The Vancouver Half, a victorious defeat

When life gives you lemons … suck it up. Isn’t that how the saying goes? Well, at the Scotiabank Vancouver Half Marathon last weekend – my second barefoot half – I sucked it up and it was sour.

The saga began a few weeks prior, when I was spontaneously struck with debilitating chest pain. It gripped me intensely, leaving me barely able to breath and fearing a heart attack. An X-ray showed a healthy heart, lungs and ribcage, yet the pain persisted for weeks. Massage, active release and chiropractic adjustments brought some temporary relief, and although I’ll never know for sure, I now suspect it was a strained pec or intercostal muscle. Many days, running was impossible. On good days I could eke out a short, slow, uncomfortable trot. To make matters worse, the stress and tension in my chest and back trickled down to knock the rest of my body out of wack. My opposite leg felt weak and limp, as if it were dragging powerless behind me … as if it belonged to someone else, completely out of my neuromuscular control. As race day neared, I began to abandon my hopes of running at all, mentally preparing for a restful vacation exploring a new city.

Come race morning, I convinced myself anything was possible and knew I would regret not at least trying. The gun went off and to my great surprise, my chest quickly loosened up and my breathing was fluid. My right leg, on the other hand, forgot how to move. For the first seven miles, it took every ounce of mental focus to coerce my muscles into lifting and propelling forward my dead leg. The sun blazed as the pack of runners hugged every smidgen of shade to escape the 80 degree heat. My battle to maintain a semblance of a functional stride intensified as I pranced precariously over nasty stretches of gravel. Eight miles in, a tiny stone sent a zinger through my toe and I pulled to the side for several minutes waiting for the ache to subside. I fought the discouraged voices rationalizing an early finish and pushed ahead. The toe pain gradually dissipated and I even enjoyed a brief surge of strength and fluidity.

But by that point, it was too late and the damage from my wonky gait coupled with the hot, rough and canted roads, had been done. My right heel began to burn and I felt an escalating squish as my bare foot struck the pavement with each step. I refused to inspect my foot and acknowledge that a monstrous blood blister had developed, with four miles still remaining. I refused to focus on the distance ahead, allowing myself to think only of the present moment. “Just take one more step. One step is nothing. Then, just take one more.” I convinced myself that the pain was illusory – that it only existed if I gave it life – and somehow, this denial empowered me through, single squishy step by squishy step. As I sprinted to the finish, a huge smile was plastered on my face and a flood of endorphins masked the havoc I had wreaked on my body. And just like Cinderella at midnight, as I crossed the finish line and broke that invisible endorphin wall, my ecstatic sprint transformed into an awkward hobble over to the medical tent.

VacnouverHalf

As I saw my finish time, I was surprisingly unfazed by learning I had raced my slowest half ever. Those 13.1 miles were more painful than any I had raced before, but they hurt far less than a DNF or worse – a DNS. Despite the physical pain and frustration, I genuinely enjoyed almost every moment. There is a reason runners return again and again to race, through heat, injury and fatigue … the energy of the running community, the intoxication of the journey, and the discoveries along the way entice us back as addictive rewards.

Several years ago this race would have devastated me. Indeed, by dwelling on insignificant matters of time and speed, racing can destroy a runner and quench the very passion that fuels us to run. But by embracing each experience as a novel opportunity for growth and self-discovery, we can only evolve into better runners – and better human beings. For me, the aggregate challenges of my years of running have reinforced one invaluable lesson. We runners are so much stronger, and our bodies capable of so much more, than we’re aware. Our power is only bounded by the limits of our mind and the integrity of our spirit. To paraphrase a particularly accomplished marathoner, my fastest days may be behind me, but my best running days lay ahead.

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Barefoot Running Workshop 2: Lower and Upper Biomechanics

In the first of our Barefoot Running Workshops, we explored facts and fiction of barefoot running, sensory awareness and mechanics of the foot. In our second workshop today, we introduced basic running kinematics before moving north from the foot to cover mechanics of the lower and upper body. Here’s a recap of the workshop highlights for those who missed it.

RUNNING KINEMATICS

Before diving into the nitty-gritty of leg, hip and torso function, it’s essential to understand how one gets from zero to running in the first place. Running has been described in a multitude of ways, from a controlled fall to alternating one-legged hops to a springy, aerial variant of walking. Given this confusing jumble of terminology, what then are the essential movements that convert a stationary body to a running body? The basic motion is far simpler than most runners would imagine. There’s no jumping, bouncing or flying required! In essence, running is nothing more than marching while moving forward.

March. Simply pick up the feet, the ankle gliding parallel to the shin up to the knee. Return the foot to its starting position and repeat with the other leg. That’s it. The 100-ups are a great exercise to reinforce this motor pattern.

Lean. Once you’ve mastered marching in place, it’s time to transform this into forward motion. This too is simpler than it sounds. To move forward, the body must lean forward. This lean should NOT come from bending at the waist; “sitting” or folding forward will cause a host of problems from the back to the hips to the knees. Instead, the lean should originate at the ankles, the entire body leaning angled together along the same plane. By simply adopting a slight lean from the ankles, you will fall forward and be propelled from stationary marching into forward travel. March, lean, and BAM … you’re magically running!

BIOMECHANICS II: LOWER BODY 

Lift the legs. A constant upward motion should be maintained throughout the gait cycle. This is especially important after striking, when the legs should immediately lift up. The feet should land directly under the hips, neither reaching forward nor crossing over the midline. Both overstriding and a cross-over gait can lead to various injuries. The Gait Guys offer an excellent series of videos on correcting a cross-over gait (part 1, 2 and 3).

Bend the knees. To facilitate a smooth ride, bend and relax the knees. The knees can serve as shock absorbers when allowed to flex, so the greater the bend, the less impact will be sustained upon landing. This is especially helpful when running downhill.

Stable hips. The shin bone’s connected to the thigh bone … the thigh bone’s connected to the hip bone … Yes, it’s all connected, and these chains are particularly notable in the context of how the legs move in response to the hips. The hips are indeed the powerhouse and main driver of a strong running stride. Strong, stable hips are essential, and muscular imbalances or poor hip mechanics are the source of many leg and foot injuries. Don’t let the hips sink or drop, but keep them level on the horizontal plane. The hips serve as the body’s steering wheel, so be sure to keep them facing forward and aligned with the shoulders.

