I Finally Found a Training Shoe That Does It All — Meet the NOBULL Outwork Flex
Most of my workout routine is cross-training. While I'll occasionally hit the gym just to lift, I'm more likely to be in a group workout class that covers all the basics: dynamic stretching, sprint work, lifting circuits, and a cool-down.
That means I spend a lot of time debating footwear. My go-to running shoes are too cushioned and flexible; great for cardio, but too soft and unstable when you're loading up a barbell. Weightlifting shoes offer the firm, grounded base your squats need, but they're punishing during sprints or any movement that requires your foot to move dynamically.
For years, I've bounced between the two, accepting that no single shoe could do both jobs well. Then NOBULL launched the Outwork Flex, and I've finally found a solution to my biggest cross-training woe.
FYI
What is the NOBULL Outwork Flex
The Outwork Flex is NOBULL's newest iteration of its popular Outwork training shoe: a silhouette already beloved by gym-goers who need a shoe that can handle both lifting and conditioning work.
Think of the Flex as the Outwork evolved. It keeps the same foundational DNA—the 4mm heel-to-toe drop, the wide base, the stability-forward build—but introduces a handful of targeted updates that make it meaningfully more versatile for dynamic, mixed-format training. It's not a reinvention, but a refinement.
What's new in the Outwork Flex
The most significant change is an extra 1mm of stack height in both the heel and forefoot, paired with an extra 0.8mm of EVA strobel i.e. memory foam. These additions sounds minor, but in practice, they translate to slightly more arch support and a more cushioned underfoot feel without dramatically compromising the shoe's stability. When I put the shoe to the test in last week's class, I was impressed by how well the new iteration absorbed during high-impact movements, like jump squats or box step-ups.
The other major update is a more flexible upper. Where the original Outwork has a stiffer, more structured upper that locks your foot in place, the Flex allows your foot to move more naturally. During dynamic movements (think: lateral shuffles, burpees, running sprints) that flexibility makes a real difference. Your foot can respond to the ground rather than fighting against a rigid exterior.
What you need to know
No shoe is perfect, and the Outwork Flex comes with a couple of honest caveats. The extra stack height, while beneficial for cushioning and arch support, does marginally reduce the ground-feel stability that makes the original Outwork so effective for heavy lifting.
If you're a competitive powerlifter or someone who prioritizes maximum stability above all else, you may notice the difference under a heavy load. The Flex also has slightly less grip than the OG, which is worth noting if you train on slick surfaces or do a lot of lateral cutting movements that demand traction.
There are trade-offs, but for most recreational and intermediate gym-goers, they're unlikely to be dealbreakers—especially given what the Flex gains in return.
Why footwear actually matters for lifting
Before I get into how the Flex performed, it's worth pausing on why training shoe choice matters more than most people realize.
Research consistently shows that footwear has a direct and measurable impact on squat biomechanics. A review 1found that weightlifting shoes decrease trunk lean and generate more plantar flexion compared to running shoes and barefoot lifting—meaning your torso stays more upright and your ankles move more efficiently through the range of motion.
Another study2 found that weightlifting shoes reduced trunk lean and increased foot segment angle, and recommended them specifically for people prone to forward lean who want greater knee extensor activation, which, frankly, is most of us.
For athletes doing mixed training, i.e. lifting and conditioning in the same session, the challenge is finding a shoe that supports both demands. That's exactly the gap the Outwork Flex is designed to close.
How I tested it
I wore the Outwork Flex to my regular Monday and Wednesday group fitness classes for one week. These classes are the kind that expose every weakness in a shoe. You need flexibility for the warm-up, responsiveness for the sprints, and a stable base for the weighted work. I also have a history of plantar fasciitis flare-ups, which has made shoe selection feel especially high-stakes.
Performance breakdown
Sprints and dynamic movements: The flexible upper was immediately noticeable during the cardio portion of class. During running sprints and burpees, my foot could move naturally through each stride without the stiffness I sometimes feel in more structured training shoes. The extra EVA cushioning also helped absorb impact during high-rep jump movements. My feet felt less fatigued by the end of the conditioning block than they typically do.
Strength circuits and squats: This is where I was most skeptical, and most pleasantly surprised. Despite the additional stack height, the Outwork Flex still felt grounded and stable during weighted squats and strength circuits. I didn't feel like I was squatting on a sponge. The shoe held its shape and gave me the base I needed to feel confident loading up. Research on CrossFit athletes3 has shown that weightlifting-style shoes produce a lower hip torque contribution and a higher knee torque contribution compared to conventional footwear, which aligns with the more upright, knee-forward squat position the Flex supports.
Plantar fasciitis: This was the real test for me. I've had flare-ups triggered by everything from pickleball to long walks in unsupportive shoes. After two full sessions in the Outwork Flex, including sprint intervals, I had zero plantar fasciitis symptoms. The combination of the slightly elevated stack height and the EVA strobel seems to provide just enough cushioning and arch support to keep things comfortable without tipping into the overly soft territory that can actually destabilize the foot.
Outwork vs. Outwork Flex
Both shoes share the same 4mm drop and NOBULL's signature wide, stable base. The differences are subtle but meaningful depending on how you train:
- NOBULL Outwork: Stiffer upper, slightly lower stack height, more grip, maximum ground-feel stability. Best for lifters who prioritize heavy strength work and want the most locked-in, stable platform possible
- NOBULL Outwork Flex: More flexible upper, +1mm stack height, +0.8mm EVA strobel, slightly less grip. Best for mixed-format training, anyone whose workouts include both lifting and conditioning, or who wants a single shoe that can handle a group fitness class from warm-up to cool-down
If your training is primarily barbell-focused, the OG Outwork is still the stronger choice. But if you're doing anything that blends cardio and strength—HIIT, group fitness, CrossFit-style workouts, or circuit training—the Flex is the more versatile option.
Fit and sizing
One thing I can confirm without hesitation: no break-in period required. I wore these straight out of the box to a full class and had zero discomfort. Sizing is consistent with both the original Outwork and NOBULL's All-Day Knit, so if you already own either of those, order your usual size with confidence.
Don't forget
The verdict
The NOBULL Outwork Flex solves a problem that a lot of gym-goers have quietly accepted as unsolvable: The need to choose between a shoe that's good for lifting and one that's good for cardio. By adding a modest amount of stack height, a touch more EVA cushioning, and a more flexible upper, NOBULL has created a shoe that genuinely bridges both worlds, without gutting the stability that makes the Outwork worth wearing in the first place.
For anyone who does mixed-format training, group fitness classes, or simply wants one shoe that can handle everything from a sprint to a squat, the Outwork Flex is worth serious consideration. It's the Goldilocks solution I didn't know I needed—and now I can't imagine training without it.