Do you remember the first time you went to the gym? I do. It was the year 2000 and I was serving in the army. I joined a bunch of guys to go lift some weights.

In front of me, I saw a room full of weird looking devices and machines, each designed for a particular style of torture. So I tried one that was free.

Turns out, you need to choose settings. You can't just jump on. Machines have little pegs. Free weights go from 1kg to 25kg. The barbell seems to have unlimited combinations of small and big plates. What the heck am I supposed to do?

So, years later, and through a collection of gym heroes and old wives tales, trial and error, you end up with a program like 3x8 or 5x5. You add as much weight as you can handle. Once you can do more reps, you add more weight. Super. Problem solved. Right?

Wrong.

Despite the fact that most people think fitness is an art, it's actually science #truestory. It's complicated science, combining gooey things like Biology and Chemistry with hard Physics. Isn't trial and error just easier?

Prilepin. Learn the name.

You know when you go to the gym, and you sort of wonder if there's a relationship between weights you choose, sets you do, and reps. Well, a smart Russian did the math a long time ago. Olympic lifting is kind of based on his tables, so I guess that qualifies. 

 Imagine that the colorful lines represent maximum INTENSITY. Starting from the left in blue, you can only do a total of 4 reps at 100% of your maximum weight in one workout, even if you take a long rest period. Cell energy finished. No more reps. If you lower the weights a tad, you can do up to 10 reps total, say 5 sets of 2 reps each with plenty of rest in between. So how come you can only do 6 total reps in the red area? Because you're doing more reps per set! Like 2 sets of 3 reps. Then you hit the wall again. What if you fall below the line? Well, you left gas in the tank.

Imagine that the colorful lines represent maximum INTENSITY. Starting from the left in blue, you can only do a total of 4 reps at 100% of your maximum weight in one workout, even if you take a long rest period. Cell energy finished. No more reps. If you lower the weights a tad, you can do up to 10 reps total, say 5 sets of 2 reps each with plenty of rest in between. So how come you can only do 6 total reps in the red area? Because you're doing more reps per set! Like 2 sets of 3 reps. Then you hit the wall again. What if you fall below the line? Well, you left gas in the tank.

Confused yet? I certainly am. Why is 5x2 so different to 2x3? What mysterious force is behind this trickery? Is it... The Force..? Let's figure this out!

FACT: INTENSITY = ENERGY

To explain INTENSITY we need to look at where strength comes from, and how it's possible to run out of it, rest, and get it back. Imagine that situation where you're busting out that final bench rep, hands shaking, face red like a watermelon.

 The type of face you should be making when hitting the right level of INTENSITY, because workout. Or you opened the Lost Ark.  Copyright Lucasfilm Ltd.

The type of face you should be making when hitting the right level of INTENSITY, because workout. Or you opened the Lost Ark. Copyright Lucasfilm Ltd.

What's going on? Why does strength suddenly end in the first place? If I do 20 pushups, why can't I do as many after resting? What happens during resting anyway?

Strength available = Energy available

Therefore INTENSITY is about depleting that energy. If you didn't break a sweat during your workout, I'm guessing it wasn't that intense. At the same time, sweat like a pig, but don't feel any burn in your muscles or lungs, it wasn't that intense. 

So how the heck am I supposed to know when things are INTENSE enough?

FACT: Energy isn't just Energy

Your body has three types of energy it can use, and they all work differently for different purposes. I'll use normal words instead of fancy PHD words to make this simple.

Cell energy: 0 to 10 seconds

You're burning up energy from within your actual cells. As you can imagine, the tank is pretty small, but packs a lot of punch! This is basically your heavy lifting energy, and why you squeak out fewer and fewer reps on the bench as you add more sets. Your body doesn't have enough time to regenerate this cellular energy.

Muscle energy: 30 seconds to 2 minutes

You know that feeling when lactate builds up and starts burning your muscles? That's a byproduct of your muscles burning their energy stores, in the form of glycogen, a really fancy word for carbs. As before, you can only store so much of the stuff inside the muscle, so it will run out. When you sprint as fast as you can, you will slow down a lot once the cell energy is out, and fall down panting when the muscle energy is finito.

Body energy: Until love handles run out

So how come you can still run for a long time if you lower the INTENSITY? Now you're getting there. When the INTENSITY is low enough, your body no longer taxes those little energy packs inside your cells and muscles, and switches to oxygen. That's why this energy system is called aerobic. As in aerobic exercise, you know? Spandex leotards for all! 

Here the body's burning on a slow flame, and with a practically endless source of energy through burning carbs, fats and oxygen. That's how people do marathons and other crazy feats.

FACT: You can replace your heavy squat with an exercise bike

Hooold up now. That's straight up testo-blasphemy! Bikes are for warmups, a.k.a. wimps!

So if you put 2 and 2 together with the energy Systems, what it means is that all movement taxes all energy systems. Nature doesn't know what a bench press is, nor does it care. If you do a Bench Press with a twig, you can make it an aerobic exercise and do it forever, or until bored. If you do single reps close to your max with rest in between, you're still only exhausting your cell energy, since each rep only lasts a few seconds. Of course you'll get stronger, but you're doing way more work than you need to, and leaving gains on the table. Don't do that. Gains are good.

No INTENSITY, no gains.

Likewise, you can take traditional aerobic movements like running or cycling, and make them heavier than your killer squat sesh'. Simply add INTENSITY. Try it. Max out the wattage on your grandpa's dusty exercise bike, and go as hard and fast as you can. Visualize a lion chasing you. Or velociraptors. Or clowns. Whatever freaks you out. Pedal for your life!!!

 Visualize not being this close to a lion. Copyright The Huffington Post.

