Runner’s Knee: Knee Pain Isn’t Just for Old People

Don’t knee problems only plague old people or people who have run for a lifetime? I questioned this when, for the seventh time in a row, my knee was hurting only a mile and a half into my run. I’m too young for this! However, a plethora of information suggests that knee pain is perhaps not so uncommon in younger runners and athletes as I thought.

The American Family Physican published an article detailing one form of knee injury informally called “Runner’s Knee”. A shockingly high number, between 16 and 25 percent, of running related injuries fall into this categorization. Medically termed patellofemoral pain syndrome (PFPS), the ailment manifests in pain or stiffness in the knee, particularly when bent in load-bearing scenarios such as walking, running, jumping, or squatting. The patellar region experiences shocking loads even in the day to day: in walking alone the region experiences up to a half the person’s body weight while in an activity like squatting it can experience up to seven times one’s body weight. Often the pain is hard to pinpoint but occurs in or around the front of the knee within a circular range. It can inhibit or put a stop to training, however, if addressed early on, can often be healed or corrected much more quickly.

an animated image of a runner mid-stride with the pain region for patellofemoral pain syndrome highlighted
Photo by www.scientificanimations.com from Wikimedia Commons

In PFPS, the patella (the kneecap) moves abnormally within the groove on the end of the femur (called the femoral trochlear groove) due to imbalanced or unusual loads on the joint. This results in over-stressing the joint and causing pain. Several possible causes exist for PFPS; here, I will focus on three of most commonly cited: increased intensity of activity, weak hip muscles, and overpronation.

an image of the muscular and skeletal structure of the knee, including the patella
Photo by BruceBlaus on Wikimedia Commons

Increased Activity

One review explored that women are more likely to suffer from PFPS. In this study they saw that women of higher activity levels were not necessarily more likely to experience pain due to PFPS than women who had a lower activity level. Rather, a substantial increase in activity level seemed to be the cause of pain. Therefore, more than overuse of muscles or joints, PFPS often develops with increased amounts of activity, or temporary overuse, such that the body is not prepared to handle the increased and repetitive forces on the knee.

Weakness in Hip Muscle Strength 

This study shows that lower extremity mechanics and motion can be affected by hip strength. For example, inward rotation of the hip can be lessened through strengthening of hip muscles that counteract that rotation. With less internal hip rotation, the knee abduction moment (the tendency of the knee, due to reaction forces from the ground, to rotate  inward and away from the balanced midline of the knee joint) decreased which often resulted in less stress in the knee. Therefore, the review suggests that strengthening hip muscles can lower the patellofemoral joint stress and help treat PFPS. 

Overpronation

Pronation refers to the natural movement of one’s foot and ankle slightly inward while stepping. When the ankle rotates too far inwards, it is called overpronation. Overpronation can lead to further improper structural alignment in the lower body as the tibia rotates improperly in response to the ankle rotation. The tibia’s rotation then disrupts the natural movement of the patellar joint and can contribute to PFPS. In many cases, overpronation can be corrected through use of orthotic shoe inserts that prevent the over-rotation of the foot and ankle.

In conclusion, while we may often associate knee problems with older people or arthritis, PFPS affects many athletes, particularly runners, at any age. Often, proper training programs that do not accelerate activity too quickly, strengthening exercises that focus on the hip muscles, and proper, overpronation-correcting footwear can treat or prevent an individual from being affected by PFPS. Check out some strengthening exercises here.

The Shoulder: Super Joint or Super Hazard?

The shoulder joint is one of the most incredible joints in the human body.  Humans have been recorded throwing 100+ mph fastballs, pressing nearly 600lbs overhead, and performing incredible gymnastics moves. The shoulder is a ball-and-socket joint, and it is by far the most mobile joint in the human body.  But this great range of motion comes at the price of being the most unstable joint in the body.

