All posts by doctor blake


So there are lots of resources that I use with my students, and I got to thinking, ‘Hey, maybe some other people could use this stuff too!”

Most of these things I made at one point or another to help myself learn a particular idea, but then I turned around and gave them to my students.  Personally, I think making your own chart, diagram or model is the way to go, but sometimes you can get good ideas from the work of other people.

In most instances, I have tried to keep things simple, and I can think of exceptions to a lot of the stuff I have written. These charts are not absolutely comprehensive, since they are written with curious people, not professionals in mind.  I encourage you to ask questions, either here or elsewhere, and hopefully we can get to the bottom of the reason why something is or is not the case.

I would ask that if you take something from here, you just do the honorable academic thing, and say where you got it from.  For my part, I have distilled this information from books and resources too numerous to cite, but rest assured, I did not come up with the information on my own!

Joints Categorized by Movement
Not every joint of the body can do every movement.  These are the major movements of the major joints.

Muscles of the Body By Function
This handout considers the major muscles at each joint, and the movements they generate.

Back Movement Analysis Diagram
This diagram is a groovy illustration of how the muscles of your back cooperate to produce the awesome movements you can do. Is a muscle on one side of a line? Then it does the kind of movement on that side of the line.  Pay special attention to the rotational movement!

Neck Movement Analysis Diagram
This diagram is a graphical illustration of how the muscles of the neck work to produce movement.  All the muscles falling on one side of a given line produce the movements on that side of the line… you’ll see what I mean.

Lower Leg Functional Handout
This handout compares the muscles of the lower leg with the stuff they do. The reason such a thing might be helpful is because some muscles are positioned in such a way that it might be confusing.  The tibialis anterior, for example, is on the lateral aspect of the leg, but crosses and attaches to the medial side of the foot.  In the diagram, there are areas depicting a kind of movement: if a muscle is on one side of the line, it causes that movement. Look at the diagram… it will be clearer.


Ballet Turnout for Gymnasts

A friend on Facebook asked the following question:

“I’ve been asked to teach/coach gymnasts – who compete at a provincial and national level – “ballet basics” to help with artistry and refining foot, leg, core, shoulder and arm work. It’s not rhythmic gymnastics, just regular.

What are the rules for teaching turnout? It gets utilized in various moves but their feet mostly stay in parallel for safety and strengthening reasons during tumbling and anything using an apparatus. Thank you for any help!”

She gave her permission to share the question, and here was my response, which I though might engage my friends on the blog.


“Turnout” is simply the amount of outward rotation of the femur at the hip joint. The value of the the turned out leg is that it allows the dancer to move transversely across the stage while facing the audience, something which is very appealing in ballet, and around which much ballet vocabulary has been developed. This general idea has developed into the aesthetic of turned out legs for their own sake. This development is not bad per se, but has caused some students and teachers of ballet to merely approximate the look of a highly turned-out hip.

The reason all of this preamble is necessary, is so we can talk about the things that people should do to maximize their turnout, in contrast to what they try to do to make it look like they have lots of turnout, and the special considerations of gymnasts who tend to have anteverted pelvises (lumbar lordosis) and hyper-extended knees.

As a general rule, the kneecap reveals the rotation of the femur in the hip joint. When the kneecap points forward, the femur is at zero degrees rotation. When the femur is outwardly rotated, the knee caps point outward. The feet should follow the alignment of the femur, with the line between the second and third toe pointing in the same direction as the kneecap. This alignment is evident and impossible to ‘cheat’ when a dancer is en pointe or demi pointe. When the dancer is standing on straight legs, it is possible to sneak the toes and lower legs into a false turnout by using the friction of the floor to hold the foot and lower leg in greater turnout than that possessed by the femur. Likewise, while in plié, the ligaments of the knee joint are slightly lax, and the tibia can be cheated into greater turnout than the femur. The problem with this cheating is that it causes considerable stress on structures of the knee, particularly the medial collateral ligament, the anterior cruciate ligament, and the medial meniscus.

At the hip joint, turnout is limited by bony impingement between the acetabulum and neck of the femur, by ligaments (especially the iliofemoral ligament or ‘y’ ligament) and the joint capsule, over-tight inward rotating muscles of the hip (not so common) and under-recruited or weak outward rotating muscles (more common). In young dancers and gymnasts, exaggerated lumbar curvature (lordosis) tips the pelvis forward, and slackens the iliofemoral ligament. In the younger dancer the lordosis can be caused by weak or under-recruited abdominals, while in the gymnast it is more likely caused by habitual hyperextension of the low back. This pelvic tilt allows greater turnout, however such malalignment of the pelvis carries its own risks and problems. In a similar manner, individuals with hyperextended knees tend to have greater ligamentous laxity, and greater risk of injury to the ligamentous structures of the knee, however this sloppiness in the knee permits greater outward cheating of the tibia relative to the femur, giving the appearance of greater turnout.

All of this is to say, that with a gymnast, there are some important considerations. First, start with a neutral pelvis: The anterior superior iliac spine (ASIS) and pubic bone should be perpendicular with the floor, or the coccyx and pubic bone should be parallel with the floor. These bony landmarks are a good rough guide. A neutral pelvis can be maintained using the image of having the pelvis be a bowl of water that you don’t want to spill out the front.

Equally, the knees should be neutral in stance. For those with naturally hyperextended knees, ‘neutral’ may feel like the knee is slightly flexed, so it will be challenging to have them not push back into hyperextension. Once you have these two important considerations addressed, you can move on to turnout. There are two very good ways to determine maximum turnout for an individual. The first is to put the person on two freely rotating platforms and ask them to maximally outward rotate from parallel stance. Because there is no friction on the floor to hold the foot beyond the rotation of the femur, the feet will accurately reflect the turnout of the femur. You could also use very slippery socks on a polished floor. The second way is to have the person stand in parallel, then bring one gesture leg to coup de pied parallel, turn out the leg, then place the foot on the floor from this position. Do the same on the opposite foot. Be careful that the student does not move the gesture hip backward nor slide the toe backward along the floor. It will be astonishing to many that this is the limit of their turnout.

Turnout can be increased in stance by use of the gluteus maximus, but this muscle is phasic and tires quickly, so not good in the long run. Further, because it is a hip extensor, it inhibits forward locomotion. The six deep outward rotators (pyriformis, obturator internus, obturator externus, gemellus superior, gemellus inferior and quadratus femoris) are better suited for this role, and in some individuals must be strengthened. I am not convinced this would be the case for a gymnast however it might be necessary to train the gymnast to recruit those muscles without engaging the glute max. So you would be looking for increasing turnout while keeping the glute soft. Likewise, I doubt that tightness of the internal rotators would be a problem for this population.

If I were working with this group, I would encourage them to understand that they are learning a different aesthetic with slightly different objectives than gymnastics, then use their remarkable body awareness to focus on neutral pelvis and knees, a modest, natural turnout aligning knee and the middle of the foot, and working toward healthy movements within that range. I hope you have lots of fun with them.