Visualize not being this close to a lion. Copyright The Huffington Post.

You didn't make the 2 minute mark, did you? How does it feel, after you can no longer move the friggin' pedals? You can taste the lactic acid, burning your muscles. Your lungs hurt. You should sit. You ran out of cell energy, and spent all your muscle energy. All gone. The INTENSITY was too much for your body to run on oxygen alone, so the pedals stopped. The lion got you, because INTENSITY.

More sets means less INTENSITY

Most gym heroes and bodybuilders love volume. They split routines by body part, just so they can do 2 hours a day at the gym, squeezing out 5 to 10 sets on each exercise. Usually in front of the mirror. While effective and brotastic, it certainly isn't necessary.

When you introduce multiple sets, you are actually just allowing your body to recover. Again, recovery is just another word for your energy systems. So instead of emptying the everything on the first set, you may spend 90% of your cell energy, which recovers quickly, and maybe 70% of your muscle energy. If you rest for a short period like 60 seconds, you'll keep those numbers from getting back to 100%, and eventually come to a point where you can't lift a finger.

INTENSITY = ENERGY = TIME UNDER TENSION

So which one is actually harder, a high-volume bodybuilding workout or the bike in grandpa's garage? It all comes down to Time Under Tension. That means the amount of time that your muscle was fighting for survival. 

With the bike, you're under tension the whole time. There isn't even a place to hide between reps. No rest, no recovery. As long as the resistance is high enough, you will hit the wall in under 2 minutes having depleted all the energy in your cells and muscles. With added sets you're just postponing the inevitable. Dancing around muscular failure, without ever necessarily getting there. Even between reps, you can rest a second or two at lockout, allowing instant recovery within the set. It simply isn't as effective for emptying your energy systems. Seems grandpa was onto something in the 80's! 

How to use INTENSITY

You know that phrase, what doesn't kill you makes you stronger? Well, that's exactly how the body works. It's called hormesis. Any workout you do is trying to kill you a little bit. Usually, it doesn't.

If you empty those little energy stores in your cells and muscles, they will immediately start refilling when you stop. If you empty them often, and empty them completely, guess what? They store more energy! You now have more energy, and you're stronger! #sciencewin

I wonder, could you design a workout that did exactly that...? Just imagine, you could do cardio and strength in a single workout! Hmm...

H.I.T. it hard

Yes, you can. #obama

Word of warning: This is the optimal workout you can do from a scientific standpoint, but you might not like it. Hard is rarely fun!

High Intensity Training. Not to be confused with your aunt’s HIIT workout on Sunday television.

HIT is the worst 15 minutes of your life, basically. I'm not even kidding. It's like that feeling you have squeaking out that final Bench rep, except non-stop for 15 minutes with a constant burn all through your body. No joke.

You can replace going to the gym every day, multiple sets, hours of cardio and corny gym smalltalk with a SINGLE 15 MINUTE WORKOUT. #intensity #sciencewins

A lot of professional trainers are adopting HIT, because it's just so damned effective. All you have to do is some form of movement that takes you to momentary muscular failure in less than two minutes. Now that being said, momentary muscular failure isn't something that most people are familiar with. It means you have to make it so hard, that you can no longer move the weights, even at the risk of your face melting. It's painful.

HIT cheat sheet

Here's a simple recipe for your HIT workout.

TIME NEEDED: 15 minutes

That sounds fast, but once the suffering begins you'll wish it was less!

FREQUENCY: ONCE PER WEEK

The thing is that these HIT workouts not only tax your muscles and energy systems heavily, but they also hit your nervous system pretty hard. You might pull off 2-3 sessions per week for a while, but then you would crash really hard, get injured or get sick. Trust me, once a week will work wonders. Try it!

exercises (GYM): SQUAT, BENCH, DEADLIFT, SHOULDER press, SEATED row

Since you're working to muscular failure, machines are the safest way to do HIT. When you hit the wall, you just let go. You don't want to do that with free weights. Remember you can also try this on an exercise bike, or even do a whole body elliptical explosion. That sounds painful.

Example gym HIT workout from Dr Doug McGuff

EXERCISES (HOME): BODYWEIGHT squat, pushup, pullup

There's an endless amount of variations, but try to stick to movements that you feel comfortable with. You don't get points for acrobatics here.

  • If Squats are too heavy, you can try a nice Wall-Sit. If too light, try an Ice Skater Squat, or Pistol Squat. Look it up.
  • If regular pushups are too heavy, put your knees to the ground. If they're too light, try a Diamond Pushup. Google it.
  • If you don't have a Pullup bar, you could try a Door Towel Row. Youtube it.

An example bodyweight HIT routine from James Steele

Weights: muscle failure within 2 minutes

So how do you know which weights to set? Well, I recommend starting real light and work your way up. If your exercise takes 2 minutes or more to hit failure, increase the weights next time.

Reps: 10 seconds up, 10 seconds down

Don't worry about this one excessively. The simple idea is that keep the movement going without locking out or resting between reps, keep breathing, and keep the movement slow. That should naturally put you around 15-20 seconds per each rep. 

SETS: just one per exercise

You heard that right. Single set, then move on. If you hit muscular failure, there was nothing left in the gas tank. Job done!

REST: time to set up next exercise

Since you're working single sets for each exercise, you don't really have a rest period. Just move to the next exercise, take a quick breath, and hit it even harder.

Your new workout schedule

So how does this look, when we put it all together?

Monday: 15 minute HIT workout

Tuesday: Nothing

Wednesday: Laziness

Thursday: Chillin'

Friday: Partying

Saturday: Hangover

Sunday: Netflix

Sounds pretty good to me!

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