The contact between the shoulder blade and the humerus (upper arm) is analogous to the contact between a golf ball and golf tee.  A golf ball is perched precariously on top of a tee, and can be removed from its resting place with very little force.  Thankfully, the shoulder joint is a bit more complex than a golf tee, giving it more stability.  However, it is still very weak in relation to the rest of the human body, as it is only held together by the four, small rotator cuff muscles, the glenoid labrum, the biceps tendon, and several ligaments.

graphic of a shoulder joint with muscles, tendons, and bones labelled
Image from Wikipedia

One of the most common shoulder injuries is a shoulder dislocation.   This injury occurs about 200,000 times per year.  This injury occurs most often in men in their 20s and in men and women above age 60.  The younger group sustains this injury most often from a violent incident, either from a sports injury or a motor vehicle accident.  The older age group sustains this injury mostly from non-violent injuries, such as falling.  This causes a tear in the labrum, resulting in future instability.

image showing the difference between a healthy labrum and a torn labrum
Image from Huang Orthopaedics

The labrum is a cartilaginous ridge around the joint that adds stability by creating a seal between the humerus and shoulder blade.  Returning to the golf ball analogy, the labrum is like a rubber ring around the top of the golf tee that helps keep the ball from falling off.  When this is torn, it does not often heal, as there is very little blood flow in the shoulder joint.  This tear remains and makes it more likely for future dislocations to occur.

This lack of stability can be addressed both surgically and non-surgically.  Non-surgically is generally the preferred, but less successful option.  It involves strengthening the shoulder muscles to make up for the lost stability of the labrum.  The rotator cuff muscles as well as other larger muscles are strengthened to compensate for the torn labrum.  While the muscles can help immensely with reducing instability, they cannot always entirely replace the labrum.  If this is the case, surgery can be done to re-attach the labrum and give the shoulder nearly all the stability that it had prior to the tear.

One example of someone who had this surgery and then returned to a near pre-injury level of function is Saints’ quarterback, Drew Brees. Brees suffered a torn labrum and had it repaired with twelve anchors. He then would return to the NFL and become one of the greatest quarterbacks of all time.  He was the MVP of Super Bowl XLIV and is a twelve-time Pro-Bowler.  A labral tear can be devastating, but as can be seen by Brees’ story, it can be overcome. So while the shoulder comes with its fair share of liabilities, it is still one of the most impressive joints in the body.

 

Sources and Further Reading:

The Story of Drew Brees and the ‘1 in 500 Injury’ That Couldn’t Stop His Historic Career

Mayo Clinic – Dislocated Shoulder

Huang Orthopaedics – Shoulder Dislocation and Instability

Teach Me Anatomy – The Shoulder Joint

PMC – Anterior Shoulder Dislocation

Can we 3D print our own skin?

Can you imagine a world where amputees receive replacement limbs which are able to detect temperature and pressure like an actual limb? How about a world where when you get a cut, you can 3D print some of your own skin to patch the wound?

To the average citizen, this might seem like something out of a science fiction movie. To researchers at the Graz University of Technology, the Wake Forest School of Medicine, and the Universidad Carlos III de Madrid, this is a reality that they are helping bring ever closer. Both of these scenarios are discussed in a recent article by Mark Crawford, who investigated the recent breakthroughs in 3D printing human skin and creating sense-sensitive artificial skin.

photograph of an arm reaching into the sky to feel the rain in the palm of their hand
photo by Alex Wong on Unsplash

At the Graz University of Technology, researchers are working on creating an artificial skin that can sense temperature, humidity, and pressure. Currently, artificial skins can measure one sense at best, but with the use of the nanoscale sensors that these researchers are developing, sensing all three at once could be possible. This is achieved through the materials that the nanosensors are created out of: a smart polymer core and a piezoelectric shell. The smart polymer core can detect humidity and temperature through expansion, and the piezoelectric shell detects pressure through an electric signal that is created when pressure is applied. With this technology, prosthetics could be made which could allow the wearer to retain some of their lost senses.

At the Wake Forest School of Medicine, researchers have created a handheld 3D printer which produces human skin. This device could be used to replace skin grafts, as it can apply layers of skin directly onto the wound. Through the use of bioink, this handheld printer can create different types of skin cells. After scanning the wound to see what layers of tissue have been disrupted, it can print the appropriate skin needed to correct the injury.

Photograph of the 3D skin printer created at the Universidad Carlos III de Madrid, which is still in its prototype phase.
modified from Crawford, ASME January 2019

At the Universidad Carlos III de Madrid, researchers are also 3D printing human skin using bioink. They are creating both allogenic and autologous skin to create the optimal skin, which is a combination of the patient’s own cells and cells created from a stock. Although they have managed to print functioning skin in its natural layered state, it is tricky to create the cells in such a way that they do not deteriorate.

