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!

https://pubmed.ncbi.nlm.nih.gov/23199422/

https://pubmed.ncbi.nlm.nih.gov/23299827/

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

Sources

Sumbre, G. “Control of Octopus Arm Extension by a Peripheral Motor Program.” Science, vol. 293, no. 5536, Sept. 2001, pp. 1845–48. DOI.org (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). https://doi.org/10.1007/s00359-019-01332-6

Levy, Guy, et al. “Arm Coordination in Octopus Crawling Involves Unique Motor Control Strategies.” Current Biology, vol. 25, no. 9, May 2015, pp. 1195–200. DOI.org (Crossref), doi:10.1016/j.cub.2015.02.064.

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.
Source: https://doi.org/10.1177/0883073807309244


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.

Sources

Rebecca A. Langmaid, Nicole Papadopoulos, Beth P. Johnson, James G. Phillips, Nicole J. Rinehart. Handwriting in Children With ADHD. Journal of Attention Disorders. https://doi.org/10.1177/1087054711434154. 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. https://doi.org/10.1177/1087054712461936. 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. https://doi.org/10.1016/j.ridd.2017.08.003. Original Research.

“Whirlybirds, helicopters, and Maple seeds”

Photo by Annette Meyer on Pixabay – Samaras of a Japanese Maple, with the seeds inside.

As Maple trees shed their fruits, it is hard not to be captivated by the view and stare in admiration. The free fall of maple seeds is simply graceful. Commonly referred to as helicopters, samaras are the fruit of Maple trees. Inside of each fruit one can find seeds that are used by the parent plant to produce new ones. The nickname helicopter refers to the similarity that exists between its motion as it falls to the ground and that of a helicopter. Indeed, a remarkable aspect of the samaras is the behavior they display as they fall. As the fruit of the Maple seed descends to the ground, it performs a rotating motion that mimics the rotor blade of helicopters in unpowered descent, a behavior that has intrigued scientists and has been the subject of many studies. The auto-gyration motion and flight mechanics of the samaras have been observed in order to explain why and how the fruit rotates on itself as it leaves the tree.

Importance of understanding the whirling motion of Samaras:

The use of seeds to produce new plants is called seed dispersal. Since trees are unable to move, they rely on different means for the dispersal of their seeds, such as the wind, water, animal, or human beings. Samaras being carried away by the wind are an example of wind dispersal. Seed dispersal is important for the survival of species. It allows the plant to spread in its environment. By allowing the seeds to fall at great distances from the parent plant, decreases the chances of interference of the growth of new plants with the development of the parent plant and allows it to colonize new environments. Studying the flight of samaras helps understand how this process can be enhanced. However, not only does it help with seed dispersal, but it may also have applications that can help advance the field of aviation and the conception of flying devices. (Sang Joon Lee et Al. 2014)

Flight Mechanics:

There are two principal categories of seeds that have the ability to use oncoming winds to travel away from the parent plant, pappose seeds, and winged seeds. Maple seeds fall within the second one. As the name indicates, winged seeds tend to have appendages that resemble wings and act as such. While pappose seeds use draft force to maintain their flight, winged seeds rely on lift force. While they share common traits, not all winged seeds rotate. The rotation of samaras is due to the location of its center of gravity which is found near the terminal end of the wings. The wings of the seeds of the Maple tree generate a stable leading-edge vortex (LEV) which accounts for the lift force slowing down the descent. Note that an LEV is a type of airflow that is halfway between a steady and a turbulent flow. Upon being detached from the tree and is released into the air, the very shape of the wing initiates the stable vortex. The mechanism used by samaras has been identified to be similar to the LEVs of insects such as flower flies. 

Packing a punch: Does strength indicate boxing performance?

