Myth #4
Never exercise a sore muscle.
Before you skip that workout, determine how sore you really are. "If your muscle is sore to the touch or the soreness limits your range of motion, it's best that you give the muscle at least another day of rest," says Alan Mikesky, Ph.D., director of the human performance and biomechanics laboratory at Indiana University-Purdue University at Indianapolis.
In less severe instances, an "active rest" involving light aerobic activity and stretching, and even light lifting, can help alleviate some of the soreness. "Light activity stimulates bloodflow through the muscles, which removes waste products to help in the repair process," says David Docherty, Ph.D., a professor of exercise science at the University of Victoria in Canada.
The real expert says: If you're not sore to the touch and you have your full range of motion, go to the gym. Start with 10 minutes of cycling, then exercise the achy muscle by performing no more than three sets of 10 to 15 repetitions using a weight that's no heavier than 30 percent of your one-rep maximum, says Docherty. Myth #5
Stretching prevents injuries.
Maybe if you're a figure skater. Researchers at the Centers for Disease Control and Prevention reviewed more than 350 studies and articles examining the relationship between stretching and injuries and concluded that stretching during a warmup has little effect on injury prevention.
"Stretching increases flexibility, but most injuries occur within the normal range of motion," says Julie Gilchrist, M.D., one of the study's researchers. "Stretching and warming up have just gone together for decades. It's simply what's done, and it hasn't been approached through rigorous science."
The real expert says: Warming up is what prevents injury, by slowly increasing your bloodflow and giving your muscles a chance to prepare for the upcoming activity. To this end, Dr. Gilchrist suggests a thorough warmup, as well as conditioning for your particular sport.
Of course, flexibility is a good thing. If you need to increase yours so it's in the normal range (touching your toes without bending your knees, for instance), do your stretching when your muscles are already warm.
Myth #6
You need a Swiss ball to build a stronger chest and shoulders.
Don't abandon your trusty bench for exercises like the chest press and shoulder press if your goal is strength and size. "The reason people are using the ball and getting gains is because they're weak as kittens to begin with," says Craig Ballantyne, C.S.C.S. You have to reduce the weight in order to press on a Swiss ball, and this means you get less out of the exercise, he says.
The real expert says: A Swiss ball is great for variety, but center your chest and shoulder routines on exercises that are performed on a stable surface, Ballantyne says. Then use the ball to work your abs.
Myth #7
Always work out with free weights.
Sometimes machines can build muscle better—for instance, when you need to isolate specific muscles after an injury, or when you're too inexperienced to perform a free-weight exercise.
If you can't complete a pullup, you won't build your back muscles. So do lat pulldowns to develop strength in this range of motion, says Greg Haff, Ph.D., director of the strength research laboratory at Midwestern State University in Wichita Falls, Texas.
The real expert says: "Initially, novice athletes will see benefits with either machines or free weights, but as you become more trained, free weights should make up the major portion of your training program," says Haff.
Free-weight exercises mimic athletic moves and generally activate more muscle mass. If you're a seasoned lifter, free weights are your best tools to build strength or burn fat.