It is also tricky to correctly deposit the product. To illustrate, more research needs to be done on the mechanical properties of artificial skin before it could be used on humans. The artificial skin must be able to stretch and react to tension in a similar manner to the real skin it will be connected to. Additionally, researchers must figure out how to safely send the signals the artificial skin is detecting to the brain.

Overall, both advancing artificial skins and 3D printing human skins could largely impact humanity. Even though we have yet to use these skins on people, they are already being used in industries, such as L’Oreal, to limit testing on humans and animals. Already, these skins are being used on robots, as seen in this video, to help prepare the skin for human transplant:

 

Interested in seeing more? Check out some more articles on the advancement of artificial skin from Caltech and Time.

3-D Print a New Leg for Your 4-Legged Friend

3-D printing is a quite exciting technology that has come to light in recent years. The process involves a nozzle much like in a regular inkjet printer that layers material upon material to build up a 3D structure. The printer receives this data from a computer designed file that maps out where the printer should add material. Combine this with filler material that serves to hold everything in its final upright position, and the final product is born, after setting and clearing off the filler. This process has been used to make many different things, from simple objects like phone cases and luggage tags to complex scaffolds used to hold cells for tissue engineering, or as in this post, specific implants for dogs and other animals. The usual types of orthopedic implants that have somewhat of a cookie cutter size distribution for humans do not always fit in dogs or other animals. So, 3-D printing has been employed to create implants used to repair and replace bones in veterinary situations.

Examples of computer-modeled custom implants
Examples of computer-modeled custom implants on dog legs

The most prominent veterinary application for 3-D printed implants is dogs. This is due to their slight differences in body type, even within breeds, that can make finding a pre-sized and pre-made implant difficult to find. One such example of this is a dachshund, named Patches, that received a custom made skull implant after other implants were found to be ineffective or dangerous to her long term health. Patches had a brain tumor, one that grew to a very large size and began encroaching on her eyes. The tumor was successfully removed, but the process involved the removal of large portions of her skull, leaving her brain unprotected. If a preexisting implant were tried, the way it would fit would leave her head vulnerable to an impact, making the implant quite pointless. A 3-D printed implant was made, and old Patches made a full recovery.

The process involves taking a CT scan of the area in question and gaining an understanding as to the layout of the area. This allows designers to make a 3-D model of the implant using a computer, and that model can be printed out using a 3-D printer. In the case of implants, titanium is usually used due to its biocompatibility and great mechanical strength. The implants can be used for surgery and repair, or an array of other applications, even studying the cranial activities of primates. In any case, these exciting new developments in 3-D printing are leading to advancements in the medical and biological fields. So, the next time you fire up you 3-D printer to make a cool-looking hood ornament, know that the same technology is at work, saving lives and giving scientists new knowledge about animals they previously had no good way of studying.

Sources:

<https://www.3dprintingmedia.network/dog-3d-printed-titanium-bone/>

<https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5482398/>

<https://www.nytimes.com/2018/09/25/science/3d-print-dog-skull.html>

How to Shine at Karaoke and Master the Art of Singing

Woman singing with microphone
Photo by Josh Rocklage on Unsplash

Are you tired of going to karaoke with your friends and not being able to master those high notes like singers Whitney Houston or Mariah Carey? While this blog post cannot promise the high quality of those amazing singers, it will demonstrate how through practice you can master the art of singing. To master singing you must first understand the biology and mechanics of your singing voice, so you can learn how to manipulate both to your benefit. This can extend to vocal production and communication studies, but the focus will be singing.

Diagram of vocal system including larynx, vocal cords, trachea
From University Physics Volume 1 on Wikimedia Commons

The vocal anatomy in the human body is composed of vocal chords, the larynx or voice box, trachea, diaphragm muscle, and airflow passages. Vocal chords, commonly referred as vocal folds, are flexible and delicate tissues that can withstand high frequency vibrations. The larynx is a tube in the human neck that holds the vocal chords. The trachea is a long tube that extends from the larynx and passes air to and from the lungs, otherwise known as the windpipe. Lastly, the diaphragm is a large muscle that separates the cavity containing the heart and lungs from the abdominal cavity. These definitions will become useful when discussing the process of singing.

