By:   Linda Melone, CSCS

Getting in shape isn't always easy, and trying to decipher all the bogus fitness info only adds to the frustration. What can you believe?

As a fitness professional who's worked in the business for over 15 years, I cringe when I hear the latest celebrity "secret" or read up on the newest diet craze. Often the advice stems from a germ of truth that somehow grew up to be a big fat... spin on reality. For example, leg exercises can tone your muscles, but no amount of leg lifts will transform short, athletic legs into Victoria's Secret giraffe gams. (I wish!)

Before you read another pixel of fitness advice, first consider the source. Does the author have fitness credentials (CSCS, ACE, ACSM, NSCA, NASM are tops) and/or a college degree in exercise physiology? Has he or she worked with real people or simply have a great PR rep? The answer may mean the difference between advice you can use and info you should toss out with the coffee grinds.

Here's a sampling of the most frustrating fitness misconceptions out there... and the real science behind the truth:

1. Mythical advice: yoga and Pilates lengthen muscles -- weight training bulks them up.

Debunked: The length of your muscles is determined by the distance between your joints. Period. Yoga, Pilates and stretching cannot alter this measurement. So, while you can gain flexibility, balance and core strength from these modalities, you can't make your muscles longer than your genetics allow. Weight training tightens, tones and lifts muscles. It only bulks you up if you train—and eat—with the intention to do so.

2. Mythical advice: working your stabilizer muscles is the safest way to avoid getting too muscular.

Debunked: This recent myth touted by a "celebrity trainer" has no basis in science whatsoever. Stabilizer muscles do just that: support the main muscle doing the work. For example, triceps muscles (backs of your arms) stabilize your chest muscles when you perform chest exercises. Your biceps (front of your arms) kick in during back exercises. Working these small muscles and ignoring the primary muscles ensures you won't see any noticeable results, let alone get "too muscular."