BIOMECHANICS III: UPPER BODY

Core rotation. Some rotation is key to balancing the body’s left-right movements, but excessive rotation, or from the wrong place, can be problematic. Most of the rotation should originate in the core. Imagine the pelvis as a chandelier, the torso as its suspension cable and your head as the ceiling. The pelvis should dangle, relaxed, and rotate freely from the waist, supported by the strength of the strong, elongated core. As the right legs swings back, the right pelvis rotates back. It’s not forced or pulled, but swings naturally, allowing greater leg extension without over-stressing the hips. (The chandelier example was adapted from this excellent article.)

Shoulders and arms. Keep the shoulders low and relaxed, but don’t slouch. Some shoulder motion is fine, but be careful not to dip them or overly rotate the chest. After the hips, the shoulders serve as a second steering wheel, so they should remain stable and facing forward. Keep the arms close to your sides, elbows at a 90 degree angle and swinging forward and backward rather than across the chest. The rhythm of your arms directly affects hip and leg motion; a rapid arm punp can encourage faster leg turnover, and fluid forward-backward swinging will minimize inefficient lateral movements.

Head and posture. Your head leads and guides its body below. Keep your head up and neck stretched tall and long. Unlike owls, humans are blessed with eyes that move independently from the head, so you can still look at the ground without titling the head down. The entire body – from the ankles up to the tip of the head – should form a strong, continuous line, without kinks from poor posture or bending at the waist. Imagine being lifted upwards, suspended by a bird or plane (or pick your favorite flying power-creature) directly above your head.

PUTTING IT ALL TOGETHER

Now it’s time to integrate these elements into your perfect running form! This video from the Natural Running Center is a beautiful example of a strong, efficient stride. Revisit this video and try to mimic Mark’s fluid, light motion whenever you need a refresher.

The final key to optimizing your stride is forgetting everything you just read and just run. Yes, I am (mostly) serious. Sometimes less can be more in terms of tapping into your optimal gait. Running is one of the most natural movements for humans, and a strong, healthy body will readily fall into it’s own unique running stride. Obsessing about every component of your form will not only take the joy out of running, but can also backfire, inducing unnecessary tension or forced, inefficient motor patterns. If you find this occurring while tweaking your running mechanics, abandon the effort and simply allow your body move fluidly and aimlessly. You might find that your muscles were one step ahead of your mind, and knew the route to efficient running all along.

Join us for the final session of our Barefoot Running Workshop series Sunday, July 12 at 3 pm. As usual, we’ll meet at the Founder’s Statue at the northwest corner of Balboa and El Prado in Balboa Park. In this final session, we’ll wrap up with how best to run hills and do speed work, as well as safety and practical considerations of running barefoot. More details and RSVP here.

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Task Shifting may Shift our Understanding of the Default Network

Originally published on the PLOS Neuroscience Community

Over the past two decades, one of the most impactful discoveries to come from the surge in functional MRI (fMRI) research has been the existence of the brain’s “default network”. Countless studies have found that that this system, mainly comprising medial frontal, parietal and temporal, and lateral parietal regions, is most active during rest or passive tasks such as mind-wanderingimagining or self-reflection. A new study, recently published in eLife by Ben Crittenden, Daniel Mitchell and John Duncan, presents a striking finding that may flip our understanding of the role of the default network on its head.

Task-switching: the common thread?

Many of the experiments evoking default network activity compare relatively unconstrained states conducive to rest or mind-wandering against rigid task conditions with targeted cognitive demands. Thus, while these studies contrast active and passive conditions, they also incidentally contrast states of sustained attentional focus with unrestricted, dynamically changing mental landscapes. Crittenden and colleagues argue that these shifting cognitive contexts may be the common thread to default network activity and thus explain its promiscuous involvement across such heterogeneous conditions. First author Crittenden explains how their seemingly radical diversion from classic theories came about through a serendipitous pilot experiment: “I developed an initial version of the current experiment to test the idea of which regions may be involved in orchestrating large switches, and the default network came out as really strong at the individual subject level. If these results held out we could be onto something quite interesting. We tweaked the task a bit and fortunately it followed the pilot data really nicely!”

To test their new hypothesis, the researchers conducted fMRI while participants performed three levels of task switching–make a major cognitive switch, a minor switch or no switch. For example, if they were previously asked whether two geometric figures were the same shape, a minor change would be determining if two figures were the same height, whereas a major change would be determining if a dolphin is living or non-living. The minor-switch condition is similar in cognitive load to other tasks that have not shown reliable default network activation. If context changes are driving the default network, then radical task switches should more effectively engage it.

Task conditions. A switch from the red-box to the blue-box tasks would be a minor switch, whereas a switch from the red-box to the green-box task would be a major switch. Adapted from Crittenden et al., 2015

Task conditions. A switch from the red-box to the blue-box tasks would be a minor switch, whereas a switch from the red-box to the green-box task would be a major switch. Adapted from Crittenden et al., 2015

Major task switches recruit the default network

Past studies have found that the default network does not function as a whole, but roughly dissociates into three subnetworks – “core,” medial temporal lobe (MTL) and dorsomedial prefrontal cortex (DMPFC) networks. Suspecting that these subnetworks are not equally involved in switching, they analyzed each subnetwork separately.

Compared to repeating the same task, major task switches activated the core and MTL networks. Small task switches did not activate any of the subnetworks. Using multivoxel pattern analysis, they further showed that the pattern of activity (versus the overall activation level) in all three subnetworks distinguished between the highly dissimilar tasks, but only the DMPFC network discriminated similar tasks. Thus, although both the overall magnitude and pattern of activity signaled contextual shifts, Crittenden raises some caution over interpreting the source of the pattern discrimination. “I imagine that a considerable amount of the classification accuracy between dissimilar tasks will be driven by lower-level visual features. However, it is still interesting that the default network is reliably representing this task information, which given the usual definition of the default network as task-negative, one may not have predicted.”

