If you’ve been kicking around the fitness space for a while you’re probably familiar with the story of ‘Milo Of Croton’ 
Milo, a 6th Century wrestler [and all ‘round Badass] is most famously known for lifting a baby calf everyday, until eventually it becomes a fully grown bull. Doing this everyday, in turn, increased Milo’s muscle mass and strength.
The story is used to illustrate the foundation principle of strength and size : Progressive Overload.
Let’s talk about that…
The History Of Progressive Overload
During World War II, the amount of American soldiers who were sustaining orthopaedic injuries was exceeding the rate at which hospitals were able to rehabilitate them. This was in part due to the sheer amount of soldiers involved in the war and part due to the poor rehab protocols that required lengthy recovery times.
During this time, army physician Dr. Thomas L. DeLorme, began using strength training as an integral part of the rehabilitation process.
DeLorme’s protocol consisted of multiple sets of resistance exercises in which patients lifted their 10-repetition maximum. He later refined the system to 3 progressively heavier sets of 10 repetitions, and he referred to the program as “Progressive Resistance Exercise.”
Thus ‘Progressive Overload’ was born. The principle of progressive overload is simply that in order for you to grow and get stronger, you need to increase the demands placed on your body during successive workouts for improvements to be achieved (i.e gainz).
Think of progressive overload like building a house.
You lay a few bricks the first day, go away, rest, recover. Come back the next day and add some more bricks. Over time you have a house [or in this case an Adonis-esque physique].
The Problem With Progress
The story had Milo lifting the calf everyday, and as the calf grew day by day, so did Milo’s strength and size.
While this makes for a great story, there’s one problem.
Progress is never linear.
It comes and goes, more so in waves. You’ll make progress in some months. Others, you’ll stay the same and sometimes you may even go backwards. But, over the long run, the trend will [should] be going upwards — like the graph below illustrates.
In the real world, there’s only so much you can keep progressing, both in strength and size, before you can’t progress anymore.
When you initially start training [Lv.1 No0b] you can make progress extremely fast, as your body adapts to the new stimulus and has more ‘room’ for growth.
This is why you make some of your best gains during the first 6–12 months of your lifting ‘life’. But the more you keep lifting, progress begins to slow and becomes harder to come by.
What I like to call : ‘The Law Of Diminishing Gainz.’
As you keep lifting and getting stronger, eventually, you reach a point where you just can’t keep making progress in a linear fashion as you would have done in your first few months of lifting.
This is where the story of Milo is flawed.
While it would be great to keep progressing and getting bigger and stronger for the rest of our lives, unfortunately we have built into us a little something that stop us from being able to do that.
The plateau is a biological phenomenon that occurs as a result of our bodies becoming accustomed to a certain stimulus and stops responding.
Think of the plateau as the arch enemy to progress. (‘The Joker’ to ‘Batman’, if you will) 
You go into the gym and do 3 sets of 10 reps on the Bicep Curl. Initially, your biceps respond to the new stimulus and your body adapts to it by growing (bigger biceps) to be able to handle that load the next time.
However, if you keep going into the gym and doing the same weight and/or reps week in week out [as is common amongst the common gym Bro] your body has ‘adapted’ to this stimuli and is no longer responding as there isn’t a new stimuli for it to ‘adapt’ to.
Ironically enough, the plateau is actually a defence mechanism that’s built into us to help us survive. See, our bodies can only keep progressing so much before we put ourselves at a higher risk of injury or even worse, death. The plateau helps to stop us getting to that point (hence why you can’t keep growing forever or keep getting stronger forever)
I’m willing to bet if you went back to the time of Milo, you’d probably have seen something similar occur.
One day Milo rolls up to the Bull, and just like he did the day before, he attempts to pick it up but he just can’t do it. Confused, he tries again, nothing, and again, same thing.
Eventually, he gives up, kills the Bull and eats it.
Only if Milo understood progressive overload, eh? He’d still have a Bull and he’d probably have made some more gainz.
