I Trained One Side HEAVY vs LIGHT For 60 Days (Bad Idea)
Duration
26:46
Captions
1
Language
EN
Published
Sep 21, 2025
Description
Get FREE 2-week access to smarter training with the BWS+ app: https://bws.plus/f1 Get $300 off your whole body scan at Prenuvo: https://prenuvo.com/JEREMYETHIER Should you lift heavy or light? You have to train with heavy weights for the best muscle growth; at least, that’s what many people say. But not everyone agrees. Light weights vs heavy weights for growth is one of the most debated questions in fitness. So, I’m putting lifting heavy vs lifting light to the test MYSELF. For 60 days straight, I’ll split my body in half. One side with heavy weights, the other with light weights. Here’s my 60 day heavy vs light weights plan. Every major muscle will be trained unilaterally. Each side will receive the exact same number of total sets, and every set will be taken as close to failure as possible. But the heavy side must reach failure within 3-6 reps whereas the light side must reach failure within 15-30 reps. Plus, to make sure there’s actual changes in muscle growth and strength, I’ll also be eating in a small calorie surplus. I have years of training experience; I’m curious if a beginner’s muscles would respond differently to this lift heavy or light experiment. So I roped in Dennis. His report shows that he’s also a right-hand frequent user, with a starting body fat of 18.4% with 113.6 lbs of lean mass. Week 1: Given that the average beginner can gain around 8-10 lbs of muscle in their first year of training, I’m confident Dennis can gain at least a couple of pounds of muscle if we dial in his training during this lift light or heavy experiment. Wondering about training volume in this heavy vs light weights experiment? By multiplying total sets × reps × weight from week 1, the light side came out to over 100 thousand lbs, whereas the heavy side was about half of that. Some people think total volume lifted and time under tension are keys to growth; if that’s the case, the light side should dominate. So, can the heavy side keep up despite lifting less total volume, taking half the time per set, feeling no burn, and having less soreness the next day? Week 2: To help Dennis grow, we focused on his diet with a daily calorie and protein target. Both of us noticed quicker progress on our heavy weight sides. Why? When lifting heavy, going from 100 to 105 lbs is a 5% increase. With light loads, 50 to 55 is 10%, making it tougher to add weight when doing high reps. For the light side, the smart move is to beat last week’s reps rather than bumping weight too quickly. Both of us noticed the light side gets a WAY bigger pump. The pump happens when blood rushes into your muscles faster than it can leave; research is mixed on whether it helps long-term growth. Weeks 3–6 of the lift heavy or light plan: Dennis’ heavy right side kept progressing with the weight, while his light side barely moved. My Bulgarian split squat went from 205 to 215 on the heavy side, whereas my light side stayed at the same weight. The extra fatigue from many high-rep sets was taking a toll on recovery and mentally burning me out. Then: sharp pain at the top of my knee during a heavy set. Heavy weights put more stress on joints, which can make tendons stronger over time, but if you only ever use heavy weights—especially on exercises that aren’t a great fit—it can become too much. I switched my heavy leg to lighter weights for high reps and burned out WAY faster. That’s endurance adaptation. By consistently training with higher reps, your muscles create more mitochondria to reduce the “burn” and your brain increases its tolerance to pain. The downside to training light? Your bigger, more powerful fibers grow your muscles the most, but they’re only called into action if needed. With heavy weights, they’re activated from the first rep. With light weights, they join only when smaller fibers fatigue, so if you stop because of the burn, you miss them. Weeks 7–8 of the lifting heavy vs lifting light plan: Form creep and ego lifting can create the illusion of progress. I corrected Dennis when I caught it. Meanwhile, my elbow started acting up on isolation moves. Day 60 Strength Test: Strength was movement-specific. On unpracticed tests, results were surprising; on practiced lifts like preacher curls, the trained pattern mattered. With the chest press machine and flat dumbbell press, stabilization and transfer told a nuanced story. Time for results of the lifting heavy vs lifting light experiment. Overall, I gained about 2 pounds; just over half a pound (~0.66 lbs) was actual muscle. The lighter-weight side grew just slightly more in almost every muscle, but the differences were tiny and within measurement error. Dennis gained ~3 lbs of lean mass; his body fat dropped from 18.4% to 17.8% because he added more muscle. Every muscle on Dennis trended toward the lighter side growing just slightly more, but again the difference was tiny and nowhere near statistical significance.