Activity for regions of the core (yellow), MTL (green) and DMPFC (blue) subnetworks for major (light colors) and minor (dark colors) task switches. Major switches activate many regions of the core and MTL subnetworks. Adapted from Crittenden et al., 2015

Activity for regions of the core (yellow), MTL (green) and DMPFC (blue) subnetworks for major (light colors) and minor (dark colors) task switches. Major switches activate many regions of the core and MTL subnetworks. Adapted from Crittenden et al., 2015

A shifting theory

If this finding is replicated, it could be the beginning of a major shift in our understanding of default network function. In contrast to the wealth of prior studies implicating the default network as “task-negative” – shutting down during demanding task conditions – here the default network was maximally engaged during dramatic contextual changes. These large task switches were objectively more challenging (participants responded more slowly) than the small-switch or no-switch conditions, in striking opposition to the notion that task difficulty suppresses the network. This implies that cognitive control or effort aren’t the key factors modulating these regions, but rather changing contextual states.

But does this model fit with the other mental states that reliability recruit the default network? Although it’s not yet clear what aspects of task shifting drive the observed response, the authors convincingly argue that indeed, many common default network activations can be accounted for by changes in cognitive context. At rest, during mind-wandering, imagining or reflecting on one’s past experiences, the mind is relatively free to jump between cognitive states. This contrasts with the constrained task conditions used in most fMRI studies that typically deactivate the default network. This relative cognitive liberty may give rise to radical mental shifts, for example, from thinking about the loud banging of the MRI scanner to planning your afternoon errands. Whether these spontaneous contextual changes are frequent enough to ramp up default network activity as observed remains to seen. Alternatively, the key factor may not be adoption of a new task, but the attentional release to do so. When switching from one task to another, the brain must let go of its attention to the first task before focusing on the next. In passive cognitive states, attention is relaxed, liberating the mind to focus on various tasks at will.

Until their findings are replicated and expanded, Crittenden explains that these possibilities are yet speculation. “I think that switches could be a contributing factor to the signal, however, by its nature the signal that we are envisioning is likely to be quite transient. More sustained activation such as during reminiscing/prospection/navigation etc. is likely to be a strong driver of default network activity. As we all like to say – more experiments are needed!”

Any views expressed are those of the author, and do not necessarily reflect those of PLOS.

References

Addis DR, Wong AT and Schacter DL (2007). Remembering the past and imagining the future: common and distinct neural substrates during event construction and elaboration. Neuropsychologia. 45(7):1363-77. doi: 10.1016/j.neuropsychologia.2006.10.016

Buckner RL (2012). The serendipitous discovery of the brain’s default network. Neuroimage. 62(2):1137-45. doi: 10.1016/j.neuroimage.2011.10.035

Crittenden BM, Mitchell DJ and Duncan J (2015). Recruitment of the default mode network during a demanding act of executive control. eLife. 4:e06481. doi: 10.7554/eLife.06481.001

Mason MF et al. (2007). Wandering Minds: The Default Network and Stimulus-Independent Thought. Science. 315(5810):393-5. doi: 10.1126/science.1131295

Gusnard DA, Akbudak E, Shulman GL and Raichle ME (2001). Medial prefrontal cortex and self-referential mental activity: Relation to a default mode of brain function. PNAS. 98(7):4259-64. doi: 10.1073/pnas.071043098

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A sitting injury in disguise

Six months ago I wrote in jubilation that I had finally overcome my 17-year long struggle with high-hamstring tendinopathy. What first emerged as a nagging high school running injury has since haunted me with its frustratingly sporadic flare-ups. It seemed to rear its ugly head at random, with no clear relation to any aspect of my training – not distance, speed or hills. It must be my form, I reasoned. Since rehabbing with PRP, I’ve devoted these past several months to optimizing my running mechanics to prevent another resurgence of the dreaded hamstring pain. And these efforts have been paying off, as I’ve felt stronger and more fluid in my running than perhaps ever before. I considered myself officially victorious over this decades-long injury.

That is, until one week ago … one week ago, on a rest day (i.e., no running) at the end of an easy, low-mileage recovery week. After some light morning yoga and a day spent sitting at lab, I began to feel an achy spasm and cramping in my hamstring – an all-too familiar sensation that literally appeared out of nowhere on my drive home. The pain escalated over the subsequent hours and I was soon in the throes of my worst hamstring flare-up in a year. Tension and pain radiated from my neck down through the back of my knee and I fantasized about a chiropractic adjustment of my misaligned back and pelvis. I struggled through each run this week, but rest was not an option. In fact, the greatest pain was at rest; sitting, and especially driving, were torturous and even sleeping was a challenge. A week later, I’m finally seeing some light at the end of the tunnel, thanks to some aggressive ART, Graston and dry needling. While encouraging, this does not answer what caused the flare-up in the first place. I had done nothing obvious to exacerbate it, and had even been cautiously respecting my recovery week.

04The answer, I’m now convinced, lay in a tiny skin irritation at the ischial tuberosity where the hamstring tendon attaches to the sit bones – the exact spot where I felt the most intense pain. The spot appeared coincidentally – or so I thought – around the same time the hamstring pain first set in. The “coincidence” didn’t faze me until a week later, and I finally began putting two and two together. The irritation was at the epicenter of my pain, which escalated to unbearable when sitting. Incidentally, there have been only two periods of my life when I’ve enjoyed extended relief from the injury: First, during a six-month trip around the world, during which my days were spent walking, hiking and exploring. Second, another six-month period while briefly working in a lab that required me to be on my feet at length. A clear pattern began to emerge. Freedom from desk-work and sitting correlated with symptom relief, whereas excessive sitting (with a sore on my tush as proof) correlated with spontaneous hamstring flare-ups.

Could my running injury have been a sitting injury all along? Perhaps this is wishful thinking. Perhaps there remains a running training error at the heart of the issue that I have yet to discover. But until then, I’m confidently adding hamstring trauma to the growing list of reasons sitting is hazardous to our health and a threat to the sanity of a running addict.

