Don't Cross Your Eyes...They'll Get Stuck That Way!: And 75 Other Health Myths Debunked (22 page)

There is also evidence that stretching has some negative effects. Stretching does improve your flexibility, but this is not always a good thing. Instead of improving your performance, stretching has been associated with temporary deficits or decreases in your strength, with increased blood pressure, with worse jumping performance, and with worse flexing strength of your ankles. These is also some suggestion that people who are more flexible do not run as well, but these results are mixed.

Let’s summarize the research: Stretching does not prevent injuries. Stretching does not keep your muscles from getting sore later on. Stretching can actually make you perform worse. This seems like craziness! Rachel can hear the gasps of horror and disbelief from her fellow runners (most of whom are much faster than she is and who also spend a lot of time stretching). And yet study after study tells us that you are not going to get any benefit out of stretching before you run. One of the most recent studies, done by the USA Track and Field organization, looked at about 1,400 runners who were randomly assigned to stretch or not stretch before their runs. Even this pro-running organization found that stretching did not prevent running injuries.

What about warming up? Studies of warming up look at activities other than stretching, such as walking, running, or calisthenics, that are done before a more vigorous athletic activity. The evidence on warming up is not as clear. While study after study tells us that stretching before exercise does not prevent injuries, some of the studies of other forms of warming up before exercise show that this practice will reduce injuries. In a systematic review compiling all the randomized, controlled studies (i.e., the good studies) of warming up before exercise, three of the studies showed that warming up first did reduce injuries later. The other two studies did not find any effect from warming up. The conclusion was that there is not sufficient evidence to say whether a routine warm-up before your exercise will help you prevent injuries, but there is some suggestion that this might work.

Continue those warm-ups if you must (although we’ll have to keep compiling the studies on whether or not that really works), but stretching is not going to help you be a better or safer runner!

Sugar

Eating sugar causes diabetes

Many people know that diabetes is a sugar problem, and that people with diabetes cannot have too much sugar. Along those lines, many people believe that eating sugar causes diabetes. They blame diabetes on having a chronic sweet tooth or on not being able to resist a sugary diet.

In order to understand diabetes, it is helpful to have an idea of what your body does with sugar. Your body gets much of its energy by converting the sugar and carbohydrates you eat into a special form of sugar called glucose. Glucose is the sugar that most of your body needs to operate. In order to absorb glucose, your body manufactures a special hormone called insulin that regulates the amount of glucose in your blood and the amount that is absorbed into different parts of the body. Your pancreas makes this insulin, and without insulin, you cannot absorb glucose into your body’s cells. If you do not have enough insulin or if your body does not respond to insulin, you cannot absorb or use sugar in the way your body needs.

There are two types of diabetes, called type 1 diabetes and type 2 diabetes. Type 1 diabetes usually develops in younger people, typically in children, when the pancreas stops making the insulin your body needs in order to absorb sugar. How much sugar you eat has absolutely nothing to do with developing type 1 diabetes. It is caused by genetics and other factors that trigger the pancreas to stop working normally. Type 2 diabetes usually develops in adults, although it sometimes develops in children as well. In type 2 diabetes, your body becomes resistant to the effects of insulin, so your body does not absorb sugar in the ways it is supposed to. Type 2 diabetes is caused by both genetic factors and lifestyle factors. In particular, being overweight significantly increases your risk of developing type 2 diabetes. It is possible that you could be overweight from eating too much sugar, but you could also be overweight from eating too much fat or any other diet high in calories. While eating a lot of sugar can certainly make your diet very high in calories, the sugar does not directly cause the diabetes.

Several studies in large groups of people have found that those who drink more sugar-sweetened beverages have higher rates of diabetes and more cases of type 2 diabetes. While this suggests a connection between sugar and diabetes, it is the connection that occurs because sugary drinks make you gain weight. In a systematic review that compiled studies looking at sugar-sweetened beverages and weight gain, the researchers found that drinking more sweet beverages was connected to more obesity and to being overweight for children and adults. Taking in sugar is not independently connected to developing diabetes; obesity is what is really connected to developing diabetes.