Every sport has a different “ideal” body type, which is largely dictated by the muscle groups it focuses on training. Swimmers prioritize developing the muscles in their shoulders and backs, which allows them to propel themselves through the water with their arms. On the other hand, runners prioritize the hamstrings and quads in their legs, which allows them to generate greater force when pushing off of the ground. So, what is the ideal body type for boxing? Strength is clearly important when punching an opponent, but is it even the most important factor in boxing performance? Should either upper- or lower-body strength be prioritized over the other?

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Photo by Bradley Popkin for Men’s Journal.

The overall goal in boxing is to either knock out your opponent with a single punch or land more punches in the scoring area than your opponent. One of the best ways to achieve the latter is by wearing down your opponent with powerful strikes to reduce their ability to retaliate. Therefore, hitting your opponent, and hitting them hard, is crucial within the sport of boxing. 

First, let’s take a look at upper-body strength. Boxers execute punches by using muscular force to accelerate their arms, so it is easy to assume that arm strength is the most important factor in punch performance. However, this may not be the case. One of the most common upper-body strength exercises is the bench press, and research has shown that there is no significant correlation between the maximum weight a boxer can bench press and the force they deliver in a punch. While this may be surprising, the relationship between upper-body strength and punching actually comes down to speed rather than force. Based on data from both professional and elite amateur boxers, the maximum speed at which a boxer can bench press is indicative of improved punch performance. More specifically, professional boxers showed a strong relationship between the maximum velocity of their bench press and maximum punch velocity of their rear, or dominant, arm. 

If upper-body strength does not indicate punch force, then does lower-body strength? A study of amateur boxers found a positive correlation between maximum punch force and lower-body strength measures, including countermovement jump (see video below) and isometric midthigh pull. In contrast to the upper-body exercises, the maximum force generated in lower-body exercises is more important for increasing maximum punch force than the speed at which the exercise is completed.

Plot of countermovement jump force in Newtons versus punch force in Newtons. The data has a correlation of 0.683 and a p-value of less than 0.001. Plot of isometric midthigh pull force in Newtons versus punch force in Newtons. The data has a correlation of 0.680 and a p-value of less than 0.001.
Plots showing a strong, positive correlation between punch force and the lower-body strength exercises, countermovement jump, CMJ, (left) and isometric midthigh pull, IMTP, (right). Adapted from “Relationships Between Punch Impact Force and Upper- and Lower-Body Muscular Strength and Power in Highly Trained Amateur Boxers” by Emily C. Dunn, et al.
Video of how to execute the countermovement jump test by Training & Testing.
Kinetic Chain: Force is generated from the floor and transferred from foot to fist. Leg force, hip and torso rotation are key. Arrows show movement of force from foot, through the body, to fist.
Graphic of Kinetic Chain in a boxer from Boxing News.

When executing a punch, a boxer gains forward momentum by pushing off of the ground with their legs. Through a kinetic chain, force moves through a boxer’s body from the floor to the foot, then through the legs and torso, and finally, to the arm and hand. This phenomenon is what explains why lower-body force is crucial to a boxer’s maximum punch force. 

So, what does this all mean? How should boxers train in order to improve their punching performance? Most importantly, boxers should focus on their lower-body strength, as it is the most direct indicator of maximum punch force. While lower-body strength should be a primary training goal, exercising muscles within the upper-body, specifically while focusing on the speed of the movements, will also likely improve overall punch performance. We now know that developing strength is clearly beneficial in improving a boxer’s punch; however, brute force alone does not win a fight. Boxers should develop correct boxing technique through methods such as those suggested in this article, which will allow them to implement their new strength in the most effective manner.    

For additional information on the impact of strength on athletic performance click here and here.

Living Off Balance

Person walking in woods, balancing on a fallen tree

Imagine yourself walking at a normal pace down the sidewalk. Maybe you are on your way to class. The sidewalk has a little bit of a tilt causing your left foot to be higher than the right as it plants on the ground. Imagine how your body may compensate after a few minutes of walking on this path. We have all walked on uneven ground and began to feel the effects with sore knees or hips. But what if you felt this same way all the time even on perfectly flat terrain? This is the reality for those with leg length discrepancies.