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Barefoot Running Workshop 1: Myths, Sensations, Foot-strike

Thanks to the awesome crew who attended my first Barefoot Running Workshop, lessons were learned and loads of barefoot fun was had! We dispelled myths, explored the pleasantness of soft pine needles and the not-so-pleasantness of hot, rough pavement, and most importantly, left with happy, dirty feet.

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As a recap for attendees or those interested in future workshops, below is an overview of the highlights from our first session. In this introductory meeting, we covered: 1) the facts and fiction of barefoot running, 2) the importance of sensory feedback and awareness, and 3) mechanics of the foot (don’t fret … we’re not foot-centric and will address mechanics above the foot in the next workshop).

BAREFOOT RUNNING: FACT & FICTION

MYTH 1. Barefoot running will cure my injuries.

Fact: Injuries are often the result of training errors, such as overtraining or incorrect form. Taking off your shoes can’t compensate for these mistakes, but the increased awareness and sensations from being barefoot can help you better listen to your body and train smarter.

MYTH 2: Barefoot running causes foot fractures, Achilles tears and calf strains.

Fact: Running carries a risk of injury, regardless of what is or is not on your feet. There are certainly reports of sustaining such injuries when running barefoot, but these are almost always due to transitioning too aggressively, or doing too much too soon (see also here and here). A gradual, conservative transition while respecting your body’s warning signs will let you run safely and injury-free.

MYTH 3: Barefoot running is just another fad and a gimmick.

Fact: Barefoot running is as old as man, and was how humans first began running. Conventional running shoes are only a very recent invention (introduced only in the 1970’s with the advent of recreational jogging). Despite misleading marketing, the cushioned soles and raised heels of typical running shoes have never been shown to improve running or prevent injury (See Pete Larson’s great book for more on the science of running shoes).

MYTH 4: I will cut my feet on glass, step on rocks or catch a disease.

Fact: Sure, these are possibilities, but the ground is much less dangerous than the fear-mongerers will have you believe! Most of the earth is not, in fact, littered with broken glass and dirty needles. You will quickly learn to automatically pay attention to your surroundings to easily avoid such dangers. Your feet will also become more resilient against lesser dangers like stones, twigs or gravel.

MYTH 5: I need to build up calluses to toughen up my feet for barefoot running.

Fact: Calluses results from excess friction and are a sign of poor form. If you develop calluses or blisters, you are likely shearing, shuffling or pounding excessively. Over time your skin will become thicker and more resilient, but should not be rough or callused.

MYTH 6: Barefoot running will make me a faster or more efficient runner.

Fact: While barefoot running will change how you run and is unlikely to impair it, there is conflicting evidence as to whether it will improve or not affect your running economy. When first learning to run barefoot, the body will naturally demand a slower pace and reduced mileage. But as the body adapts over time, runners will gradually return to their earlier performance level. One’s response to going bare depends on many factors, including training history, running conditions and distance.

MYTH 7: You cannot run competitively or quickly barefoot.

Fact: There have many exceptional competitive barefoot runners throughout history, including Abebe Bikala (winner of the 1960 Olympic marathon in Rome) and the 1980’s Olympian Zola Budd.

MYTH 8: It’s best to run barefoot on the grass or sand.

Fact: If you’re looking for a bit of fun, go ahead and frolic barefoot through a grassy park or along the beach. But if your aim is to learn proper running form, stick to firm ground. Soft surfaces – just like cushioned shoes – can encourage lazy technique, particularly heel striking and heavy landing, and may even be more stressful to the body. Firm, even surfaces will provide the best feedback and sensations to train your neuromuscular system to run well.

MYTH 9: I can get the same benefits from minimalist shoes, without the risks of going barefoot.

Fact: Running in footwear – yes, even the most minimal shoe – will change how your run. Zero drop and thin-soled shoes carry certain advantages over conventional shoes, but a key benefit of being barefoot is the rich sensory feedback from your skin. You cannot experience these benefits with rubber between your foot and the earth.

MYTH 10: I can’t run barefoot because I’m flat-footed, overweight, too old, etc …

Fact: Anyone can run barefoot, regardless of age, shape or size. Running barefoot naturally encourages you to run lighter, easing the impact on your joints and tissues. Weak feet result from disuse, and will quickly become stronger with foot exercises and barefoot activities.

SENSATIONS

Enhanced sensory input lies at the heart of the many benefits of barefoot running. To maximally reap these benefits, we must become aware of our body’s response to the environment. What do you feel when running on concrete, pavement, gravel, dirt or grass? How about on hot, cold or wet surfaces? How do your sensory experience and gait change on various terrains? Note any sensitivity on the skin of your feet, your sense of stability and your proprioception. Do you run more lightly, quickly or fluidly on any particular surface?

AWARENESS

Along with intensifying sensory experiences, running barefoot also heightens awareness of your internal and external environments. Running requires constant feedback to the body from its surroundings, and listening to these messages is key to safe, healthy and strong running. Take advantage of all your senses – especially your vision, hearing and touch – to maintain contact with your external environment. With a bit of practice you will begin to automatically scan for hazards (rocks, thorns, traffic, cyclists or playing children!) and for the optimal placement of your next step. At the same time, your internal awareness will naturally increase. Acknowledging your body’s responses to the environment will help refine your form, correct mechanical errors and prevent injury. If something feels off, play with your stride until you regain fluidity. But if you feel you’re pushing too far, listen to your body’s call for rest.

BIOMECHANICS I: THE FOOT

Foot-strike. What part of the foot touches first (forefoot, heel, midfoot)? Barefoot running encourages a mid- to forefoot strike, which research suggests may beneficially redistribute impact forces compared to heel-striking. However, there’s still no clear consensus over the “right” foot strike, or whether it even matters for injury prevention or performance.

Do you land more on the outside or inside of the foot? A natural strike will involve both pronation and supination, beginning with a slight inward roll followed by an outward roll at push-off. As these motions should come naturally, it is best not to force them, but to focus on landing with the whole foot at once. A helpful tool is visualizing the foot as a tripod; it is most stable when all three corners – the base of the big toe, base of the little toe and the heel – all contact the ground together.

Relax. Are the feet tense or relaxed? The feet may clench as a defense mechanism, especially on rough terrain. This can be dangerous and lead to excessive foot slapping, heavy impact and foot or shin pain. Relax the ankle and let the foot land softly.

