On the morning before Thanksgiving, 14 people are in a warehouse-like workout room, furiously doing sets of pull-ups, pushups, and squats. It’s about 8:30 a.m. and most Americans are looking forward to that day devoted to overeating, but these 10 women and four men are focused on a routine called the “Chelsea.”

The Chelsea involves doing five pull-ups, 10 pushups, and 15 squats every minute on the minute for 20 minutes. Almost everyone gets through the first few rounds with varying degrees of ease, many with seconds to spare, but by round five, many start to fall behind.

As the group exercises, Tracey Garito Mahaney and her husband, Andy Mahaney, owners of Transform CrossFit, on Reed Road in Pennington, shout out words of support like “You can do this,” and “Do the squats quicker than you think you can.” The phrases are encouraging, but it is clear that the Mahaneys mean business. The red numbers of a digital clock count down each minute as Alien Ant Farm’s cover of “Smooth Criminal” blares from a boom box. Near the boom box is a sign that reads: “I will give everything I have. And then I will find more within myself.”

Since October, 2010, the Mahaneys have been leading Transform Crossfit workouts. Tracey is 37 and Andy is 46. They have no children together, but Andy has three daughters, ranging in age from 16 to 23, from a previous marriage. He was formerly a pastor for 20 years at a church in Pennington

Transform CrossFit is an official licensed affiliate of CrossFit, whose founder is Greg Glassman. It is not a franchise. The Mahaneys are called affiliate owners: they pay a yearly fee for the rights to use the name and for support and access to information from the national CrossFit entity.

A CrossFit “box,” as it’s called, isn’t a bit like a typical gym. There are no machines such as treadmills or exercise bikes or stations devoted to weightlifting. Weights are often used here, but CrossFit exercises are, according to Tracey Mahaney, focused on “constantly varied, functional movements” performed at “high intensity.”

The varied part comes through classes featuring different combinations of exercises performed at different paces. The main part of each class is the “workout of the day” or WOD. On the day I visited that workout was the Chelsea. Once clients, who are referred to as CrossFitters, miss that on-the-minute standard, they continue doing the sets at whatever pace they can. Many participants mark their progress on the mat-like floor with chalk, and when the workout is over, scores are recorded based on how many times they did the routine on the minute and the total times they completed the routine.

Other WODs might involve doing five rounds of three exercises as quickly as possible without stopping or doing a routine as many times as possible in 20 minutes without stopping. Each CrossFit class lasts about 45 minutes, including a warm-up and a post-workout discussion. Actual workouts can range from five minutes to 25 minutes, with most lasting about 20 minutes, according to Mahaney. Participants don’t know what their WOD will be until they show up at class and see it on the board.

Another aspect of CrossFit exercises is that they are “functional,” meaning they involve movements people use in everyday life, such as squatting, throwing, running, jumping, pushing, and pulling. “The majority of our clients, I would say, are in their 40s, some are in their 50s,” Mahaney says. “And even though a lot of our people are getting in great shape — they look great, their body composition is improving (and) I’m sure there is some vanity to it — a lot of it is they just want to be functional into their old age. They want to be able to play with their kids, lift things without help, take care of themselves, just simple things.”

CrossFit claims to help people do all of that through its nine foundational movements: the air squat; front squat; overhead squat; shoulder press; push press; push jerk; deadlift; medicine ball cleans, a sort of squat done while holding a medicine ball; and sumo deadlift high pulls, a weight-lifting exercise.

These are all designed to help people do those simple things with ease. The primary goal, Mahaney says, isn’t to look good, even though a lot of people participating in the class look pretty darn good.

“A lot of people, when they start, can’t even squat,” Mahaney says. “And if you think about it, in your life you have to be able to squat, to sit down, to stand up. Most elderly people, that’s the first thing that goes, they can’t squat anymore and that limits so many things that they’re able to do in their life.”

In October Dolph Geurds opened CrossFit Nassau at 255 Nassau Street (the former site of Wild Oats), his second CrossFit “box” — he also owns CrossFit Mercer, 2101 East State Street in Hamilton, which he opened in 2009. Previously he owned a landscape design and construction business.

