Fitness fads come and go. Some are classics that are as popular today as they were decades ago. Others are out of style and distant memories.

Still Hot

Jazzercise. It has been around since 1969. The music has changed and so have some of the exercises, but the class itself is still going strong. Today, Jazzercise classes combine cardio with strength training and stretching to sculpt, tone, and lengthen muscles for maximum fat burn. Choreographed to today's hottest music, Jazzercise is a fusion of jazz dance, resistance training, Pilates, yoga, and kickboxing.

Step aerobics has been a major fitness focus since the late 1960s, but step aerobics didn't hit the scene until the late 1980s. That's when gyms and studios started adding individual step platforms to boost the intensity of their aerobics classes. Almost 25 years later and step aerobics is still a popular fixture in most gyms. In fact, today's classes are likely to utilize strength and flexibility training.

Yoga has been part of every day life in India for thousands of years, but only became popular in the U.S. in the 1960s. Today's yoga studios offer a range of yoga styles including gentle, athletic, and even hot classes, but the basic poses or asanas have remained the same. In fact, yoga is still gaining popularity as more gyms have offered classes customized for specific age groups or physical needs.

Pilates was created by Joseph Pilates, from Germany, born in 1883. He was considered the father of the modern-day Pilates exercise movement. His unique method for strengthening, lengthening, and toning muscles through mat and machine-based exercises didn't gain traction in the U.S. until it became popular with dancers in the 1940s. Today, Pilates is offered in almost every gym and fitness studio with classes that incorporate yoga-like moves with unique Pilates exercises and breathing techniques.

Bodyweight/circuit training workouts. The names have changed, but many of the exercises haven't. Think pushups, pull-ups, jumping jacks, running in place, and old-school calisthenics. Most of the exercises your grandfather did while watching Jack LaLanne on TV are still popular in bodyweight and circuit training classes all over the world.

Definitely Not

Single movement weight lifting. We used to think the safest way to build strong muscle was with regular workouts on the gym's weight machines. Working one muscle at a time, however, isn't necessarily the safest way to work your whole body and in fact, can lead to injury. To insure you use proper technique and range of motion and avoid injury, work with a fitness trainer to design an isolation weight-training program that's safe for you. For a strength-training program that more closely mimics normal body movements, fitness experts recommend working several muscle groups at a time with free weights and bodyweight exercises.

All-cardio workouts. Gone are the days when all we needed to be fully fit was hour after hour on the stationary bike or treadmill. Now we know that the key to total and balanced fitness depends on aerobic, strength, and flexibility training.

Pre-workout stretching. We used to say stretch before exercise, but now we know that's likely to put muscles at risk for injury. Stretching is still important, but let your muscles warm up first and then stretch after your run or workout.

What's the best way to keep your workout safe and current? Check in with a gym or fitness studio and take a few classes or make an appointment with a personal trainer from time to time to make sure your workout is still effective.

Mike Ceja, Certified Personal Trainer/Sports Therapist, reviewed this article.