Lift, don’t push. Do the feet push off or pound the ground? They should instead touch only briefly, followed by an immediate lift. The overall motion of the foot should be upwards, lifting from the ground rather than slamming downwards. This will prevent shuffling, shearing or twisting, which can lead to blisters or calluses.

Over-striding. Where do the feet land relative to your center-of-mass? They should land directly beneath the hips, not in front. Over-striding – or striking with the feet too far forward – is one of the most common sources of running injuries.

Cadence. Are the feet turning over rapidly? Aim for a high cadence (turnover rate), as this may help minimize impact forces and improve efficeincy. 180 steps per minute is roughly considered ideal.

Check out the recap from our second session, in which covered the fundamentals of running form, including lower and upper body mechanics. In our third and final session July 12, we’ll explore hills and speed and practical concerns of barefoot running.

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How does Sports Training Restructure the Brain?

Originally published on the PLOS Neuroscience Community

The impact of regular exercise on the body is obvious. It improves cardiovascular fitness, increases strength and tones muscle. While these transformations are visible to the naked eye, changes to brain structure and function by physical activity occur behind the scenes and are therefore less understood. It’s not news that the brain is wonderfully plastic, dynamically reorganizing in response to every sensory, motor or cognitive experience. One might imagine therefore, that elite athletes–who train rigorously to perfect specialized movements–undergo robust neural adaptations that support, or reflect, their exceptional neuromuscular skills. Different sports, invoking different movements, will target unique neural substrates, but most physical activities similarly rely on regions that are key for eliciting, coordinating and controlling movement, such as the motor cortex, cerebellum and basal ganglia. In a new study published in Experimental Brain Research, Yu-Kai Chang and colleagues explored how microstructure in the basal ganglia reflects training and skill specialization of elite athletes.

Runners, martial artists and weekend warriors

The study enrolled groups of elite runners and elite martial artists, along with a control group of non-athletes who only engaged in occasional, casual exercise. Although both groups of athletes were highly trained (averaging over four hours of training daily), their uniquely specialized skills were key for determining whether basal ganglia structure varied by sport or by athletic training generally. The groups did not differ in terms of basic physical attributes, demographics or intelligence, but as expected, the athletes were more physically fit than the controls.

Measuring microstructure

The researchers focused on the basal ganglia, a set of nuclei comprising the caudate, putamen, globus pallidus, substantia nigra and subthalamic nuclei, since these structures serve critical roles in preparing for and executing movements and learning motor skills.

Structures of the basal ganglia

Structures of the basal ganglia

They used diffusion tensor imaging (DTI), which measures how water flows and diffuses within the brain. Since water diffusion is determined by neural features like axon density and myelination, it is more sensitive to finer-scale brain structure than traditional MRI approaches that measure the size or shape of brain regions. Fractional anisotropy (FA) and mean diffusivity (MD) are common metrics to assess, respectively, the directionality and amount of diffusion. Typically, higher FA and lower MD are thought to reflect higher integrity or greater organization of white matter.

Globus pallidus restructures in athletes

The basal ganglia microstructure of the athletes and controls were remarkably similar, with one exception. The internal globus pallidus showed lower FA and a trend for higher MD in the athletes than the non-athletes, but there were no differences between the runners and martial artists.

This result in intriguing for two reasons. First, it’s notable that both athletic groups showed a similar magnitude difference from non-athletes. Thus, acquiring and refining skilled movements more generally, rather than any particular movement pattern unique to running or martial arts, may restructure the globus pallidus. As study author Erik Chang explains,

“With the current results, we can only speculate that the experience of high intensity sport training, but not sport-specific factors, would trigger the localized changes in DTI indices we observed.”

This would make sense, considering the area is an important output pathway of the basal ganglia, broadly critical for learning and controlling movements. It’s likely that other regions may undergo more specialized adaptations to sport-specific training. Chang expects that future studies using a whole-brain approach with “distinctions between sport types and reasonable sample size would find cross-sectional differences or longitudinal changes in brain structure related to motor skill specialization.”

Second, although we expect athletic training to enhance regional brain structure, the reduced FA and increased MD observed in these elite athletes would commonly be considered signs of reduced white matter integrity. This is somewhat surprising in light of other studies reporting positive correlations between physical fitness and white matter integrity in non-professional athletes and children. But as Chang points out, “Professional sport experience is quite different from leisure training.” Although unexpected, this finding aligns well with similar reports that intensive training in dancersmusicians and multilinguals is associated with reduced gray or white matter volume or reduced FA. Why would this be? For starters, DTI doesn’t directly measure axonal integrity or myelination–only water diffusion. So while sports training has some clearly reorganizing effect on basal ganglia, we can’t yet infer what changes are occurring at the neuronal level. One interesting possibility is that the development of such expertise involves neuronal reorganization or pruning as circuits become more specialized and efficient. Chang cautions that their findings “could reflect the manifestation of an array of factors, including increased neural efficiency, altered cortical iron concentration in the elite athletes, or other training-specific/demographic variables.”

In the broader context, this study is a striking example of why care is warranted in interpreting neuroplasticity. Depending on the study conditions, the same intervention–here, athletic training–can apparently remodel the brain in opposing directions. This is an important reminder that although we like to assume that bigger is better in terms of brain structure, this is not always true, highlighting the need to more deeply explore exactly how and why these neural adaptations occur. Chang eagerly anticipates that future studies incorporating “HARDI (High-angular-resolution diffusion imaging) and Q-ball vector analysis, together with larger sample sizes and longitudinal design, will be very helpful in revealing finer microscopic structural differences among different types of elite athletes.”

