Radiation Explained

Spent a good part of last week working on this radiation level infographic, for Studio 20's Building a Better Explainer Project. Check it out over at the Scientific American Guest Blog!

Shoes, Politics, and Willpower

Two stories and a blog up on Scienceline (several more coming soon).
A few conclusions I have reached:

1. From now on, every difficult task is energizing. I have heaps of self control. And a will of steel. (I just gotta repeat this often enough and it'll be true, I swear)

2. "Scientific articulacy" is a pretty cool term. I think we should adopt it. 

3. Apparently every shoe recommendation I've ever read in Runner's World is wrong. I should really stop buying those expensive Asics Kayanos. Sigh.

The Reins of Self Control: Changing your expectations could change your willpower
December 15, Scienceline

Scientists, Get Political: To move forward on climate change, the illusory boundary between science and politics must come down
November 17, Scienceline

No Glass Slipper for Runners: Current running shoe recommendations won’t protect you from injury
November 16, Scienceline

Article Published in ACSM Health & Fitness Journal!

"Injury Risks for the Female Athlete" is finally out in print!! After hopping and squealing around my room in excitement, I sat down and read the From the Editor at the beginning of the journal:

The risk of injury is low when doing moderate-intensity physical activity, but increases with exercise intensity, especially in a competitive environment. And in this regard, female athletes are at a higher risk than male athletes. In her feature, Injury Risks for the Female Athlete, Marielena Groeger, B.A., provides a concise review of women’s unique physiological and biomechanical responses to exercise that influences risk, and outlines measures that can be taken to prevent injury. Given the large number of girls and women involved in fitness programs and competitive sports, this article is an important read for all of us.

Yeah! So super happy about this.

(If you wanna read it, email me and I'll send you the final PDF)

And thanks to Hannah for this very relevant article in the NY Times about exercise science and women.

You Don't Know That You Don't Know (and Other Such Puzzles)

This series is making my brain hurt... in a good way.

The Anosognosic’s Dilemma: Something’s Wrong but You’ll Never Know What It Is
(Part 1)

DD: There have been many psychological studies that tell us what we see and what we hear is shaped by our preferences, our wishes, our fears, our desires and so forth.  We literally see the world the way we want to see it.  But the Dunning-Kruger effect suggests that there is a problem beyond that.  Even if you are just the most honest, impartial person that you could be, you would still have a problem — namely, when your knowledge or expertise is imperfect, you really don’t know it.  Left to your own devices, you just don’t know it.   We’re not very good at knowing what we don’t know.

EM:  Knowing what you don’t know?  Is this supposedly the hallmark of an intelligent person?

DD:  That’s absolutely right.  It’s knowing that there are things you don’t know that you don’t know. Donald Rumsfeld gave this speech about “unknown unknowns.”  It goes something like this: “There are things we know we know about terrorism.  There are things we know we don’t know.  And there are things that are unknown unknowns.  We don’t know that we don’t know.”  He got a lot of grief for that.  And I thought, “That’s the smartest and most modest thing I’ve heard in a year.”

(Part 2)

In a brief communication presented to the Neurological Society of Paris, Joseph Babinski (1857-1932), a prominent French-Polish neurologist, former student of Charcot and contemporary of Freud, described two patients with “left severe hemiplegia” – a complete paralysis of the left side of the body – left side of the face, left side of the trunk, left leg, left foot. Plus, an extraordinary detail. These patients didn’t know they were paralyzed. To describe their condition, Babinski coined the term anosognosia – taken from the Greek agnosia, lack of knowledge, and nosos, disease.

The contemplation of anosognosia leads to many questions about how the brain puts together a picture of reality and a conception of “the self.” It also suggests that our conception of reality is malleable; that it is possible to not-know something that should be eminently knowable. It may also suggest that it is possible to know and not-know something at the same time. But additionally, it puts the question of how we “know” things at the heart of a neurological diagnosis, and raises questions about how we separate the physical from the mental.

The Cost of Machines That Think = People Who Don't?

As I marvel at the new iPhone 4 – and hope to get one of my very own, very soon – I can't help but notice the flurry of recent articles on the mind-altering impacts of technology. The half-empty: irreversible, fundamental changes to the brain caused by the deluge of incoming information, from e-mail to video games to tweets to newsfeeds. Essentially, this digital multitasking is rewiring us to be shallow. The half-full: those same changes could actually be pretty useful – even making us smarter.