To give you an example of what it costs to workout at CrossFit, CrossFit Mercer charges $125 a month for unlimited workouts. The drop-in rate is $20. At CrossFit Nassau, the monthly unlimited price is $185; the drop-in rate is $20.

The Foundations program at Transform CrossFit, a four-week, two-classes-per-week introductory program, costs $200 and is a requirement for membership. Six-month memberships cost $220 per month, three-month memberships are $230 a month, and the month-to-month price is $240. Single classes cost $35.

Geurds says CrossFit’s movements are fundamental to everyday life, which involves picking up things or moving things. “How do you (do those things) without getting hurt, whether you’re in the garden, or moving a stone or a heavy water bucket? Or you’re at the grocery store and you’re picking up a case of water and you have to put it in your trunk,” Geurds says. “Those movements are what we practice every day in a workout. Being able to apply something that you would do in a real-life situation to what you practice in a gym is really important.”

It is, says, Mahaney, a more useful way of exercising. “Who cares if you can curl a 50-pound dumbbell? Because when do you ever lift something like that in your real life? You don’t,” she says. The Mahaneys’ Pennington location consists of a large open space. Bars used for pull-ups are made of plumbing pipes. Weights, medicine balls, and kettle bells line the walls.

According to Geurds, standard gyms don’t always have these kinds of equipment. In fact, he says he was once kicked out of a gym where he was doing CrossFit training because of the way he was using the equipment and because sharing equipment made it difficult to do the routines with the right timing.

“There’s not a good setup to do that kind of workout (at a standard gym) so I got kicked out with two other people I was training with one night,” he says. “And that kind of spurred the reason why we had to find our own place to do this kind of training.” But word about CrossFit is getting out, he says, largely through the CrossFit Games, a competition that airs on ESPN2.

Another key part of CrossFit workouts is the “high-intensity” element, which sounds intimidating, especially to those who aren’t in good shape. Mahaney says that “high intensity” has different meanings for different people. During the Chelsea, for example, some members of the class use bands (resembling large rubber bands) to help them do pull-ups, others do pushups from their knees. Exercises involving weights have a recommended weight amount, so some people reduce the amount of weight they use.

“We always say that it’s relative high intensity because high intensity looks different for everybody,” Mahaney says. “So every exercise and every workout can be scaled or modified based on each person’s level of fitness, but the whole class does the same workout, it just looks a little bit different.”

Mahaney grew up mainly in central New Jersey, and also spent part of her childhood in Virginia. She spent her middle school and high school years in Cranbury and is a Princeton High School graduate. Her father, Michael Garito, recently retired from PNC Bank, and her mother, Julie Garito, was a homemaker.

Mahaney attended the University of Delaware for a few semesters and also took classes at Mercer County Community College, but didn’t graduate.

Always a fitness-conscious person, she worked in the fitness industry for about 15 years at places like New York Sports Club and Gold’s Gym.

But she really wanted to run a business of her own. “As a personal trainer, you get to a point where, number one, you’re never going to make a ton of money doing it, unless you move out to Los Angeles, and you’re charging $200 an hour,” she says. “So working for gyms, I got to the point where I physically couldn’t train more people than I was. I pretty much hit my cap; I was tired and exhausted and just didn’t want to work for other people anymore.”

In January, 2005, she opened a Fitness Together franchise in Lawrenceville, where she offered one-on-one, personal training. When it was time to consider renewing her lease, the recession had hit and she and her partners decided to close the business in 2009.

“At that point, I had to start thinking, ‘What am I going to do now? Am I going to go back to being a personal trainer? Am I going to go back to a gym?’” she says.

She learned about CrossFit from a friend she worked with at New York Sports Club. That led to her training the CrossFit way. She says she was “blown away” by the results. She says she went from spending hours at the gym and getting good results to shorter CrossFit workouts and getting great results.

“My training time was cut by more than half, and my results were measurably better,” she says. “So I fell in love with it. I was totally passionate about it.”

She got her CrossFit certification and opened her first location on Main Street in Pennington in June, 2009, with a workout space of about 400 square feet, enough room for about six people. It took, she says, about $20,000 to get the operation started.