Leg Length Discrepancy

A leg length discrepancy (LLD) is any difference in your legs compared to one another. This can be as small as a few millimeters or as large as a few centimeters. Leg length discrepancies can be caused by a number of things including genetics, trauma, or disease. Leg length discrepancies can be categorized in two ways; real and apparent LLD. Real leg length discrepancies are one in which the bony structures are measured to be two different lengths. Apparent leg length discrepancies are caused by other factors such as muscle or joint tightness making the limbs appear two different lengths.

Image depicting pelvic tilt when leg length discrepancy is present
Pelvic tilt caused by real leg length discrepancy

Hopping Along

The actual significance of a LLD on posture and gait depends heavily on the magnitude of the discrepancy. It is highly debated by researchers if a LLD of less than 2-3cm has physical effects on the body and if symptoms a patient is experiencing are due to another cause. R.K. Mahar and R.L. Kirby at Dalhousie University performed a study in which people without a LLD, asking them to stand on blocks simulating a real leg length discrepancy, the researchers saw a misalignment of the hips, an increase in knee flexion and a shift in the center of gravity.

In contrast D.C. Reid conducted a study for those with actual LLD and many did not complain of pain or feeling off balance and chose to not use corrective devices. The body is able to compensate for the difference over time to minimize the displacement of the center of mass of the body. It was also seen in a study done by Gross that athletes are more likely to correct smaller LLD than the average person due to the increased loads experienced during their activity.

Lift is placed in the sole of the shoe to correct moderate LLD
Shoe lift place in sole used to correct LLD

Fix it

For people that are experiencing pain because of the difference there are several ways to reduce the pain. For small discrepancies (less than 1cm) inserts can be placed into the shoe to even out the hips. For differences between 1cm and about 5cm a lift can be placed in the sole of the shoe for the same reason as the inserts. For some special cases or discrepancies larger than 5cm corrective surgery to lengthen or shorten the limb can be performed, but this is often used as a last resort.

Do Hammer-Shaped Heads Help Sharks Swim?

With their sandpaper skin, cartilage skeleton, electroreceptive sensors, and rows of dangerous teeth, sharks fascinate many people. However, even within this distinctive group the hammerhead sharks that make up the Sphyrnidae family have attracted a special attention due to the unusual shapes of their namesake heads, called cephalofoils. Several evolutionary benefits of the cephalofoil have been proposed by researchers. The wide hammer-shaped head may allow the shark to house more sensory receptors in its snout, to bludgeon prey, and to move and maneuver through the water more easily. Here we will address the question posed by the third theory: Does the cephalofoil found on hammerhead sharks provide an advantage in moving and maneuvering underwater?

Great Hammerhead Shark
Image of “Great Hammerhead Shark” by Wendell Reed showing a close-up of the cephalofoil. https://search.creativecommons.org/photos/3fa18a9b-9085-4867-93e1-15a88b01389b

Many advancements in the aviation and nautical industries have been developed from the study of sea creatures. There is certainly some potential that research into the mobility of sharks could someday be used as inspiration to advance locomotion technologies. In addition, a deeper understanding of the physiology and behavior of hammerhead sharks could help us to better preserve their habitat and species from endangerment – a crisis which some of them are already facing.

The theory that the cephalofoil provides advantages in forward swimming to hammerhead sharks relies on it supplying some hydrodynamic lift similar to the wing of an aircraft. Aircraft wings provide lift partly by creating a pressure difference between the top and bottom wing surfaces. An area of higher pressure on the bottom surface of a wing will generate upward lift. One study by Matthew Gaylord, Eric Blades, and Glenn Parsons applied a derivation of the Navier-Stokes equations – a set of partial differential equations for analyzing fluid flow – to water flow around digitized models of the heads of the eight most common species of hammerhead. It was found that in level, forward swimming there was some pressure differential that developed between the dorsal (top) and ventral (bottom) surfaces of the cephalofoil, but for each species it was very small and often in the direction to produce negative lift. The drag coefficients of the cephalofoil of each hammerhead species were then calculated and shown to increase as the size of the cephalofoil increased. The drag created by a cephalofoil was always much greater than the drags caused by the heads of a control group of non-hammerhead Carcharhinidae sharks.

