COVID-19 Vaccines: Helping You Combat One Spike Protein at a Time

COVID-19 vaccinations reduce the risk of infection and have the potential to ensure life returns to normal. Everywhere you turn someone is talking about which vaccine they have received: Pfizer, Moderna, Janssen, AstraZeneca… But what is the difference? How do the different types of COVID-19 vaccinations protect us? And does it matter which vaccine you receive?

COVID-19 vaccine comparison chart illustrating Pfizer and Moderna are RNA vaccines and Janssen and AstraZeneca are viral vector vaccines.
COVID-19 Vaccine Comparison. Photo by BBC News on Wikimedia Commons.

To start off, it is important to understand how coronavirus enters our cells: spike protein. Spike proteins are visually the spikes protruding from the spherical coronavirus and what bind to our cells to transmit the RNA virus (a code for COVID-19), enveloped inside the coronavirus, to our cell’s cytoplasm (the area inside a cell excluding the nucleus). The spike proteins fuse to our cell membrane (the outside of the cell) and are the target for researchers and vaccine developers.

Image of SARS-CoV-2 with red spike protein protruding from the spherical coronavirus.
SARS-CoV-2 (red spike proteins). Photo by Alissa Eckert, MS; Dan Higgins, MAM on Wikimedia Commons.

There are various types of vaccines that stop the spike proteins from fusing to our cell membrane, however, the two main types of vaccines used in the United States are mRNA vaccines and viral vector vaccines. Pfizer and Moderna are mRNA vaccines, while Janssen and AstraZeneca are viral vector vaccines. Both types of vaccines have the same goal: create antibodies to bind to spike proteins to block the spikes from attaching to and infecting healthy cells.  

The Pfizer and Moderna vaccines use messenger RNA technology to deliver genetic code to our cells to instruct how to make the SARS-CoV-2 spike protein. mRNA is very fragile thus it is encapsulated in something called lipid nanoparticles (LNPs) in order to reach the cell. LNPs increase translatability and stability to ensure mRNA’s delivery to the cell. When the mRNA vaccine is delivered to our cell it breaks free of the LNPs. 

Diagram of mRNA with LNPs.
mRNA and LNPs. Photo by Andreas M. Reichmuth, Matthias A. Oberli, Ana Jaklenec, Robert Langer, and Daniel Blankschtein, “mRNA vaccine delivery using lipid nanoparticles,” NCBI, PMID: 27075952.

After the mRNA is released from the LNPs, the cell begins making spike proteins. The spike proteins then trigger an immune response to begin producing antibodies. Ultimately, the antibodies latch onto the coronavirus’s spikes making the virus unable to latch onto other cells.

The Janssen and AstraZeneca vaccines incorporate viral vector vaccine technology. The viral vector is a genetic code that creates an instruction manual for human cells to produce the SARS-CoV-2 spike protein transported into the body by a harmless virus called an adenovirus. The adenovirus acts as the delivery system for this important DNA code and helps the body to trigger an immune response. 

The vector vaccine attaches onto proteins on the cell’s surface and the adenovirus is pulled into the cell. The main difference between the mRNA vaccine and the viral vector vaccine is that the DNA in the adenovirus of the viral vector vaccine must travel into the cell’s nucleus in order to be transcribed whereas the mRNA vaccine remains in the cytoplasm throughout the process. From there viral vector vaccine acts very similar to mRNA vaccines—once the DNA is transcribed into mRNA, the mRNA leaves the nucleus and the cell begins assembling spike proteins.

Further research is being completed to determine exactly how COVID-19 vaccines enter the cell. However, endocytosis is thought to be the answer based on previous vaccine knowledge. Endocytosis is a cellular process in which something is brought into the cell by engulfing it in a vesicle (small fluid bubble). In mRNA vaccines, the LNPs take advantage of the natural process of endocytosis. The LNPs are engulfed in a bubble, triggering a reaction that allows the nanoparticle to enter the cell and eventually release the mRNA.

Image depicting endocytosis in COVID-19 vaccines.
Endocytosis in COVID-19 vaccines. Photo by Oleg O. Glebov, “Understanding SARS‐CoV‐2 endocytosis for COVID‐19 drug repurposing,” NCBI, PMID: 32428379.

Overall, both the mRNA and viral vector vaccinations are great options each with their own unique design to produce antibodies and stop coronavirus from latching onto our cells.