Thinking about thinking about science writing

My friend shared a post on my Facebook page about 10 Questions to ask when you read a story about science or medicine. I like what Steve Buist of the Hamilton Spectator has to say and to be sure, this is a good, simple guide that will get most people under way. However, I would argue there are four questions that are of greater importance in current science reporting:
  1. How many steps is this reporting away from the original science? A great deal of science “reporting” currently involves looking at a press release about a scientific study, or at times, a story about a press release about a study, or, as I have come to find out when trying to chase down a story’s origins, a story about a story about a press release about a study. Unfortunately, key details about the study are frequently omitted in the repetition of the information, rendering the science meaningless and misguiding. Equally when information is simplified or paraphrased for a new audience, nuance and important critical elements can be distorted to suggest things other than the point of the study.

  2. How many cherry picked results have been conflated into a single story? Reporters will often try to make a point about an idea, so they will look at several press releases about a single scientific topic, and choose results they believe will support a particular narrative. Of course, we all do this to a certain extent, with the exception that in science, you must not. You must take all of the results, and try to understand them in aggregate. Frequently the picture is complex and muddy, and this makes for a terrible story, but great science.

  3. Does the reader understand the topic in the study? Did the reporter understand the topic they were paraphrasing? It is easy to assume that just because we can parse all of the words in a sentence that we will necessarily understand what the author is trying to communicate. I can typically understand all of the individual words from a paper in an economics journal, but I would be hard pressed to explain the ideas to anyone. Some ideas, especially about cellular biology or neuroscience can be very complex, and although I am a neuroscientist, I can spend a lot of time trying to figure out exactly what a study showed, if anything. This can be particularly true if the technique or brain area or behaviour is unfamiliar to me.

  4. Do you have any clue what the statistics mean? Yes, more people in a study generally is better, but with a large enough group you can begin to find an effect for anything, and this is confusing unless you understand how hypothesis testing works, and what an effect size is. I am not saying you need to be statistical consultant, but in the words of Mark Twain, “There are three types of mendacity I can’t abide: Lies, damned lies, and statistics.” The bottom line is that statistics can be made to say many things and unless you are familiar with what test is allowed in a given circumstance, it can be hard to tell whether or not the result is as solid as it sounds.
Overall, if you are writing science stories, you are obliged to follow the advice of Einstein, who said “You do not really understand something unless you can explain it to your grandmother”. This involves the work of reading the ORIGINAL study, not the press release, and not someone’s paraphrase. It also involves reading any important supporting or contradictory background research. If you are unfamiliar with the techniques or ideas, it involves learning more about them. With respect to statistics, if you don’t understand them, in my view you are obliged at bare minimum to confess that lack of understanding.
The big point here is that with the “copy/paste” world we live in, we have an additional responsibility to be cautious when telling readers what to believe. Deliberate misinformation and misguided crusades in the name of weak or terrible science have been repeated to the point where the fiction is accepted as truth, resulting in misfortune and even death. The way of science is difficult, and fraught with enough peril and error— and at times, even deliberate deception. If you are going to report on science, at least do the hard work of thinking the issues through before you repeat them to someone else.

Anatomical Robots

I invented this game to help my students learn about the movements at each joint, view pill and how to use anatomical language to describe movement.  I eventually want to make an interactive game for the blog, but thought some of you might enjoy this as it is.  As a teacher, I typically will be the robot first, and the students each take turns programming.  I start kneeling, with my left index finger touching the ground , and my right hand shaped like a cup on the right thighas the start, and my left index finger in the cup as the finish.  Then I have my students work in pairs. I troubleshoot any problems or errors my students make, and answer questions as they are working through. Let me know if you have any suggestions about how to make it better, or if you come up with other variations.

You can use this PDF (Joints Categorized by movement) as a guide to what movements are possible at each joint. The GetBodySmart website has excellent resources to help you learn more about these movements, but they focus on the level of muscles, rather than the joint. I hope to eventually provide a more simple explanation.

Have fun!

Anatomical Robots:

Get the robot from the start position to the finish position


  1. Divide into pairs. One person is the ‘programmer’, the other is the ‘robot’. You can also have more than one programmer, and during ‘programming’ the programmers will take turns.
  2. The robot demonstrates a starting posture and announces “This is the start”, then demonstrates a finishing posture and announces “This is the finish”.[1]
  3. The programmer then tells the robot to move, one joint at a time, ONLY using anatomical language, for example, “Flex your left elbow”.
  4. The robot will then move the joint in the appropriate manner, i.e., flex the left elbow slowly.
  5. When the position for that joint is satisfactory, the programmer says ‘Stop!’ If the robot moved too far, the programmer(s) must correct the over-movement on the following turn.
  6. If the programmer uses incorrect language, for example asks the robot to ‘Flex your arm’ (not a joint), or to ‘Abduct your elbow’ (not a possibility at that joint), then the robot must tell the programmer ‘I’m afraid I can’t do that. Dave.’ and the programmer must revise the command.
  7. The programmer continues until the robot reaches the finish position.
  8. Switch roles: the programmer becomes the robot, the robot becomes the programmer.

Vermont Rules[2]

  1. The programmer decides the start position for the robot, and does not tell the robot the end position. Surprise!


[1] It is very important to choose postures that can be held for a long time, since programming can be challenging. It is equally important to not choose postures that require shifts of center of gravity, since these moves are very difficult to execute one joint at a time: your normally make many changes at once when shifting weight.

[2] Invented at a retreat by some of my students from Vermont.

Thinking (!) about brains and yoga

I am preparing my materials for the 2016 Toronto Yoga Conference and Show, and Ruth, the conference director asks me every year if I want to write a little blur for the conference guide.  I always want to, but then think: “What would I want to say to a group of yogis and yoginis who might never attend one of my workshops?” and “Would anyone care?” Then paralyzed between inertia and confusion, I miss the deadline.

This year I was determined not to miss the deadline, and thought hard and long about my above question.  After a few stabs, I realized there is something that I would like to share.

In the end, I want yoga people to see science as an ally, not an adversary. Western science and Eastern practices have had an uneasy relationship. The caricature is one of warring factions, with Western science sneeringly dismissing anything that was not generated in a lab and measured to the milligram, micrometer and nanosecond; and with Eastern practices suspiciously rejecting the over-compartmentalized and dogmatic ways of thinking. In the end, neither way of thinking is better than the other, but they bring different things to light.  Each makes mistakes. Each finds different kinds of truth (this comment could be expanded into a post of its own!).

With that in mind, I wanted to write a brief post on how to think about brain science and yoga, since it is a big confusing world, and lots of people are making lots of claims.


What’s the deal with brains? Suddenly it seems like everybody is going on about them, which is surprising, because humans have had brains for a very long time. We haven’t had yoga for nearly as long, but people have been yammering about it for years!  But yoga and brains seem to be showing up everywhere. From 2005 to 2010, the research database PubMed logged 851 articles for ‘yoga’, 122,502 for ‘brain’ but only 225 for ‘yoga’ and ‘brain’ combined. From 2010 to 2015, these numbers changed to 3524 for ‘yoga’, 341,577 for ‘brain’ and 1147 ‘yoga’ and ‘brain’. The increase for each was 314% for ‘yoga’, 178% for ‘brain’ and a whopping 409% for ‘yoga’ and ‘brain’.