People with diabetes do not need to stay away from sugar altogether. They can eat sweets or starches, but they should eat them in moderation, as part of a healthy meal plan. Having a healthy diet means eating plenty of fruits and vegetables, some meats or proteins, and not more than a few servings of foods containing carbohydrates.

Even if you are not diabetic or if you now understand that sugar will not give you diabetes, there are plenty of reasons to eat sugar in moderation. Gaining too much weight or developing lots of cavities are bad effects from a diet too full of sugar. However, you do not need to worry that diabetes will automatically follow from your sweet tooth.

Television

Sitting too close to the TV will ruin your eyes

“Don’t sit so close to the television! It will ruin your eyesight!” Many a child has heard this admonishment when staring at the TV or peering intently at a computer screen. Aaron watches more television than most people (despite being a highly productive researcher and professor), and he is blind as a bat without his glasses. Is his television-watching to blame for his nearsightedness?

This is one of those myths that we cannot disprove definitively because no one has done a great big study where some children are forced to watch television up close for hours and hours. (And no one is going to do that study.) We can tell you that there is absolutely no evidence that sitting close to the television or computer screen ruins your eyesight. Whether you sit within inches of the screen or whether you watch for hours and hours, there is no evidence that television will ruin your eyes.

This myth may have come from the early days of television. The first television sets actually emitted a lot of radiation. In fact, these televisions put out more than 100,000 times the radiation that the federal health officials deem safe. Sitting really close to those old televisions in the 1950s might have been a risk for a person’s eyes. But this radiation from televisions is not a risk anymore. Televisions have improved in so many ways since then, and they no longer emit lots of radiation.

The reason this myth may stick around is because sitting close to the television can give you eye strain. When you sit close to the television, when you stare at a screen for a long period of time, or when you read in the dark, you do strain your eyes. Eye strain can cause eye pain, make your eyes dry and your vision fuzzy, and can even give you a headache. Thankfully, eye strain is a temporary condition. When you stop watching television or when you move into better conditions, your vision returns to normal. Just like running may give you tired legs but does not weaken your leg muscles permanently, most eye strain does not ruin your eyes forever. When you rest your eyes, they return to normal.

It is important to note that there may be a different kind of connection between a child who sits close to the television and a child with bad vision. When children need glasses, they will often start to sit closer and closer to the television or other screens, blackboards, or books. This is not because the television is ruining their eyes, but because they need help seeing! Children should have their vision tested regularly, and parents should be even more quick to get this testing for a child who seems to be sitting closer and closer to the television.

As pediatricians, we feel obligated to remind parents that there are other reasons why it might be a good idea to limit how much television a child watches. Even if their eyes are perfectly safe, watching too much television is connected with children being overweight or obese. Television might be particularly bad for babies and young children. Watching television, even educational videos or programs designed for babies and toddlers, has been associated with delayed learning and development. The American Academy of Pediatrics recommends that children under the age of two years not watch any television at all, and that television watching be limited to less than two hours per day for older children. Your mother was wrong about television hurting your eyes, but she may have been right on track about it hurting your developing brain.

Toilet Seats

Touching a toilet seat will make you sick

Despite the fears of countless parents, no reputable health organization has ever targeted toilets as a serious way to catch an infection. It’s important to remember that most serious viruses and bacteria can’t live for very long outside the body. They are no more likely to survive on a toilet than on any other household surface. Let’s face it. Most of you are really concerned about picking up a really bad disease from the toilet. So let us put your mind at ease. You can’t catch HIV from a toilet. Nor are you likely to catch a sexually transmitted disease from a toilet (see our next toilet seat myth for more information about that). You’re pretty much safe from parasites as well. That’s not how those are spread.