From the NY Times article: Hooked on Gadgets, and Paying a Mental Price

Scientists say juggling e-mail, phone calls and other incoming information can change how people think and behave. They say our ability to focus is being undermined by bursts of information.vThese play to a primitive impulse to respond to immediate opportunities and threats. The stimulation provokes excitement — a dopamine squirt — that researchers say can be addictive. In its absence, people feel bored...

While many people say multitasking makes them more productive, research shows otherwise. Heavy multitaskers actually have more trouble focusing and shutting out irrelevant information, scientists say, and they experience more stress. And scientists are discovering that even after the multitasking ends, fractured thinking and lack of focus persist. In other words, this is also your brain off computers.

“The technology is rewiring our brains,” said Nora Volkow, director of the National Institute of Drug Abuse and one of the world’s leading brain scientists. She and other researchers compare the lure of digital stimulation less to that of drugs and alcohol than to food and sex, which are essential but counterproductive in excess.

From the WSJ article: Does the Internet Make You Dumber?

The picture emerging from the research is deeply troubling, at least to anyone who values the depth, rather than just the velocity, of human thought. People who read text studded with links, the studies show, comprehend less than those who read traditional linear text. People who watch busy multimedia presentations remember less than those who take in information in a more sedate and focused manner. People who are continually distracted by emails, alerts and other messages understand less than those who are able to concentrate. And people who juggle many tasks are less creative and less productive than those who do one thing at a time.

The common thread in these disabilities is the division of attention. The richness of our thoughts, our memories and even our personalities hinges on our ability to focus the mind and sustain concentration. Only when we pay deep attention to a new piece of information are we able to associate it "meaningfully and systematically with knowledge already well established in memory," writes the Nobel Prize-winning neuroscientist Eric Kandel. Such associations are essential to mastering complex concepts.

When we're constantly distracted and interrupted, as we tend to be online, our brains are unable to forge the strong and expansive neural connections that give depth and distinctiveness to our thinking. We become mere signal-processing units, quickly shepherding disjointed bits of information into and then out of short-term memory.

From the NY Times book review: Our Cluttered Minds

There is little doubt that the Internet is changing our brain. Everything changes our brain. What Carr neglects to mention, however, is that the preponderance of scientific evidence suggests that the Internet and related technologies are actually good for the mind. For instance, a comprehensive 2009 review of studies published on the cognitive effects of video games found that gaming led to significant improvements in performance on various cognitive tasks, from visual perception to sustained attention. This surprising result led the scientists to propose that even simple computer games like Tetris can lead to “marked increases in the speed of information processing.” One particularly influential study, published in Nature in 2003, demonstrated that after just 10 days of playing Medal of Honor, a violent first-person shooter game, subjects showed dramatic increases in ­visual attention and memory.

Carr’s argument also breaks down when it comes to idle Web surfing. A 2009 study by neuroscientists at the University of California, Los Angeles, found that performing Google searches led to increased activity in the dorsolateral prefrontal cortex, at least when compared with reading a “book-like text.” Interestingly, this brain area underlies the precise talents, like selective attention and deliberate analysis, that Carr says have vanished in the age of the Internet. Google, in other words, isn’t making us stupid — it’s exercising the very mental muscles that make us smarter.

Related Link: The Edge Question 2010: How is the Internet Changing the Way You Think?

Matters of Value

 The House passage of a health care bill means we're a little bit closer to getting some real health care reform in the United States. But the health care debate will undoubtedly continue even after a final vote on the matter (whenever that happens... fingers crossed for this year!) Health encompasses so much more than insurance and medical care – income, education, and other background social conditions all play a crucial role in improving health. And all of these conditions, which provide the structure and support for a healthy society, are informed by our deeper values: liberty, efficiency, responsibility, and fairness, to name a few. Exploring these values in more detail is a collection of essays by the Hastings Center, Connecting American Values with Health Reform. It's worth a read, as it both grounds the current discussion about reform to greater ideals, and also points to constructive ways to continue the conversation, regardless of the final legislation.

Don't eat egg salad from a vending machine.

Michael Pollan (The Omnivore’s Dilemma, In Defense of Food), who’s written a lot about nutrition science and the politics of food, now gives us something with a more home-style flavor: personal food rules from real people (mom’s advice, from real moms). He’s collected these bits of “food wisdom” from hundreds of submissions and will publish them as part of a book in January. Until then, here are a few of his favorites:

“Eat foods in inverse proportion to how much money its lobby spends to push it.”

“Never eat something that is pretending to be something else.”

“It’s not food if it comes to you through the window of a car.”

“If a bug won’t eat it, why would you?”