References

Chang YK, Tsai JH, Wang CC and Chang EC (2015). Structural differences in basal ganglia of elite running versus martial arts athletes: a diffusion tensor imaging study. Exp Brain Res. doi: 10.1007/s00221-015-4293-x

Chaddock-Heyman L, et al. (2014). Aerobic fitness is associated with greater white matter integrity in children. Cortex. 54:179-89. doi: 10.1016/j.cortex.2014.02.014

Elmer S, Hänggi J and Jäncke L (2014). Processing demands upon cognitive, linguistic, and articulatory functions promote grey matter plasticity in the adult multilingual brain: Insights from simultaneous interpreters. Front Hum Neurosci. 8:584. doi: 10.3389/fnhum.2014.00584

Hänggi J, Koeneke S, Bezzola L and Jäncke L (2010). Structural neuroplasticity in the sensorimotor network of professional female ballet dancers. Hum Brain Mapp. 31(8):1196-206. doi:10.1002/hbm.20928

Imfeld A, et al. (2009). White matter plasticity in the corticospinal tract of musicians: a diffusion tensor imaging study. Neuroimage. 46(3):600-7. doi: 10.1016/j.neuroimage.2009.02.025

Tseng BY, et al. (2013). White matter integrity in physically fit older adults. Neuroimage. 82:510-6. doi: 10.1016/j.neuroimage.2013.06.011

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A call for acceptance of career polygamy in science

Throughout my academic career from undergrad to my current postdoc, I’ve been perplexed by my atypical relationship with science. Yes, research and I have maintained a long, passionate love affair, but an affair apparently unlike those enjoyed by my colleagues. My unconventional attitude towards my work has served as a disconcerting voice that I’m just not cut out for a serious scientific career. I’ll certainly never win a Nobel, probably won’t publish in Science and may never even hold a faculty position. This reality has never really bothered me, but my lack of bother has been a subtle source of concern.

Only now, as a postdoc years into my Neuroscientific career, am I beginning to understand what makes my love affair with science so unusual. It’s by no means less genuine or less impassioned than those of colleagues madly pursuing tenure-track jobs; rather, it’s set apart by its polygamous nature. I get enthralled by new theories, overwhelmed with the excitement of shiny new data, and bore friends and family with my ecstatic ramblings about my research. I am a scientist for no other reason than I love it. However, it’s not the only object of my affection. I have never been, and probably never will be, able to suppress my love for so many other facets of life. A monogamous relationship with Neuroscience would just never suffice for me.

20131007-001611Since I was a teenager, a certain passage from Sylvia Plath’s the Bell Jar has always haunted me. She shared her predicament of being unable to choose a single fig – a life path, and as her indecision gripped her the figs wilted, leaving her starving and without a future. I’ve long been distraught by this similar fear of foregoing any one of my many dreams, wavering among so many enticing options and failing to commit to one whole-heartedly. As did Sylvia, I too considered this a flaw … a characteristic that would hold me back and prevent me from attaining my goals. As I’m finally understanding that these scattered passions or lack of focus – call it what you will – lie at the heart of my atypical approach to my work, I am also finally accepting that this is not necessarily a flaw.

“Good” scientists come in all shapes and sizes, but common to all is a sincere curiosity, a longing for answers and a rigorous devotion to unveiling them. Although these are precisely the factors that originally drew me to Neuroscience, I have always struggled with the conviction that I must not love my work quite enough – or at least not as much as the rock-stars around me, spending grueling hours in the lab, aiming for the highest impact-factor journals and power-networking with the bigwigs in their field. To a certain degree, these are crucial elements of a successful research trajectory, and I too have worked hard, held my research quality to the highest standards, and of course reveled in the rewards of grants and publications. But I have worked equally hard outside of the lab. Throughout grad school and my postdoc, I’ve allowed myself to pick several of those ripe, juicy figs and have savored every one of them. I’m not talking about the conventional concept of work-life balance that we’ve come to accept – at least superficially – is essential for job satisfaction. I’m referring more specifically to work-work balance. I indulge my writing addiction through freelance writing and editing and won’t hesitate to take on other side-projects as I’m so inspired. These endeavors are often neuro-related, but sometimes sprout from my obsession with running and fascination with sports physiology and biomechanics. These extra-neuro pursuits are as much “work” as my research, and I approach them all with the same intensity and devotion. They have not limited my productivity as a Neuroscientist, but have actually fostered it, by keeping me fresh, motivated and engaged with novel perspectives within and beyond the science community.

I’ve been blessed with both graduate and postdoc advisers who’ve been remarkably supportive of my promiscuous work habits, which has doubtlessly contributed to my own recent acceptance of my choices. Yet, I suspect my fortune is the exception rather than the rule, with the admission of this sort of behavior being met with disapproval or condemnation in many labs. In the current academic environment, time spent outside lab or even (gasp!) enjoying yourself is too often considered a sign of laziness or lack of drive. Tales of researchers working themselves to poor health or even suicide are rampant. It’s not clear how a field based on incentives so beautiful as curiosity and understanding has become so ugly, but it’s far time this trend is reversed. Outside interests or other professional pursuits should not be sources of guilt, and are not – contrary to common belief – prohibitive of a flourishing scientific career. Any culture that discourages the nurturing of broad interests can be toxic, stifling both personal growth and, ironically, professional development and productivity.

While there is certainly nothing wrong with the driven pursuit of a focused scientific career – and I strongly admire my dedicated colleagues who have chosen this path – it’s time we reject the myth that this is the only honorable or effective route to scientific success. As a first step, I’m embracing my relationship with Neuroscience, idiosyncrasies and all, and proudly proclaiming that we’ve been polygamous all along.

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San Diego Barefoot Running Workshops

I’m thrilled to announce … the first in a series of FREE San Diego Barefoot Running Workshops!

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THE MOTIVATION

This past International Barefoot Running Day, the small crew of San Diego barefoot runners gathered to share our love for natural running. This was my third consecutive year celebrating #IBRD and each year I come away with a renewed appreciation for the barefoot running community and new insights into how to maximally reap the benefits of the practice. Each of us have come from distinct backgrounds, have traversed unique paths and have made our own discoveries along the way, but we’ve all arrived at the same conclusion … Barefoot running is the way for us. For several months I’ve been toying with the idea of how best to share the lessons I’ve garnered from barefoot running with others in the hopes that they too may experience similar joy and growth. Reuniting with other barefooters last weekend reaffirmed the conviction that sharing these experiences and supporting others in their barefoot journeys is a worthy endeavor. As such, I’d like to invite you to participate in my San Diego Barefoot Running Workshop Series. These workshops are crafted with the novice barefooter in mind, but will ideally also serve as a welcoming environment for all – even lifelong barefooters – to nurture their evolution as strong, healthy, empowered runners.

