her to a proper sport.

Ask yourself why you want to get bigger, because I'll bet you haven't framed the question right. So there. OK, I admit I am grumpy, because I've had a lot of people ask me how I "get so big." What they mean is that I look really well defined and this is most always not because I've gained mass, but because I've been doing a lot of cardio and lost weight. You see,  most people want to look stronger. This does not necessarily involve either strength or hypertrophy! This involves reducing the amount of bodyfat until your muscles stick out. This is crucial because hypertrophy training requires that you up your intake of calories to grow more muscle. As such, you get a corresponding although hopefully small increase in fat. Body sculptors are really good at playing off these two modes and refer to a growth vs. cutting phase ("cutting" is just that, cutting your calories and if you do it enough your muscular definition increases and you look "cut". The slang for even lower bodyfat is "shredded".)  Losing weight means you lose muscle too. If you have a 1,000 calorie/day deficit you will lose 1 kg (2 lbs.) or so a week. This is about the most you can safely lose and about 1/4 of the weight lost will be lean tissue. Can't be helped.  I'm a pretty skinny guy to start with, so being a bit overactive and dropping, say, 5 lbs means I might well go from 8% bodyfat to 5% which is extremely lean.  Even though I know I've lost some muscle, I get compliments on how I've bulked up. Nope, this is a strictly cosmetic effect. Below is a famous sequence of shots of the bodybuilder Sebastien Cossette (known as "Da Freak" to other body builders). He lost 20 lbs. between the left hand photos and right hand photos (210 lbs to 190 lbs.) which means he actually had approximately at 4 - 5 lbs. loss in actual muscle.
Sebastien Cossette loses 20 lbs.

The bottom line I've gleaned from training oh so many years is that functional strength just looks better and being skinny helps show muscles. Most body sculpting is really high maintenence because you have to balance all the various body parts with isolation exercises or you look pretty lopsided. This can be done but you'll be in the gym 4 hours a day, no joke. Generally functional training just keeps your muscles more balanced looking and you will look and be strong. I had pooh-poohed hypertrophy training until post-op after hip replacement surgery because I had to actually grow muscles (the so-called "butt project").  This blurb organizes (at least I hope it does) my experiences. I thought I'd just put it all in a webpage and have done with it.  It is good to know how to do this and how it works.

So how much muscle can I actually gain?

Let me guess, you just read up on a program that offers to pack 40 lbs of muscle on in a month, right? Hang on there for a sec before you sign up... You must make a difference between weight and muscle. In a highly conditioned athlete, as much as 40% of the muscle is glycogen, a form of sugar. A lot of programs will claim you can gain a ton of muscle in a month but that is really rubbish. Really. Here is the lowdown on what happens. When you train hard you damage muscle which is replaced with stronger muscle. This rate at which this happens is called protein turnover and for human muscle (regardless of gender) this takes about 180 days or 6 months. That is right. To completely change how a muscle is put together takes at least 6 months. Studies on very strong people (this is important) show that about the maximum anyone can gain runs at theoretical limit of about an ounce (25g) per day (about 24 lbs/year), over their whole body. This works out to a few grams for even the largest muscles. The actual maximum sustained observed amount was about 18 lbs in a year. A year is a really long time to be on a training program like that so the max is probably only attainable for a little while. Note that the amount of muscle you can grow is proportional to the amount present (yeeee-haaaa a first order differential equation!). The people in these studies were normally top-notch athletes who have a large amount of muscle to begin with, and knew how to lift correctly so they could maximize gains. A more reasonable amount (what I have sustained for several months) is roughly .5 - .75 lbs/month -- and this takes into account gaining fat, water weight and whatever else. I am just talking about pure, verifiable muscle.

Another issue here is not just that gaining muscle takes time and hard work, but there is a learning curve in getting your body ready and able to do this. It requires good technique in the lifts and diligence in their performance. You will do nothing much if you work like everyone else, i.e., head to the gym for a few weeks to "get stronger" and kinda sorta pick up stuff, then quit, although you could end up sporting a major injury. Most of the progress people see in that case is neurological in origin, meaning that after a few weeks their central nervous system is finally starting to operate at a sufficiently high level to get some work done. (This effect is more pronounced the less physically active you have been and it is well known among trainers that a client of this sort can get major gains in all their lifts from even riding a stationary bicycle for a bit. All is because they are so neurologically inactive that they can't even figure out how to turn the muscles on voluntarily. A simple repetitive movement that they can do will make their central nervous system start to operate.) A neurological increase is faster than growing muscle and this is point at which most people declare victory and move one.

To get serious growth is a multi-month if not year program. Getting really big (like one of the pro body builders) will take up to 5 years of sustained, hard training -- it takes time to gain 50 - 60 lbs. of quality muscle. There are no shortcuts here. Anyone who is "hyoog" has put in serious training and time.