“If you’re not hungry enough to eat an apple, then you are not hungry.”

“Avoid snack foods with the “oh” sound in their names: Doritos, Fritos, Cheetos, Tostitos, Hostess Ho Hos, etc.”

Liberals and Conservatives – A Moral Difference?

I tend to like debate. I see discourse as fundamentally human and critical to any functioning society. Which is why I am so disappointed with debates in which two sides seem to be talking right past each other – each trying desperately to engage with a brick wall. Aspects of the current debate on health care seem to exemplify this type of standstill, particularly surrounding issues that deal with the boundaries of human life. Jonathan Haidt addresses this problem in a recent TED interview, where he explains that liberals tend to take a more materialist and utilitarian view of life, seeing nothing inherently wrong with abortion, voluntary euthanasia, and stem cell research. Many conservatives, on the other hand, tend to place a higher value on the sacredness of life, and will see these practices as abhorrent and profoundly immoral. Because of the different emphasis placed on sanctity, liberals and conservatives each see the other side as making outrageous claims or just missing the point. But Haidt doesn’t stop at health care – he has an entire theory about the differences between liberal and conservative thinking, and relates it back to fundamental differences in moral sentiments.

(Side note: I acknowledge that I’m using broad terms that by no means accurately represent all conservatives or liberals. Haidt certainly does this as well. I do think, however, that at the risk of simplification, such generalizations can be useful in understanding some dimensions of political debate.)

Intrigued by anyone claiming to have a grand theory of morality, I read more about Haidt’s work in moral psychology. His “Moral Foundations Theory” is as follows: there are five psychological foundations (or intutions) that provide the basis of human morality. He labels them harm/care, fairness/reciprocity, ingroup/loyalty, authority/respect, and purity/sanctity. These foundations are not rigid determinants of morality, but they do place constraints on the range of human virtues that can be easily learned and cultivated. The extent to which they are valued and taught can vary greatly between different cultures – likened to tastebuds, these moral foundations are universal, but each society can have different “tastes”. Therefore, some societies may place much greater emphasis on virtues that protect the group, like subordination, obedience, and duty.  In these societies the loyalty and authority intuitions are much stronger. Other societies may build up a morality based more heavily on protecting individuals; in these societies the care and fairness intuitions are stronger.

Haidt takes this five-dimensional view of morality and uses it to explain many political disagreements in the US, mapping political liberals and political conservatives onto his system. In a series of surveys he asked participants to answer a set of moral judgment questions and identify which concerns were the most relevant to their decision. After matching up their responses with their self-rated political orientation (from extremely conservative to extremely liberal), Haidt observed an emerging pattern. Liberals in general rated care and fairness as their two main concerns, while conservatives tended to see all five moral foundations as highly relevant. The more extreme the political orientation, the more acute this difference.  In essence, liberals have a narrower focus to their morality than that of conservatives – individual rights and social justice take up most of their moral domain. Conservatives place additional value on the moral foundations that maintain order, provide stability, and bind the community together, and so their morality is more expansive.

Thus, as Haidt goes on to say:

“Conservatives have many moral concerns that liberals simply do not recognize as moral concerns. When conservatives talk about virtues and policies based on the ingroup/loyalty, authority/respect, and purity/sanctity foundations, liberals hear talk about theta waves. For this reason, liberals often find it hard to understand why so many of their fellow citizens do not rally around the cause of social justice, and why many Western nations have elected conservative governments in recent years.”

He uses this theory to explain the reaction of so many liberals after the 2004 election – shocked at how the majority of voters who regarded “moral values” as the most important issue ended up voting for George W. Bush. Seen through a liberal care and justice morality, a president who cuts taxes for the wealthy and has no regard for the environment is hardly “moral.” For conservatives, however, morality doesn’t stop there – it includes values like allegiance, authority, and tradition. So showing support for an ongoing war (solidarity and loyalty) or opposing same-sex marriage (authority of traditional institutions) may follow as moral positions. It is not hard to see why this leads to disagreement.

So, is there anything that can be done? Haidt argues that a better understanding of the five moral foundations and how they are valued in different societies (or different political ideologies) is crucial. Dismissing values like loyalty, authority, and purity as “backwards” or  “ignorant”, as many liberals do, fails to acknowledge the moral concerns that drive many people’s decisions. And it’s hard to persuade people when you don’t understand their motivations. Haidt says that “recognizing these latter foundations as moral (instead of amoral, or immoral, or just plain stupid) can open up a door in the wall that separates liberals and conservatives when they try to discuss moral issues.” I do hope so.