WORKSHOP FORMAT AND AIMS

This first (beta-series, if you will) of workshops will comprise three meet-ups, each session focusing on a unique aspect of barefoot-running form, training and lifestyle. Each session will involve discussion and drills, and will conclude with a short fun-run to put into practice what we’ve learned. These runs will be designed to develop technique, rather than speed or endurance, so they will be short, easy and appropriate for runners of all levels. The workshops will be spaced apart (between two to four weeks) to allow runners sufficient time between sessions to incorporate lessons into their training. They will be casual, interactive and collaborative, with the hope that all participants will share their knowledge and experiences, and continue to learn from one another. The ultimate aim is to re-discover the pure, basic joy of running, by reinforcing natural movement patterns, learning safe training practices and increasing awareness of our bodies and environment.

Workshop #1 will take place Sunday, May 31 at 3 pm in Balboa Park.

We’ll meet at the Founder’s statue at the northwest corner of Balboa and El Prado. Please wear comfortable clothing (but leave your shoes at home!) and bring any hydration or supplies that you’d like. We’ll schedule the time, frequency and location of future workshops based on feedback from this first session. If you have suggestions for topics you’d like covered or how these workshops should be organized, please comment below. If you plan to attend (which I hope you do!) please RSVP at the Facebook event page, and please pass this along to other runners or barefoot enthusiasts. I’m looking forward to sharing the joys of barefoot running with you!

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A New Mechanism for Neurovascular Coupling in FMRI

Originally published on the PLOS Neuroscience Community

Although fMRI is the most commonly used tool for detecting human brain activity, the blood oxygen level dependent (BOLD) signal does not directly reflect neuronal activity, but instead, measures changes in blood flow and oxygen metabolism. This “neurovascular coupling” – the translation of neural to vascular signals – lies at the core of fMRI’s utility as a proxy for neural activity, yet there’s still uncertainty over exactly how neural processes drive vascular signals. The neural-to-vascular link is largely obscured by the complex cascade of events involved in neural activity, including glucose metabolism, oxygen consumption, neurotransmitter release and recycling, and changing membrane potentials. Past research has pointed to astrocytes as key players in the neurovascular coupling game, as these cells envelop both neurons and blood vessels. A key signaling molecule, both within astrocytes and between astrocytes and other cells, is ATP, best known for its role as the “cellular energy currency.” In their recent paper published in the Journal of Neuroscience, Jack Wells, Isabel Christie and colleagues explored the physiological mechanisms by which astrocytes might serve as the neurovascular interface of fMRI. Their study tested whether astrocytic purines – including ATP and its products ADP and AMP – are critical for the BOLD response.

ATP is key to eliciting the BOLD response

The authors speculated that, if astrocytic ATP mediates the vascular response to neural activity, blocking ATP should impair the BOLD signal. In normal rats, electrically stimulating one forepaw induces a BOLD response and ATP release in the somatosensory cortex of the opposite side of the brain. Therefore, to test if ATP is required for the BOLD response, they first disrupted ATP on only one side of the somatosensory cortex, and then stimulated both forepaws. They expressed TMPAP, which breaks down purines, into one side of the forepaw region of the rats’ somatosensory cortices, and a control into the other side. Oddly enough, although these vectors weren’t cell-specific, they were mainly expressed in astrocytes – but not neurons – a convenient pattern for testing the selective role of astrocytes in neurovascular coupling.

As expected, the BOLD response to forepaw stimulation was typical in control somatosensory cortex. But the signal was reduced in cortex expressing TMPAP (see Figure, A left and B top). This suggested that purine signaling is indeed important for a normal BOLD response. But what if the altered signal resulted from some other effect of the TMPAP expression, besides the intended purine reductions? For instance, breaking down ATP and its products could lead to build-up of the inhibitory neurotransmitter adenosine, which could interfere with normal neural activity. The authors repeated the experiment, this time using an adenosine antagonist to block any effects of adenosine accumulation. The results were the same. The BOLD response was reduced with TMPAP and did not normalize by blocking adenosine (see Figure, A right and B bottom), confirming that the effect wasn’t simply an artifact of adenosine build-up.

Group activation maps (A) and response curves (B) show that the BOLD response to forepaw stimulation is reduced after blocking purine signaling (TMPAP), compared to control (EGFP). The effect remains even after accounting for adenosine build-up with the adenosine antagonist DPCPX. From Wells et al., 2015.

Group activation maps (A) and response curves (B) show that the BOLD response to forepaw stimulation is reduced after blocking purine signaling (TMPAP), compared to control (EGFP). The effect remains even after accounting for adenosine build-up with the adenosine antagonist DPCPX. From Wells et al., 2015.

Does ATP support neural and vascular signaling or just their coupling?

If astrocytic purine signaling is truly involved in the translation of neural activity to a cerebrovascular response, interfering with purines should diminish the BOLD effect (as they showed), but neural activity and the background vascular state should remain unchanged. Indeed, multiunit recordings showed that TMPAP did not affect the neural response to forepaw stimulation, and arterial spin labeling indicated no change in resting blood flow or vascular reactivity.

Astrocytic ATP: One piece of the puzzle

Results from each of these experiments provided a critical piece of the neurovascular puzzle, illustrating the role of astrocytic purines in the series of events translating neural activity to the BOLD response. Together, they suggest that ATP signaling in astrocytes is critical for a normal vascular response to neural activity, but importantly, is not needed for either neural or vascular function alone. In other words, astrocytic ATP selectively underlies the coupling of neural and vascular activity.