Doses of the Pfizer COVID-19 vaccine.
Doses of the COVID-19 vaccine are seen at Walter Reed National Military Medical Center, Bethesda, Md., Dec. 14, 2020. Photo by Lisa Ferdinando on Wikimedia Commons.

Ditching the shoes: Minimalist trend or natural advantage?

The discussion of returning to minimalist ways, namely walking or running barefoot, is a question that rises in many circles, from new parents to elite runners. For example, parents are told to let children learn to walk barefoot, as studies have shown early use of footwear can lead to feet deformities and can alter natural gait, which is especially important when learning to walk. Likewise, many avid and elite runners have shown interest in barefoot running (or minimalist running shoes), as some are convinced that the forefront strike (FFS or also known as NRFS – non rear foot strike), more commonly used during barefoot running, lowers the loading rate on the foot and minimizes injuries from the repeated stress that occurs in the feet during running. 

Diagram illustrating four phases of foot contact with the ground for forefront strike and rear foot strike patterns
Forefront strike (top) and rear foot strike (bottom). Modified from Daniel E. Lieberman et al., Springer Nature 2010

In general, walking or running barefoot yields more frequent steps, a smaller stride length and a slower velocity (most noticeable while running). Barefoot running is thought to reduce some of the injuries many runners are prone to, such as shin splints, stress fractures or plantar fasciitis. Additionally, the stiff fit of modern shoes limits the width and spreading of feet in the natural walking or running motion. However, barefoot running also comes with a cost, with injuries in the achilles region more prevalent. 

A study in the Gait & Posture journal examined foot motion in children and found modern commercial footwear does have a large impact on gait, especially in regards to range of motions of different muscles and joints in the foot, likely due to the stiffness of shoes. More flexible shoes, similar to minimalist running shoes, were found to have a smaller impact on foot motion in reference to bare feet, but still had a significant difference in regards to the added support in the arch area. 

The common belief that barefoot motion lowers the impact on the body has been questioned by a recent research study from Southern Methodist University. The findings indicated that while running barefoot with a forefront strike, the feet strike the ground at a more pronounced angle which generates a longer contact time, thus decreasing the loading rate and allowing the muscles in the back of the feet and legs (especially the Achilles) to absorb some of the loading stress. When humans adapted to running in shoes, especially shoes with thick cushioning, the landing switched to a rear foot strike that allows the heel cushioning to absorb some of the loading stress, resulting in a fairly equal loading rate for both cases. The heel cushioning, with a flatter angle of contact, also allows for decreased impact time with the ground surface, which is why higher running speeds are achieved with footwear. 

barefoot person walking outdoors during the day
Photo by ‏🌸🙌 في عین الله on Unsplash

While the advice to encourage barefoot walking in young children certainly makes sense as they continue to grow and learn to control their bodies, the choice to use shoes or go barefoot for older children and adults remains an individual preference. There is no significant difference in the stresses the body experiences, but the footwear choice does influence the likelihood of certain, which is important for runners with past injuries to consider.

For more information, check out this extensive technical review of studies on barefoot vs. footwear mechanics or this video from Exercising Health comparing running shoes with minimalistic barefoot shoes.

Why is heading the ball so dangerous for youth soccer players?

young girl attempting to head an incoming soccer ball
Photo by Carson Ganci on THE42

I received my first concussion while playing soccer at 15 when I was knocked out by a ball that was “accidentally” punted directly into the side of the head. It seemed to me like this was one of the few, rare ways to get a concussion from the sport – an unlikely occurrence combined with an unusually aggressive impact. I was proven wrong, however, after I received two more concussions just from heading the ball – a frequently used technique involving seemingly mild impact forces. I have since come to discover that concussions, particularly due to heading the ball, are a huge problem for youth soccer players: currently, in the United States, youth soccer players aren’t allowed to start heading the ball until age 11 in an effort to reduce the risk of concussions. But how do headers cause so many youth concussions, especially when the speed of play is so much lower than for adults?