You also need to remember that most infections do not enter through intact skin. They need to get into the mouth, an open wound, or a mucus membrane. So even if you sat on a germ, it wouldn’t necessarily infect you. If you wash your hands, anything you touched should be taken care of. Again, toilets pose no special danger.

Studies indicate that hardier viruses, like influenza A, can be found on toilets in day care centers. But viruses can be found even more commonly on kitchen dishcloths and diaper-changing areas. Toilets aren’t special.

In fact, there are lots of other things that are likely far more infectious than the toilet, and we bet you don’t think about them at all. Do you know how dirty money can be? Think about how many people have touched that. How about the phone? Your keyboard? In fact, people who eat at their work desks are far more likely to get infected than those who touch the toilet.

Of course, we will still flush it with our feet when we can. Come on.

You can get gonorrhea from the toilet seat

In an episode of one of our favorite television shows,
Seinfeld,
one of Jerry’s girlfriends has a mysterious “tractor story” that she is reluctant to tell him until their relationship progresses. Jerry thinks the story is going to explain the mysterious scar on the girl’s leg, but instead, the story ends up being that she supposedly got gonorrhea from sitting on the seat of a tractor in her bathing suit (at least, that is what her boyfriend told her was the cause).

While relatively few people spend time on tractor seats, a lot of people believe that they might get a sexually transmitted disease from a toilet seat. The fear of toilet seats springs from the idea that public toilets are filthy places full of bacteria, but also because many have heard that toilet seats could be to blame for such an infection. It seems a lot easier to blame the toilet than to blame your boyfriend.

When we refer to sexually transmitted diseases, we are talking about infections caused by either bacteria or viruses that are typically passed only when one person has sex or contact with the sexual organs of another person. These are diseases like chlamydia, gonorrhea, herpes, and infection with HIV. The scary idea that you could get one of these serious infections from a toilet seat is enough to make anyone want to hover over the toilet bowl, but it also offers an excuse for how you may have gotten one of these infections without sex being involved.

There is no research proving that people get infected with sexually transmitted diseases from sitting on toilet seats. This does not mean that it is impossible to get infected from a toilet seat, but there is no evidence either way. There are a few published cases where physicians describe patients who they believe may have become infected after direct contact with exceptionally dirty toilet seats, but in these cases, they cannot prove that the patients did not have physical or sexual contact of some kind with a person who was infected. The majority of experts, including the president of the American Society for Microbiology, report never seeing or hearing about cases of people actually acquiring an STD from a toilet seat (unless they were having sex with another person while on the toilet)!

Even though it may be theoretically possible to get infected from a toilet seat, there are many reasons why this is very unlikely to happen. First of all, most of the bugs that cause sexually transmitted diseases in humans do not survive well outside the human body. The viruses that cause herpes and AIDS do not live outside of the body for long. They dry out and die when exposed to air, and there have been no proven cases of people getting herpes or AIDS from a toilet seat. The bacteria that cause infections like chlamydia and gonorrhea do not live much longer. Second, for these bacteria to get onto the toilet seat, someone would first need to leave their bodily fluids on the toilet seat. Obviously, public toilet seats do end up with a lot of urine on them, but urine is not where these germs live. These germs live in the fluids in your vagina or penis, or sometimes in your blood. It is much less likely that someone would be rubbing against a toilet seat or sitting in a way that would leave discharge or secretions from their vagina or penis on the seat. People also do not usually bleed onto the toilet seat. Even if the bug did get onto the seat in one of these secretions and did manage to survive, it is not a sure thing that someone coming into contact with that bug-infested fluid would become infected. In fact, it is quite unlikely. The bugs would have to be transferred from the seat into your urethra or to your genital tract, or maybe into a cut or sore somewhere on your private parts. You would need to touch the gunk on the toilet seat with one of these parts. Finally, even if someone did leave a germ, it survived, and you touched it, it very well might not be enough of the germs to cause you an infection. For many of these infections, you need to come in contact with a pretty large number of them to make you sick. It is theroetically possible that just one or two germs might infect you, but it is incredibly unlikely.