Further links:

Morals Authority, a more detailed article on Jonathan Haidt and his ideas on morality and current American politics.

What's the Frequency Lakoff?, an article that discusses the ideas of both Haidt and George Lakoff, who also tries to identify mental frameworks that can help explain political ideology. Lakoff  traces many differences between liberals and conservatives to their conceptual metaphors of government as family – either a “nurturant parent” or a “strict father”. The article is pretty critical of Lakoff's ideas about political language, and sees Haidt as more accurately addressing the problem.

Injury Risks for the Female Athlete - Part 3

Ok... last section!

Interestingly, repetitive loading sports like distance running are not correlated with higher bone density, although the high impact nature of running would suggest otherwise [11]. This may be due to other factors specific to distance runners, such as the high prevalence of disordered eating or menstrual irregularities. Amenorrhea or other menstrual irregularities are correlated with low bone density, and the risk of a stress fracture in athletes with amenorrhea is almost four times greater than athletes without [23]. It has been hypothesized that estrogen can modify the threshold for damage accumulation of the bone, offering a clue into how menstrual function is linked to bone health. Estrogen may exert its effects on the metabolically active trabecular bone, the porous type of bone found in the spine and all joints. Furthermore, studies have indicated that even without any menstrual dysfunction, energy deficits and disordered eating are related to low BMD and a higher risk of stress fracture [11]. Runners, who commonly have high training volumes and restricted eating patterns, may be at a higher risk of energy deficit than other athletes. Running is also a sport that places immense value on leanness and low body weight, which has independently been found to be a predictor of BMD. Therefore, female athletes with amenorrhea who strive to reach or maintain a low body weight through restrictive eating are at a very high risk for developing stress fractures and osteoporosis later in life. It is crucial that this population in particular be aware of the dangerous and lifelong effects of low bone density.

Although sports like running and gymnastics that emphasize leanness and very low body weight can be dangerous, the majority of Americans are on the opposite end of the weight spectrum. Overweight or obese individuals, while at risk for many other life-threatening conditions like diabetes, heart disease and cancer, have relatively high bone mineral density. Increased body weight is associated with a decreased risk of any type of fracture [22], and has a positive effect on bone turnover and bone density [16]. While not completely understood, the protective effect of higher body weight is possibly due to the increase in skeletal loading (due to more weight on the bones) as well as higher levels of certain hormones like insulin. Weight loss has been found to decrease BMD, but studies suggest that exercise incorporated into a weight loss program may help prevent this bone density decrease. Weight loss through dieting has been repeatedly shown to cause rapid bone loss, but weight loss achieved through exercise alone showed none of these harmful effects. Therefore as obesity is confronted as a nation-wide problem and more people are attempting to lose weight, it is important to consider the impact of the method of weight loss on bone health.

Several nutritional factors are critical in maintaining proper bone health. Calcium is perhaps the most well known mineral to be associated with osteoporosis, and it is true that calcium plays a large role in the disease. If not consumed in the diet, calcium will be leached from the bones, where it forms an integral part of the bone matrix. Other nutritional factors that play a role in bone health are Vitamin D, which must be present for calcium to be absorbed, Vitamin K, phosphorous, potassium, and sodium.

Bone mass can be maintained during adulthood, but there are very few treatments that can reverse bone loss. Current treatments for osteoporosis include estrogen replacement therapy or biphosphonates, which block or slow down the breakdown of bone, or agents like fluoride or parathyroid hormone, which promote the formation of bone [1]. No treatment can “cure” osteoporosis, but some can maintain a sufficient bone mass for normal everyday function and activity.

Overall, women are prone to many of the same exercise-associated injuries as men, such as patellofemoral pain syndrome, iliotibial band friction syndrome, medial tibial stress syndrome, Achilles tendonitis, ACL tears, plantar fasciitis, and lower extremity stress fractures. Both men and women can benefit from the same preventative measures like adequate stretching, appropriate warm-up and cool-down, sport-specific strengthening and conditioning exercises. Treatment options are also generally applicable to both men and women, such as relative rest, icing, anti-inflammatories, and physical therapy [2]. However, to tailor the most effective training regimen for the female athlete it is important to consider sex-specific susceptibilities to injury. By exploring the biomechanical, neuromuscular and cellular mechanisms of injury risk, it is possible to develop and implement appropriate preventative and treatment options tailored specifically to the female population.

