Gym StairMasters full? Forget ‘em — those dinosaur machines are for amateurs, anyway.

If you want a real quad workout, and a taste of Santa Monica culture to boot, head outside to where 4th Street meets Adelaide Drive, to an area locals simply call “The Stairs.”  At Adelaide, head right — or just walk toward the steady stream of sweat bedazzled, tennis-shoe clad pedestrians clogging the street – and you’ve found them: two sets of breath-takingly steep, seemingly never-ending stairways promising a workout session your read-end and thighs won’t soon forget.

The outdoor stairway workout has become a Santa Monica landmark, where the fit go to get fitter, and the faint of heart don’t even dare… And yet, hard as the workout may be, on a gorgeous weekend morning, it can be a challenge to find your spot among the throngs of dedicated walkers moving steadily down the stairs, then up the stairs, then down the stairs, and up the stairs…

You get the idea.

It can be daunting, standing at the bottom of those stairways, looking way, way up. But don’t be intimidated. Go ahead, jump into it, embrace the challenge. No one’s telling you how many rounds to take on – once? Twice? Nine? It’s up to you. Even one round is enough to get your heart pumping, your calves tingling, your thighs embracing that fitness burn.

Regulars simply swear by this workout, claiming the leg and gluteal sculpting results have kept them coming back for more.

“Sure it’s tough,” admits local Paula Resley. “But that’s why I come, because there’s no workout like it. And it’s not in the gym, I’m outside, enjoying the gorgeous weather, surrounded by stunning homes in the neighborhood, the ocean’s not far away… What’s not to love? Except all the sweating, I guess.”

At the top, you’ll usually find bottles of water left for purchase, on the honor system, $1 each. Stairway access is free.

We suggest starting with the wood-planked stairway. It’s a straight walk, with stairs that are wider, steps fewer (154 from bottom to top). If you’ve by chance mastered those effortlessly, just a few yards away are the concrete stairs, a little more difficult to maneuver with its shorter steps, curving pathway, and roughly 30 additional stairs.

Some fitness fanatics may even suggest you try “The Loop” – local lingo for running down one set of stairs, jogging the short distance to the second, shooting up those stairs, repeat…

When you’ve had your fill, drag your weary muscles to Santa Monica’s own “grassy knoll” area, patched along 4th Street, where athletes pause to catch their breath (you have our permission to ignore the show-offs there, pounding out sit-ups). Then make your way up to Montana Avenue for a hearty meal at one of the many boutique restaurants.

And go ahead, order-up those carbs this time. You’ve earned it.