More Than One Way
When most lifters think of progressive overload, they tend to think that there’s only one way to keep progressing and that is to continuously add weight or do more reps every session.
You will eventually get to a point in your training where you can no longer simply keep adding weights or reps in a linear fashion, as you reach a point where physiologically, your body just won’t allow this to happen.
So what do you do then?
Well, luckily there’s more than one way to approach progressive overload.
1. Increase Training Density
The general definition of Density is how much of one thing exists in a given area or space.
So, when we refer to training density, we are actually looking at the manipulation of two aspects :
Volume and duration.
More specifically, how much volume we can do in a given amount of time.
Volume: Total work done in the workout [Sets x Reps]
Duration : How long your workout lasts
Training Density = The amount of volume you can do in a given amount of time.
If your programme has you doing 5 sets of 5 reps for squats and this workout usually takes you 30 mins to complete. To increase the training density, you would simply aim to complete the whole workout in a shorter time frame, for example, 25 mins or even 20 mins.
To do this, shorten the rest periods between sets. If you usually rest 5–6mins between a set, you would simply rest 3–4 mins.
By doing this, you are lifting the same amount of volume as before but in a shorter time frame.
2. Increase The Number Of Sets
As mentioned above, volume = total work done in a workout, and generally is measured by the amount of reps and sets you do.
So, if you lifted 100kg for 5 sets of 5 reps this is 2500kg of total volume /work.
But what if you’ve tried adding reps and weight but you are still stuck [plateauing] ?
You can increase the volume by adding in an extra set.
If your programme calls for you to do 3 x 10 on squats, and you’re finding that you simply aren’t able to increase the weight or reps, simply add an extra set in.
So now you would aim to do 4 sets of 10 reps and when you’ve successfully achieved 4 sets of 10, you can add more weight or increase the reps.
By adding in an extra set you automatically increase the amount of work you are doing. This in turn, increases your work capacity, now that you’re able to handle more work with the same weight so you’ve just progressed.
To illustrate this point :
3 sets of 10 reps @ 100kg = 3000kg total workload
4 sets of 10 reps @ 100kg = 4000kg total workload.
Which is an increase of 1000kg total workload.
3. Improving Form
One often overlooked aspect of progressive overload is the most simplest one.
Simply work on improving your form.
If you start squatting and you can only squat just above parallel (also known as the dreaded ‘quarter squat’), over time as you keep improving your form and getting lower, you’ve just employed progressive overload.
By improving your form you’re going to be working more muscles in the process and stimulate more growth.
4. Increasing The Frequency Of Training
Training frequency is the number of training sessions per week in which a particular muscle group is trained.
If you are currently training every body part once a week and your progress has slowly grinded to a halt, It may be time to bump up your training frequency.
Hitting chest once a week? Bump up the frequency to two times a week. This will increase the amount of volume you are doing which in turn will help stimulate more growth.
In Summary [The TL;DR]
- Milo lied to you
- Progress Is never linear
- The more advanced you become, the smarter you need to be with your training
- Increase training density by doing the same amount of volume but in a shorter time frame
- Increase the number of sets done in a workout if you find that you aren’t able to add weight to the bar or increase the number of reps done.
- One of the simplest ways to employ progressive overload is to improve your form [also because quarter squats suck ass]
- If you are currently hitting every body part once a week and find that you aren’t progressing anymore, bump up the training frequency by hitting the same body parts two or three times per week.
Unlike our Bro Milo, you now have a few more ways of employing progressive overload when simply adding weights or increasing reps stops being feasible.
Hopefully, once quantum physics advance a tad more, we can send this article back in time to aid Milo in his bull bearing adventures.
References / notes :
2. Optimizing Strength Training: Designing Nonlinear Periodization Workouts By William J. Kraemer, Steven J. Fleck
3. I had to get a comic reference in to this article somehow.
4. All Illustrations/graphs done by yours truly