A wave of nausea struck me after a grueling set of lying hamstring curls.

'You can go outside for a few minutes and get some fresh air, or if you can walk, you can go upstairs to the women's locker rooms and let it out,' Dwayne McDaniel, owner of Diamond Gym in New Jersey, said to me.

The thought of vomiting made me anxious, which worsened the nausea. I glanced at my bodybuilding friend, Eda Greene, then at Dwayne and said, 'I’m going to step outside for a second.'

As Eda led me to the front door, she comforted me, saying she’d had her fair share of workouts where she thought she 'wasn’t going to make it.'

Located in Maplewood, it has been a pillar in the bodybuilding industry for 50 years and hailed for its 'never give up' training style that tests everyone who steps inside. 

Known for brutal workouts, Dwayne said he once saw a 150lb lifter deadlift 500lbs and someone lose a fingertip because they were not paying attention while spotting a bench press. 

As I caught my breath, I realized why Diamond has the tagline 'home for the hardcore' and what makes it so 'dangerous.' It pushed me beyond limits I didn’t know I had. 

'It was always hardcore. That's what kept me coming back,' Dwayne, who went from being a member to taking over the business in 2007, told me, explaining how he used to travel from the Bronx to New Jersey every day. 

'It was always that drive, that mentality of "one more rep,"' he said, that brought him back every time. 

Founded in 1976 by professional bodybuilding judge and National Physique Committee Vice President John Kemper, the gym became a bodybuilding mecca, hosting celebrities and athletes. 

Mark Wahlberg used to pump iron there with Dwayne in the 1990s, and musicians including Queen Latifah, Wyclef Jean and comedian Matt Rife have also had a taste of just how hardcore it is. 

Some of bodybuilding’s biggest names have trained there, including Akim Williams, who once pulled an 800lb deadlift - roughly the weight of a grizzly bear.

In recent years, trainers Shay ‘Unc’ Fletcher and Haddy Abdel have played a major role in boosting the $50-a-month gym’s online presence with their social media content. 

Known for their no-nonsense training, the duo regularly pushes 300 rep sets, push-up supersets, and the infamous 'run to the hill,' where Unc sends trainees sprinting up an outside incline. 

Videos show them shouting, joking, and constantly hyping each other up. They also gather afterward for real talks, encouraging the gym as an outlet, emphasizing mental health and positivity.

Haddy even 'lost' a toe during a workout after dropping a 455lb hex bar deadlift and catching it on his foot. 

As blood poured from the injury, he recalled in a video that his ears were ringing, while Unc urged him to finish the set, saying: 'What do you need? You don’t need 10 toes, you only need nine.' 

Unc enforces a strict set of rules for every workout: no jewelry, no sitting down, no closing your eyes, no dropping your knees during pushups, and a mandatory hoodie. 

Influencers and athletes travel from around the world to train with the duo. Their most viewed YouTube video has over a million views and shows Super Bowl champ AJ Brown being put through an unforgiving workout.

Together, they’ve racked up over two million followers and more than half a million YouTube subscribers. 

Despite the gym's rise in social media popularity, Diamond still operates under strict rules.

'We call people out who are on their phones, texting on the workout benches. I've lost members because they can't talk on the phone, which I'm fine with,' Dwayne said.

As a competitive bodybuilder myself, I earned my professional status in the fitness division at the 2026 Arnold Amateur Classic.

Fresh off that achievement, I wanted to see if I was tough enough to complete a session at Diamond. When I called Dwayne to fix a time he warned me: 'Diamond Gym is not for everyone.'

Dwayne greeted me at the front desk, and we decided to train legs. I told him I was excited to be pushed. 

Eda laughed, and Dwayne said, 'Don’t say that' as he’d take it as a cue to push me even harder. 

Social media doesn’t fully capture the gym. Inside, it stretches across two floors and four connected rooms, packed with some old-school machines I’d never seen before. 

Artwork lined the walls alongside snaps of bodybuilders. One picture read: 'Diamond is a girl’s best gym.'

There’s a strong presence of female athletes at Diamond despite its 'male-dominated' reputation. They train just as hard as the men, sometimes alongside them, Dwayne said.

Eda, who has trained at Diamond since 2012, beamed as she gave the tour, talking up the gym’s camaraderie: 'You don't get that at any other gym, here people will just run over to you and help you, or push you to add more weight.'

She used to be local to the gym but now lives two hours away, and like her, many people travel from around the world to train at Diamond. Just days before, a group of guys from Sweden came in to workout. 

After the tour, I warmed up with a 10-minute walk upstairs in the cardio room, then moved into the leg machine area. 

I started each exercise with no weight to warm up. After that, Dwayne chose a weight that would push me to about 75 percent of my maximum strength, allowing me to do more reps while still lifting heavy. 

Each set followed a pattern: 30 reps for the warm up, then 25, 20, and 15 reps, with the weight increasing each time. The resistance varied depending on the machine.

