With 2014 in full swing, there is arguably no hotter workout than CrossFit. 

The military-style fitness regime -- defined by varied functional movements done at a relatively high intensity -- has seen its popularity skyrocket across North America.

Former warehouses and abandoned factories have now been transformed into CrossFit gyms, where ropes hang from ceilings and stepping blocks line the floors. 

Exercises like running, burpees, chin-ups, sit-ups, push-ups and weightlifting are combined in different ways to create a mixed-workout regimen. The workout you did on Monday is very different than the one on Tuesday - and that variety is essential to CrossFit's appeal.

CrossFit also comes with a reputation of being an intense workout, and many gyms are now offering programs for children.

So is it safe? Yes, says Maguid Nicholas, a certified children's CrossFit trainer at Tidal CrossFit in Toronto, noting that children's workouts are lighter than adult version and focus on different things.

"Our biggest goal is to make exercise enjoyable for kids," Nicholas says. "The age from five to 12 (is) where you can build good habits. And one good habit is thinking that exercise -- not just sports or games -- is in and of itself fun and valuable."

In fact, some experts say CrossFit-style exercises -- if done properly -- can strengthen children's muscles and joints, as well as decrease their chances at getting injured.

Understanding the CrossFit workout

Founded in 2000, the CrossFit company licenses gyms to allow them to offer its particular brand of fitness; there are now more than 8,300 gyms around the world offering the strength-and-conditioning program.

A CrossFit workout could be a combination of any number of exercises repeated several times. A daily workout recently featured on CrossFit's official website was 100 double-unders (whipping a rope twice under your feet each time you jump), 10 deadlifts, 10 front squats, 10 handstand push-ups and, finally, an additional 100 double-unders. The goal of this particular workout was to see how fast it could be completed.

Workouts, however, can be customized based on strength and endurance. And they're also being customized for children as young as three.

In fact, a kid-friendly branch of the popular regimen - CrossFit Kids - was established as its own company in late 2004.

In Canada, Children's CrossFit programs have popped up in Vancouver, Edmonton and Ottawa. Even the small town of Goderich, Ont., has a children's CrossFit program.

Nicholas says children's workouts centre around functional movements such as rolling, jumping, pushing, and pulling.

"The most common thing I hear is that parents don't want their kids to train with weights," he said. "I can dispel that by saying: 'Your son is only six, and we're not going to be doing any weighted exercise.' "

He says a typical children's workout might look like this: A warm up of 10 forward rolls, 10 squats, and 10 box jumps, repeated for two to three minutes That's followed by the workout of the day -- known as the WOD in the CrossFit community: a 10-minute circuit of 10 step-ups onto a box, 10 squats, followed by a bear crawl across the gym. Children might repeat that five times or do as many rounds as they can in seven minutes.

A child's WOD would never last more than 10 minutes, Nicholas says.

Other exercises that can be incorporated into a kid-focused workout include jumping for distance, pull-ups and pushing a sled across the gym.

A new skill, like a deadlift, might be introduced, but young children would simply be making the motions -- and not actually picking up a weight. Older children might pick up a plastic tube, with the idea being to teach children the proper lifting techniques. A workout is often finished with an activity, something as simple as Duck, Duck, Goose or a game of dodge ball.

Benefits for children

According to Nicholas, one big benefit of CrossFit workouts is that it avoids focus on one particular area of the body. And he says the varied workouts make it fun for kids.

"Psychologically, it becomes easier for people to continue training if they're not doing the same thing over and over," he said.

Kristian Goulet, an Ottawa-based doctor who specializes in pediatric sports medicine, says many of CrossFit's functional exercises can have significant health benefits, too.

Much of CrossFit, he says, can be categorized as neuromuscular training, exercises that he says helps build children's joints and muscles.

"The literature has been showing that if you can do some of this training … you can actually prevent injury and increase overall wellness and increase health," he said.

Not only that, says Goulet, but it can actually improve athletic ability.

"It's not all genes," he said. "You can actually manipulate and make kids who are not predetermined genetically to be athletes … better athletes by starting this neuromuscular training early on."

Goulet stresses that all children should be working on functional movement. He says he doesn't specifically endorse CrossFit, but rather many of the exercises featured in its workouts.

"If you do it right, you're preventing injury," he said. 

Like Nicholas, Goulet says children should never train with weights.

Goulet suggests a good age to start such exercises is 10, and that parents should limit workouts to three times per week. He urges parents to seek out certified trainers who have experience with children.

And he says the same precautions should apply as when parents get their children involved in any type of intense activity: children should see a doctor before beginning sports and get checked for heart conditions like hypertension.

"Another thing we know is that when kids perform an activity … 15 hours a week is kind of the threshold of what they can tolerate."