Even so, the research so far has been pretty limited, with most effects of yoga on the brain still unknown.  We do know yoga appears to modulate cortisol, the stress hormone; it increases brain waves associated with relaxation; it improves production of a brain chemical known to reduce anxiety and another involved in the growth of new brain cells. It is also linked with improvements in mood, eye-hand coordination and stroke recovery.  But the mechanisms are not really understood. In fact, pranayamic breathing might be responsible for at least some of the benefits, regardless of whether or not people practice the postures. Even then, it is worth wondering if Tai Chi or Chi Gong or breakdancing might do the same thing, but we just don’t know. We are still at early stages and the some of the evidence seems uncertain and even contradictory.

Yet there are reasons for optimism. The impact of yoga on the brain is finally getting serious scientific attention, which will increase the profile of yoga and its acceptability as an effective intervention. Yoga is being researched as a real treatment for Parkinson’s disease, stress, cognitive function, psychiatric disorders and other brain-related issues.  Yoga doesn’t really ‘need’ scientific validation to prove that it works.  It just works. However, ‘alternative’ treatments need support from research before they will be taken seriously, and who knows? possibly even prescribed by doctors.  Also there might be some conditions that yoga helps more than others or certain things that it does not benefit at all. More important perhaps, is what yoga might contribute to the discussion about how brains and bodies work together and how that impacts yoga practitioners, both as individuals and as communities of people.

We also need caution. On one hand, the quality of much existing research is poor, and often the experimental design does not have a control group or condition to see if yoga was really what caused the change; or results are coloured by what the experimenter wanted to see. On the other hand, even well-meaning people misinterpret, misunderstand and overstate the claims of research.  Further, because ‘brain’ has become such a potent buzzword, people ironically give up thinking critically as soon as they see it: hucksters and snake oil salesmen rush in to fill the gap.  ‘Brainyoga’ and ‘Neuroyoga’, and other products and services promising a glorious union between brain and body, with unprecedented benefits, are surely a thing by now, or will be very soon. However we must remember, ALL yoga is ‘Brainyoga’, just as all walking is ‘Brainwalking’ and everything you do with your body is ‘Brain-Everything-You-Do-With-Your-Body’, because that is just how brains and bodies work. Together.  Yoga by its very nature is an exploration of this link. The important question for any practitioner may be ‘How mindful am I?

In the end, it might turn out that yoga is not the only or best thing that helps the brain in the ways explored so far, or that it doesn’t have some of the benefits we thought it did, but this is not cause for alarm or concern. Although some in the worlds of yoga and science might see the two as mortal enemies— adversaries in an imaginary war, simply, they are two paths of discovery.  Science works not by “proving” or “disproving” ideas, but by accepting the idea supported by the best available evidence. The early research is providing a footing against which new ideas can push and move forward. Continued research and work by thinkers like Dr. Chris Streeter and Dr. Kelly McGonigal is slowly establishing the field. Great resources like Google Scholar (look it up!) and many open access journals are giving more people than ever the ability to read the research themselves.

Still, both as yoginis and as scientists, we must do the important work of letting go, exploring the places where we seem to be stuck, observing carefully and without prejudice, and applying the truth to our lives, whether we like it or not. Let’s step to the top of the mat, and begin.

A Neuroscientist Looks at Destin Sandlin’s Backward Bicycle

Being a neuroscientist, a kinesiologist, a learning and training researcher and a cyclist, a lot of my friends have sent me a link to the remarkable video where a guy learns to ride a special bicycle. The Smarter Every Day podcast presents us with some cool problems, ideas, and challenges to the way we think. In an episode that has gone viral, our host Destin Sandlin tries to ride a bicycle that has been engineered so the turning the handlebar to the left results in the front wheel steering to the right. You can see the episode here.

After a few attempts, he states that “your brain cannot handle it”. He challenges others to ride the backwards bike and even offers a $200 reward all over the world to the person who can successfully ride it. Destin decides to spend a few minutes every day learning to ride the bike, and finally manages, only to find that he can no longer ride a regular bike. The episode is really amazing for a lot of reasons, but Destin says some things about learning, about brains, and about bicycles that are not quite correct. It is not my desire to be a kill-joy, because the overall thrust of the episode is beautiful. However, I study brains, movement and learning and so he is playing in my play-ground: my playground, my rules.

“Knowledge ≠ Understanding”

Sure, sure. This is kind of obvious, except for a very important thing: The video conflates two very different kinds of brain activity, and our host talks about cognitive activity and motor activity like they are the same thing. You see, knowledge and understanding are descriptors about learning in the cognitive domain, and they represent different levels of cognition. A great modern example of this difference can be found in Einstein’s famous equation describing special relativity: E=mc2. Some people know the equation and can repeat it back to you. Some people even know that E is energy, and m is mass and c is the constant, or speed of light in a vacuum. A relatively (ha! GET IT?) small percentage of the population understands that the equation explains the equivalency of mass and energy, or a speed limit to light, or any number of other things, and fewer still understand why or how this is so, and in what ways the theory might be limited or incorrect.  But these are all cognitive processes, and there is more than one kind of learning, and bike-riding belongs to a different kind, called sensori-motor learning or procedural learning. Procedural learning, by its very nature, is difficult to describe. In other words, his comments don’t relate to learning a motor skill: they relate to learning facts.

There was a very famous brain patient named H.M. (Henry Molaison) who was studied extensively by Brenda Milner from McGill University in Canada. He had severe epilepsy which doctors attempted to cure by removing part of a brain structure called the hippocampus.  The hippocampus is associated with memory. After the surgery, his epilepsy was cured, but H.M. lost all of his short-term memory. If you introduced yourself to H.M. in a room, then left the room for a moment, and returned, he would not remember that you had met. If this sounds like a cool idea for a movie, Christopher Nolan already beat you to it with Memento.

Still,  Suzanne Corkin found something fascinating about H.M.. She and her team taught him a new motor skill, and very importantly for the discussion here, the skill was drawing a picture while looking in a mirror.  This is a challenging thing to do, and involves reversing certain parts of the motor program in conjunction with vision. People who practice this skill over time get very good at it, and can eventually draw just as well looking in a mirror as they can without. For Henry, the interesting thing is that his skill improved in mirror drawing over time, but he never remembered having come to the room, or having met the researchers, or the names of certain things. This story illustrates how knowledge aspects of learning are different from motoric ones.  In fact this difference is so clear and important, in the learning research community, people talk about training, which is about procedural things, and education, which is about information and ways of thinking.

Ultimately, riding the backward bike is a motor learning problem, and we have to be careful about using words like “thinking” or “knowledge” or “understanding” because motor learning is not about those things.

“Your brain cannot handle this”

I think this comment points out something important about motor learning, and may indicate the difference between rationally or explicitly knowing what the rule is, and being able to perform the task. In studies where experimenters explicitly tell people what the secret is (“the mouse cursor goes left 90° when you move the mouse forward”), the subjects actually end up doing worse, then eventually give up on the explicit strategy before just figuring it out by doing. Knowing the rule actually hinders the learning, perhaps in part because cognitively considering the information introduces more delay in responding to disturbances in balance, which is catastrophic. It also consumes important attentional resources in this very complex task.