First up was hip abductors, adductors, then glute kickbacks, all back-to-back. This counted as one set. 

By the second round, I was relying on Dwayne to count and just focused on walking without a limp. 

'That was only the warm up,' he said to me as I tried to catch my breath.

Dwayne adjusted and critiqued my form, especially on adductors - if my knees didn't touch when they came together, it didn't count. 

In between sets, he explained that training intensity varies day to day based on factors like nutrition, and encouraged me to always listen to my body. 

Feeling humbled, I wobbled downstairs to my next exercise - lying hamstring curls, where he turned my feet inward to isolate my posterior muscles. 

It felt nearly impossible to add resistance to this, curling my legs upward was like trying to cut through a diamond. 

I had an intense dryness in my mouth after the first set. I’d seen on social media that Unc doesn’t let his athletes drink water, but I asked anyway. Dwayne allowed me, advising me not to gulp it down.

He added water can sit heavy in your stomach during intense workouts, triggering nausea and even vomiting, though some get a second wind after they 'let loose.' 

I took small sips just to keep my mouth from going dry, but my stomach churned after the second round of curls.

Afraid of getting sick, Dwayne had me pause and stretch, saying nausea fades when you keep moving. I pushed through and finished, surprisingly without feeling sick during the set. 

'How we train is a way of life. That also comes from John Kemper, he wouldn't let you drink water,' Dwayne said of his mentor.

I was exhausted and my legs felt like jelly. I was barely halfway through the session.

Eda stayed by my side as I stepped outside for fresh air and to hold back the nausea. But after that, I was ready for more. 

Next was a seated hamstring curl, where I turned my toes inward and leaned forward. 

I clung to the safety bar and cranked out the curls, my legs exploding with a burning sensation.

Dwayne’s motivation was contagious. His rep counts and constant support were all I could hear as I pushed through.

'It's the bicep curl for your leg,' he said, making sure I controlled the movement.

He helped me at the end of each set when fatigue peaked. Between sets, I stood stretching, wondering why we chose a lower body workout instead of upper. 

To give my posterior leg muscles a break, we moved onto leg extensions to target my quads. 

I tried another unfamiliar variation that had me seeing stars. I leaned a bit further back on the machine and as my legs straightened, I engaged my core and lifted my thighs off the seat. 

This was the biggest challenge yet, each rep was more brutal, and toward the end I could barely lift my legs up like he wanted me too. 

The last set was the hardest. My legs felt anchored down, I could barely move them, and I didn’t feel like I had anything left to keep going and even shook my head and almost said, 'I can't.'

But hearing Dwayne shout: 'let’s go,' 'push,' and 'I’m here,' while spotting the movement helped me find the strength to finish.

Some clients have quit when things became difficult, but Dwayne said they always found their way back.

'They came back because they didn't realize what they were getting here. I'm not just pushing you to push you. I'm pushing, because I can see you can do more,' he said.

That gave me the drive to finish the final exercise, an alternating bicycle leg press that absolutely destroyed me. 

Dwayne guided me through the workout, making sure I bent my legs properly and pushed through my heels. 

I dealt with an intense toe cramp mid-set from not relaxing my feet, but at least it wasn't from dropping 400lbs on it.

After he adjusted my form, I grinded out the last rep, drenched in sweat.

I nearly collapsed to the ground as I reflected on the experience I endured. I came in expecting to be tested and gave it my all.

My boundaries were pushed, I got uncomfortable, and felt like a different person. My legs are still sore days later, but it was the best leg workout I’ve ever had. I’d go back in a heartbeat.

Throughout my lift, other gymgoers were doing the same - working quietly toward their own goals. They were supportive, greeting us as we moved through the gym. 

'I know a lot of people that come in, I got a family here,' 26-year-old Iven Champagne told me in between his heavy hack squat exercise. He's been a Diamond member for over four years.

Champagne was working out legs just as I was, and he told me the heaviest he ever squatted on the machine was eight 45lb pound plates - around 360lbs in total.

'The gym is a vibe. I like a gym where everybody gets busy. I like to get busy, I don't like other gyms where people are on their phone.

'We're on the phone all day so you come here for an hour or two - that's how you're going to grow,' he said.

And the gym has grown since it first opened it's doors. Kemper created the 'give it your all' culture, while also giving young people a place to belong.

Dwayne also commended Unc and Haddy, calling them motivating and a source of inspiration for the youth. 

'They give hope and energy to young men who don't have that,' he said. 'They're very positive, no matter what.' 

'I was brought here as like a troubled kid, had a lot of energy, no break, all gas pedal. Came here and I never left,' Dwayne recalled.

'Everybody understands if you're here, that means you're serious about your goal. I think hardcore is for everybody. You know, it just depends on how bad you want.'

And what does he think about it being dubbed 'dangerous?' 

'"Dangerous" is good, in a sense. To me, it's like, be careful, because you're gonna get what you ask for,' Dwayne said.