1. Bonaiuti D, Shea B, Iovine R, Negrini S, Robinson V, Kemper HC, Wells G, Tugwell P, Cranney A. Cochrane Review on exercise for preventing and treating osteoporosis in postmenopausal women. Eura Medicophys. 2004;40(3):199-209.

2. Cosca DD, Navazio F. Common problems in endurance athletes. Am Fam Physician. 2007;76(2):237-44.

11. Mudd LM, Fornetti W, Pivarnik JM. Bone mineral density in collegiate female athletes: comparisons among sports. J Athl Train. 2007;42(3):403-8.

16. Reid IR. Relationships among body mass, its components, and bone. Bone. 2002;31(5):547-55.
 

22. Villareal DT, Fontana L, Weiss EP, Racette SB, Steger-May K, Schechtman KB, Klein S, Holloszy JO. Bone mineral density response to caloric restriction-induced weight loss or exercise-induced weight loss: a randomized controlled trial. Arch Intern Med. 2006;166(22):2502-10.
 

23. Warden SJ, Creaby MW, Bryant AL, Crossley KM. Stress fracture risk factors in female football players and their clinical implications. Br J Sports Med. 2007 41: i38-i43.

Injury Risks for the Female Athlete - Part 2

The risk of injury may be related to an ability many women consider beneficial: increased flexibility. Studies have shown that women in general are significantly more flexible and show greater joint laxity (lack of stability of joints) than men [5]. However, joint laxity has been linked to increased incidence of injury. Lax joints are prone to excessive motion and strain, and may require increased muscle activity to provide support. However, the increase in muscle activation places more strain on the surrounding ligaments. For example, muscle activity of the gastrocnemius (the largest muscle of the calf of the leg) works together with the quadriceps and hamstrings to stabilize the knee joint. Gastrocnemius activity has been shown to be higher in women than in men [12]. Because the female knee joint tends to be more lax than the male knee joint, this additional muscle activity is necessary. However, the higher gastrocnemius activation leads to more strain on the ACL, even though it helps protect the knee [7].

More recent studies have investigated hormonal effects on connective tissue, especially collagen synthesis. Collagen protein is one of the major components of connective tissues like ligaments and tendons. In response to a load – such as an acute bout of exercise – the connective tissue will begin to synthesize collagen at higher rate to repair the tissue. However, estrogen has been reported to inhibit this response [10], and may explain why women have much lower rates of collagen synthesis at rest and after exercise than men do. The lower rate of tissue repair after a strenuous exercise may lead to decreased recovery and higher injury risk. Furthermore, tendon growth in response to exercise is much greater in men than in women [8]. This suggests that training adaptations are different between the sexes – while men respond to long-term training by increasing tendon size, women do not have any detectable tendon size change. Because of both increased collagen synthesis and tendon growth, men have greater collagen strength than women [8], which may independently reduce their likelihood of injury. In studies comparing the cartilage in the knee, men had collagen of greater thickness [4]. Therefore it may be that the sheer volume of collagen serves as an injury prevention factor, and female’s lower volume places them at higher risk.

Female athletes are also more likely to develop a stress fracture, a common sports-related overuse injury — some studies indicate that females are at 2-10 times the risk [23]. Bone health is of particular concern for females in general, as they are at risk for developing osteoporosis, a skeletal condition characterized by low bone mass and deterioration of bone tissue leading to increased risk of fracture. Approximately 30% of postmenopausal women have osteoporosis, with projections for the next decade being closer to 50% [1]. Most fractures occur in the hip, spine and wrist and are termed “fragility fractures” because they occur as a result of a fall from standing height or less, indicating extremely fragile bones. In contrast to the sudden, severe nature of these fragility fractures, stress fractures are a different type of injury that are characterized by tiny hairline cracks in the bone. The predominance of stress fractures in young female athletes, as well as the alarming number of fragility fractures due to weak bones in elderly women, has led to more investigation into the mechanisms of bone physiology in women, and its relation to exercise.

Each individual has a maximum bone mass that they are able to reach at skeletal maturity – or around 20 years old – referred to as peak bone mass. Bone mass is primarily determined (60-80%) by genetics [18]. Since almost all bone mass is attained during adolescence, it is critical to maximize bone growth during this time. Thus many intervention studies have targeted teenagers [3]. It has been suggested that the adolescent years offer a “window of opportunity” to build up bone mineral density (BMD), but environmental or lifestyle conditions can impede the process. Inadequate dietary calcium, oligomenorrhea or amenorrhea, low body weight, insufficient energy intake, and low estrogen levels have all been suggested as risk factors for low BMD and minimal bone growth. Weight-bearing exercise can enhance bone mineralization and increase bone mass in this age group, and therefore the role of physical activity in youth in ensuring bone health is crucial [18].