Captions (1)
Lightweight for high reps or heavy
weight for low reps. Which is actually
best for growth? Some argue the first
builds a leaner, toned physique, while
others swear you need the heavy stuff
for any real size. So, I decided to put
it to the test. For the next 60 days,
I'll be training half my body with light
weights and the other half with heavy
weights. I'll be taking daily photos.
And everyone is worried I'm going to
look like this by the end of it. But too
late. Today is day one.
To decide which side of my body I'll be
training heavy and which I'll be
training light. I'll be using the most
scientific way possible and it only
costs a dollar. Heads is going to be
right side heavy. Tails is going to be
left side heavy. Let's see.
Tails. Okay. The science gods must be
looking out for me because my left side
is actually my weaker non-dominant arm
and leg. So the heavy weights might
actually balance them out. But I've
never trained like this before. Even on
the first set with a heavy weight. It's
a lot tougher than I expected to stay
balanced.
Okay, so that was 90 pounds for five
reps. Definitely felt super weird. It's
hard to balance. I've never trained like
this before. That already feels like
kind of
lopsided on this side. I am scared for
the light side, though. Let's see how
this goes.
Easy money. Let's go. Oh god.
The burn on that side is way more
intense. Like the first 10 it was easy.
Once I got to like 12, 15. Oh, I'm just
not used to that. Pump feels a lot
bigger. Definitely. But you might be
wondering why I've decided to risk
lopsiding my physique for the sake of
this experiment. Well, like most people,
I grew up thinking you got to lift big
to get big. Even when my joints used to
bug me, I wouldn't lift light because
deep down, I felt like there's no way
these light weights can build the same
muscle. But what if curling these 20 lb
dumbbells is in fact the same as curling
these 60s? Recent studies suggest it's
possible, but they rarely test very low
rep ranges. Most are done on complete
beginners, and we still don't know if
certain muscles like the chest might
respond differently to heavy versus
light weights since they've never really
been tested. So, here is my 60-day plan.
Every major muscle will be trained
unilaterally, meaning only one arm or
leg at a time. Each side will receive
the exact same number of total sets, and
every set will be taken as close to
failure as possible. But the heavy side
must reach failure within 3 to six reps,
whereas the light side must reach
failure within 15 to 30 reps. Plus, to
make sure there's actual changes in
muscle growth and strength, I'll also be
eating in a small calorie surplus. But
first, we need a baseline. I got an
hour-ong full body MRI scan that not
only measures my muscle growth
precisely, but also reveals individual
muscles that ultrasound cannot
distinguish. Studies hardly ever use MRI
because it's expensive. But thanks to
the coin flip, I do have some change to
spare. Plus, Prouvo hooked me up with
the discount link below for anybody who
wants their own full body MRI scan and
health report. You guys now see
everything in me, and lots of things are
a lot smaller than I thought, like my
brain. But I'm also using DEXA,
ultrasound, and body circumferences as
backups and to get a clear picture of
the hole stored. Not to my surprise, as
a right-hand frequent user, my right
side is slightly bigger. After 60 days,
I'll come back for another scan to see
how much each muscle grew and if there's
a difference in either side. Now, we all
know size matters, but strength is just
as important. I'll be tracking
everything using the Built with Science
Plus app throughout the experiment. At
the end of the 60 days, I'll be
switching sides to see if they can keep
up with each other, but I have several
years of training experience, and I'm
curious if a beginner's muscles would
respond differently. Hey, you? Yeah. Do
you lift weights? This? So, I found this
Dennis guy on the street, the perfect
beginner guinea pig.