Physical vulnerability to concussion mechanics

illustration showing a head impacting a an object with arrows decribing the movement of the skull and the brain towards the object just before impact
Illustration of the movement of the skull and brain just before impact with an object. Upon impact, the movement of the skull decreases rapidly while the movement of the brain has a delayed response. Original image created for Wikipedia

In most sports, concussions are commonly caused by rapid acceleration/deceleration of the head that causes the exterior of the brain to crash into the interior wall of the skull, which is suddenly accelerating in a different direction. When headers are performed in soccer, this rapid acceleration is caused by impact with the ball, and the risk of concussion depends on both the acceleration of the head and the duration of the impact. The acceleration of the brain can be modeled by Newton’s Second Law (F = ma) for a given impact force F, and the resulting acceleration depends on the effective mass of the players head m, which depends on both the strength and weight of the players head and neck as well as their relative movement compared to the ball (which boils down to technique). This means that a major portion of the risk of concussion relies on the size, strength, and technical ability of the player, all of which have an inverse relationship with player age. So while the relative speed of play and impact forces may seem lower for youth players that can’t run as fast or strike the ball as hard as their adult counterparts, these factors are offset by their relative physical vulnerability.

Issues with injury recognition and response

Another factor contributing to the threat of concussions for youth players is their relatively low ability to recognise and respond appropriately to a brain injury when one occurs. Between 2008 and 2012, researchers observing elite female players aged 11 to 14 for 414 player-seasons (288 athletes were observed for a single season and 63 were observed for two seasons) discovered that 59 concussions occurred, with headers being the most frequent cause at 30.5%. In addition to this injury frequency, it was found that over half of these middle-school-aged athletes continued to play with symptoms after receiving a concussion. This is an additional a logistical problem for youth players, for as age decreases, athletes on average have less access to on-hand, qualified medical personnel and less of an ability to self-diagnose and respond appropriately to injury, putting them at increased risk for long term damage.

The Ultimate 2-for-1: the Power of Contralateral Strength Training

For the competitive athlete, injury often means loss. Loss of playing time, loss of skill development, and most importantly, loss of training time. These are all unfortunate consequence of getting a bone or tissue injury requiring a long-term healing prognosis. Injuries can be so devastating because the road to recovery is often times an arduous two-step process. First, the athlete must wait for their broken bones, torn ligaments, or pulled muscles to naturally heal. During this time, the athlete’s injured limb is likely immobilized in a cast or brace, leaving the resulting muscle to slowly atrophy as the body tries to heal itself. As a result, an athlete must spend the second part of their recovery process re-training the weakened muscles in the immobilized limb to return to full-strength. What if there was a way to heal and train the body at the same time? This is the power of a neurophysiological phenomenon known as “contralateral strength training.”

First observed in 1894, this phenomenon describes the increase in strength seen in an untrained limb of the body after strength training the opposite limb. For example, performing strength training exercises using the left arm has been shown to also induce an increase in strength in the right arm without working out the right arm at all. This effect can be seen in all different muscle groups in the body, in both males and females, and in people of all different ages. Researchers have hypothesized that high-force contractions used in resistance strength training can have a “spillover” effect on the neurons controlling the opposite limb. These neural circuits can carry motor output signals from the trained muscle to the untrained contralateral muscles which works to increase the electrical activity of the untrained muscle and effectively activate the muscle as if it were being trained as well. The video from the YouTube channel “House of Hypertrophy” helps illustrate this effect.

This video is from the YouTube channel “House of Hypertrophy” and helps illustrate the contralateral strength training phenomenon.

Harnessing the power of this neurophysiological phenomenon is key to injury recovery especially when one limb is immobilized for an extended period of time. It’s not just for competitive athletes either. Anybody with an injury can take advantage of contralateral strength training to dramatically speed up injury recovery. This can be especially useful for the elderly population where maintaining balance is an important factor of injury rehab. Imagine being able to maintain the strength and mobility of an elderly patient’s leg after a common surgery such as a knee replacement. Although the leg will be immobilized by a brace or a cast to keep the knee stable after surgery, it could be possible to prevent the muscles from atrophying by simply training the opposite leg with effective physical therapies. This could mean the difference between a smooth recovery versus one where the patient faces serious balance and stability issues as a result of a weakened limb that was immobilized in a cast for weeks to months at a time. Whether it be for injury recovery or specialized strength training, contralateral strength training has an amazing 2-for-1 effect in which the body’s own neural mechanisms allows both homologous muscles to experience the effect of a single unilateral training.

A Second Chance: Robotic Exoskeletons May Be the Future of Mobility for Patients with Spinal Cord Injuries

No one ever imagines themselves getting seriously injured. Accidents do happen though, like car crashes and unexpected sports injuries. These events can drastically change a person’s life, leaving them unable to perform simple daily tasks without assistance, such as walking. One injury that can radically impact a person’s life is a spinal cord injury. There are approximately a quarter of a million people in the United States with spinal cord injuries, and that number grows by 12,500 each year.

