Long before it became a place for deadlifts, rope climbs and rowing sprints, the Conex box was a tool of war.
Steel shipping containers were invented by the U.S. military during World War II and then refined by the U.S. Army for use in the Korean War to solve a logistical problem: how to move massive amounts of supplies quickly, efficiently and securely across continents. Designed to be portable, stackable and nearly indestructible, the containers became the backbone of global shipping — the same steel boxes now seen hoisted by cranes at ports and stacked high on container ships.
At the Miami-Dade Sheriff’s Training Center in Doral, the latest variation of the Conex, short for Container Express, sits ready to help sculpt muscle.
Gunfire cracks steadily from a nearby shooting range, sharp and sporadic, echoing across the grounds. For first-time visitors, the noise can be jarring. For those who train here regularly, it barely registers — just another layer of sound in a facility built around readiness, repetition and physical demand.
This is where candidates for the Miami-Dade Sheriff’s Office endure the academy, and where seasoned deputies return to sharpen skills, update certifications and stay in shape. Spread across the campus are two indoor fitness centers, a full-length indoor basketball court, an Olympic-sized outdoor swimming pool and a large sandlot used for strength and conditioning work. Nearby sits an indoor mixed martial arts facility known as the Hive, its name a nod to the constant and collective hum of movement inside.
The grounds also include a running track, an obstacle course and extensive classroom space for instruction. Tucked into one corner is “Survival City,” a carefully constructed slice of what resembles a city block, where deputies train for real-world encounters in a controlled environment. Nearly every inch of the training center signals physicality and preparedness.
The Conex Performance Training Locker is the latest addition to that footprint — and, in its own way, adds to the noise.
Officially opened during a ribbon-cutting ceremony January 15, 2025, the Conex is a fully outfitted gym housed inside a steel shipping container, positioned between the fitness center and the shooting range. Inside are roughly 20,000 pounds of equipment, including bumper plates, dumbbells, barbells and benches. Affixed to the outside are nine squat racks, along with crossbars that allow at least 108 people to train at once. At one end, a rope climb rises high enough to test grip strength and resolve, especially for those uneasy with heights.
The opening event reflected a broader view of fitness that extends beyond lifting. Vendors and specialists were on hand to discuss recovery, sleep, nutrition and overall wellness — a recognition that physical readiness is sustained not just through exertion, but through rest and care.
Artificial turf surrounds the container, turning what was once unused space into an outdoor training zone. Rowing machines stored inside can be rolled onto the turf for conditioning sessions, and plans are already underway to expand the area with a covered workout space and an additional Conex. The design allows workouts to spill outdoors without sacrificing structure or capacity.
Performance training lockers like this one have been installed around the world, but they remain uncommon in law enforcement training environments. Miami-Dade is among the few agencies to integrate such a system into both recruit and veteran training. Professional staff are also welcome.
Dr. Kelly Kennedy (PhD, CSCS*D) the facility manager for the center’s wellness program, said the idea had been years in the making.
“At a conference over twelve years ago, I remember thinking how incredible this would be for our agency, especially without being limited by space inside the fitness center,” Dr. Kennedy said. “There were many times we tried to give recruits opportunities to better understand movement patterns and how they build strength and endurance. We’d take equipment outside and do the best we could.”
For Dr. Kennedy, the Conex represents a shift in how training space is imagined.
“I had my eyes on this for many years,” she said. “Being able to use a container like this, with all of the equipment available, really feels like the start of a brand-new day. It gives us a way to keep our employees healthy for the rest of their careers. We can train up to 108 people around this container, and I’m incredibly happy to introduce it to our agency.”
Built by Beaverfit North America, a Reno, Nevada-based company that specializes in modular training environments, the Conex was designed with flexibility in mind. Jason Clark, the company’s director of mission success, said the goal is not to impose a single training philosophy.
“We don’t marry ourselves to a methodology,” Clark said. “We marry ourselves to a system.”
That system, he said, is designed with growth in mind, both in terms of those who use it and the structure itself.