All right. No, one I can't do it.
I can't do it.
God,
look at this.
Your right bicep is not only bigger, but
it's a bit stronger than your left side.
Your chest and back pretty much even.
What side are we going to do? Heavy
versus light.
What is it?
Oh, yeah.
Light on your right side and heavy same
as me.
Oh, really? Okay,
let's go.
Somehow, his report shows that he's also
a right-hand frequent user with a
starting body fat of 18.4% with 113.6
lbs of lean mass. Here is his full body
report. Okay, so all the tests are
wrapped up and it's time to work out.
And lucky for you, today is leg day.
Oh god.
All the way down. Come on. All the way.
All the way. All the way.
This is not light.
Oh my god.
15. Keep going. Keep going.
No. No. You're not done.
You said 15.
Failure means that you literally I think
that's surpassed failure.
Control. Control.
As you can see, Dennis makes lifting
just his body weight seem like he's
lifting 300 lb. Not to mention, all the
machines look completely foreign to
Dennis. He even had trouble inserting
himself into some of them. But that's
okay. Some things you just can't wing on
your first try. But given that the
average beginner can gain around 8 to 10
lbs of muscle in their first year of
training, I'm confident Dennis can gain
at least a couple pounds of muscle if we
dial in his training. Up
I see my grandmother. But it didn't take
long for Dennis to start complaining
about the burning sensation on his high
rep, lowweight side. Stay on the way
down. Let's go.
17. Let's get to 20. 18. Slow the way
down. Slow down. Last one. Go slow on
the way down.
The burn is just getting like more and
more.
See what I mean? The burn is crazy.
It goes like gradually.
Yeah.
Like this.
Yeah.
You go like that.
Now, this burn sensation, it comes from
metabolic stress during exercise. And
it's common when you climb stairs
quickly, bike uphill, or even carry
heavy groceries from your car to your
door.
I feel the burn like around 16 to 18.
Yeah.
But before that, it was comfortable.
That's the thing with the the light
side.
At first, it's like, oh, this is easy
and then it gets very hard. Whereas the
heavy side is like it's hard from the
beginning, but you never really get the
burn. You know what I mean?
Yeah. You feel this like a fire slowly
burning up and this one just like fire
and put down fire and off. When you lift
with higher reps, your muscles
accumulate more and more hydrogen ions
and other metabolites. The nerves in
your muscles detect this and for reasons
we're not yet aware of. Signals are then
sent to your brain to create a painful
burning sensation in response. Now, some
believe this is actually beneficial for
growth, but it comes with the cost of
pain and often more soreness. Today's
the second day of the experiment. I feel
my right side is a little bit more sore
and my biceps I don't feel anything.
Chest a little bit. I think they look
pretty much the same like yesterday. On
the other hand, no pun intended with
heavier weights, the set ends in half
the time. You don't need nearly as many
reps to reach failure. So, you avoid the
burn completely.
So far, what I'm noticing, especially on
the leg days, is that the heavier side,
fewer reps. I could probably do one or
two more sets, no problem. Definitely
noticing the lighter weights for higher
reps. Performance
tanks, especially if I do, you know,
three, maybe four sets, whereas the
heavier weights some more consistent.
So, why do our light sides feel like
they're getting absolutely wrecked every
workout, but our heavy sides feel like
they're barely getting worked at all?
Well, this is not just because of the
burn. When I look closely at my app to
see the total volume we lifted from our
first few workouts, I found something
surprising. By multiplying the total
sets, reps, and weight I lifted across
my week 1 workouts, on my light side
came up to a total of over 100,000 lbs.
Whereas on the heavy side, because I'm
doing far less reps, it actually came up
to just half that. Now, some people
believe that total volume lifted and
time under tension is a key to growth.