It’s important to note that, although these findings show that ATP is important for neurovascular coupling, it’s unlikely this is the only mechanism supporting the BOLD response. While this study doesn’t directly trace the intricate events by which ATP mediates neurovascular coupling, the authors offer several plausible pathways. ATP is known to trigger calcium responses in astrocytes, which – through a series of downstream processes – could cause vascular effects like blood vessel dilation that are key to the BOLD response. However, ATP does not just support communication between astrocytes, but is also involved in neuron-to-astrocyte and astrocyte-to-blood vessel signaling. Any of these interactions could feasibly explain why ATP is required for the vascular response to neural activity. Of course, we can’t rule out the influence of ATP in neurons, which also may modulate vascular function independent of astrocytes. Although TMPAP was primarily expressed in astrocytes, this wasn’t exclusive; it’s possible that ATP levels were also reduced in neurons and may have affected the BOLD response in distinct ways.

Many questions remain regarding the physiological origins of the BOLD response to neural activity. However, these findings from Wells, Christie and colleagues help to solidify the role of astrocytes, and to introduce ATP as a key player, in the neurovascular coupling game.

References

Wells JA, Christie IN et al. (2015). A Critical Role for Purinergic Signalling in the Mechanisms Underlying Generation of BOLD fMRI Responses. J Neurosci 35(13):5284-92. doi: 10.1523/JNEUROSCI.3787-14.2015

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The structure-function paradox: Thoughts from a barefoot-curious reader

One perk I’ve enjoyed since starting this blog has been connecting with like-minded readers … runners, barefooters and scientists. Occasionally readers will reach out with their personal stories or questions (which I love!) The other day I received an email from a reader curious about the importance of toe and metatarsal alignment for foot health. His insights into foot biomechanics, enthusiasm for optimizing his own barefoot experience, and curiosity for the best path to do so – were striking. As he raised some interesting questions that are relevant for anyone considering transitioning to a barefoot lifestyle, I’m sharing his message, along with my response, below (note that I’ve removed his name for privacy and have trimmed the email for brevity).

I’d like to say thank you so much for documenting your experience, it is an invaluable source of information. I have great investment in this movement for myself (patellar tendonitis, fallen arches), and my family (bunion sufferers). I’m going to cut right to the chase. You seem very knowledgeable about the biomechanics of the foot, and I feel there is a significant sliver in the venn— diagram between our two philosophies. What about our toes alignment with our metatarsal shafts?

This is an idea that I see very rarely addressed among barefoot runners. I’m not sure how much of this information you’re familiar with, probably all of it but just in case I’m going to breeze through it. The shod VS the unshod life, a developed condition. I feel like this is so often ignored. In my rehabilitation from conventional footwear, I’ve been made aware of the deformation that has taken place in my bones and tendons that has bent my big toe inward, bent my small toes outward, and given me hammertoe. Why do I see so few barefoot runners addressing this? I work everyday to stretch and re-align my great toe into its natural place, a continuation of the metatarsal shaft, so that it can once again be in its place of maximum support.

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I even invested in a product that re-alignes my toes back to the way they were, so as to, over time, affect the bone and tendon structure, pushing them back into alignment. But seeing your story, how you came through without the use of these, and how your toe alignment between 2011 and 2012 didn’t seem to change much. In your recent pictures it’s hard to discern the alignment of your toes, have you seen a difference since 2012?

Does this idea hold water to you at all or do you consider something else entirely more important than alignment. I would love to know, I’ve been trying to make sense of going completely barefoot, but with my great toe alignment (about the same as yours in 2012) it just doesn’t make sense to me, I feel like I’d be putting weight on a delicate system that no longer is in the proper alignment to do its job properly. Am I completely off the mark? Any thoughts would be extremely appreciated.

I love this last picture, and it is the most profound and affirming to me, a (mostly) un-contacted tribe within the amazon. Their toes are my every day goal. I know little biomechanics, but this has philosophy has resonated with me. Am I wasting my time with this? Is this new information to you? What made you feel your path was best?

AmazonTribe

MY RESPONSE:

Thanks for your email. I love hearing from others with a shared interest in natural, barefoot living. Indeed, I’m aware of the deformations shoes make on our feet, and that toe separators can help reverse this (I actually have some myself).

I think the answer to most of your questions lies in your goal. If your main aim is simply to realign your bone structure, then sure, work on this just the way you are. For me, better toe/metatarsal alignment has been an incidental consequence of pursuing my other goals – overall healthier, stronger feet that allow me to move the way my body is meant to. So there are two, albeit related, issues here: structure and function. You seem very focused on changing your foot structure, but for what purpose? If it’s so that your foot (and body) will also move better, the best way to achieve that is simply to use your feet the way they’re meant to be used. By going barefoot as much as possible you will quickly build muscle, tendon and bone strength and as a consequence, your foot shape will also change.

I gave up shoes four years ago and have indeed noticed major changes since then. The toe splay hasn’t been dramatic, but my arches have become strong and high and my feet and ankles have gone from soft and dainty looking, to thick, toned and defined. This sounds odd, but my feet have become my favorite physical asset – I’m proud of their transformation into powerful, beautiful structures. At this point, I could care less how my toes splay, since my feet are functioning magnificently, allowing me to walk and run for miles on end, pain-free and carefree!

You’re concerned that you could injure yourself by going barefoot if your bone alignment isn’t perfect. This is a slight possibility, but easily avoided by simply listening to your body. I would be concerned less about proper alignment than general foot weakness. The risks of walking or running barefoot excessively before you’re ready come from inadequate strength, and the only way to strengthen your feet is to use them! Sure, going out and sprinting a 5k for your first barefoot run will injure you. Instead, go for a short walk until your feet start to fatigue. Then call it a day. Or run around the block for 2 minutes. Give yourself enough rest to allow your feet to recover and rebuild before you try again. Over time, you’ll be able to walk further, run longer and start noticing remarkable changes in how your feet feel, look and function. When I gave up shoes in 2011 I couldn’t walk barefoot more than a few minutes before my feet hurt. I walked barefoot for a couple years to build up base strength, then began running barefoot – literally starting by running one block. I now regularly run 40-45 miles a week barefoot.

I seem to have written a novel, but this is an important and interesting topic for me! My last tidbit of advice is to not over-think it … just enjoy the improved sensory experience and awareness your feet give you and savor the growth, however gradual it may be. Happy barefooting!

What are your thoughts on the relative importance of foot structure and function, and how they influence one another?

I love hearing my readers’ experiences and questions, so please don’t hesitate to reach out!

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