What is hybrid density training, and why does Raymond Gutierrez’s trainer highly recommend it?

We’ve all seen Raymond Gutierrez lately, right? He looks great, and based on his continued dedication to health and fitness, he feels great. And he’s the first to tell people that there’s no magic pill to his transformation.

It’s the same sentiment his trainer Arnold Aninion shares. Aninion, whose stable of celebrity clients include really fit women like Aubrey Miles, Anne Curtis, Solenn Heussaff, and Isabelle Daza—collectively known on social media as #arnoldsarmy—recently led a quick-ish but intense workout session that’s all about hybrid density training as part of SaladStop!’s Eat Wide Awake movement.

Hybrid density training. We know and love/hate HIIT (high intensity interval training), but HDT sounds kind of new to our ears. “Oh, it’s been around for a while,” Aninion explained to Garage a few minutes before the workout session started. “There are two different types of principles when it comes to training: there’s high volume, and then there’s high density. High density is basically stacking one exercise with another. You work on your upper body, you work on your lower body, and then you do some sort of aerobic activity. “

Canadian physical trainer Jon-Erik Kawamoto further explained HDT as “taking the density training approach to the next level, [i.e.] I like to add a third exercise [like] a 20-second all-out sprint.” Density training is meant to gear up one’s caloric burn and endurance while preserving or even increasing muscle mass through a high intensity circuit-style training system.

Preserving and increasing muscle mass is key, because according to Aninion, “nothing burns fat other than muscle.”

For this particular session, the celebrity coach and trainer had participants, which included volleyball player Michele Gumabao, do eight reps of weighted exercises: shoulder presses, bent over rows, weighted lunges, and “suicide runs,” or quick sprints. After five rounds, they then switch to Tabata training, doing 20 seconds of jumping lunges, plank walks, mountain climbers, and walk-outs with press-ups; in between, there’s a 10-second rest, for a total of four rounds.

Spoiler alert: we made it through to the end, but not without feeling like giving up. Mountain climbers are the worst.

Constantly reminding myself that traveling is never an excuse to miss a workout! Made it home just in time for our quick but intense session with coach @arnoldaninion 💪🏻 Glad to share this experience with other movers of the #EatWideAwakeMovement of @saladstopph ❤️ wishing you guys a Happy Salad Month! Love your body, treat it right! ❤️ 📸 @rynong 😘 Always @adidasph 👌🏻

A post shared by Michele Gumabao (@gumabaomichele) on Sep 16, 2017 at 5:12am PDT

“It’s the same movements over and over again,” Aninion described. “You learn the movements first then do the cardio, so the first part is learning form and how to do the movements properly and in sequence. As you go, the muscle memory kicks in, so you get better with every round. By round five, you’re flying—but then, just as you’re familiar with the routine already, you’re getting tired. Now, you’re no longer figuring out how to do the move, but how to keep on. You’re just trying to survive. There’s a part where you go into auto-pilot—that’s the difficult part. It’s hard to think when you’re tired.”

 The variety of movements also keeps the workout from feeling monotonous, making it pretty fun despite also being difficult. “Most people who do HDT like the energy [it gets out of them]. Because you’re doing weights and running around, you’re doing movements that cover more than one muscle group.”

 Sure, a muscular dude who looks like he could dead-lift anyone he meets on the street can no doubt take on something as intense as HDT. But take it as well from a guy who has worked with people and has seen them transform through sheer will power. “Oh, anyone can do it.”