 

Diagram of the respiratory system including the diaphragm, lunch, and trachea
From BruceBlaus on Wikimedia Commons

The organization Learn to Play Music described the biological process involved in singing in a blogpost. As humans inhale, the diaphragms contracts, the lungs expand and draw in air. During exhalation, the diaphragm relaxes, and air exits through the lungs. As air exits the “breath” travels upward through the trachea and vocal chords which begin to vibrate. This vibration leads to the production of sound which is then augmented (made louder) by areas of mouth, throat, and behind the nose. Additionally, these spaces allow the sound by vibration to last longer and affect the tone of a person’s voice. The shape of a person’s mouth, tongue, and lip movements can change the way the sound leaves the mouth by shaping the sound produced.

Music Professor Leigh Carriage at Southern Cross University analyzed how to use biomechanics to improve singing in an article. Singing involves varying pitches, loudness, voice quality (raspy, breathy, clear sounding) which requires control and coordination of muscles. These muscles must be flexible and strong which can be formed by practicing breathing control. To master singing a person needs to control the air pressure in their lungs and use their abdominal muscles to control the air flow. The most efficient way to control this pressure is through repetition or regular singing. This practice would strengthen the vocal system and improves vocal tone and power. Additionally, further expanding the abdomen when inhaling can lead to an increased contraction of the diaphragm. This would allow for more breath support when it comes to changing tone, pitch, or holding a note.

There are many biological and mechanical aspects to singing that can be analyzed to control the singing voice. See two additional readings here and here to learn more. Overall, practicing the control of your breathing during inhalation and exhalation helps master singing. By controlling the air flow, you can improve tone, pitch, and the power behind your voice at karaoke!

 

Check out this cool video!

 

 

What’s more important for athletes training or genetics?

Usain Bolt, Michael Jordan, and Wayne Gretzky are arguably some of the greatest athletes of all time. You watch them on the television breaking record, winning titles or making impossible shots, and you can’t help to wonder, how are they that good? Do they use some secret training method, maybe even a special diet? Possibly, they are genetically gifted? Sports author David Epstein tackles this debate of training versus genetics in his book, “The Sports Gene”. Yes, athletes need to practice to become good, but some are just going to be naturally better than others. If you are 5’6” inches you are going to have to practice dunking a basketball a lot longer than someone who 6’6”. To see how some athletes are naturally better than others lets look at some talented athletes and see what makes them biomechanical specimens. First, we’ll look at Michael Phelps, an American swimmer who not only has multiple world records but also the most decorated Olympian of all time with 28 Olympic medals.

 

For swimmers, biomechanics have found the ideal body for performance. Body features that have been found helpful for swimming is a long torso and long arms.  The long torso reduces the drag on the swimmer and long arms allow for more powerful strokes. Michael Phelps’, who is 6’4”, has the torso proportions of someone who is 6’8” and the leg proportions of someone who is 5’9”, giving him an extremely high torso-to-leg ratio. Not only is Phelps’ torso long, but he also has a long wingspan, measured at 6’7”. Along with Phelps’ unreal proportions, his feet are another huge advantage when it comes to swimming. His size 14 feet help place more force into the water when he kicks. This is a benefit because 90% of a swimmer’s thrust comes from their feet. His ankles also hyperextend 15-degree when he kicks, creating more force. Biomechanically, Michael Phelps’s is a walking fish.

Modified from Hart Blenkinsop, Michael Phelps: The man who was built to be a swimmer 2014

You might be wondering, what would happen if you took someone who has trained to mastery and put them up against someone who is just perfectly gifted. David Epstein mentions this scenario in his book a battle between training and genetics. In the 2007 world high jump final, there are two jumpers left, Stefan Holm and Donald Thomas. Stefan Holm, has a personal best of 7’10.5”, only 2 inches off the world record. Holm has been training most of his life, since he was a child and even won the previous Olympic High Jump final. He is also 5’10” tall, which is very small for a high jumper. Donald Thomas, has a personal best of 7’8.5”. Thomas, on the other hand, is 6’3” and has been jumping for a little over a year and had started high jumping because of a bet with a friend. The two finish the completion and Thomas won clearing a 7’8.5” bar. Even though Holm’s technique was near perfect, Thomas just had the athletic edge. Being taller, Thomas already had a higher center of gravity meaning he had to travel less distance to get over the bar. Thomas also had much longer legs and Achilles tendon. This allows him to store and transfer much more energy into a jump. Thomas was just made to win.

