Distance running is a potent fitness enhancer, leaving few of the body's systems untouched. It increases the efficiency of your cardiovascular system, makes your leg muscles stronger and more toned, helps you lose or control body weight and generates endorphins that contribute to stress relief.
But running does pose a mental and physical challenge, even for seasoned endurance athletes. Further, since most runners typically train outdoors, they face a tremendous range of environmental conditions that may affect their health or performance.
Because very few of the millions of regular runners have backgrounds in human physiology, many get their information about factors such as nutrition, hydration and post-workout recovery from running partners and hearsay rather than from more credible sources.
Finally, different people train at vastly different levels of intensity and volume. Some marathoners regularly exceed 100 miles a week and do plenty of fast track repetitions, while others prepare on 35 miles a week of mostly jogging. The result is that a great deal of ostensibly universal running advice does not, in fact, apply equally to everyone. Therefore, misconceptions about "must-dos" abound, some of them with surprising persistence.
Myth 1: Frozen Assets
People who have never run in very cold conditions, whether because they're new to running or because they live in temperate climates, often express concern that their lungs will freeze if they run in temperatures below 0 degrees Fahrenheit. This seems to stem from the fact that the increased rate of breathing during running can be uncomfortable in any setting -- especially among less-conditioned novice runners -- and because cold weather can, in fact, exacerbate respiratory problems in those with pre-existing maladies such as exercise-induced asthma.
Nevertheless, concerns about physical damage to the lungs and respiratory tract are unfounded.
"The lungs are very well-protected," said Cathy Fieseler, a physician and ultra-marathoner. "When cold air is inspired, the warming process begins immediately. The tissues lining the nose have an extensive blood supply. The warm blood from the heart flows throughout the body, including the nose. Additionally, the mucous that lines the respiratory tract assists in warming the inspired air. The inspired air continues to warm as it moves farther into the trachea in the center of the chest, presenting no danger to the lungs."
The upshot: Unless it's too cold to be safely outside for other reasons -- for example, a high risk of frostbite -- you have nothing to worry about.
Myth 2: Smoking Joints
The myth that running can lead to arthritis or simply to "bad knees" persists to a great degree among sedentary observers, who note when their running friends complain of aches and pains.
Naturally, some runners are concerned there may be truth in this belief. While certain runners do suffer injuries to the ligaments, tendons and cartilage of the hip, knee and ankle joints, evidence actually suggests that running not only won't lead to osteoarthritis, but may even help reduce the risk of its onset.
In his article "The Joint Myth: Running and the Risk of Osteoarthritis," Benjamin Ebert, M.D., writes that running may actually prevent or treat arthritis, a condition that affects a large number of people over 65 and is a result of simply aging.
Ebert says that the way in which your joints adapt to running can forestall the degeneration associated with a sedentary lifestyle.
Myth 3: The Acid Test
If you've been running for more than a month or two and have been doing your homework, you have almost certainly learned of lactic acid. More to the point, you've probably seen or heard it demonized.
The folklore goes something like this: Lactic acid is produced in response to intense, anaerobic running, such as sprinting all out for a minute or blasting up a hill. As a result, muscle acidity rises -- that is, pH drops -- and, consequently, muscle work grinds to a halt. Lactic acid then pools in your legs and remains there, causing soreness and tightness, unless it is actively cleared away by massage or something similar.
The truth, however, is more nuanced. As explained by Matt Fitzgerald, a senior editor for "Triathlete" magazine and the author of more than 15 books on fitness and nutrition, lactic acid as such does not even exist in the body. Instead, the body synthesizes lactate, the dissociated form of the acid.
So although the concentration of hydrogen ions in muscle does rise during intense running, the hydrogen ions do not come from lactic acid. And even if they did, muscle pH does not drop low enough to interfere with muscle functioning.
Myth 4: The Great Wall
Just as shorter-distance competitors hear about the evils of lactic acid early and often, aspiring marathoners are conditioned by their peers to fear "the wall."
The 26.2-mile marathon, so the story goes, doesn't really begin until 20 miles in, when your body runs out of stored glycogen and has to turn to stored fat for fuel. If you pace yourself poorly or if you don't practice long, slow "fat-burning" runs in training, you'll invariably hit the wall sometime around 20 miles, then shuffle painfully to the finish, demoralized and far off your goal.
While it's true that poor preparation can lead to hitting the wall -- or "bonking," as many runners put it -- it's far from inevitable. Fitzgerald outlines several ways to stave off the feared late-race monster.
"The single most effective measure for escaping the wall is increasing your weekly running mileage," he said. "So if you're hitting the wall at 40 miles per week, aim for 45 or 50. Research has shown that weekly running volume is one of the best predictors of marathon performance -- an even better predictor than the distance of the longest run."
Fitzgerald also suggests doing at least one run during your training buildup in which you spend as much time on your feet as you expect it will take to finish the marathon, even if you have to include walking breaks.
Finally, he emphasizes the critical importance of smart pacing.
"It's best to start a little slower than your goal pace. Listen to your body and stay comfortable as long as you can, and then push hard in the last six or eight miles. Once you've completed a marathon without hitting the wall, then you can race more aggressively in your next one."
By: L. T. Davidson
Follow LIVESTRONG.COM on Twitter: www.twitter.com/LIVESTRONG_COM