The spine is the center of support in the body. It adds structure and facilitates movement. Its other extremely important job is to protect the spinal cord, which is a column of nerves that runs down the length of the neck and back. The spinal cord is part of the nervous system, and it acts as a messenger, taking orders from the brain and relaying these messages to the rest of the body, telling the muscles what to do. If the spinal cord is injured, the messages can’t be delivered properly. This often results in a loss of mobility.

Diagram of the central and peripheral nervous system showing how the spinal cord connects the brain to nerves that run throughout the body
From OpenStax Anatomy and Physiology on Wikimedia Commons

Most people don’t think about the mechanics involved in the simple act of walking. However, in order to walk, various joints such as the hip, knee, and ankle need to work together, rotating and bearing loads to allow for movement. When your foot hits the ground, the ground imparts a force through the foot which is translated up through the lower extremities to the spine. When a spinal cord injury occurs, the brain is unable to communicate with our muscles which inhibits this load bearing and the resulting movement.

Studies have shown that powered exoskeletons have numerous benefits for patients with spinal cord injuries to help with walking and mobility. These powered exoskeletons are built in various ways to bear loads and encourage movement, and a review of different exoskeletons, along with other rehabilitation devices, discusses differences in design and control of the systems. For example, to allow for control of movement, one exoskeleton was built with motors located at the joints while another was designed with a braking system at the joints.

Photo of the Indego powered exoskeleton
Indego Exoskeleton – From

One study researched mobility outcomes for patients with injuries that varied in severity and location on the spine. Some patients were paraplegic, which means their lower extremities were paralyzed, and some patients were tetraplegic/quadriplegic, which means the paralysis affected both their lower and upper extremities. Also, some patients had complete spinal cord injuries, which means all feeling was lost below the injury, while others had incomplete spinal cord injuries, which means they had some feeling and some ability to control movement below the injury. This study showed that powered exoskeletons, specifically the Indego exoskeleton, could help a patient move in both indoor and outdoor settings, and there is potential for patients with paraplegia caused by injuries to the lower spine to use this device to allow greater ease of mobility in public spaces. For patients with more severe injuries, such as those with quadriplegia, the powered exoskeleton allowed for slower movement with supervision and occasional assistance from a therapist. These patients also needed assistance with putting on and removing the device. Therefore, the powered exoskeleton won’t help patients with more severe injuries move on their own in public settings, but it was excellent for exercise and rehabilitation.

These exoskeletons are also proven to be safe and feasible. Patients with complete spinal cord injuries did not report discomfort or injury, and they were able to use a powered exoskeleton more easily than previous rehabilitation technology.

Powered exoskeletons may be the future of movement for those who thought they would never walk again. This further reading contains examples of paraplegics who walked using a powered exoskeleton. Another man even walked marathons using one of these devices:

From Freethink on YouTube

There are limitations on these devices, but the robotics field is swiftly evolving, and the technology is giving patients something they never thought they would have: a second chance.

Which is more stable, washing machines or birds? The answer might surprise you

What do birds and washing machines have in common? Shockingly, it’s not the ability to wash clothes. Rather, most birds and washing machines are great examples of vibration isolation systems.

Now that’s cool and all – but what is a vibration isolation system?

Better known as a mass-spring-damper system, vibration isolators are generally a mechanical or industrial mechanism that can reduce the amount of vibrational energy produced by a system. Vibration isolators are incredibly important; studies show “undesirable vibrations” can shorten a machine’s service life and even permanently damage the machine and those using it. Considering this, engineers are constantly improving upon current vibration control systems, and are now looking to birds for inspiration.

But why birds? Well, to understand this, let’s consider a bird as a simple mass-spring-damper system.

Avian vibration isolation system represented as mass-spring-damper-system
Simple approximation of avian vibration isolation system as mass-spring-damper system. Taken from the 2015 study: ‘The role of passive avian head stabilization in flapping flight.”

First, visualize vibrations as an oscillating force stemming from the bird’s body moving back-and-forth. Vibrational forces can be generated by the flapping of wings, unexpected gusts, and/or movement of legs. Now, if we continue up from the body to the neck, we can see where avian skeletal and muscular structure really begins to “show off its feathers.”

Characterized as a multi-layered structure, the avian neck contains many sections of “hollow” bones, connected by surrounding muscles. The structural units (muscles and bones) of the avian neck have properties of both springs and dampers, optimizing them for vibration isolation.