“Suddenly my brain clicked back into the old algorithm”

If you do something in a unique context often enough, your brain will build a forward model for that context. In the Henriques motor control lab at York University, they have found that the model for an altered mouse cursor will last up to 24 hours with only 240 training reaches. As another example, you can walk in the water then on the beach, and your brain can adjust the amount of force for each step pretty much instantly. There does not appear to be any limit to how many models you can have. With continued practice and switching back and forth, he would eventually be able to do both equally well.

Our brains become quite adept at resolving this kind of backward mapping problem, as when we shave or brush our hair in a mirror: we must reverse depth (forward and back) but side to side remains the same. The idea for the bicycle is very similar to learning to reverse a car pulling a trailer, only you are messing with balance, not just direction. Eventually your brain just swaps one map for another. In fact, there are a great number of studies about having people learn to throw darts while wearing special prism glasses that swap left and right or up and down, and in my own PhD lab, we rotated forces or directions when people reach for something using a mouse or experimental robot arm.

Bicycles, Balance and Brains

Part of the issue may be the bicycle itself, and I puzzled over this for some time. The bicycle is not simply reversed left for right. The axis of rotation of the handlebars is further away from Destin than the axis of rotation of the wheel fork, and this may be important in what is happening here.

On your bicycle, there is a part called the stem: it is the part that juts forward from the headset, which is the part that turns the forks. If you have ever changed your stem, especially for a longer one, you know how important it is for steering.  I put a longer stem on my road bike and had trouble steering at first: I kept over-steering. The arrangement on the backwards bike creates a longer stem, which is the first strike against Destin, but not the most important.

In normal bicycle riding, to steer to the right, you extend your left elbow while flexing your right, but you also perform an action at each shoulder. On the left the action is called horizontal flexion, and involves bringing the more or less horizontal humerus bone closer to the midline of the body. On the right, you perform a corresponding horizontal extension at the shoulder, moving the humerus further away from the body midline. But to steer successfully to the right, you musn’t go too far, so the antagonist muscle groups work to do the opposite things to recover from over-steering: Left elbow flexion, left shoulder horizontal extension, right elbow extension, right shoulder horizontal flexion. Over the course of your life, your brain develops a model of how this linkage between the actions of the two arms work together, and a lot of this coupled action is handled by a brain area called the supplementary motor area (SMA). The patterns of movement in kinesiology are called kinematics.

To complicate things, how much force you require to flex or extend your elbow changes at each degree of flexion or extension. Gym equipment manufacturers know this, and they put cam-shaped pulleys in their machines so that the amount of force required at each degree of movement remains more or less the same.  Again, your brain makes a model of how much force is required and how fast it must be delivered. In kinesiology this is called dynamics. Over your life, you develop very clear relationships between the pattern of movement and the amount of force required to achieve the movement under certain conditions.

The backward bicycle creates a situation where the torque required  at the elbow and shoulder to turn the offset handlebar does not match the torque required to turn the stem.  Simply put, we need to push harder to turn, and regulating movements must also be harder. This is not a really big deal for your brain, since power steering reduces the amount of force you must apply in your car, and you can learn that pretty quickly, but all the same it is yet another thing.

One more complication. The human motor system is noisy and slow. Yes, we get feedback on movement using a sense called proprioception, but that information must compete with all kinds of other sensory information, including information from the inner ear, which senses linear and angular accelerations. All of this information must make it to your brain, be interpreted, and then generate a compensatory movement command.  The information often arrives too late to make a difference, so over time your brain generates a forward model.  This is like a plan that your motor system creates to anticipate the kinematics and dynamics of a movement and allows us to compare the actual consequences of movement with the expected consequences.  This is why it feels so weird when you take the extra step when you are carrying laundry up the stairs: the forward model generated forces and movements to accomplish that task. You have one model for walking across the floor, another for across the carpet and another for up the stairs.

Which brings us back to the backward bicycle.

If you point the wheel of a two wheel vehicle to the right, the inertia will cause the center of mass to fall to the left of the front wheel UNLESS you project your center of mass more to the right. This normally happens when we turn the handle bars to the right: the bent right elbow and straight left elbow means that your mass is now to the right. The issue here is that there is a basic motor pattern that even extends to walking: greater rightward pressure will result in rightward movement, whether walking, running or riding a bike. Equally, shortening the right side is also the way to turn to the right. Smaller steps on the right side is the way we turn to the right. The inner ear is facing a dire, fundamental conflict. Shortening to the right and center of mass to the right mean a rightward turn. Equally, if the vestibular system of the inner ear sense a fall to the left, it will project our body mass to the right, often by bending the right elbow slightly and horizontally extending the shoulder (think about balancing on a curb or parking block). On the backward bicycle, this fundamental, neurologically determined behaviour is denied and this is not bicycle learning, but fundamental neurological synergies. The challenge of riding the bike is bigger and more basic than Destin assumes, but it has nothing to do with the “way you think”. It has to do with basic physics, biomechanics and neural behaviour.

The Bottom Line

Destin comments early in the video: “It is a complicated algorithm: affect one part, it wrecks the whole thing.” With the axis of rotation of the handlebars in front of the axis of rotation of the headset, a change in the torque required at each joint, a conflict between the inner ear and the motor system, a reversed mapping for steering, altered physics for steering, the welder did not just change one thing, he changed everything.

He claims over and over that it is “a pattern” or “an algorithm” but it is more than that: it is the way physics works. It is the way basic neurophysiology works. It is the way biomechanics work. Still, as he demonstrates we can overcome patterns, even natural ones, and I think that is a reasonable message, and perhaps an encouraging one in a world where people do bad things and claim it is normal. We can still define the way we behave, even in the face of incredible pressure, and even if it seems to go against the way things are. And that is worth thinking about.


He says a couple additional things that are also worth considering:

“Once you have a rigid way of thinking in your brain, you can’t change it.” Well not with that attitude you can’t! But seriously folks, he demonstrated that he can, and we all know that it is possible.  Sometimes it takes remarkable effort.

“Any small distraction at all, even a cell phone ringing in my pocket would throw my brain back into the old control algorithm”. This highlights two things: the difficulty of the task, and the finite nature of attention.  When people stand still, they sway a little. This is the dynamic nature of balance. When people solve math problems while standing, the amount of sway increases. Imagine how fragile the control is when you are learning such a difficult task!


Science News: Missing link found between brain, immune system; major disease implications

So there is a lot of buzz about the recent discovery of lymphatic vessels that carry fluid away from the brain. There are a couple of reasonable questions: 1) Is this legit? 2) What does this really mean? See below for more details on my parsing of this study.

What is the journal?

Nature, cheap the gold standard of scientific journals.

What is the title of the original article?

Structural and functional features of central nervous system lymphatic vessels

Read the abstract here.

Who are the researchers?
What did they do?