BMD is measured by a dual X-ray absorptiometry (DXA) bone density scan. A BMD lower than peak bone mass but not low enough to be classified as osteoporosis is called osteopenia. While osteoporosis and osteopenia have been typically defined based strictly on BMD, more information on the quality of bone may lead to changes how bone health is diagnosed. Bone protein content, structure, geometry, and mechanical properties may also play a role in fragility fracture risk [17]. Exercise has two distinct effects on bone. On the one hand bone responds to exercise as a tissue, able to withstand and adapt to increasing load. Muscle contractions place a strain on the bone as it provides internal support to work against gravity. The strain induces remodeling and increased bone strength to compensate for these new loads. The remodeling of bone is caused by the activity of two types of bone cells: osteoblasts, responsible for bone formation, and osteoclasts, responsible for bone breakdown. Together they work on the mineral matrix of the bone, increasing or decreasing bone mass depending on signals sent to the bone cells on the surface. Bone activity thus acts in a negative feedback loop — when the mechanical strain of the bone reaches a certain threshold, adaptation and remodeling occurs [17]. On the other hand, bone is also a material that can be weakened by repetitive stress and microdamage. Bone has repair mechanisms to meet these material failures, but when the bone cannot withstand the accumulation of strain, an overuse injury can occur. The magnitude of the load, how quickly it is introduced, and how often it is repeated are all factors that affect how much damage is accumulated. Without proper care, the continuation of this loading results in a progression of damage from a stress reaction to a stress fracture to a complete fracture. It is not surprising therefore that stress fractures are frequently seen in distance runners, gymnasts, or military recruits, whose bones undergo unusually extreme and repetitive loads [23].

Kept under a certain threshold and not in excess, exercise can be beneficial to building bone mass. The type of exercise is particularly important in regards to bone health. Studies often distinguish between “weight-bearing” and “non-weight-bearing” types of activities — weight-bearing includes any activity in which there is a load placed on the bone, such as walking or running. These activities are usually touted as being the most beneficial for building bone mass. However, weight-bearing activities can be further divided into impact and non-impact exercise. For example, jumping is both weight-bearing and high-impact, while using an elliptical machine is weight-bearing but non-impact. More recent studies have shown that high-impact exercises provide the most bone density benefit, although all types of exercise put a load on the muscle and therefore are beneficial to bone. Brief bouts of high impact loading, for example in activities like jumping or weightlifting, have been shown to build bone in childhood and adolescence [13]. Non-weight-bearing activities like swimming are associated with lower bone density in the spine, while high impact sports like volleyball, squash, soccer, or track events like hurdling have been shown to improve bone density. Therefore the type of mechanical loading, rather than simply the fact that the activity is “weight-bearing”, is important in determining bone strength and mass.


1. Bonaiuti D, Shea B, Iovine R, Negrini S, Robinson V, Kemper HC, Wells G, Tugwell P, Cranney A. Cochrane Review on exercise for preventing and treating osteoporosis in postmenopausal women. Eura Medicophys. 2004;40(3):199-209.

3. DeBar LL, Ritenbaugh C, Aickin M, Orwoll E, Elliot D, Dickerson J, Vuckovic N, Stevens VJ, Moe E, Irving LM. Youth: a health plan-based lifestyle intervention increases bone mineral density in adolescent girls. Arch Pediatr Adolesc Med. 2006; 160(12):1269-76.

4. Ding C, Cicuttini F, Scott F, Glisson M, Jones G. Sex differences in knee cartilage volume in adults: role of body and bone size, age and physical activity. Rheumatology (Oxford). 2003;42(11):1317-23.

5. Huston LJ, Wojtys EM. Neuromuscular performance characteristics in elite female athletes. Am J Sports Med. 1996;24(4):427-36.

7. Landry SC, McKean KA, Hubley-Kozey CL, Stanish WD, Deluzio KJ. Neuromuscular and lower limb biomechanical differences exist between male and female elite adolescent soccer players during an unanticipated side-cut maneuver. Am J Sports Med. 2007;35(11):1888-900.

8. Magnusson SP, Hansen M, Langberg H, Miller B, Haraldsson B, Westh EK, Koskinen S, Aagaard P, Kjaer M. The adaptability of tendon to loading differs in men and women. Int J Exp Pathol. 2007;88(4):237-40.

