Ever since Jane Fonda slipped into a pair of leg warmers, the health and fitness industry has come up with new ways to keep people interested and excited about working out. Some are fads that fade away; others have (well-defined) legs.

“There is a finite amount of body parts and just so many ways you can train those body parts,” says Jake Steinfield, CEO of Body by Jake Global and chairman of the California Governor’s Council on Physical Fitness and Sports. “It really has more to do with the personality of the training or the methods of how people get their exercise that make it interesting.”

This year was no different: Even in the throes of the Great Recession and a swine flu (H1N1) pandemic, people didn’t give up on fitness and health in 2009.

While some fitness faithfuls stuck with traditional, long-term trends—yoga and Pilates, for example—others found motivation in fun new products and programs to help them get in shape. Here, Health.com compiled the top fitness trends and fads of the year. Read on, and then check them out at a health club near you.

1. Personal training

Today’s in-demand personal trainer isn’t the high school jock who gets a job at his local gym after graduation, says Walter Thompson, Ph.D., a professor of exercise science at Georgia State University. Thompson compiles and writes the American College of Sports Medicine’s (ACSM) Worldwide Fitness Trends prediction reports, which forecasted educated and experienced fitness professionals as the No. 1 trend for both 2009 and 2010. “People who are really interested in becoming personal trainers are seeking the proper education; they’re going back to school and getting the right credentials,” he adds.

So why the increasing number of certified trainers at a time when money is so tight? “Even though people have less discretionary funds, they’re also a lot more prudent about who they hire,” says Thompson. “A few years ago they may have hired just anyone, but now people are looking for quality instruction if they’re going to spend their hard-earned money.”

Personal trainers have also become much more business savvy, he adds: Small group sessions—which are cheaper for the clients but make more money per hour for the trainer—have become the new way to train. “The old definition of personal training was one-on-one. Now it’s one-on-two or one-on-three.” Online and mobile personal-training programs, like Fit Orbit (founded by Steinfeld), which launched earlier this year, give money-conscious consumers another way to access a real trainer for less money.

2. Home gyms

For people who may not have the disposable income to pay a health club membership fee each month—let alone a personal trainer—at-home workout systems have long been a lower-cost solution. But it used to be that “whole-body workout” contraptions could take up an entire room.

This year saw the continued success of small, compact systems that can be mounted in a doorway, stored neatly in a closet, or even fit in a suitcase for travel purposes. Body by Jake’s Tower 200, which launched in June, comes with an 11-minute workout on DVD, offers up to 200 pounds of resistance, and touts the slogan, “Gotta door? You gotta gym.”

3. Strength training

Strength training and toning has been a top trend in the ACSM’s annual report for several years, and is predicted to get even more popular in 2010. “The public, particularly the female market, is realizing that they can lift weights and not bulk up and start looking like a body builder; for a long time, they were fearful of that happening,” says Thompson. “Even a decade ago, women would not have gravitated toward something called strength training. But now personal trainers are educated and they can explain that it is important for fitness, for weight loss, for bone health—and that you could lift weights every single day and not still look like a man.”

For this reason, strength training has become much more than just men lifting barbells and doing bench presses; gyms and fitness classes today feature all types of hand weights, resistance bands and machines designed for sculpting and toning.

4. Yoga and Pilates

Yoga and Pilates are nothing new, but they continue to dominate the fitness market with classes and facilities springing up across the country, new DVDs and home workouts, and accessories and apparel sales still going strong. YogaWorks, a Los Angeles–based company, opened new studios in San Francisco and New York City this year and reported that overall class attendance was up in 2009, as was enrollment in their teacher-training program. “The last place people want to get frugal is with something that’s making them feel better,” says Phil Swain, the CEO of YogaWorks.

Traditional yoga or Pilates enthusiasts, however, may take issue with the growing trend to modify traditional practices in order to market more types of classes: Some gyms offer combination “Yogalates” sessions, for example, while others incorporate yoga or Pilates techniques into strength training or cardio aerobic classes.

