By Stephanie Stahl

MEDFORD, N.J. (CBS) – Get ready for summer at the shore, or anywhere, with some sand. 3 On Your Side Health Reporter Stephanie Stahl has more on this new kind of shape up.

Get ready for the summer season on the beach, with a workout in the sand. Welcome to the pit – as in sand pit.

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This is the sand pit workout at 7 Deuce Sports in Medford, New Jersey. Tra Thomas, the former Eagle, came up with the sand idea, to make ordinary exercises, sprints and drills at his gym more challenging.

“My legs are tighter, my butts a little higher,” said Diana Short, a 39-year-old who got her figure back with the sand pit workout. She was a size 16 after her third child, but is now a two.

“I haven’t had a better workout,” said Diana.

Unlike a hard surface, the sand provides resistance so the workout is more intense, but it’s not as hard on your joints.

“It takes all the compression forces off your knees, off your low back because it’s such a soft surface, so you don’t get the pounding forces you do on a hard ground,” said Joey Johnsonbaugh, a trainer at 7 Deuce Sports.

The sand might be soft, but this is no cushy workout.

“It makes you work harder. It’s an unstable surface, so your body now has to adjust and stabilize within the muscle of the hips, abs, low back to really get you going,” said Joey.

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“I feel less pain,” said Karen Columbus, who does the workout. The 42-year-old used to have knee problems, not anymore. And she says the sand pit workouts, have made it easier for her to keep her weight down.

Karen said, “I was probably up there between 160, 172.”

Stephanie said, “172 pound, and you’re how tall?”

Karen said, “Four foot, ten inches. That’s tons of weight for me. I had two children and with both pregnancies my body just packed on the pounds.

When she started the sand pit workouts in September she was already down to 123. Karen says now her metabolism is revved up. And she has more muscle, the best way to burn calories. And she’s at her goal weight of 100 pounds.

“I can’t get over the way my body, I guess I’m now becoming more chiseled,” said Karen.

And now for the first time in a decade, she’s looking forward to being on the sand at the shore this summer.

“Ya know, I can’t wait to be comfortable on the beach in a bathing suit. It’s a first in a long time,” said Karen.

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The sand pit workout is part of a class at the gym that costs 20 dollars a session, but there are discount packages available. The sand pit is also used for physical therapy. And you can do the sand workout on your own at the beach.

Stephanie Stahl