10. Miller BF, Hansen M, Olesen JL, Schwarz P, Babraj JA, Smith K, Rennie MJ, Kjaer M. Tendon collagen synthesis at rest and after exercise in women. J Appl Physiol. 2007; 102(2):541-6.

12. Myer GD, Ford KR, Hewett TE. The effects of gender on quadriceps muscle activation strategies during a maneuver that mimics a high ACL injury risk position. J Electromyogr Kinesiol. 2005;15(2):181-9.

13. Nichols JF, Rauh MJ, Barrack MT, Barkai HS. Bone mineral density in female high school athletes: interactions of menstrual function and type of mechanical loading. Bone. 2007;41(3):371-7.

17. Rittweger J. Can exercise prevent osteoporosis? J Musculoskelet Neuronal Interact. 2006;6(2):162-6.

18. Ruffing JA, Nieves JW, Zion M, Tendy S, Garrett P, Lindsay R, Cosman F. The influence of lifestyle, menstrual function and oral contraceptive use on bone mass and size in female military cadets. Nutr Metab (Lond). 2007;4:17.

23. Warden SJ, Creaby MW, Bryant AL, Crossley KM. Stress fracture risk factors in female football players and their clinical implications. Br J Sports Med. 2007 41: i38-i43.

Can't sleep? There's a mutation for that.

Forget caffeine, stress, or exercise–I have a new reason to blame for my odd sleeping habits: my genes! Or rather, a mutation in one of them. Here's a part of the recent NY Times article on this discovery:

The scientists were searching the samples for variations in several genes thought to be related to the sleep cycle. In what amounts to finding a needle in a haystack, they spotted two DNA samples with abnormal copies of a gene called DEC2, which is known to affect circadian rhythms. They then worked back to find out who provided the samples and found a mother and daughter who were naturally short sleepers. The women routinely function on about 6 hours of sleep a night; the average person needs 8 to 8.5 hours of sleep....

What distinguishes the two women in the study and other naturally short sleepers is that they go to bed at a normal time and wake up early without an alarm. The two women, one in her 70s and the other in her 40s, go to bed around 10 or 10:30 at night and wake up alert and energized around 4 or 4:30 in the morning, Dr. Fu said.

“When they wake up in morning, they feel they have slept enough,” Dr. Fu said. “They want to get up and do things. They arrange all their major tasks in their morning.”

Sound familiar? Does to me. I'll keep an eye out for more info on this DEC2, which is apparently interrupting my sleep.

Injury Risks for the Female Athlete - Part 1 (the most running-related post yet!)

I've been working on an article for the ACSM Health & Fitness Journal about injury risk to the female athlete. The first submission got sent back with a bunch of comments, so I figured as I'm revising I'll post it in a few installments. To the runners/active women out there, it'll hopefully be of some use.

Injury Risks for the Female Athlete

While there are more and more studies showing differences between men and women’s physiology and specifically their response to exercise, historically nearly all studies have been done on men. Thus, most of the data available to the public (in scientific journals, textbooks, and encyclopedias), while providing a great deal of insight into the physiology of exercise, disregards large portions of the population and is severely limited in scope. Because of women’s unique set of physiological responses and health concerns, it is important to consider women as a specific sub-population in the study of exercise and athletics. This article will focus on the topic of injury risk for women, reviewing the current literature on this subject to better understand the special concerns of the female athlete.

The increasing number of women participating in sports also means that more women are likely to sustain injury. While the timing, location, and nature of an injury may vary from person to person, there are specific injury risks for the female athlete. In particular, women are more likely than men to sustain musculoskeletal injuries during physical activity [10], as well as lower-extremity injuries in general [21]. By far the most documented injury in female athletes is the anterior cruciate ligament (ACL) tear. Studies have reported the occurrence of ACL tears in women as up to nine times greater than in men [15]. In soccer and basketball in particular, women are three times more likely to tear their ACL than males [15]. Suggested reasons for greater injury incidence in women have ranged from biomechanics to coordination and fatigue to ligament and tendon properties. To further understand the sex differences associated with injuries and take steps to prevent them, it is crucial to examine these risk factors.

Biomechanical differences are perhaps the most noticeable factor that can predispose a woman to injury. Gait studies have identified particular differences in the up and down motion of the pelvis (or pelvic obliquity) and vertical motion of the whole body. Women generally have greater pelvic obliquity, which translates into less vertical motion [20]. This is a more biomechanically efficient gait, because less energy is expended lifting the body up and down with each stride. However, the greater pelvic motion also causes movement of the lower spine, which has been associated with acute and chronic back pain as well as disc damage. Thus there may be tradeoff between gait efficiency and injury risk – what serves as an advantage for women in conserving energy may promote the development of low back pain.