“I signed an 18-month lease and within six months, we were at maximum capacity,” she says, adding that when she and her husband opened their current location in October, 2010, 50 people came off their waiting list.

One of her clients is Sarah Eiseman, 41, co-owner of the Lloyd Group, an IT strategy and support firm, with her husband, Adam (who is also a member of Transform CrossFit). The Lloyd Group is located at 14 Tulane Street in Princeton and also has a Manhattan office. They have two children, Charlotte, 10, and Avery, 7. Eiseman started taking CrossFit classes about two years ago when she walked by the original Pennington location without having any idea as to what CrossFit was.

“At the time I was doing Pilates, and I felt I just wasn’t really getting anywhere or seeing an improvement in my life or even at Pilates,” Eiseman says. “So I went in and spoke to Tracey, and I said, ‘All right I’ll try it.’ I never looked at the website, I was just going to see what this was all about.”

Eiseman’s before and after photos are posted on www.transformcrossfit.com. Her performance during the Chelsea that day before Thanksgiving was impressive, as she finished the first few sets with time to spare.

“After one month, I would say, it dramatically changed my life,” she says. She admits the first few months were very difficult. “I could barely do anything. I never lifted weights before, ever in my entire life, it was very intimidating,” she says. It was the exercises she found intimidating, not the people, who she says are supportive and encouraging.

“For probably the first year, I was always afraid before I came in,” Eiseman says, which gets a good-natured laugh out of Mahaney. In addition to Pilates, Eiseman had joined gyms and health clubs, but she would go sporadically or not at all. Now she attends three CrossFit classes a week. “It was definitely for me.”

Mahaney says that CrossFit is more than a workout regimen that helps people lose weight, it’s a way of life that results in people doing things they didn’t think they can do, including pull-ups. She adds that she sees more people sticking to CrossFit than she saw people stay with gym routines when she was a personal trainer.

“Some of the movements are more technical, some of them are downright scary for a lot of people,” she says of CrossFit exercises. “So it’s empowering, especially for women but I think for men too, it’s empowering to do something that you’re afraid to do, and then you do it successfully. It kind of bleeds into the rest of your life. You leave here going, ‘Oh my God, I can’t believe I just did that,’ and it affects everything about you. They stick around because they see results, but the results go so far beyond just losing a few pounds and building a little bit of muscle. It really affects your whole person.”

Transform CrossFit requires all of its clients to participate in what’s called CrossFit Foundations before they start classes. Foundations meets twice a week for four weeks with each classes lasting about an hour. During classes, the Mahaneys discuss the nine foundation movements of CrossFit, nutrition, theory, and technique. These classes also include a warm-up and a sample workout, with the workouts getting more intense as Foundations progresses.

Another element to CrossFit is the Paleolithic diet (called the Paleo diet for short), which some people refer to as the Cavemen Diet (a name Mahaney isn’t thrilled with).

“The principle behind it is you’re basically eating what a caveman would have had access to, which is meat, vegetables, nuts and seeds, some fruit, very little starch and no sugar,” she says.

The diet avoids grains, processed food, and dairy products. Following the Paleo diet isn’t necessary to participate in CrossFit classes, but Mahaney says clients are encouraged to follow it for 30 days and reintroduce foods slowly. That’s done so that people can learn how different foods affect them and if they have any sensitivities or allergies.

“By reintroducing them one by one after 30 days, you quickly figure out what you’re sensitive to,” she says. For example, if someone doesn’t eat grains for a month, then eats some bread, and then doesn’t feel well, it’s an indication that they may have some sort of reaction to bread or gluten.

“Some people feel like crap all day every day, and they don’t realize it, so they actually (experience) what feeling good feels like,” Mahaney says of people who take on the Paleo diet.

On her blog on the Transform CrossFit website, Mahaney began a “23 Days of Paleo” project counting down to Thanksgiving. She wrote about following the Paleo diet, how she made the transition, and issues pertaining to grains, dairy, caffeine, alcohol, and fat.