The scientists investigated how T lymphocytes, a cell with immune functions, could pass through the membranes that cover the brain. Specifically, they used staining techniques to look for where the T lymphocytes were concentrated, since immune cells gather at the gateways into and out of tissues. They then tested the cells next to these areas of concentration to see what kind of tissue the vessels were made of. They used mice and humans. The brains of all mammals share many features, so it is completely reasonable to draw inferences from mouse brains to human brains, but there are some important differences as well, which is why while I enjoy peanut butter, I get bored after running on the wheel for only 3 minutes.  The human samples were taken from 9 cadavers.

What did they find?

There is a tough covering over the brain called the dura mater, with channels called dural sinuses between layers of the covering. The team found that the T lymphocytes seemed to be lined up along vessel-like structures. There are blood vessels in the sinuses, and when the researchers used a dye to show where the blood vessels were, they were surprised to find that the lymphocytes were next to an as-of-yet unknown vessel. Additional dye staining confirmed that the new vessels did not belong to the cardiovascular system. The structure of these vessels has some similarities with the rest of the lymphatic system, and some differences. They only found the lymphatic structures in 2 of the 9 humans.

Importance of the study:

We used to think that the brain was largely separated from the rest of the body immunologically. Considering the results of this study, it is possible that certain neurological disorders could be linked to dysfunction of these vessels. Specifically, diseases like multiple sclerosis and Alzheimer’s disease, which seem to be related to changes in immune function, may have mechanisms- and hopefully treatments- different from those we originally thought.

Why we should be cautious:

The fact that only two human brains out of nine showed the structures should make us think twice. Still, there is the possibility that in the cadavers the vessels had collapsed or that t-cell function might not be as robust in dead people.  Also, whole brains were used for the mice, and only samples of the dura mater were used for the humans, so those differences might change things too.

Grade on the reporting: C

The image of the location of the proposed vessels in humans that is widely being used is NOT from the study. There is in general too much speculation about what the study found, and not enough focus on the actual findings. There also needs to be more caution about these structures in humans.


That Persnickety Piriformis Muscle

So, I have been running a bit more than usual recently, kilometers creeping up to around 60 per week, and long runs of 20 each Saturday. I have also been stretching a little less, you know, the perils of everyday life.  I began feeling a dull, constant ache in my buttocks, which then started creeping down my leg. I recognized this in myself as being piriformis syndrome. All of this got me thinking about the piriformis muscle, and its relationship to the sciatic nerve, and I thought it would make a good topic for a post.

The piriformis (piriform  = pear-shaped) muscle is typically considered one of the 6 deep outward rotators of the hip, along with the obturator internus and externus, gemellus inferior and superior and the quadratus femoris. The piriformis, obturator internus and gemilli share a more or less common tendon on the greater trochanter, common innervation, and seem to work together under many circumstances, leading some researchers to call them the quadriceps coxae. (Standring et al, 2008). Of course, the big power rotator is gluteus maximus, but the deep rotators, like most deep muscles, are slow twitch or phasic muscles, and are therefore involved in most outward rotation.

When the femur is in anatomical neutral, the piriformis always acts as an external rotator. This is because the origin is on the anterior part of the sacrum, and the insertion is on the greater trochanter of the femur. The muscle runs posterior/medial/superior to anterior/lateral/inferior, and the angle of pull will draw the greater trochanter posteriorly relative to the femoral head, which results in outward or lateral rotation, and weak abduction. Fortunately for the sake of movement, but unfortunately for easy understanding, the femur can be flexed and extended, adducted and abducted, inwardly and outwardly rotated, allowing for many movement possibilities.

All any muscle really wants to do is get its two ends closer together. So when because of movement of the femur, the greater trochanter changes its relationship to the sacrum, the line of pull will change. In fact, at a certain point of hip flexion, piriformis switches from being an outward rotator to being an inward rotator. This is not just a minor weirdness or problem for biomechanics students, but has clinical significance, since many people wish to stretch the piriformis, and some of them suffer from a condition called piriformis syndrome. When the femur is moved to a certain point of flexion, the relationship of origin and insertion is changed: the direction becomes posterior/medial/inferior to anterior/lateral/superior. In this position the angle of pull will cause the greater trochanter to move more medially and superior, and combined with a fixed point of rotation in the socket, will result in inward rotation.

When I first started investigating this idea years ago, everybody seemed to be referencing The Physiology of Joints by I.A. Kapandji (1970) who argues the change occurs at around 60° of flexion. I am a little surprised at the generous citing of Kapandji, a source I suspect it somewhat like the bible, where everyone quotes it, but few have actually read it. Kapandji is certainly a venerable name in the pantheon of biomechanical demigods, but even the revised edition of “The Physiology of the Joints: Annotated Diagrams of the Mechanics of the Human Joints” only has citations as recent as 1974. Some of the information was derived from cadavers at a time when technology and tissue baths may have not allowed for full range of movement, so that may have reduced observed angles, but even so, there is no indication Kapandji did any primary research: he appears to be citing someone else, unnamed.

Furthermore, Travell and Simons (who say the role of piriformis changes at maximum flexion, or ~ 150°) and Kapandji (~60°) cannot both be correct. If we average the difference, we come up with the modern idea of about 90-110° (Delp, et al. 1999, Dostal et al. 1986, and Neumann, 2010). These measures were obtained with modern radiographic, ultrasound and kinesiological techniques, and in my experience, are more consistent with in vivo clinical assessment and anecdotal evidence. (These also appeared in peer reviewed journals, rather than monographs.)

A paper by Pressel and Lengsfeld (1997) using a computer model of the human body that indicates the change from external rotator to internal rotator occurs at 70 degrees of hip flexion. Still, I think the angle of piriformis is more likely to make it an abductor at 70 than an inward rotator unless there is significant neutralization by the adductors (but that’s just a guess based on observation of movement and clinical practice). As Neumann points out, this is very easy to prove with a skeleton and a piece of string.

A really interesting paper by Vaarbakken and others was published in 2014. In the study, they used cadavers to look at the length of the piriformis muscle under combined conditions of flexion/extension, abduction/adduction and inward/outward rotation. By doing this they could also determine peak ‘moment arms’ for the muscle, a measure of when the muscle could be expected to produce the greatest force given its length and angle.  They found two really important things. One, the piriformis is stretched the most when the femur is flexed to 105°, adducted by 10°, and outwardly rotated more than 25°. Two, the piriformis is actually disadvantaged in terms of power production when we are in anatomical neutral, but has its greatest moment arm as an extensor and abductor when the hip is flexed between 60-90°! In other words, friends, the piriformis’ main job is NOT as an outward rotator, but as a hip extensor and abductor when we are propelling ourselves from squats.  Obviously this idea would need to confirmed with EMG studies, but still my mind is cautiously blown!

The important idea however is that what happens when the hip is flexed more than 90° determines what stretches the muscle.  Normally, you just work out the opposite of a muscle’s function to determine its best stretch. So the gastrocnemius muscle plantar flexes the ankle and flexes the knee.  Do the opposite and stretch the muscle: in the case of gastroc, dorsiflex and extend the knee. In the case of piriformis, if we only think of its job in anatomical neutral, then inward rotation and adduction will stretch it.  But this is actually a poor stretch for the piriformis. A simple modification to improve this stretch is to slightly flex the knee. This position is similar to the F.A.I.R. (flexion, adduction, internal rotation) test for piriformis syndrome, which is hypothesized to actually trap the sciatic nerve in the notch (citation needed), and so this might not be the best stretch for the muscle, nor the safest test for piriformis syndrome.