If that's the case, then we should see
the light side completely dominate. So,
this begs the question, can my heavy
side actually keep up in growth despite
lifting less total volume, taking half
the time to finish each set, feeling no
burn, and less soreness the next day?
We'll see what actually happens after
the next 7 weeks. But to make sure
Dennis gets enough muscle growth, we
have to focus on his nutrition. So, I
made Dennis use our app to start
tracking his diet, giving him a daily
calorie and protein target to slowly
gain weight. But Dennis was still
suffering from belly fat trauma, and he
seems to be really attached to the idea
of getting abs. So, eating more scared
him. Like, this is a mental thing. I
just sometimes I purposely eat half of
the burger. I'll throw the half out
because it's really hard to cut out my
belly fat and I just don't want to go
back to what I was before. And I don't
blame him. For people who work so hard
to lose weight like he has, eating more
calories can be intimidating. But deep
down, I really want to show Dennis how
adding more muscle can also really
improve his look. And for someone who
doesn't have much fat on his body,
current research suggests that even just
a small calorie surplus can help promote
more growth. Luckily, just 2 weeks in
and it seems like the diet is already
working. At least on one side.
Last one. Go all the way down. All the
way down there. up.
Dude, you're getting so strong. Let's
go. 50 lb dominated.
But this side is still the same weight.
Now, there's actually an explanation to
this. When lifting heavy, let's say you
go from 100 lb to 105 lb, that's only a
5% increase in weight. But when you lift
light, let's say going from 50 lb to 55
lb, that's a 10% increase in weight,
making it much tougher to add weight
when you're doing light weight for high
reps. So, for our light sides, the
smarter way to keep forcing growth is to
focus on beating our last week's reps
rather than trying to bump up the weight
too quickly. However, even though we see
the heavy side is lifting more and more
weight, both of us notice that our light
side gets a way bigger pump. Damn, it
looks big, man. Now, the pump is one of
the best feelings in the gym. Arnold
famously described it as
it feels fantastic. It's as satisfying
to me as coming is. Now, the pump
happens when blood rushes into your
muscles faster than it can leave. During
a set, your muscles contract so hard
they squeeze the veins shut, trapping
blood inside while the arteries keep
pushing more in. The more reps you do,
the more fluid builds up, swelling the
muscle and making it bigger. What? So,
this one increased by 1 cm. This one
increased.3
cm. I can feel it, too, though. This is
like super full. And this one's like
didn't even work out. Before was 31.5
and then it went to 32.5. This one plus4
cm. But does the pump do anything
beneficial for growth or is it just a
short-term eagle boost? Well, research
is mixed. A lot of tricks designed to
maximize the pump like super short rest
periods or painfully slow reps. They
often don't lead to much long-term
growth at all. That said, some
scientists believe the swelling effect
from high reps provides an additional
growth signal to your muscles, giving it
a growth advantage over lower reps.
We'll see what actually happens after
the 60 days are up. But with the midway
point of our experiment approaching, I
reviewed Dennis's food log, and I
noticed that he's been having a hard
time eating enough calories because he
hasn't been coming to work with enough
food prep. So, I introduced him to the
quick and easy solution I used to use,
the muscle monster.
This is something I made back in
university when I was struggling to eat
enough. I mixed protein powder with
peanut butter to make a spread and added
sliced banana for creaminess. The whole
thing packs 800 calories and 50 g of
protein.
Pretty good. The key is the banana.
Banana, right?
But the bananas aren't the only thing
getting Dennis excited. His heavyweight
side keeps progressing with the weight,
while his weights on the light side have
barely moved. I'm experiencing the same.
My Bulgarian split squat has gone from
205 lbs to 215 lbs on the heavy side,
whereas my light side is still at the
same weight. So, I was starting to
wonder if this experiment was going to
leave me with a giant strength gap by
the end of it. To make matters worse,
I'm assuming because I'm doing so many
sets with light weights for high reps
that the extra fatigue is really taking
a toll on my recovery and mentally
burning me out. So, by this point, I was
convinced if the muscle growth is the
same, heavy weight for low reps is the
way to go. until this happened.
