Together with NOBULL
A shoe is just a shoe. Until it’s not. 

And if we’re being honest, one of the first mistakes we made years ago was not considering how our footwear influenced our performance.

Yes, you can train barefoot. And there are benefits to that. Arnold did it, and it didn’t affect his ability to hit a squat PR of more than 600 pounds. 

But your feet shouldn’t be an afterthought in the gym. 

Because if you put on the wrong shoe for the wrong activity, the thing you take for granted could be working against you the moment you load a bar. 

When we started speaking to performance experts two years ago to help us understand footwear, they all made a simple point: Different shoes should be built for different activities. 

But most people wear the same shoes for all activities. And if they get hurt or feel off, the footwear can make a real difference. 

Your everyday running shoes are built for forward motion. A tall, cushioned heel that tips your weight toward your toes. Great on a run. But a problem at the squat rack. 

When researchers had trained lifters squat in running shoes, that cushioned heel pushed them almost an inch farther forward than a flat shoe did. 

An inch doesn't sound like much.

But that lean dumps the load off the bar and onto your lower back. Rep after rep. Set after set. Same shoe you wore on your run. Completely different job. And it's costing you.

That's the trap with footwear. It's one of the few things you own where the right choice depends entirely on what you're doing in it. And the wrong one can look identical on the shelf. Same laces. Same logo. Opposite job.

So when readers ask us what to lift in, and they ask a lot, we don't just hand over a name.

We do what we do with every topic in Arnold’s Pump Club: we went to the research. 

We recommend plenty of products long before any partnership exists. We recommend even more products that never become partners at all. 

If you go back through the more than 1,000 emails we’ve sent, you'll find the receipts there. 

The partnership doesn't earn the spot. The process does. Before we tell you we like anything, whether that’s a supplement, a set of pans, or a pair of shoes — we do the same thing every time: 

We test what the thing is actually supposed to do. We build a set of tests around it. We dig into the research to sort what's real from what's marketing. Then we put it through its paces and tell you what we honestly think.

This is the first trip through the lab in a new series, and the idea behind it is simple. 

When we tested more than half a dozen shoes in the gym, NOBULL Outwork came back as the highest-rated shoe. And then the NOBULL Outwork Flex came back with even more positive reviews from Pump Club members.

But we want to hand you more than a verdict. We're handing you the work. 

Because the real value isn't a name to go buy. It's walking away with the test, so you can take our pick or run the checks yourself. 

Either way, you come out a little wiser. And a little harder to sell to, which means you’re less likely to be fooled or waste your money. And that’s a win for us. 

You wanted to see our work, so that’s what we’re showing today.

We used six tests, and we focused on strength and athletic performance. Because if we’re talking running shoes, it’s a different story. 

Strength is the force you put into the ground. Anything between your foot and the floor either helps you deliver that force or quietly eats it. The whole job of a strength shoe is to get out of the way.

Here's what we look for, why it matters, and how to check each one yourself the next time you train.

Don’t Miss It: If you want the shoe we recommend, there’s a special $50 OFF discount exclusive to Pump Club readers this weekend only. To access your discount, use the code APCFLEX. 

Test 1: Can you feel the floor?

We start with the most basic question. Does the shoe let you feel the ground under you?

Stability comes from your foot reading the floor and adjusting. A hundred tiny corrections you never notice you're making. 

Bury that foot in foam, and you mute the signal. 

When one team filmed lifters squatting barefoot, in running shoes, and in flat trainers, the running shoes changed how they moved. And the lifters themselves kept saying that the flat, barefoot setups felt steadier and more connected to the floor. They could feel the difference before anyone showed them the footage.

Want to feel it yourself? Next leg day, do a couple of warm-up squats in your running shoes. Then kick them off and do the same weight in your socks. You'll feel your weight ride forward in the cushioned shoe and settle back into your heel and midfoot the moment it's gone. 

That settling is the thing we want a shoe to keep. Then add grip and protection so you're not literally lifting in your socks.

One 2025 trial had participants perform deadlifts in flat minimalist shoes versus regular ones and found the flat shoes produced a little more force, a little faster. 

The gap was small enough it could've been chance. A signal, not a verdict. We're telling you anyway. The direction matches the physics; it matches what we feel under a heavy bar and what allowed our testers to perform best, while also making them feel more comfortable wearing shoes in a gym rather than walking around barefoot.

Test 2: Does it hold still when you load it?

How a shoe feels in the store and how it behaves under a barbell are two different stories. So we stop trusting the showroom and load it up.

If you want to know how your shoe will hold up under load, start with your thumb. Press it into the middle of the sole. If it caves in your hand, it'll cave under weight. 

Soft foam isn't bad. It's just built for a different job. A review of more than 60 footwear studies confirmed soft midsoles are excellent at soaking up impact, exactly what you want when you're running or landing a jump. But the same review named the tradeoff. 

That softness dulls the signal coming up from your foot. The very feedback you lean on to stay balanced under load. And tall, plush soles bring their own wobble. Runners in the tallest, softest shoes were less steady at the hip and rolled through the foot more than those in lower, firmer ones.

So this isn't "cushioning is bad." It's that a shoe built to absorb force is the wrong tool for a movement built to create it. 

Foam that squishes under your foot is foam eating the force you meant to send into the bar. It's the difference between jumping on sand and jumping off hardwood. Same legs. The sand just swallows your hops.

What to notice: load a heavy set and watch your feet at the bottom of the rep. If you feel a roll or a sink, like standing on a mattress, the shoe is moving while you're trying to be a statue. The ones we keep feel like a firm little platform that doesn't care how much weight you stack on top of it.