Aside from being a biomechanical conundrum, the piriformis muscle also has a very important relationship with the sciatic nerve. The sciatic nerve is the largest single nerve in the body, made up of branches that emerge from the bottom two lumbar vertebrae and the front of the sacrum. The nerve is about the thickness of your thumb at this point, and it passes out through the sciatic notch or foramen, which is bounded above by the iliac bone and sacrum, and below by the piriformis muscle. Then, most typically the nerve will run under the piriformis and down the back of the thigh and leg, also being the longest nerve in the body. It receives sensory information about the skin, and provides motor commands to the outward rotators of the hip (but not piriformis or quadratus femoris), the hamstrings, and muscles of the lower leg and foot. At some point along its length, as early as immediately after emerging from the sacral plexus, and as late as the back of the knee, the sciatic nerve will divide into common fibular and tibialis branches.

This is one of the great “jazz” moments in the human body, where there is so much variation on a theme, you would think the forces of creation had just dreamt up Miles Davis and then started thinking about the piriformis/sciatic nerve relationship. In most instances, the nerve passes entirely behind the piriformis. In about 16% of cases, there is some kind of variation, with one both branches of the nerve passing in front, or through the muscle, or some combination one branch or the other passing in front, behind or through. (Roydon-Smoll, 2010).

If the sciatic nerve becomes damaged or compressed, it will cause intense pain, often seeming to originate in the buttocks and shooting down the back of the leg.  Pain that is caused by the sciatic nerve in this way is called sciatica, and frequently occurs because of compression of the nerves as it emerges from between the vertebrae, because of a dysfunction of the skeleton.

A different possible cause of sciatica is overuse, overtightness or inflammation of the piriformis muscle, which because of its close relation to the sciatic nerve will cause it to become compressed, a condition known as piriformis syndrome. The syndrome, like all syndromes, is a collection of related symptoms that usually stem from a common cause, and which symptoms emerge will vary from person to person. The symptoms can vary a great deal, but are basically the same as the symptoms of sciatica: nerve pain in the buttocks which radiates down the leg, often with numbness and loss of function.  It is always important to find the root cause of pain, and qualified professionals will use functional diagnostic tests or imaging to determine the cause.

Those who have sciatic nerve variations do not suffer from piriformis syndrome any more than other members of the population, however manual therapy may be more complicated for those individuals.  Stretching remains beneficial, however piriformis stretches with inward rotation, flexion and adduction may actually apply pressure to the sciatic nerve because they necessarily bring the piriformis closer to the sciatic notch. Therefore stretches with the femur in flexion above 90°, with outward rotation and adduction may be preferable in the case of piriformis syndrome, and some good stretches can be found in yoga.

What body part a yoga pose helps varies greatly from body to body, and even from one side of the body to the other, but for the reasons listed above thread the needle (the outwardly rotated leg) and pigeon pose (the front leg) tend to help the piriformis greatly. Here is an article by Natasha Rizopoulos describing these poses. Her description of the poses is excellent, but she doesn’t really discuss the piriformis anatomy here.  Another pose, the seated spinal twist may be too intense for some individuals with tight piriformis because it combines extremes in flexion, adduction and outward rotation.  Modifications here to lessen the stretch could be very helpful.

Information from suggests that manual therapists should avoid direct pressure to the piriformis (or to any muscle they suspect of entrapping the nerve), since that will reflexively compress the sciatic nerve running underneath. Instead, by applying pressure to the inferior border of the piriformis and bowing it superiorly to the client’s ipsilateral (same-sided) shoulder, you can apply an effective stretch that may be safer for the nerve. Slow stretches of long duration will be less likely to cause inflammation or a reflexive contraction of the muscle.

Additional points here are that piriformis syndrome is often accompanied by sacro-iliac joint dysfunction, or tight iliotibial band, or sciatica of the spine, or tight hip flexors  or all of the above, and it is important to understand these coincident problems. There is also biceps femoris syndrome, where one of the branches of the sciatic nerve is entrapped by the biceps femoris, but there is no reason why the piriformis or biceps femoris are the only possible causes of entrapment. In one instance, I had burning, ‘nerve-like’ pain running down the lateral side of my leg, just about where the common peroneal nerve passes under the distal attachment of the IT band. I applied a release technique to the IT band, and felt immediate relief, and I suspect it was yet another sub-species of sciatica. Again this is why it is important to connect with people who know more and to enlist their help.

For me, I have been applying a regimen of stretching, strengthening and self-massage, careful to apply appropriate pressure.  I have gotten a great deal of relief, but things still aren’t quite right. I think I need some help with my sacro-iliac joint, and will be seeking care from the doctors and practitioners who will help me to move further along the continuum to full health.

Those of you who are interested in piriformis syndrome should look here for a really good discussion of the topic by people who have thought about it much more deeply than I. is dedicated to the exploration, understanding, diagnosis and treatment of sciatica, and they provide many great resources.





Brains, Bodies and Faith

A friend of mine recently asked me a fascinating question on Facebook, and I asked if he wouldn’t mind sharing it here, since it touches on the topic of embodiment, and also considers the idea of belief. This question, and my answer, treads at the edge of what we can currently know and may make some science types uncomfortable. I have tried to keep the ‘sciency’ parts on the science side, and be clear where I am crossing the line.

Markus asks:
‘Does faith reside in the brain or the heart? As a neuroscientist, do you believe the brain to be a transducer or a generator? Perhaps both? As a man of faith, where does one determine mind to begin? These questions are sincere as I have experienced through meditation that I am not what I think, that I cannot determine where some perceptions originate and that sometimes I can perceive the thoughts or emotions of others without being physically near them. It leads me to suspect that consciousness, awareness reside beyond the cerebral organ itself. Spiritually, I feel connected to and informed by a source greater than the grey matter I am currently renting. Your thoughts?’

Tell me where is fancy bred.
Or in the heart or in the head?
How begot, how nourishèd?

It is engendered in the eyes,
With gazing fed, and fancy dies
In the cradle where it lies.

Let us all ring fancy’s knell
I’ll begin it.—Ding, dong, bell.
Merchant of Venice, Act 3, Scene 2

That was a little Shakespeare to address the same question but with respect to love. The singer in the Merchant of Venice concludes it is born in the eyes. While I can entertain the notions of faith and love from a poetic standpoint, and conceive various bodily origins as an artist, as a neuroscientist I can say that they are both born in the brain. However, I would be very quick to add they are born in processes that we normally ascribe to the heart. So I would say faith is born in the ‘heart’ of the brain: it is an affective process that emerges after we have, in the words of Bruxey Cavey, ‘run the ramp of reason’.

