With Americans constantly striving to lose weight and get in shape, weight-loss and fitness industries are always introducing new products to help people quickly and painlessly reach their goals. This often leads to disappointment and temporary results, if any at all. CrossFit and P90X are two highly popular exercise systems revolutionizing the way people think about fitness. Here is what you need to know about them:

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P90X is a 90-day workout plan designed to work out the entire body. The system consists of 12 workout DVDs, a nutritional plan, and supplements. Based on "muscle confusion" it is a cross-training method that constantly challenges the body and prevents fitness plateaus by constantly switching the order of exercises. P90X uses forms of cardio and weight training as well as yoga, plyometric exercises, and kickboxing. There is entire program takes 13 weeks to complete and promises a fitter, more athletic body at the end of the program.

CrossFit is a strength and conditioning program aimed at overall fitness. Unlike many specialty workouts, CrossFit is based on being competent in ten key fitness areas: speed, agility, balance, coordination, cardiovascular endurance, stamina, strength, flexibility, power, and accuracy. CrossFit workouts combine sprinting, traditional weightlifting, and gymnastics. Each 20-30 minute workout consists of activities that range from lifting dumbbells and carrying heavy objects over long distances to rowing and jumping rope. Many law enforcement, military, and firefighter organizations use CrossFit to stay in shape.

So which is better? In the end, both are great ways to get in shape. The main difference is that P90X is geared more toward improving physique, and CrossFit is geared at an overall improvement in fitness. For those who like structure, P90X may be the best option, since CrossFit introduces new workouts daily that can be done inside or outdoors. Your best choice will also depend on how much time you have. CrossFit workouts take 20-30 minutes a few times per week instead of one hour, 6 days per week for P90X.

Whatever your fitness style, motivation can play a huge role in maintaining a fitness routine. Many people are more motivated when surrounded by other fitness-minded people. This is why membership-based gyms have remained strong in an age of fitness fads. Gyms are also great because they are full of experts who can give you personalized advice and guidance; something you just can't get from a gym DVD workout.

The Air Squat is one of the most important exercises in CrossFit programming. Without building a solid foundation with an excellent air squat, the rest of the exercises you perform will suffer. Even if you think you have a solid air squat, go stand up against a wall with your toes and chest pressed up against the wall and slowly lower yourself into a deep squat position (without falling backwards).

With the bending of the knees and often heavy lifting involved during a squat, it is thought by many to be an unsafe exercise, specifically for the knees. On the contrary, it has been found that the squat is, in fact, a deterrent for future injuries. Regardless, with the amount of lower body muscles that the squat targets (particularly those problem areas ladies), makes it an ideal exercise that should be included in your exercise repertoire. Most importantly, this exercise can be done without any weights at all and still be incredibly effective. Crossfit includes the air squat in many of its workouts and as part of its official warm up.

In order to perform the air squat, stand with your feet just past shoulder width apart. Keep your head above your knees and bend your knees, moving your butt down and out past your ankles. Your arm position isn't incredibly relevant, but some people find it easier to move the arms up as you squat. However, you may find that holding your arms up, straight over your head, will give you better form when squatting. Once down begin to raise back up to the standing position. You should try to get your butt down to just below your knees. If that's too far just go as far down as you can.

I would suggest working with a certified Crossfit St Petersburg personal trainer if you are just beginning. Start off with 10 full deep air squats, then hold in a squatting position with your knees bent and your upper legs perpendicular to your lower legs. Hold this position for a count of 10. Then perform 9 full deep air squats and then again, hold the squatting position for 10 seconds. Repeat for 8 and so on, working your way down to 1, holding for 10 seconds between each set. No weights involved and it shouldn't take much time at all, yet your legs will feel like jelly and you will certainly be completely out of breath. For these reasons, the squat is a great exercise.

Squatting is one of the best exercises out there. Perhaps the king of the leg exercises; squats work your entire lower half - which results in building and toning your biggest muscles. I recommend trying a few 50 rep sets of air squats in the morning before you head off to work, or class, or whatever you do. They take minimal time, effort, and if you're good you can avoid breaking a sweat. They still give you a good calories burn and are useful for toning up your legs.