A few definitions

To get the ball rolling here, you should be prepared to do a little bookkeeping and math. Your total work for a given exercise is the product of the weight and the number of repetitions. So if I do 25 reps of  100 lbs. I have done 2,500 lbs. total work for that exercise. (OK, we could get carried away and figure the distance to get the actual textbook definition of work. We could even divide by the amount of time to get the power used, but c'mon, I'm trying to keep it simple.)  Calculating lifting poundages best to do per exercise.

The baseline for movement is with no weight and if upping the weight to the point you cannot do a full range of motion for a set occurs, you are losing a functional training effect. Never sacrifice form, since bad form just means some other muscles are doing the work rather than the ones you want. Moreover, this means you are teaching your body that when the loads get heavy, you have to do something other than the lift. Think about that. Your last couple of crappy reps offsets any careful prep work. If you're sloppy, drop the poundages before you get hurt.  Also, be aware of the difference between compound and complex exercises. You should stick with simple taiso movements while you are doing a hypertrophy phase and then go back to complex exercises.

Strategic deconditioning  is where you essentially back off of whatever plan you are using. You have to do this. You grow between workouts, not during them! The reason deloading is required too is that muscles respond not to absolute load, but relative load. If you take some planned time off between hypertrophy methods, you will grow more muscle.  So,  if you have hit the end of a hypertrophy cycle, starting a new one should mean you drop the poundages back down. Good strategy is to look at your total work for an exercise and snake that down, since just looking at reps and poundages can be misleading. Remember that nobody has a good explanation as to why you can't just gradually increase loads for a few years and end up benching a couple of tons. In effect, the body is marvelously adaptive and this is the most important survival ability we got from Evolution. Once the body quits adapting, you are left with relative changes rather than absolute ones. One thought is that one of the times I looked huskiest was when I switched from using weight machines to freeweights (immediately post-op). This lasted a few months until my body adapted so that even though I am now lifting easily twice what I was then, I got physically quite a bit smaller for a while. Also in practice life interferes with training so building in peaks and valleys to your training lets you regulate better what you do, rather than having your plans thwarted by work, family and other obligations.

nRM n-repetition max. The number (n) of repetitions you can do of a given exercise at a given load with proper form. So if you can lift 100 lbs. 8 times but would fail on your ninth try you 8RM for that exercise is 100 lbs.  Note that I don't advocate going to real failure, just estimate it. There are calculators for your one rep max available online. Use these by finding a load you can lift more than a few times but less than 10 and lift until you don't think you can do another rep with good form. Plug in your numbers. Trying to directly find your one rep max is apt to be a sadly memorable affair if it goes wrong on you.

Training Myth #397: Going to failure on lifts is the best way to get bigger/strong/faster

Truth: Going to failure will screw up every subsequent lift and you can lose ground. People are confusing the intensity of the training with its merits.

How does hypertrophy training work?

In a nutshell, you must have some form of progressive overload, whereby the total work is increased according to some plan. This typically takes one of three forms either
  1. lifting high weight with low repetitions
  2. lifting medium weights with lots of repetitions
  3. decreasing the time between sets. 
The first will increase the contractile proteins in the muscles making you stronger and is the only way to actually grow these. While these will thicken, it won't probably be enough for folks to see so you'll get strong but not bigger -- think gymnast. The second will increase the sarcoplasm which is just scar tissue in the spaces between the contractile proteins. In this case this can get you bigger, but you might even find you have lost the ability to lift higher loads.  The final will give you an increase in endurance (= more mitochondria in the cells) plus a mixture of one of the first two depending on the amount of weight and reps you use.   If you want to get stronger, do 1, if you want to bulk up, do 2. Since they both grow the muscles albeit in different ways, they are both hypertrophy methods.

Which method should I use? All of the ones outlined below. Remember that your body will adapt after about 4 - 6 weeks. Therefore, do not plan on sticking with one of these for much longer than that. A lot of people claim that this that or the other method is the absolute best. Having played with a bunch of them, they really all follow the same pattern of being effective for some time followed by hitting a plateau. No exceptions. Many online authors have been stuck on a plateau for some extended time and finally actually try something new. Sure enough, it works great and they breathlessly write up something about it with all sorts of numbers to prove it is the ultimate.

Aren't these methods just for weight training? Well in theory, yes, but I use them for bodyweight exercises too. The nRM numbers below do indeed refer to weights and at least for the first time through you should stick to weights rather than bodyweight since it is easier to gauge how you are progressing, plus there are few good ways to get only part of your bodyweight. Once you get a feel for it though mix and match is the order of the day,  For instance, I do side presses alternating with pull-ups (start working on your one-armed pullups if you want to work with a higher load). By the same token one-armed pushups vs. rows are good as are pistols vs. stiff-legged deadlifts. You could even do two partner drills if you've got a buddy who wants to work.