The brain is certainly both transducer and generator. If we begin with a simple percept, like sound, the sensory apparatus of the body is stimulated by fluctuations of energy in a particular frequency range. Those vibrations are passed by neurons to specialized portions of the brain that decode and categorize the information. Interestingly, the ear itself makes sound like a noise cancelling headphone (evoked otoacoustic emissions), so that anticipated frequencies are enhanced, and unanticipated frequencies are filtered. Those emissions are generated by the brain, so that the ear is not just a passive device. In this way, the brain is clearly also a generator. Ultimately, the brain takes the percept of sound, and the person hearing chooses a response, based on current and remembered conditions: is the sound alarming or pleasant? rhythmic, melodic or both? does it have meaning to us? do we have a previous association with it? All of these things factor into our response to the sound, which requires our ongoing participation in an environmental context, or ground, through the activity of our bodies.

 The ‘beginning’ of the mind of the mind is an interesting concept. It presupposes that the body ends somewhere, and that the mind is ‘located’ in a different place. (Here, I take my lead in my thinking from Antonio Damasio, Kevin O’Regan and Mark Johnson, who are eminent neuroscientist, perceptual scientist and philosopher, respectively, but there are numerous other authors on the topic of embodied cognition.) A brain is a collection of specialized cells called neurons that can only function in a living body in an environment. Brain cells are like any other cell: they require homeostasis, that is they need the Goldilocks conditions of neither too hot, nor too cold, nor too acid, nor to alkaline… it needs to be ‘just right’. Brain cells metabolize, they use proteins to record and pass along information. They can also simulate previous experiences, allowing us to predict, remember, dream, create and imagine. A ‘thought’ is not a place in a brain, or out of it, or a thing we can touch. It is the organized activity of millions of neurons over time. Likewise, a ‘mind’ is not a thing. It is a process of millions of thoughts, both remembered and in real time. Trying to point to a ‘mind’ is like trying to point to cellular metabolism: you can witness its effect, and you can see that it is present, but you can’t touch it. To use a metaphor, we can see the evidence, effect and impact of love, but love is a process rather than a thing. As a completely different metaphor, you can see the evidence of the process of baking on a muffin, but you can’t touch baking. To quote Damasio, ‘body and mind are different aspects of specific biological processes’.
Overall, I reject the thinking of both Descartes and Plato, and do not believe that mind is distinct or separate from the body. I do not see the support for such an idea philosophically, theologically, phenomenologically or physiologically. I also think that such a division is incredibly problematic. The famous educator and philosopher John Dewey notes, ‘The very problem of mind and body suggests division; I do not know of anything so disastrously affected by the habit of division as this particular theme. In its discussion are reflected the splitting off from each other of religion, morals and science; the divorce of philosophy from science and of both from the arts of conduct. The evils which we suffer in education, in religion, in the materialism of business and the aloofness of ‘intellectuals’ from life, in the whole separation of knowledge and practice — all testify to the necessity of seeing mind-body as an integral whole.’ Of course, I do not think an integrated mind-body is simply a matter of a point of view, I think it is a tacit physical fact.
Your comment about sensing the thoughts or emotions of others from afar is interesting. I can offer no plausible scientific explanation, although that doesn’t mean there isn’t one. The closest I can come is this: We can measure the organized electrical activity of the brain. We do this using an electroencephalogram (EEG). In some instances, we can discern whether the person observed is in a restful state, if they are learning, if they are an expert, if they are tired or agitated, or any number of things. We can also influence the electrical activity of the brain using a technique called transcranial magnetic stimulation (TMS). We can stop a person’s hand from moving, or cause them to not be able to hear things, or temporarily forget, or to learn more quickly. In short, our brains give off electrical signals and are influenced and changed by electrical signals (which is why I will never wear a Bluetooth headset). What has never been scientifically proven, but is conceivable in my view, is that the electrical activity of one brain may be able to influence the electrical activity of another brain. What is the effective distance? I have no idea. But groups and cultures carry ideas and thinking as surely as do electromagnetic waves, so who knows how sentiments and ideas may travel? This is purely speculative, and I have no proof at all, and no real idea.
You spoke of your connection and information by a source greater than yourself.  In this respect, we are certainly thinkers within a cultural and social context, and without question, the thinking and behaviour of others will influence our own thinking and behaviour. There is considerable evidence to suggest that the grey matter you ‘rent’ is also inhabited by the thoughts, opinions, attitudes and ideas of others, both remembered and in real time. And now I will completely step away from my role as a scientist, and talk about things that cannot currently be proven using direct observational methods.  There is always the possibility that there may be things outside of us that are bigger than we are and which change and influence us: things that some people call God or cosmic energy or long-distance soul calls from loved ones. How do we know to call someone on the other side of the world at the exact moment they were thinking of us? Those things may have mundane everyday explanations that we have not yet understood or been able to quantify. Those things may have mystical explanations which may elude scientific investigation for a very long time. One the other hand, there may be a very clear scientific explanation that intersects with mystery in the same way that Brownian motion in boiling water intersects with the mystery of the glory of tea.  I like the words of the thoughtful Christian theologian N.T. Wright in his very thoughtful post on mind/body dualism, ‘God is always at work in the world, and God is always at work in, and addressing, human beings, not only through one faculty such as the soul or spirit but through every fibre of our beings, not least our bodies. That is why I am not afraid that one day the neuroscientists might come up with a complete account of exactly which neurons fire under which circumstances, including that might indicate the person as responding to God and his love in worship, prayer and adoration.’

Phones, Pockets and Pain

This post is in response to a question from Rich:
What are your thoughts on the effects of cellphones on our bodies? I’ve been having issues with my right hip flexor for a year. It obviously gets better when I do my stretching and exercises, but I wondered if the fact that I keep my iPhone in my right front pocket might play a role, since the discomfort emanates from the same place that my phone sits in my pocket. Have you read anything that has influenced where you keep your phone?
(I’m not talking about the structure of the phone causing discomfort. I’m wondering about the electronics within the phone…). The pain is a tension that runs up my IT band and then makes a right angle turn across the front of my quad at the place where my pants crease when I sit. Then occasional dull aching in that area. If I had my phone in my pocket, it would press on that area when I sit. (I take my phone out before I sit, btw.)
Hi Rich:

Thanks for writing. I will confess right away that I had to do more than my regular amount of sleuthing to get at this question which is interesting for a couple of reasons: one of them being that almost immediately after I received your question, a massage client asked a question about a nearly identical pain, but did not mention where he carried his phone, although he had a very tight iliacus and psoas muscles. I will come back to that in a bit. Another thing that is interesting about your question is the nature of pain. Pain has many possible inter-related causes, and is a complex affair, related to some kind of stimulus that is damaging or has the potential to damage tissues, but also related to perception, mood and many other factors which I will not really deal with in this post. Additionally, pain in one part of the body might be caused by a problem in another part of the body altogether, and this is known as referred pain. Your question asks in essence, might it be the electronics of the phone causing the pain and not the phone’s physical size and presence? I think this is a pretty reasonable question. In all instances, I should say before I get down to brass tacks, if pain is persistent, consult your medical professionals.

The easiest way to find out the answer to your question would be to take a 1200 people, stick working cell phones in the pockets of 400, just the active electronic bits in the pockets of 400, and disabled cellphones in the pockets of the remaining 400. Then have half of each of those groups put the stuff in their left pocket, and half put the stuff in their right pockets and find out who complains after a year and what side. It might be tough to get ethics approval because we aren’t really allowed to intentionally put people at risk. No one has yet done this study, so we will have to go with the existing research to see if we can figure out an answer.