This is where the NOBULL Outwork Flex really stood out with testers. 

Test 3: Can your foot spread out?

Set your feet like you're about to squat. Now try to fan your toes and grip the floor. In a lot of shoes, you can't. The front pinches everything to a point.

This is the test with consistent science, and the one almost nobody thinks about. 

When researchers pooled 28 trials involving nearly 1,400 people, they found that shoes with room for your toes to spread build real, measurable strength in the small muscles of the foot. 

Those muscles are what help you maintain balance on one leg and keep your foot steady under a heavy load. And it doesn't take a program. One group found that toe strength increased by almost 60% over six months. Just from wearing wide, flat shoes day to day. No added exercises at all. Room up front isn't a comfort feature. It's a wider, stronger base under you every time you train.

You'll notice it most when you do exercises on one leg. 

Next split squat or step-up, see whether you can drive through a flat, spread foot, or whether you're teetering on the inside edge of it. That's the test. Odds are, you’ll notice a difference.

Test 4: Does it lock you in?

Room only helps if the rest of your foot stays put. A roomy shoe that lets your foot slosh around inside it leaks power its own way.

We don't have a clean study for this one, so we won't pretend we do. 

What we have is a stopwatch and a lot of reps. We shuffle side to side. We do heavy single-leg step-ups. 

And we run the ugly one. A hard set of squats, eyes on the heel, watching for it to lift on the way up. If your foot slides when you cut, or your heel pops out the back, the force you just generated is escaping into the gap. 

The good shoes pull off an important detail: Roomy where your toes live, locked down everywhere else.

Test 5: Will it survive your workouts?

This one isn't science. It's blunt force reality of wear and tear.

We didn’t just test the shoes. We put them through every type of workout you might try. Squats, deadlifts, and lunges were the easy part. But we added athlete drills, like lateral shuffles and acceleration and deceleration drills. Sled work and gravel sessions, because that kind of work will test the sole until it stops gripping. 

Plenty of shoes feel great for two weeks. That tells you nothing. 

The real question is what's left after a month or three of real training. 

Check the toe and the inside edge then. That's where a cheap shoe gives itself up, and it's a test only time can run.

Test 6: Will you actually wear it?

The last test is the one most reviews skip, and it’s more about the practical reality of investing in something you wear frequently.

The best shoe is the one you reach for. If it needs a three-week break-in that wrecks your feet, runs hot, or feels like a board strapped to your arch, you'll keep grabbing your old pair. 

And every clever thing about that sole stops mattering. A great shoe that lives in your closet scores a zero.

Tests Designed For Real Life

None of this happens at a desk. Our team lives in the shoes first. Weeks of normal training, hunting for the stuff that only shows up over time. The hot spot that appears on session twelve. The sole that starts to slip. The fit that loosens once the upper breaks in. 

Then we pass them around the Pump Club community. Different bodies, different training, different demands. The person doing four classes a week catches things the lifter chasing a heavy single never would. And the other way around. 

We're looking for patterns, not one-off opinions. And we hold every shoe against all six tests. Most never make it through. That's the whole point of having a bar in the first place.

The Shoes That Stood Out

For the past year, when readers asked what to lift in, our answer was the NOBULL Outwork. And yes, eventually NOBULL became a Pump Club partner. But the six tests came first. And we originally reviewed shoes for an entire year.

The original Outwork, the OG, is flat, grippy, nearly indestructible, and stiff. That stiffness is on purpose, and it's exactly why we've loved the OG for heavy work. Grinding out a max deadlift or fighting up from a deep squat, you want a platform that refuses to give, so the force goes into the bar instead of the shoe.

But stiffness comes with a cost, and it shows up everywhere outside of max-effort lifting. It takes real time to break in. It's less forgiving when your session is a mix of strength, conditioning, and accessory work. 

If your week is classes and circuits and just getting strong, with no interest in pulling 500 pounds, the OG can be more shoe than the job needs.

That gap is exactly why NOBULL built the Outwork Flex. We had three months to test it, and it offers much of what we love about the original Outwork, with adjustments we think will make it a Pump Club favorite.

The Outwork Flex keeps everything the testers care about: the same low, flat, grounded ride, a roomy toe box so your foot can spread, and a platform firm re not sinking into the foam mid-lift.’ foam mid-lift. 

What changed is the demand it makes on you. A breathable upper and a softer, more flexible build that breaks in over days instead of weeks. A smoother feel underfoot. And better lockdown. An updated harness that holds your foot down without choking it.

If you’re chasing a one-rep max and you want the stiffest, most grounded platform under you, we recommend the original Outwork. The break-in period earns its keep. 

If you want a strong, comfortable, locked-in shoe you'll put on without thinking twice, the Outwork Flex is the one. It passes the test that settles all the others. You'll actually keep wearing it.

The shoe, and the criteria

We were able to test a shoe for months that wasn’t available. But as of this week, the Outwork Flex is now available for anyone to purchase. Seven colorways. Normally $150 a pair.

Here's the part with a clock on it. 

For the next 48 hours, you get $50 off the launch. That puts the shoe that passed all six tests at $100, this weekend only. The window closes Sunday night. Monday it's back to full price. To access your discount, use the code APCFLEX.

That's the first trip through the lab. This shoe is our pick. The six tests are yours to keep. Next time someone tries to sell you a training shoe, you'll know exactly what to put it through.

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Publisher: Arnold Schwarzenegger​

Editors-in-chief: Adam Bornstein and Daniel Ketchell