It did not feel good. I don't know. I
felt like a little bit of sharp pain
right at the top of the knee.
Heavy weights puts more stress on
your joints, which isn't bad. It
actually makes your tendons stronger and
more resilient over time. But if you
only ever use heavy weights, especially
with exercises that may not be the best
fit for it, it can quickly become too
much for your joints to handle. I
usually use this pad during my normal
workouts and it's totally fine, but I
think the heavy weight it was just too
much stress. I'm just going to call it a
quits for leg extension on both sides.
Hopefully, it's it's back to normal next
time. I wasn't alone. Dennis also
noticed that his joints on his heavy
side started hurting as well. Now,
because I didn't want to aggravate my
knee more by lifting heavy, I tested
something on my final set. I trained my
heavy leg with lighter weight for higher
reps. And here's what shocked me. My
heavy side burned out way faster. By 10
reps, the burn hit hard. By 13, I had to
completely stop. While my light side
could have easily kept going. Now,
what's happening here is called
endurance adaptation. By consistently
training with higher reps, your muscles
not only adapt quickly by creating more
mitochondria to reduce the burn buildup,
but your brain also increases its
tolerance to the pain. So, it seems each
side of my body is getting stronger in a
different way. By the end of this
experiment, we'll actually test both
sides head-to-head, and the results were
not what I was expecting.
So, by week six, Dennis has become a
monster. He's lifting heavier every
week, and his body weight has also been
slowly increasing. This is week six, the
heaviest weight I ever done in my life.
That's all. From all his moaning echoing
throughout the office, I could tell he
was working hard. He's now lifting more
than double what he started with on the
heavy side. But I noticed a problem with
his light side.
14
15. Okay,
Dennis. Not enough. This is actually a
big problem. Your muscles are made up of
a bunch of small muscle fibers, but also
bigger, more powerful ones, which are
actually what grow your muscles the
most. But the thing is, these bigger
fibers are only called into action if
they are needed. So with heavy weights,
they're activated right from the very
first rep. But with light weights, they
sit on the sidelines until the smaller
ones fatigue. And the problem is by the
time you're 15 plus reps deep, most
people can't push through the pain and
just stop their sets, failing to ever
recruit and grow their bigger muscle
fibers. I even decided to pull out my
EMG machine, which measures muscle
activation, to prove to Dennis the
importance of pushing through the pain.
The higher it goes, the closer to
failure you are, so I could tell if
you're cheating, if you're stopping
short. No matter what your face says,
this tells me the truth.
Keep going.
What do you mean?
You're not even close. Curl. Use your
bicep. Up, up, up.
I can't anymore.
Three more. One.
Good.
There you go. Good job.
So on the heavier side, the muscle
activation spiked right away. Every
single rep, it was super high.
Okay.
Whereas this one, it started really slow
and then as you push harder and harder,
it got up and up. If Dennis wants his
light side to keep up with his heavy
side, every workout, he's going to have
to continue mentally pushing through
that discomfort. There you go. Keep
going. Keep going.
Keep going. I noticed another problem. I
think Dennis's ego is actually growing
more than his muscles.
Dennis,
all the way down.
I'm doing this for one the whole time.
Yes, apparently. Remember, only increase
if you can with good form. When people
chase numbers and forget about form,
this is what happens. Even though it
looks like you're lifting more weight,
your exercise might actually be way less
effective at targeting the right muscle.
All you get is an illusion of progress.
Luckily, I have been watching over
Dennis every week and catching him
whenever I see it. But if you don't have
someone like me, that is exactly why I
created the Built with Science Plus app.