How often do you do this? I like to train body parts more often than most people. It's gospel in some circles that you should only do a part once a week or some such. Nope. I try to hit everything 3 times a week for this type of training. 

What exercises should I do? You should always train opposing motions. Remember, I do not "do" muscles I only train movements since I have a strong requirement for functional strength.  The last thing I want is some sort of training that will increase my chances of getting hurt.  Oh, stick with the same basic exercises for all of these. Small variations are a good thing, e.g. one good suite of exercises is to alternate deadlifts with rack pulls, high pulls (aka jump shrug, but don't leave the floor!) and various grip RDLs. Some of these you cannot go nearly as heavy on as others and that is a good thing. Key point is that strength is a skill. Have some basic movements you train for strength and get very good at them. As long as they are large-scale compound exercises (pretty much everything in taiso is anyway) and you can do them (so no joint pain, for instance) don't bother looking at other variations.  For instance, thanks to an old shoulder injury, I can only do (one-armed) pushups or dumbbells chest presses. Standard barbell chest presses make my should hurt because the actual motion is not anatomically quite correct.  What I do is more than sufficient and I can assure you that doing a chest press I have excellent poundages, but why give myself a chronic condition?

How much and what should I eat? You'll get a bit hungrier and your metabolism will be higher. Plan on an extra 250 - 500 or so calories a day, depending on how much you do and your size. Protein powders and weird supplements are not encouraged and I don't use them much, though they are very helpful if you get stuck without a meal. Oh, timing is everything. Have a snack (better, a meal) ready as soon as you finish your workout. This should be reasonably high in protein and complex carbohydrates. Thinks like a candy bar or donuts are a no-no. (Although right after a serious cardio session this can be fine since your body will take and carbs and stick them back into the muscle. One remembers the Olympic sprinter who swore by pizza with mayonnaise on it post workout.) This does two things, first it will stabilize blood sugar so you don't feel so tuckered, secondly as a consequence it will regulate the amount of insulin, which is a hormone needed to spur growth and finally your body will get the message that it can grow. This sort of training is actually damaging the muscles in a certain way and by not eating, the body will tend to cannibilize resources unless it knows it has sufficient food not to do that. It is gospel in many powerlifting circles that cardio will counteract lifting. Sort of. If you do heavy aerobics, for instance, you can largely offset your strength training, but this takes a lot of aerobics mind you, like running 50 - 60 miles a week. If you run that much you probably also just don't have time to lift too. One of the worst strategies you can adopt, by the way, for losing weight is trying to do hypertrophy training while seriously cutting calories. The muscles you train will certainly not weaken, but the extra protein has to come from someplace and that means anything you aren't using.  Gain size and then if you need to lose weight, do so separately. If you plan on doing hypertrophy training and aerobic conditioning, do the weights first so you are not too tired. It is even better if you can have a break of some hours between them to allow for recovery. Don't lift when tired since a mistake can get you hurt.

Major hypertrophy methods and how to do them

There are several methods I've tried and they all work. These are listed in no specific order. The number refers to the list above. Note never ever go to failure on any exercise. Some people say it's ok to do so on the last rep of the day, but this just teaches your body to fail.  If you want to really bulk, do each one for a month, then repeat.  Again, for taiso type training, strength is a skill to be maintained so you want to find a comfrotable plateau. Hypertrophy training is a great way to get a change and get a different plateau.

Wendler's 5-3-1 protocol
Overload mechanism (1): Having a planned increase in load weekly. This is a good protocol to use to get really strong because it has good(=safer at high loads) ideas about how to decrease reps as you increase the load
Main idea: Choose a big bang lift, like deadlift, bench press or squat. Figure out your loads and stick with the program. You increase the load for 3 weeks then have a fourth deload week build in.
How to do it: Figure your 1RM for an exercise.  Take 90% of that, called your target. All percentages are calculated from the target!
Week 1 Warmup     75% x 5     80% x 5     85% x 5    
Week 2 Warmup 80% x 5 85% x 3 90% x 3
Week 3 Warmup 75% x 5 85% x 3 95% x 1
Week 4 (Deload!) Warmup 60% x 5 65% x 5 70% x 5

Notes: Sets refers to actual work sets. Do however of whatever you deem necessary to warm up first. Do not just launch into the heavy stuff cold since that is asking for a serious injury. It is fine to repeat the sets that are not max if you want/need to. If I feel a bit slow I will do this to make sure I am good and ready for wat comes next. If you really feel amped, you can keep going on the last set. So if the last week you have done your set of singles and want to do a couple of more, go for it.