Studies on the biomechanics of landing from a jump have demonstrated several differences in men and women. Women land with their knees less flexed and turned slightly more inwards than men [14]. The inward turning of the knee is called knee valgus. Both knee flexion and valgus angle have been associated with knee injury and ligament damage. While landing with knees less flexed (and legs more extended) helps decelerate the body from a fall and can absorb more impact from the landing, it puts much more strain on the ACL. Even slight increases in valgus angle (as little as 2 degrees) can increase the force on the ACL by threefold and potentially cause injury. Women have an average of 4.5 degrees greater knee valgus than men during jump landings [14]. This biomechanical difference has important implications for females participating in sports that require jump landings, such as volleyball, basketball, and track and field. Awareness of women’s higher susceptibility to ligament injury may encourage injury prevention and emphasis on correct landing techniques.

Another explanation for increased injury risk in women is neuromuscular fatigue. There is a significant link between fatigue and injury, for example game-related injuries occur much more often at the beginning or end of a season [9]. Injury may occur due to vigorous pre-season training or the accumulated strain of many competitions at the peak of the season. Other studies have reported a higher incidence of knee injuries during the last 15-30 minutes of soccer or rugby matches, which corresponds to the time at which athletes are physically exhausted from the game. Neuromuscular control of the legs is important during maneuvers like landing from a jump or moving from side-to-side, and lack of control is likely to cause injury [9]. High intensity sports that incorporate quick movements and place a high load on the joints (like basketball, soccer, and football) require sustained effort that can fatigue an athlete. The accumulation of fatigue lowers the force-generating capacity of the muscle, affects motor control, and slows reaction times [6]. These deficiencies may change how an athlete performs landing and side-to-side movements, which may lead to injury. Several studies have indicated that women show a greater performance change with fatigue than men, such as a reduced capacity to control the knee and hip joints [6]. These abnormal movements may increase female athlete’s risk for injury, especially of the ACL.


6. Kernozek TW, Torry MR, Iwasaki M. Gender Differences in Lower Extremity Landing Mechanics Caused by Neuromuscular Fatigue. Am J Sports Med. 2008;36(3):554-65.

9. McLean SG, Felin RE, Suedekum N, Calabrese G, Passerallo A, Joy S. Impact of fatigue on gender-based high-risk landing strategies. Med Sci Sports Exerc. 2007;39(3):502-14.

10. Miller BF, Hansen M, Olesen JL, Schwarz P, Babraj JA, Smith K, Rennie MJ, Kjaer M. Tendon collagen synthesis at rest and after exercise in women. J Appl Physiol. 2007; 102(2):541-6.

14. Pappas E, Hagins M, Sheikhzadeh A, Nordin M, Rose D. Biomechanical differences between unilateral and bilateral landings from a jump: gender differences. Clin J Sport Med. 2007;17(4):263-8.

15. Prodromos CC, Han Y, Rogowski J, Joyce B, Shi K. A meta-analysis of the incidence of anterior cruciate ligament tears as a function of gender, sport, and a knee injury-reduction regimen. Arthroscopy. 2007;23(12):1320-1325.

20. Smith LK, Lelas JL, Kerrigan DC. Gender differences in pelvic motions and center of mass displacement during walking: stereotypes quantified. J Womens Health Gend Based Med. 2002;11(5):453-8.21.

21. van Gent RN, Siem D, van Middelkoop M, van Os AG, Bierma-Zeinstra SM, Koes BW. Incidence and determinants of lower extremity running injuries in long distance runners: a systematic review. Br J Sports Med. 2007;41(8):469-80.

The Ethical Dimensions of the Health Care Reform Debate

To get this whole blog thing going, here’s something to consider – two things, actually. Two very insightful articles about the ethical issues raised by the current debate on health care reform. Cohen talks about the rhetoric used by critics of the public option in the Senate health care reform bill, accusing them of being intellectually dishonest (why don’t we have a Debate Umpire to supervise public discourse?). Singer explains why avoiding any discussion of “rationing” health care for fear of sparking opposition is both unrealistic and unethical. He says that health care will inevitably be rationed in some way or another (by ability to pay, by access to advanced medical technology, etc), and we should not–and cannot afford to – forgo responsibility in making these tough decisions.

How Not to Talk About Health Care, by Randy Cohen

Why We Must Ration Health Care, by Peter Singer