You may think you've mastered all there is to know about getting stronger, faster, fitter. But most of the ideas you hear circulating in your local weight room today have about as much basis on scientific fact as the notion that the world is flat. We're calling out these myths once and for all. Class is in session. Are you ready to be schooled?
1. Lactic acid causes muscle fatigue.
How It Started: Research conducted nearly 100 years ago (on frog muscles, no less) suggested that lactic acid levels within muscles increased with fatigue.
The Truth: "Lactic acid increases with fatigue because it's fueling your muscle contractions," says Chad Waterbury, a strength coach in Los Angeles. It causes the painful burning sensation in your muscles that makes you want to stop lifting, but your liver is also converting lactic acid into more energy, so it's actually helping to offset fatigue. Muscle fatigue is prompted by an accumulation of protons within the muscles, which is caused by the breakdown of glycogen, the stored carbohydrate that helps to fuel exercise.
2. It's safer to lift weights slowly.
How It Started: In rehabilitation settings, patients are told to perform exercises at slow tempos in order to retrain their bodies to execute a movement pattern smoothly. Consequently, some trainers got the idea that training slowly reduces the risk of injury.
The Truth: "As long as you always control the lifting and lowering phases of an exercise," says Waterbury, an expert in neurophysiology, "you won't set yourself up for injury." In fact, Waterbury tells all his injury-free clients to perform their reps with speed "because it trains the muscles to react quickly in unexpected, real-world situations, which is how you really protect yourself from injury." Furthermore, lifting weights with speed activates more muscle fibers, leading to greater muscle gains.
3. Light weights and high reps tone muscles.
How It Started: Bodybuilders have long used lightweight, high-rep sets in the weeks prior to a contest. The more reps they're able to perform, they figure, the more calories (and fat) they burn, helping them get as lean as possible.
The Truth: Bodybuilders always accompany this kind of training with low-carb, calorie-restricted diets; that's what accounts for their rapid fat loss. "A toned appearance is dependent on your level of body fat and muscle development," says Jim Smith, C.S.C.S., a strength coach in Sayre, Pa. In other words, to see more muscle tone, you need to get bigger muscles and lose flab.
4. Machines are safer than free weights.
How It Started: Exercise-machine manufacturers advertise that their equipment isolates target muscles and prevents injury by having the trainee perform an exercise through a preset path of motion, thereby eliminating room for error.
The Truth: The restrictive movements of machine exercising might actually increase the risk of injury. "Machines are fixed and rigid and therefore limit the natural movements of the lifter," says Smith. They can't accommodate a person's individual limb length and strength curve, and as a result can place shearing forces on joints. "When you use free weights," says Smith, "your body naturally makes adjustments throughout the exercise's range of motion according to your strength level, speed of movement, and proficiency at executing your reps." Machines don't allow this.
5. You need to "shock" your muscles to make gains.
How It Started: It's hard to target the exact origin of this one, but it most likely began with bodybuilders who noticed that if they changed up their training after several weeks of using the same routine, they made quicker gains.
The Truth: Switching up exercises, sets, and reps is one thing, but purposely overloading your nervous system is a sure precursor to overtraining and injury—not muscle gains. "Your muscles operate under the laws of science, not trickery," says Vince DelMonte, a personal trainer in Ontario. Making gains is simply a matter of outdoing your previous workout. Once you can perform one more rep or lift one extra pound over what you did last week, "you've achieved progressive overload," says DelMonte, "and it's time to move on to the next muscle group."
6. You must train to failure for the best results.
How It Started: It was probably "those bodybuilders" again, who this time assumed that if hard training builds muscle, then training as hard as humanly possible must build the most muscle.
The Truth: "There is no activity outside of training that demonstrates that going to failure is critical," says DelMonte. "Construction workers often have phenomenal muscularity, but you don't see them carrying bricks around until they drop." Taking your sets and workout length to the point of using lighter weights will not result in progressive overload—the cornerstone of muscle growth. You will not give your muscles a reason to change, your motivation will dip, and you may even lose interest.
7. You have to get a "pump" to gain muscle.
How It Started: People noticed that doing moderate- to high- rep sets for a muscle group with little rest in between gave them pumps and (later) bigger muscles.
The Truth: There's nothing wrong with getting a pump, but it's only a reflection of how long your muscles have been under tension—it's not necessarily a harbinger of growth. "As your muscles stretch and contract," says DelMonte, "they become engorged with blood," and if you don't rest them long enough for your blood pressure to drop so that the blood flushes out, you can enjoy that swelled-up look and feeling for an hour or so. "You can get a pump just by running up a hill," says DelMonte, "but that doesn't mean you'll build big legs." Muscles need to be placed under a lot of tension to grow, and that means lifting heavy weights. Training specifically for a pump may cause you to use loads that are too light and reps that are too high, "and that leads to muscular fatigue, not muscular overload," says DelMonte.
8. Your muscles need high-volume training to grow their biggest.
How It Started: When steroids became pervasive in bodybuilding in the 1960s and '70s, trainees discovered that using the drugs allowed them to perform more sets for a muscle group without endangering their recovery. As a result, they could force their muscles to perform more work and grow at a faster rate.
The Truth: Take away the 'roids, and you place yourself at high risk for overtraining. In the '40s and '50s, movie star Steve Reeves and weightlifting icon Paul Anderson trained with brief workouts using heavy weights and built the kind of bodies most of us still aspire to today. The fewer sets you perform for a muscle group, the faster that group can recover from the training and be trained again. Rather than thrashing a body part one day with as many sets as you can stand and then waiting a week before you can hit it again, you can perform approximately two sets per exercise and be ready to train that area again later in the week. "Now instead of 52 workouts for that body part in a year, you'll do 104," says Men's Fitness adviser Jason Ferruggia, a performance-enhancement coach in Warren, N.J. "This allows you to double your stimulus for growth and ultimately get even bigger."
9. You should never let your knees go past your toes on squats and lunges.
How It Started: One too many injuries during the squat or lunge—but it was probably the result of accidentally rotating at the hips during a rep, which can cause ligament damage in the knee.
The Truth: Where your knees end up during any lift is highly dependent on the length of your legs and where on your joints the muscles attach. Some people (usually shorter guys) can squat easily without the knees passing over their toes in the down position, but others (usually taller guys) may find that their knees drift far forward. Purposely trying to keep your knees behind your toes when your body doesn't want to puts a lot more strain on your hips and lower back, and that can lead to worse injuries. As the late exercise scientist Mel C. Siff, Ph.D., noted in his book Facts and Fallacies of Fitness, "The Japanese sit on the floor with their knees folded fully flexed beneath them, bearing all their body weight for prolonged periods daily without producing an epidemic of knee injuries."
10. You should wear a lifting belt whenever you go heavy.
How It Started: Lifting heavy weights always poses a risk for injury. Somebody somewhere hurt his back during a heavy lift, and the lifting-belt craze took off.
The Truth: "If you're going for a new max and want the additional mental boost a belt may give you," says Joe Stankowski, C.P.T., a trainer in Wilmington, Del., "by all means, wrap your midsection in cowhide." But beware that if you use a belt on lighter sets or in every workout, your body will get accustomed to having that aid, and soon you'll find that you won't be able to lift heavy weights without it. "It's entirely possible to lift massive weights safely using your body's own support system," says Stankowski, who notes that some elite powerlifters have squatted upwards of 900 pounds without a belt. Forgoing the belt will force your abs to work harder to protect your spine, which of course has the added benefit of building a more muscular midsection.