Escalation Density Training (EDT)
Overload mechanism (3): Increasing the per session number of reps done in a given amount of time and weekly increasing the load.
Main idea: Keep the time you train constant. You increase either the number of reps or amount of weight in a session.. 
How to do it: Figure your 6RM for an exercise.  Start with sets (depends on you) of three rep for the first workout, then 4 reps then 5 reps. Increase the weight by 5% and start the cycle over again with the same number of sets and 3 reps per set.
Notes: You are on the clock for this one. The idea is to do more exercises within a given time period. Remember this one if you work on a project with a deadline.  It really helps to block out a fixed amount of time and hustle to get it all in.

German Volume Training (GVT)
Overload mechanism (2): Huge numbers of repetitions, small weekly increases in weight
How to do it: Figure your 20 RM (you read that right). Your goal is to complete 10 sets of 10 (for lower body) or 10 sets of 6 reps (upper body).  Every week increase the load by 5%.
Notes: This is really high wear and tear but it also really does work. I plan on doing something like this over the summer or at Xmas when I am on vacation and have no martial arts to do and limited weights available. The reason is that I won't be doing anything else and I can usually scrounge up the lower weights needed at some random gym or hotel.  Since this offers a real prospect of overtraining injury if (note that word!!) you do it while working out in other sports, it's in a special category of high-risk.  It is perfectly fine if done alone though. Mind you,  what I'm saying: This is a lot of work and all by itself for a month is great, just don't plan on doing much else for training since it also takes a lot of time to do all those reps.

Robertson's Volume Training (RVT)
Overload mechanism (1):Working with lots of smaller sets at higher weights.
How to do it: Find a weight you can lift with good form (say start light, then add until your reps drop) until you can only do 3, a triple with good form. Drop the weight by 5% and do as many sets of triples that day as you can. When you are no longer able to lift the triple with good form, stop. Be honest too. Do this weekly for 3 weeks and a deload down to 8 reps per set for the fourth week.
Notes:Kicks butt, yours, mine and probably the guy's down the hall too. Only use on really big bang lifts (deads and DB bench press are my personal favorites). You should "rest" with supplementary exercises. So for instance between deadlifts I do side bridges or wood choppers, then after a few sets of those, stability ball hamstring curls, prone jack-knife on a stability ball of TRX blast strap.

The major difference between this and German volume training are the vastly higher loads and fewer reps overall. GVT gives bulk if you just need to get something larger (which is useful after an injury to restore size to something and not max out whatever it was). RVT will get you seriously strong and you should eat like a horse too with both of them.

5 by 5's (5x5)
Overload mechanism (1):

How to do it: Find your 5 RM. Try to do 5 sets of 5 reps for each exercise. Once you can do a workout fully increase the load by 5%. 
Notes: that you probably won't be able to complete the sets the first few times. Only increase the weight when you can do 5x5, i.e. all five sets at 5 reps.

Overload mechanism (1): Adding more weight on a per session basis, but dropping the weight in a regular timetable.
How to do it: Find an exercise you like. Add 5% weight  every other session for 6 sessions running, then drop back a notch. So if you are lifting, e.g., 50 lbs., you would train sessions  50 - 50 - 52.5 - 52.5 - 55 - 55 then restart as 52.5 - 52.5 - 55 - 55 - 57.5 - 57.5. Do this type of cycling for 4 weeks.
Notes:Another good method that works. If you max out on a cycle (so you can't lift the top level weights) drop back down or switch methods.

One rep training
Overload mechanism (1): Lifting almost the maximum you can in a single rep, but doing this several times in a workout.
How to do it: Find your 3RM. Do 5 or 6 single reps with no more than 15 seconds between them.
Notes: Warm up well with lower weight before you do this.  Not suggested for folks with a bad joint. In my case I would not do a chest press type exercise with this method since the load exacerbates an old injury.

Final comments

One way of doing this might be to change over all of your exercises, so you are doing the same mechanism for everything. This is a great way to get big and strong, but tends to be a lot of work. Try it every so often. Body sculptors obsess about this since they have to have everything come together for a competition. You don't have to do this, so you can mix and match any way you want. 

These are all pretty standard in various weightlifting communities. They actually are implicitly subsumed in taiso. The way that, for instance, one is to work on an exercise is to take a workout goal (e.g. 10 one-armed pushups) and do a random one or two of these in the course of a workou until the goal is attained (this is exactly one rep training). Then you try to do smaller sets of these, say 3 or 4 in a row (a lot like 5x5's) and the goal is then to be able to do several of these more or less back to back (escalation density training). Finally working these into a program where you do many sets of these over the course of a session (high volume training). None of these methods were articulated, it's just good common sense. Once you are comfortable, you put these into complex exercises, do them plyometrically,  &c., &c. the point being that aleatoric training is the way to maintain these as a skill (this often ends up as cycling). Nice to know there is independent corroboration of its efficiacy plus a coherent explanation of the mechanisms.