5. Dancing off the weight

“Dance is hot, especially with the strength of TV shows like ‘Dancing With the Stars’ and ‘American’s Next Dance Crew,’” says Steinfeld. “People who don’t exercise on a daily basis are looking for something fun and innovative to get them started, and this is a great way to get them moving.” Crunch gyms this year offered dance classes ranging from Ballroom Blitz to Country Line Dancing, while Latin-fusion Zumba classes—held everywhere from upscale fitness clubs to schools and community centers—have taken the nation by storm.

6. Stunt fitness

In October, MTV premiered its new “Ultimate Parkour Challenge,” just around the time that Equinox introduced Parkour classes focused on core conditioning and balance. Parkour—or free running, as it’s sometimes called—involves rolling, jumping and diving to get from one point to another.

Another extreme way to get fit in 2009 was through mixed martial arts classes, such as kickboxing and jujitsu. “These are sprouting and will continue to sprout up in 2010, where not just men but women as well are not interested in the actual fighting part but in the fact that it’s an insane workout,” says Steinfeld. “It’s a totally different way to train yourself and discipline your mind and body, and it really pays off.” Even the Pilates industry has meshed with mixed martial arts, in the form of Piloxing classes and an at-home DVD.

7. Distance races

The Wall Street Journal reported in July that interest in marathons, triathlons and road races was up even as employment rates were down—possibly because out-of-work people had more time on their hands to train and, in some cases, less workplace stress to hold them back. Marathons are also becoming more accessible to the everyday athlete, too (a trend that not everyone is happy about), with more and more slow runners, joggers and even walkers entering the fray, according to an October New York Times story.

Even kids are getting into road races and triathlons at younger ages than ever before. And we’re betting that with an American winning this year’s ING New York City Marathon—for the first time since 1982—the distance-running trend will continue to grow.

8. Core and lower-body training

“Core training seems to have stood the test of time, as it again appears at No. 5 just as it has for the past four years,” writes Thompson in the ACSM’s 2010 predictions report. Both men and women continue to use props such as stability balls, BOSU balls, wobble boards and gym equipment like benches and hanging bars to target and condition the muscles of the abdomen, pelvis, lower back and hips—a skill that provides support for the spine and improves balance and stability.

Lower-body training is another popular fitness target, especially for women, notes Steinfeld. “Total body fitness is important, but to be able to zone in and isolate body parts has been very hot,” he says. New York–based trainer Rebecca Kordecki has taken advantage of this trend with her Booty Slide classes (attendees wear slippery booties on their feet and lunge/slide across the floor); you can get a similar at-home experience with the Gliding Disks exercise system and DVD.

9. Barefoot shoes

Should humans be running barefoot? It’s an idea that most people don’t want to even think about, but one that’s been tossed around for centuries—and it’s picked up traction this year with the May release of the book Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World Has Never Seen, in which author Chris McDougall advocates the technique.

Even if you aren’t ready to bare your naked soles to the pavement (we certainly aren’t), you can at least simulate it with several minimalist-style shoes released in the last few years. Vibram Five Fingers shoes wrap around your foot and around each individual toe to give you a barefoot feel; the Nike Free line offers lightweight, flexible shoes with deep grooves in the sole to activate muscles; and the start-up company Skora will launch a minimalist running shoe in 2010.

10. Childhood obesity prevention

More community groups, fitness clubs and nonprofit organizations are recognizing the need for programming specifically designed to get kids moving more and eating healthy. “Childhood obesity is not going away and most people, including the Centers for Disease Control and Prevention, will tell you that it’s getting worse,” says Thompson. “This is a terrific opportunity for commercial clubs to open their business up to kids.”

Steinfeld has seen large companies get more involved with prevention programs, as well—including food and beverage brands whose products are often targeted or threatened with additional “fat taxes.” “These companies are ready and willing to put their resources toward educating and helping kids, whether it’s putting fitness centers in schools, adding parks and ball fields, or sponsoring education programs.”