Simplified representation of multi-layered neck as spring-damper structure

For starters, we see the muscles largely act as springs. Springs have the unique ability to move a body with its vibrations. This behavior is present in the muscles connected to the bone segments, in that they are capable of instantaneously compressing, elongating and twisting in response to rapid changes in the body’s movement. This elastic response prevents not only the head, but the whole bird, from shaking when bombarded when vibrations from any form of movement.

Simplified visualization of multi-layered spring-damper structure. The transparent grey portion represents the hollow bone, which is connected by the black lines, or strong spring-like muscles. The empty space between each unit would consist of the softer, damper-like muscle. Taken from the 2021 study: “A novel dynamics stabilization and vibration isolation structure inspired by the role of avian neck.”

Alternatively, the muscles, primarily those not connected to bone, can act as dampers. Effective dampers are similarly identified by the ability to move with vibrations; however, they can dissipate some of the vibrational energy as heat, or store energy until relaxed. The interior muscles are capable of slowly deforming (changing shape) if exposed to steady vibrations, allowing for dissipation of excessive vibrational energy.

But hey, what about those bones?

The avian neck has nearly three times the number of bone sections than most mammals, on top of muscles entirely surrounding the neck. This drastically increases the bird’s flexibility, helping it maneuver through sharp positional changes, thereby further limiting the effect of vibrational forces.

Finally, what makes the avian vibration isolator truly superior is its passive activation. As engineers at Shanghai Jiao Tong University point out, manmade passive vibration isolators fall short because they require sensors and input energy to adjust for “shocks and random vibrations.” As previously explained, the multi-layered neck is well equipped to handle random oscillations, yet, more importantly, the bird’s neck muscles can passively change position to brace for incoming vibrations.

A recent study from Stanford University proved this concept by recording a whooper swan’s reaction to different strength gusts. They found that swan’s neck adjusted to protect the head, and that even when the flapping doubled, the movement of the head reduced by a quarter. Finally, it is important to note that passive activation is not limited to the sky; researchers have found that mainly terrestrial birds like chickens and pigeons have a similar neck structure and system for maintaining stability and clear vision.

Overall, continuing to study the avian vibration isolation system could prove very beneficial for many different applications. For a more in-depth look at the current work out, check-out the studies referenced throughout the article. Otherwise, enjoy watching this chicken work its body control magic!

Mercedes-Benz “Chicken” Magic Body Control Advertisement, highlighting the chicken’s amazing head stabilization ability.

Why We Need to Re-Evaluate the RACIALIZED History of Spirometry

One of the leading indicators of good health is adequate lung capacity. Lung capacity, as defined by Bajaj and Delgado is the volume of air in the lungs upon the maximum effort of inspiration. For an average healthy adult, that is about 5.5 liters of air. But how do we measure our lung capacity? A spirometer is the answer. Even though the device has undergone multiple revisions since it was first invented in the 1840s, it has not deviated away from its original purpose of measuring lung capacity.

Luckily, the function of a spirometer is very intuitive to understand. One type of spirometer, called the pneumotachograph spirometer, measures the amount of air a person exhales and inhales in a second. Here is a quick run through of how that happens. The pneumotachograph spirometer typically consists of a tube, a flowmeter and a sensor. The tube is responsible for converting the information gathered by the sensor to an electric signal. The information carried by the signal is then displayed using a spirogram, a graph with flow rate (volume per second) plotted against inhaled air volume (meters cubed). Based on the characteristics of the graph, the health personnel conducting the test can then analyze the lung capacity of the subject.

Basic set-up of a spirometer test Source:Wikipedia

What are some lung conditions that a spirometer can help us diagnose? It can help us diagnose Asthma, determine if our airways have become narrowed or if our lungs are congested by mucus (pulmonary fibrosis). Another condition on the list of diagnosis is cystic fibrosis, a rare chronic condition that alters  the function of body parts such as the lung and liver by producing mucus. Our vital capacities can be compromised for different reasons eventually causing the aforementioned defects in our health. Some of the reasons are partly hereditary(such as cystic fibrosis) but most of these are caused by external factors such as smoking and exposure to polluted air. Other factors cited in early medical studies include race, gender and age.

The difference in lung capacity between white people and colored people has been a widely accepted phenomenon. For a long time the broader medical community believed that lung capacity difference was innate. As a result, “race corrections” are applied on the spirometer results in an attempt to get a more accurate value. The correction factor shrinks the benchmark for standard lung capacity of black people by 10% and Asian people by 4% to 6%.