Images of the pressure contours at zero angle of attack on the dorsal (top image) and ventral (bottom image) sides of the cephalofoil. The eight leftmost sharks are the hammerheads. Taken from Gaylord, Blades, Parsons.

However, the same study showed that the pressure difference between either surface of the cephalofoil did significantly increase in some species if the shark raised or lowered its head. This extra hydrodynamic force caused by the pressure differential at nonzero angles of attack would help the shark to turn its head up or down very quickly. This more explosive maneuverability was particularly present in the hammerheads that commonly feed on fish and less present in the species that feed predominantly on slower bottom dwellers. Another study by Stephen Kajiura, Jesica Forni, and Adam Summers theorized that the unbalanced, front-heavy cephalofoil may provide extra stability during tight turns by preventing banking. The unbalanced head would create a moment – or torque – to counteract the force from the tail that causes most sharks to roll into their turns. Not banking around turns could be important to some hammerhead sharks that often swim so close to the seafloor that banking into a turn could cause their head or fins to bump into the floor. It is likely that hammerhead sharks evolved the cephalofoil at least in part to provide more explosive and stable maneuvering.

Featured image “Hammerhead Shark” by bocagrandelasvegas.

Dolphin Magic or Dolphin Muscle?

Because of the film Bee Movie, many people at one point were intrigued by the idea that bumblebees should not physically be able to fly due to their large bodies and tiny wings. But, they fly anyway. Technology is advanced enough to study bee wing movement and determine that they produce enough lift to allow them to fly, disproving the previous notion. Similarly, Gray’s Paradox for a long time inferred that dolphins should not be able to swim nearly as fast as they do. But, they still consistently swim at speeds over twenty miles per hour. It was not until recent history that advancements allowed researchers to determine why they are able to reach such high speeds.

Gray’s Paradox

All the way back in 1936, Sir James Gray observed the high speeds dolphins could reach in the ocean. He calculated an approximation of the amount of power the dolphins would need to produce to sustain these speeds, based on the drag force on the dolphin as it travels through the water. Gray compared this to the amount of power he expected the dolphin to be able to produce. In order to compute this, Gray used muscle power data from oarsmen. When he compared the muscle mass of these oarsmen compared to dolphins, he determined that the power dolphins could produce was only about one seventh what was needed to travel at the high speeds of which they are capable.

Force Diagram, showing that the same forces that the swimming mammal applies to water are applied back on it. Allows observation of max speed to determine these forces.
This diagram shows that the drag force, D, thrust force, T, and net axial force, Fx, must be equal for the swimmer and the fluid. The lateral velocity, u, can be used to determine the resulting drag force, allowing researchers to estimate how much thrust is needed. Credit: [2]

And now we have arrived at Gray’s Paradox. What allows dolphins to move so quickly? To Gray and other researchers for most of a century, this was a mystery. If the assumptions they had made were correct, that would mean dolphins have some way of travelling through water more efficiently than was thought to be possible. This sparked a large amount of speculation into how dolphin skin could reduce the drag force of the water, which was originally believed to be the way Gray’s Paradox would be resolved.

Answering Questions while Creating More

Finally in 2008, Timothy Wei’s research team was able to definitively disprove Gray’s Paradox. He set up an experiment that would allow the force that dolphins exert to be measured. This mainly consisted of having dolphins swim through a curtain of bubbles in a tank. By recording at high resolution the movement of these bubbles as the dolphins swam by, the researchers determined the speed of the water around the dolphin as it traveled. With this information, Wei’s team showed that dolphins are able to produce over 300 pounds of force at one moment, and over longer periods of time 200 pounds of force. This is approximately ten times more force than Gray estimated.