It'll not only program every single
workout for you based on your body and
your goals, but it'll also show you
exactly how to do every single exercise
in your routine to maximize your growth
and minimize your injury. And if you
want, you can try 2 weeks completely
free over at buildwithcience.com or scan
this QR code here. As for me, the joint
issues continue to get worse. for
overhead tricep extensions. I think I
got like four and a half reps. But my
main concern is just my elbow. It's not
bothering me too much right now. I feel
like a little bit something. Maybe it's
just like I'm not used to going that
heavy, especially for isolation. But
definitely has me concerned. We'll see
how it goes the next few weeks. But I'm
thinking that I'm going to have to
switch it up to something a little bit
more elbow friendly, which is going to
suck cuz this is literally my favorite
triceps exercise. got to do what I can
to keep the joints healthy and try to
make it through the full 60 days. So, as
much as I've been team heavy throughout
this experiment, I'm starting to notice
it downsides. If light weights do
actually provide similar or even more
growth, they can actually be a great
option to work around pain and injury.
And I know for me, there's certain
exercises like overhead extensions where
as soon as I go too heavy, it doesn't
feel very good on my joints. Plus, in
some situations, like when I'm
traveling, all I have access to are
lighter weights, which I used to view as
a problem. But it might turn out they
work just as well as long as I continue
pushing hard. But with 60 days
officially over, it's time to test our
strength. Let's see if the weak Dennis
from day one is no more. All the way
down.
Ah Oh, he fell. What happened? And
as I expected, his heavy side is a lot
stronger, lifting all the way to
35.
Now, moving to the chest press machine,
we see that Dennis was able to push 55
lbs on his left side, but couldn't push
50 on his right side.
No. So, that begs the question, what
would happen if we took his day 60
weights from each side and switched
them? Starting with the 52.5 lbs of the
flat dumbbell press that he could easily
do on his heavy side.
Oh my god. Oh my god.
You okay? You okay? Yeah, I'm fine.
Dennis's right arm wasn't even able to
stabilize the weight to begin the
dumbbell press. Even with my help, he
couldn't get it up. It's happened a few
times.
I need help. Up. Up. Up. Huh?
I can't go up. There's no way.
Good.
I can't do that one.
What the hell?
Are you serious?
Yeah, I'm not joking. That's actually
good.
This is all for show.
I know.
This guy's the real MVP. Damn, that's
crazy. I honestly wasn't expecting that.
Wow. Then after doing 15 reps of 32.5
lbs on his light side, he went to test
his heavy side with the same weight.
Nice.
All the way down. Control. Oh my god.
Lower. Lower. Lower.
Lower. You're cheating.
Lower. Dennis. Lower.
That was half. That was half rep. Oh, I
can't. We're getting really slow.
I have to apologize in advance.
Why? Cuz I don't know how long it's
going to take to correct this imbalance.
Really?
Oh my god. Despite the imbalances I
created, Dennis was actually really
excited about the gains he made, enough
to convince him to continue focused on
building muscle rather than just chasing
abs. Now, I'm going to keep you guys
updated with his journey, but make sure
to like this video and subscribe to the
channel to show your support. But now,
let's have a look at how I did. By the
end of the 60 days, I managed to do six
reps of 92.5 lbs with my heavy side and
65 lbs for 16 reps on my light side. But
when I switched arms, my stronger side
couldn't keep up. I failed about three
to four reps earlier. Then I tried to
see how my light side would respond with
a heavy weight.
Nope.
I could only do four reps instead of the
six I got on my heavy side. The same
imbalance also happened on my preacher
curls.
This guy got more endurance. This guy
got more strength. Each side got
stronger in their own way, which makes
sense. But what about growth? Let's see
what people in the office think.
Personally, I got to go with team heavy.
On the uh the light side, there's kind
of more of like a mental aspect to it.
Like, you know, you might start to feel
tired and then not get to the point
where you're actually getting to
failure.
So, you're calling me a
Exactly.
Right. So, I think it'll be light.
The heavy side will be bigger and
stronger.