This obviously calls into question who the system designated as the benchmark of health and normalcy – the white population. The “race correction” doesn’t acknowledge the intersections of socio-economic status, exposure to cleaner air, or sex. These are all factors that can largely influence well-being including but not limited to lung capacity.

Why does this matter? It matters because race correction could result in the deprivation of the necessary medical attention that needs to be given to colored communities. It also overlooks the intersectionality of their experiences that exist in the spheres of social class, environmental factors, and lived experiences. Thus, we need to question how race correction was installed in the first place. Was it a pure speculation? Was it devised as a result of segregative policies? Or did it have an empirical basis? That is why it is important to put the spirometer in a historical context and reevaluate the implicit biases with which it was designed.

References and Further Readings:

Braun, Lundy. “Race, ethnicity and lung function: A brief history.” Canadian journal of respiratory therapy : CJRT = Revue canadienne de la therapie respiratoire : RCTR vol. 51,4 (2015): 99-101. Link

Haynes, Jeffrey M. “Basic spirometry testing and interpretation for the primary care provider.” Canadian journal of respiratory therapy : CJRT = Revue canadienne de la therapie respiratoire : RCTR vol. 54,4 (2018): 10.29390/cjrt-2018-017. doi:10.29390/cjrt-2018-017

Braun, Lundy. Breathing Race Into the Machine: The Surprising Career of the Spirometer from Plantation to Genetics. N.p., University of Minnesota Press, 2014. Link

González, Jorge:Spirometer Demo with Freescale Microcontrollers, NXP, 2012.
A brief history of the spirometer

Prof. Klapperich et al.

The Dangers of Using Your Head: The Biomechanics of Sports-Related Concussions

Anyone that has ever had the misfortune of banging their head know how painful it can be, but does everyone understand just how dangerous it can be? Concussions occur when the brain hits the interior walls of the skull, either due to a direct blow or a sudden start or stop. These brain injuries most often result in confusion, headaches, and loss of memory but more severe injuries can cause vomiting, blurry vision, and loss of consciousness. In rare instances, they can even cause a brain bleed and result in death. Repeated concussions can lead to neurocognitive and neuropsychiatric changes later in life as well as increase a person’s risk of developing neurodegenerative diseases like Alzheimer’s.

So, who is at risk for concussions?

Athletes sustain 1.6-3.8 million concussions every year in the US. They are most common in contact sports such as soccer and hockey, but the largest contributor is American football. Players are constantly hitting or tackling each other in football, and each impact risks serious injury for both individuals.

How does it happen?

It all comes down to conservation of energy and momentum. Newton’s second law states that an object in motion tends to stay in motion while an object at rest tends to stay at rest, unless acted on by an outside force. When player 1 starts to run, he has a set energy and momentum based on his velocity (speed). Once he hits player 2, he either slows down, stops, or bounces off in the opposite direction. However, the initial energy and momentum that he had doesn’t just magically disappear, it needs to be conserved so it is transferred to player 2. This means that player two will start moving in the direction that player 1 was initially running. This is how billiards is played: the energy is transferred from the pool stick to the cue ball and then to the intended solid or stripe.

However, injury occurs when player 2 or his head cannot move. This may be because he hit the ground or another player or even simply because his neck stabilized his head, but regardless, that energy still needs to go somewhere. When the head stops, the brain keeps going until it collides with the inside of the skull.

Fortunately, not every hit results in a concussion. The brain is separated from the inside of the skull by cerebrospinal fluid that can protect it from collision to a certain degree, so not every impact reaches the injury threshold. What that injury threshold is has become the focus of many scientific studies.

Finding the injury threshold

The search for the injury threshold is a vital one that could help in the development of more effective helmets and rule changes to the game that could keep players safe. Three factors are believed to dictate this threshold: linear acceleration, angular acceleration, and location of the impact. The linear acceleration is what causes the collision with the skull, as previously described. The rotation of the cerebrum (the bulk of the brain) about the brain stem can cause strain and shearing within the upper brainstem and midbrain, which control responsiveness and alertness (causes the confusion symptoms). Finally, certain areas of the brain are more susceptible to injury- like the frontal lobe, temporal lobes, and brain stem since they are near bony protrusions– so the location of the impact can have a major influence in the injury threshold.