The pain you describe corresponds with the location and sensations related to the lateral femoral cutaneous nerve (LFCN). The LFCN emerges from your spinal column around the level of the second and third lumbar vertebrae, dives between the quadratus lumborum and the psoas muscle, goes behind your guts, down across the front of the iliacus muscle (which lines the inside of your iliac bone), but underneath the sheath of fascia that covers that muscle. It then goes underneath the anterior superior iliac spine to emerge from under your inguinal ligament, over top of, or sometimes even through your sartorius muscle, and then under the fascia latae of the thigh. The take home message, is that the LFCN does a lot of weaving under and over stuff. The image below from Gray’s Anatomy shows where the LFCN emerges from under the inguinal ligament, which I will talk about more below. When your cell phone is in your front pocket, it is probably pretty close to the LFCN.

Looking up the right side of the pelvis from underneath. The lateral cutaneous femoral nerve is the small yellow structure on the left, just above the iliacus muscle. The big round structure is the socket of the hip joint (Gray’s Anatomy).

Part of the problem of answering your question is that cell phones are really too new and too rapidly changing in terms of size, shape and internal components to get a consistent read on what problems they might cause from either a mechanical or electronic standpoint. Cell phones only became pocket-sized in the mid-90s, and since 2002, smart-phone use has climbed from just over 50% to 90% of American adults owning one ( This all means we don’t have a long list of case-studies to draw information from. What we do know radiation-wise is that while a cell phone is in your pocket in the on position, it will ‘ping’ nearby towers intermittently to let the network know where it is so that it can receive incoming calls. This will generate tiny amounts of radiation in the radio frequency. Talking on the phone itself generates a greater amount of radio frequency radiation as would happen if you used either a wired or bluetooth headset with the phone in your pocket. What we need to know about for your question is if the cell phone’s radio frequency could produce damage to nerves that could induce the perception of pain.

Radio frequency radiation might potentially cause damage to nerve cells due to heat, or by the disruptive effects of the radiation itself. Because we typically use cell phones next to the brain, which is a big, sensitive group of neurons, most studies with cell phone radiation focus on that structure. Quite a number of experiments have been done with cell phone frequency radiation and rodents. The results are variable, with some studies showing damage to the DNA of nervous tissue (Diem, Schwartz, Adlkofer, Jahn & Rudiger, 2005), and other studies saying there is no damage (Utteridge, Gebski, Finnie, Vernon-Roberts, & Kuchel, 2002). (Of course the real problem with cell phone use in mice is the roaming fees.) In humans some studies show a link with increased brain cancer risk in long-term cell phone use (Khurana, Teo, Kundi, Hardell & Carlberg, 2009), but other studies do not show this link (Lajavaara, Schuz & Swerdlow, 2011). There have only been a few studies on cell phone radiation and thinking, but nothing conclusive. More to the point, there is no direct evidence at this moment that placing a phone next to your brain changes the way you perceive pain, and besides, your question is about putting the phone in your pocket.

Radiation can certainly cause damage to peripheral nerves (nerves outside the brain and spinal cord) resulting in pain. Such damage is found at times in cancer patients who receive radiotherapy to treat the cancer (Stoll & Andrews, 1966). However the type of radiation for cancer treatment is typically x-rays, gamma rays or some form of particle radiation, which is at a much, much higher energy than radio frequency, and the focus is remarkably tight and concentrated. In comparison, placing a phone in your pocket would produce very small amounts of radiation, would be diffuse, and would differ from day to day because of differences in the placement of your phone and your clothing.

So in the end it is possible that a cell phone’s radiation could cause the pain you describe, but I think it is unlikely. Which brings me back to my client. After I got your question, I called him to ask about where he carries his cell phone – same or opposite side of the pain. Turns out, he doesn’t carry it in his pocket at all. Which made me wonder if something else was going on.

There is literature about a condition causing a very similar pain to yours (and the pain of my client). It is called meralgia paresthetica, which pretty much means ‘thigh pain felt in a weird place’.  Meralgia paresthetica is a painful, burning, muscle aching or sometimes even numb feeling on the outside of the thigh, or along its crease, caused by a compression or entrapment of the LFCN. As mentioned before, the LFCN emerges from under the inguinal ligament which runs from the Anterior Superior Iliac Spine of each side of your pelvis, down to the pubic bone. Its big job is to keep your nerves and muscles and other leg bits from blobbing out all over the place. The inguinal ligament is what causes the appearance of the ‘fold’ at the top of your thigh (exactly where your pants crease), showing the division between your torso and your leg. Sometimes through sudden weight gain, or swelling to the tissue behind the inguinal ligament things get pressed up against it, causing a pinching or discomfort. My client, for example, had very well-developed hip flexors, particularly the iliacus and psoas muscles which were also very tight. In fact, in some people you can induce a ‘pinching’ sensation at the inguinal ligament by bringing the hip into extreme flexion, since the tissues behind are being pulled up against the ligament. In my clients with such pinching (and in myself as well), I can alleviate the pinching in extreme flexion by thoroughly stretching the hip flexors.

While the LFCN could be compressed anywhere along its length, the most common location of entrapment is where it exits the pelvis (Grossman, Ducey, Nadler & Levy, 2001). The inguinal ligament is so prominent in anatomical causes for the condition that some surgeons have developed a method of relieving meralgia paresthetica by surgically loosening the ligament (Alderich & van den Heever, 1989). And that brings us back to the phone in your pocket, which led me to think of the article ‘Meralgia Paresthetica from a Wallet’ (Orton, 1984) in the Journal of the American Medical Association. In the abstract Orton says ‘I noticed an aching, burning sensation along the left anterolateral thigh on the side of the wallet. It also was worse while driving any distance.’  The condition has also been induced by tight pants (Boyce, 1984). Depending on the way the nerve is situated, it is conceivable that the condition could be induced by any pressure along the inguinal ligament, either from pressure directed inward from the outside by clothing, wallets or phones, or from pressure directed outward from the inside, by weight gain, pregnancy or big, tight, developed iliacus muscles.

There are completely different possible causes for your pain that have nothing at all to do with rectangles or electronics in your pockets (What has it got in its pocketses?) or even with meralgia paresthetica, so I am not saying you have cellphone-induced meralgia paresthetica (because I am not the right kind of doctor to make a diagnosis), but from all evidence it seems much more likely than a nerve problem caused by radiation. And this might be true even though you remove the phone when you sit, since any irritation  at all to the LFCN could be sufficient to cause the pain.

The best thing to do in either case is to take your phone out of your front pocket, which will prolong the life of your phone and get its electronic and mechanical influence, if any away from your body. Time will tell what kind of effects these devices have, and it won’t hurt to show a little caution. Also continue to stretch your hip flexors using postures like the yoga low lunge. Even if the cause is completely different, we spend so much time sitting that such a stretch will have benefits that are well worth your time, especially after a long drive.


Doctor Blake