And to make sure the pump and swelling
on our light sides didn't skew the
results, we both stopped training for 3
days before the scans. The MRI confirmed
my brain did not grow. But thankfully,
my muscles did. Overall, I gained about
2 lb. A bit of that was fat, some was
water, but just over half a pound of it
was actual muscle. But here's the real
question. Did one side grow more than
the other? Surprisingly, my lighter
weight side grew just very slightly more
in almost every single muscle. My chest
actually had the biggest difference with
the light side experiencing double the
growth. Now, this might be because I've
just never train my chest with such high
reps before, but honestly, the absolute
difference for every muscle was tiny.
Sometimes as little as 15 g. That's
nowhere near statistically significant.
And honestly, you wouldn't even notice
that difference if you trained this way
for a full year. Both the ultrasound and
circumference measurements told the same
story. That said, there was one muscle
that MRI picked up that actually grew
more on the heavy side. You can't see
this muscle, but it did create a pretty
big imbalance. One that I think led to
some serious problems after the
experiment ended. It's the ilio soaz.
This muscle helps stabilize your hips
and back. and it grew on my left side
but actually shrunk on my right side. My
hypothesis is because of the heavy
one-sided leg exercises I did, this
muscle worked harder on my left side to
stabilize a heavy weight. And
unfortunately, after the experiment, I
went against my own advice and went
straight back into my normal heavy
deadlifts and ended up tweaking the
right side of my back for the first time
in my life. I may have to spend some
time correcting these imbalances, but
now let's see how Dennis's results
compare. Do you think you built muscle?
I definitely feel I build muscle for
sure. I can tell.
Okay. What about fat?
Maybe a little bit. I do feel I see a
little bit more here. But I need to see
a number.
Well,
you gained 3 lb. Of that 3 lb, pretty
much all of it was muscle. No way. Shut
up. Your fat, if anything, had dropped a
little bit because of that. Your day one
body fat was 18.4% and now it's 17.8%.
Because you added more muscle now your
body fat actually dropped.
No way.
Which is really good. That's sick, dude.
That's sick.
So my body fat dropped without doing
cardio.
Yeah. And you ate like
Training wise, I did not miss one day.
No, training. You were good.
Diet probably.
But now the question is, of those three
lbs,
where are they going?
So your arm circumference measurements,
your left arm, it grew by 0.8 cm, which
is really good. And your right arm grew
by
1 point something
0.9
cm
more.
Left leg grew by 0.3 cm and your right
leg grew by 0.4
cm. Now every muscle and dentist trended
toward the lighter side growing just
slightly more. But again the difference
was tiny well within measurement error
and nowhere near statistical
significance. So, while there was the
smallest trend toward the lighter side,
probably just because the light side did
more volume, but as a scientist, I'd
have to call it even. So, going forward,
how would you prefer to train? Do I want
to feel
happier during the training? And I'm my
ego, you know, on the left side, I can
go high, more weight, more weight, more
weights every week. But on the right
side, just barely doing. I might do the
heavy side.
And remember, there is a middle middle
that we didn't touch. You know what I
mean? We did like three to six reps and
then we did 15 to 25.
The range right in between what we
tested. So 6 to 15 reps with a moderate
weight. That is what I believe is the
sweet spot. It's light enough that your
joints don't get beat up, but heavy
enough that every set doesn't feel like
a mental battle. That's the rep range
I'm going to use for most of my
training. But I'll still sprinkle in a
few really heavy sets and a few really
light sets for higher reps since this
variation may provide an added benefit.
But the big lesson from this whole
experiment is simple. How much weight
you use, it matters far less than how
much effort you put in and the form that
you're using. It's exactly how so many
of our app members have transformed
their bodies with a completely done for
them system. And you can try out the app
free for 2 weeks over at
builtwithscience.com or just scan this
QR code right here. Comment below if
there's another experiment that you guys
want to see. But for now, give this
video a watch next, which covers
everything you need to know about
building muscle effectively.