Wei’s findings resolve Gray’s paradox by showing that dolphins have the ability to produce sufficient power from their tail movement to overcome the strong drag force of the water as they move at high speeds. However, this does not explain how dolphins produce so much power with their amount of muscle mass, which is still being examined. One idea is that this is caused by anaerobic muscle fibers that behave in different ways than in humans, and allow more power to be generated than Gray expected.

Future Plans: Investigating Force Generation

Timothy Wei plans to continue examining force generation in the swimming of other marine animals. This has the potential to provide more understanding of how marine animals evolved in their swimming aptitude. On the level of microbiology, this research could improve understanding of how dolphin and other animal muscles can perform such high levels of power generation over sustained periods of time.

Additional Reading and Sources

Arthritis is NOT Just For The Elderly: Early Signs Of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that, according to the Arthritis Foundation, affects 1.5 million people in the US. Women are 3 times more likely to develop RA and are usually diagnosed between ages 30 and 60, while men are rarely diagnosed before the age of 45 . Unlike osteoarthritis which is caused by wear and tear on joint cartilage over time, RA is caused by an overactive immune system that triggers unnecessary inflammation responses. One effect of this is that the body attacks its own joints causing swelling, stiffness, and chronic joint pain as well as irreversible damage. This limits joint mobility and decreases the quality of life for those impacted by it, especially those diagnosed as children or young adults.

This disease cannot be cured but treatments like medicine or dietary/ lifestyle changes are most effective when diagnosis happens early. When joint damage occurs it is irreversible, meaning the only treatment option is surgery. The joints most commonly affected in the early stages of this disease are finger joints which are usually the first sign of inflammation and will be the focus of this article. The image below shows the progression of finger joint damage in a patient with RA starting with no damage (a) to severe damage (c).

As an RA patient, a typical visit to your doctor would always include a pain/inflammation assessment. With a focus is on early stages of RA, fingers and hands would be the most important areas to look at. Each joint of focus would be felt by your doctor to check for swelling and tenderness, but the most important aspect is the patient’s self-assessment of inflammation and pain. It is important for patients to accurately assess their pain and mobility in order to find a medicine or treatment that works effectively. This was the focus of a study that was conducted on 52 RA patients (33 women and 19 men) which used a variety of tests in an attempt to quantify arthritis damage and compare it to the predictions made my patients.


The first test looked at range of motion for fingers flexed (in a fist) and extended (straightened). The next test measured grip strength in different positions like using a pencil, opening a jar or turning a key by using a device that measured the force produced by the hand in each position. Stiffness was measured visually, and pain levels were also recorded, but it should be noted that pain cannot accurately be quantified because pain tolerances vary among patients. The result of this study was that the patients predictions on grip strength and stiffness best correlated to the real results and were therefore the best predictors of hand function. This means that patient reports of strength and stiffness are the most accurate and helpful to be used by doctors when choosing medications or treatment plans.


Because joint damage from RA cannot be reversed, surgery is usually the only option to repair damaged joints, and even surgery will not bring back full mobility. Because RA treatments (both medicines and surgery options) are still very new there isn’t widely available or reliable data on the impact of hand surgery. Additionally, with the increasing use of the newer class of biologic drugs there has been a noticeable decrease in damage to the synovial tissue (the specialized tissue between the bones in any given joint) and the need for hand surgery has significantly decreased because of this. Overall, a variety of surgeries are available and there is almost always a tradeoff between mobility, vanity and elimination of pain. It is up to the patient, doctor, and surgeon to decide the best treatment option.

Overall, it is important to listen to your body and look out for early signs of RA to avoid lasting joint damage. This is especially important if you have a family history of RA. Early symptoms include, redness, pain, stiffness and swelling at joints, a lack of muscle strength, decreased range of motion/mobility, and even unexplained fatigue or fever.


References and Further Reading