On the blog she also shared what she ate. On November 1, for example, she had coffee with organic grass-fed heavy cream, leftover pork sirloin, half a red bell pepper and Salty & Sweet Toasted Coconut Flakes at 5:30 a.m. At 8 a.m. she had an organic hard-boiled egg and walnuts. Other items she ate that day included coconut butternut squash, organic turkey breast, and scrambled egg whites with red bell pepper.

The diet can be challenging, she says, especially for people who eat lots of bagels, breads, and pastas. They may struggle a bit during Foundations, but are often encouraged after they see people in regular classes who are following the Paleo plan.

“Without even asking, we know who’s eating that way and who’s not,” Mahaney says. “And not just because of body composition but it affects your athletic performance, absolutely. Even if you have a weekend where you eat a bunch of junk, your workout Monday sucks. You don’t feel good. The people who are getting stronger and faster are the ones who are eating right.”

CrossFit certification is required for people who open their own CrossFit affiliates, but after that, owners have a lot of say in how they operate their spaces. The Mahaneys design their own programs, following CrossFit’s methodology.

Transform CrossFit, for example, offers morning classes starting at 5:30, 6:30, 8:15, and 9:15 a.m., Mondays through Fridays, and evening classes beginning at 6:15 p.m. on Mondays, Wednesdays, and Thursdays. Two classes are offered on Saturdays, at 8:15 and 9:15 a.m. The same routine is followed by all classes on each day, and WODs are posted on the website each day after the morning classes, so people who attend the evening class can “cheat” if they want to.

Mahaney says that about 70 to 75 percent of Transform CrossFit’s members are women, and some of those women have encouraged their husbands to join. “The competition is always interesting, usually it’s the men trying to keep up with the women,” she says.

Among Transform CrossFit’s male clients is Chris Mollis, who lives in Pennington and owns a small, New York-based software consulting and development firm called Mutable. Mollis, 44, completed 19 rounds of the Chelsea in 19 minutes, which, according to Andy Mahaney, is the best performance of that exercise by a Transform CrossFit participant, earning him a spot on the “Benchmark Board” that records top performances in different exercises.

Mollis says he started doing CrossFit about two years ago. He says he worked out a lot, runs, and got a black belt about four years ago, and was looking for something different when he read about CrossFit online. “It turns out there was a CrossFit opening in right in town,” he says. “I thought I’d try it, I had never done anything like it before, and it’s without question the best workout and lifestyle I’ve seen.”

Mollis says he goes to CrossFit about two to four times a week, and that he likes the time element of the workouts, which leads to more focus. He also likes keeping score and competing against the group and himself.

“There’s a lot of incentive,” he says. And it’s quick too, it’s over in (about) half an hour.”

Although he has long been a fit person he says he wasn’t always as efficient at workouts as he is now. In fact, he says he was “pretty weak” in terms of upper body strength before joining CrossFit.

Geurds, who also follows the Paleo diet, says he has trained his kids ages seven and nine, alongside people in their 70s. (CrossFit Mercer offers “CrossFit Kids” and “CrossFit Lite” classes.) He also says that he has trained children with autism and people with serious health issues. He says he has always been an active person, playing soccer and tennis, and skiing, and that CrossFit fits his needs perfectly.

“The beauty of CrossFit is, it’s as difficult today as it was when I first started, and it will be even more difficult tomorrow,” he says. “It never gets easier because I can increase the weight, I can increase the distance, I can increase intensity, I can increase the skill sets that are involved. I can increase it for someone who is an elite athlete or I can decrease it.”

On that Thanksgiving Eve, as the workout ends and scores are tallied, the people at the Transform CrossFit class gather their things and head toward the exit. As they leave, the Mahaneys congratulate them on their workout, and Tracey Mahaney says, “Now you can have all the pumpkin pie you want.”

Then she pauses a bit before adding, “Not!”

Transform CrossFit, 1589 Reed Road, Unit 2, Pennington. 609-865-1034 or www.transformcrossfit.com.

CrossFit Mercer, 2101 East State Street, Hamilton. Parking is in rear of building off Sculpture Way. 609-498-5221 or www.crossfitmercer.com.

CrossFit Nassau, 255 Nassau Street, www.crossfitnassau.com.