While there is still no set threshold, one study was conducted in which 25 helmet impacts from National Football League (NFL) games were reconstructed and the resulting helmet kinematics measured. The study found that the heads of concussed players reached peak accelerations of 94 (+/-) 28 g (acceleration due to gravity-9.8 m/s^2) and 6432 (+/-) 1813 radians/s^2. A separate study focused on the location of concussions of football players and that resulted from specified linear accelerations, as seen in Figure 1.

While there is still much that needs to be learned about sports-related concussions and their long term effects on athletes, scientists are well on their way to understanding the biomechanics that cause them. The next step is using that knowledge to create better protective headgear and a safer game.

Locations of concussions and their linear accelerations.
Back: Case 13-168.71 g (1 concussion)
Front: Case 12-157.5 g, Case 2- 63.84 g, Case 6- 99.74 g, Case 4- 84.07 g (4 concussions)
Right: Case 11-119.23 g, Case 8-102.39 g (2 concussions)
Top: Case 9-107.07 g, Case 1- 60.51 g, Case 7- 100.36 g, Case 10- 109.88 g , Case 5: 85.10 g, Case 3: 77.68 g (6 concussions)
Location of concussions and their linear accelerations. Modified from Neurosurgery

To learn more, check out these links!

Nine Brains Are Better Than One: An Octopus’ Nervous System

Picture this: Earth has made its first contact with an extraterrestrial species, and, as to be expected, their anatomy and nervous system are entirely different from our own. Rather than having a single brain where all sensory information and motor controls are processed, they have nine brains. Rather than having a rigid skeleton, they have compact arrays of muscle tissue that stiffen and soften when they move, and their many limbs have an infinite number of degrees of freedom. Oh, and they can only breath underwater, too.

What was just described isn’t an alien at all, but actually the complex anatomy belonging to a common octopus, otherwise known as Octopus Vulgaris, and there is a lot we can learn from it. So how does an octopus fully control all eight of its flexible limbs? The answer lies in its partially de-centralized nervous system. When most people think of a nervous system, they think of a single brain sending out messages to move our arms and legs, then gathering information back to process everything we touch, see or hear. For an octopus, though, this process is much more complicated.

Independent Thinkers

Each arm of an octopus is able to control itself semi-independently from the central brain. An octopus has about 500 million neurons in its body, two-thirds of which are distributed amongst its limbs. This means that there are about 40 million neurons in each tentacle. That’s more than two times the number of neurons the average frog has in its entire body! An experiment conducted by German Sumbre et al. showed that even when a disconnected arm was electrically stimulated, it would still move in the same basic patterns of a tentacle being controlled naturally by an octopus. The arm even adapted its movement patterns the same way a still-connected tentacle did when the arm’s environment and initial posture were changed.

There are two columns of images. The left shows an octopus outstretching its arm over the course of 920 seconds. An arrow tracks the movement of a bend in the arm that travels along the arm until it is fully stretched out. The right column shows a single, detached octopus arm outstretching over a similar time frame. The single tentacle follows a similar movement pattern as the original octopus' arm. Another arrow also follows a similar bend that travels along the single arm as it stretches out.
An experiment shows that an electrically stimulated octopus arm (right), when detached from its central nervous system , will still move in the same basic patterns as an arm naturally controlled by an octopus (left). Image modified from G. Sumbre, Science Magazine.

Master Delegaters

So how does this partially de-centralized nervous system work? The octopus does, in fact, have a central brain located between its eyes containing about 180 million neurons. This is the part of the nervous system that determines what the octopus wants or needs, such as if it needs to search for food. These are sent as messages through groupings of neurons. Commands like “search for food” are then received by each of the tentacles, who all have their own smaller, independent brains. With these commands in mind, each tentacle gathers its own sensory and position data, processes it, and then issues its own commands on how to move by stiffening or relaxing different parts of the arm, all without consulting the central brain upstairs. As the tentacle moves, it keeps collecting and processing sensory information, and any relevant information, such as the location of food, gets sent back to the central brain to make larger decisions.

Beyond the Octopus

There is still a lot left unknown about how exactly an octopus’ nervous system functions. However, new and upcoming fields such as soft robotics and artificial intelligence are starting to look towards the opportunity for innovation that octopuses present. Learn more about how the anatomy of an octopus is being applied to science and technology here and here!

Further Reading


Sumbre, G. “Control of Octopus Arm Extension by a Peripheral Motor Program.” Science, vol. 293, no. 5536, Sept. 2001, pp. 1845–48. (Crossref), doi:10.1126/science.1060976.

