Solidcore, a Washington D.C.-based fitness studio opened its first Pennsylvania location earlier this month near Washington Square at 725 Chestnut Street.

The Solidcore method emphasizes very slow and controlled full-body movements on a resistance-based machine. The workout is low-impact, but don't let that fool you. The idea is to work your muscles to the point of failure by breaking down your slow-twitch muscle fibers. This forces them to rebuild in a stronger and more sculpted way. And as an added bonus, you'll continue to burn calories well after the class is over while your muscles work to repair themselves.

I can attest to that: After my first class, I was sore for a solid 24 hours in muscles I didn't even know existed.

During the 50-minute class, you'll perform variations of planks, lunges and squats on the signature machine, affectionately known as Sweatlana. Its built-in levels of resistance (up to 300 pounds) make it nearly impossible to plateau in this workout.

For die-hard Pilates fans, the machine closely resembles a reformer, however, Solidcore went a step further and created their own. Solidcore owner and CEO Anne Mahlum explains how the machines differ from traditional reformers:

"The highlights we are proudest about on our machine include more varied tension, sweat-proof straps, a wider-based body to accommodate different body sizes and different height adjustments for the handle bars, not to mention it has a much more sleek look that is more in line with the Solidcore brand."

With class sizes maxing out at just 14 people, you can expect Solidcore's certified coaches to be hands on in their quest to push you past your limits.

At my first class, studio manager Alex Fluharty had a mantra before guiding us into every new move: "This isn't optional, it's mandatory - so get there."

If that's not motivation, I don't know what is.

Solidcore Philadelphia is a homecoming for Mahlum who also founded non-profit Back On My Feet. The organization, which got its start in Philadelphia, uses running to help those experiencing homelessness make real changes in their lives, including employment and independent housing.

The new studio is offering a grand opening special: Buy 5 classes for $125 ($25/class, regular pricing is $32/class) or a 10 pack for $250. You can try your first class for just $20.

Visit for more information.

Read more Sports Doc for Sports Medicine and Fitness.