Zullo, L., Eichenstein, H., Maiole, F. et al. Motor control pathways in the nervous system of Octopus vulgaris arm. J Comp Physiol A 205, 271–279 (2019).

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Attention Deficit Handwriting Details: The Effects of ADHD on Handwriting

Imagine you’re in college and struggling to focus during a boring lecture with a monotone professor. Now imagine that same struggle, but every little thing around you is a distraction making it difficult to focus on everyday tasks, not just the boring ones. Individuals with Attention Deficit Hyperactive Disorder (ADHD) battle this inability to focus constantly. Yet for individuals with ADHD, about 1 in 20 children (basically a lot of children), the struggle does not stop there: these individuals who struggle to focus often exhibit fine motor coordination impairments as well.

It just so happens, writing requires fine-motor coordination. Even with computers and evolving technology, writing is a necessary skill used by most individuals throughout their lifetime. It is well-known that when taking notes, you are more likely to retain information when writing notes as opposed to typing them. We have to write when we take exams (hopefully more so once the pandemic is over because I am tired of computer glitches during online exams). We write to communicate different ideas to each other, or even to communicate ideas to future self that we wish to remember.

Writing is still a necessary part of our everyday life, yet when this writing is difficult to read, its effectiveness diminishes. Imagine finally being able to focus enough during that boring class to take notes but not being able to read them. Imagine taking a timed exam but wasting this limited time to ensure the handwritten answers are legible. When compared, the handwriting of most individuals with ADHD is worse than individuals without this disorder.

There are three subtypes of ADHD: individuals are primarily hyperactive, primarily inattentive, or combined type (both hyperactive and inattentive). Individuals with ADHD who are primarily hyperactive are more likely to write faster with shorter strokes and to write more efficiently. On the other hand, individuals with ADHD who are primarily inattentive write with inconsistent letter sizes and spacing between the letters, along with diminished legibility. These individuals will exhibit this inconsistency in their writing due to a greater variability in stroke sizes.

Image of the handwriting with inconsistent letter sizes and spacing. There are 6 letters circled out of 10 letters. The letters are circled because they are illegible and it is difficult to know what the letters are supposed to be. The four letters not circled are: t, v, x, y.
Image of the handwriting with inconsistent letter sizes and spacing, along with illegibility of letters circled.

Individuals with combined type ADHD experience an inner battle between hyperactivity and inattentiveness, resulting in faster, more efficient writing at the expense of accuracy and legibility of their handwriting. Interestingly, these individuals on Methylphenidate, a stimulant used to treat ADHD symptoms, tend to write in the complete opposite fashion: the quality of their handwriting improves while the speed diminishes. Since the illegibility of the combined type ADHD individual’s handwriting is affected by their inattentiveness, the improved handwriting quality is due to the increased focus provided by this stimulant.

It is believed that the handwriting of primarily inattentive and combined typed individuals are the results of a form of Dysmetria. Dysmetria is a lack of coordination between movements, which would result in the irregular handwriting due to an under or overshoot of the desired writing size. These individuals are unable to process the information that they receive fast enough to generate the desired response.

While primarily hyperactive individuals tend to write faster and more efficiently, their handwriting does not necessarily differ from individuals without ADHD. On the other hand, the difference in quality of handwriting in individuals with ADHD compared to individuals without is more prominent in those with primarily inattentive or combined typed ADHD. There are many individuals out there who struggle with ADHD and are at a disadvantage because of this. Accommodations for individuals with ADHD should go beyond accommodating inattentiveness and hyperactivity since difficulties are only the root of them problem that stem into more obstacles such as reduced writing quality.


Rebecca A. Langmaid, Nicole Papadopoulos, Beth P. Johnson, James G. Phillips, Nicole J. Rinehart. Handwriting in Children With ADHD. Journal of Attention Disorders. Original Research.

Marie Brossard-Racine, Michael Shevell, Laurie Snider, Stacey Ageronioti Bélanger, Marilyse Julien, Annette Majnemer. Persistent Handwriting Difficulties in Children With ADHD After Treatment With Stimulant Medication. Journal of Attention Disorders. Original Research

Javier Fenollar-Cortes, Ana Gallego-Martinez, Luis J. Fuentes. The Role of Inattention and Hyperactivity/Impulsivity in the Fine Motor Coordination in Children with ADHD. Research in Developmental Disabilities. Original Research.