 

For more information:

Michael Phelps: The man who was built to be a swimmer

Nature or Nurture?

Cause and Management of Stretch Marks

Stretch marks. How are they caused? Can they even be treated?

Stretch marks can happen to anyone, of any age, so these questions are important to many. In short, our skin is made up of both collagen and elastin, two elements that support and shape our skin through their natural elasticity. This elasticity, however, does have its limits. And when that breaking point is reached, the collagen and elastin rupture, leaving behind scars many know well – a stretch mark.

Difference between normal skin tissue and stretch mark tissue
From Ud-Din, McGeorge, and Bayat, Journal of the European Academy of Dermatology and Venereology 2015

Stretch marks are caused when skin expands or shrinks at a more rapid pace than the collagen and elastin can accommodate, resulting typically in raised scars that can appear rather inflamed at first. Over time, however, these stretch marks may fade, nearly matching one’s natural skin tone, and usually fall below the surface of the skin. This results in the feeling of a slight indentation when touching older stretch marks.

Like all scars, stretch marks are permanent. But this does not mean that they cannot be treated. There are many treatments available to diminish the visual effect of a stretch mark; not all of them are effective, and some seem not to work at all.

Collagen’s elasticity is controlled by the body’s  cortisone levels, which are commonly associated with episodes of high stress. Basically, heightened cortisone production may decrease the skin elasticity, suggesting that reducing one’s stress may be the most cost-effective and cheap treatment for stretch marks.

Researchers S. Ud-Din, D. McGeorge, and A. Bayat put these post-stretch mark treatments to the test in their paper, focusing on three topical treatment categories – marketed skin creams and oils, over-the-counter home remedies, and prescription medicines and dermatologist procedures.

These topical treatment methods are mainly marketed at increasing collagen production with both hydrating and anti-inflammatory traits. Ultimately, testing yielded mixed results about the efficacy of these treatments. Since participants both massaged their scars and used a topical treatment, the observed improvements to stretch mark appearance could be tied to either of these. Ultimately, however, the researchers did conclude that the age of the scar plays a role in treatment effectiveness, as younger, newer scars were more responsive to treatments.

Beyond these topical treatment methods tested, there are many other dermatological procedures designed to reduce the appearance of stretch marks, including chemical peels, laser therapy, and microdermabrasion. Chemical peels and microdermabrasion focus on removing layers of skin to expose new, non-scarred tissue underneath the stretch mark. And laser therapies are divided into two categories: those that stimulate collagen production and those that promote melanin production (so that the scar tissue matches the natural skin). While these dermatologist procedures can be more effective than the topically applied treatments, they are often expensive and are not guaranteed to be effective. Additionally, dermatologists often combine several procedures, eliminating this treatment for those with cost constraints.

All in all, there are no sure-fire ways to prevent stretch marks, but certain practices do demonstrate that one can prevent stretch marks or at least lessen their appearance fairly cheaply and effectively without any of the products and procedures detailed above. By maintaining a healthy weight, one may avoid the rapid weight loss or gain commonly associated with stretch marks.

For more information, check out these articles on Healthline and AAD.

The Study of Snoring is Anything but Boring

Here we take a deeper look about that noise that plagues some of our family members, our roommates…or even ourselves!

Elderly man sitting in the sun, asleep with head back and mouth open.
Photo by Stephen Oliver on Unsplash

What Causes You to Snore in the First Place?

The human upper airway contains anatomical parts that are membranous, meaning they lack support from cartilage. Some parts include the tongue, the soft palate, and the tonsillar pillars. A lack of cartilaginous support enables these parts of the airway to be susceptible to vibrations.

Anatomical diagram of the human upper airway.
Modified from Huang, Quinn, Ellis, and Williams, “Biomechanics of Snoring,” from Endeavor, 1995.

During sleep the upper airway muscles relax and cause the size of the airway space to decrease, resulting in airflow limitation and turbulence.

Whenever we inhale, the turbulent flow through the relaxed airway causes those membranous structures to vibrate and produce a sound most commonly known as snoring.

A Brief Mechanical Explanation of Snoring

Examining snoring in the view of mechanical systems, respiratory noise is created by the oscillation of the upper airway with the air passing through it. This oscillation is indicative of an issue with flow instability (turbulent flow) over a flexible structure (the relaxed airway).

An experiment was created to model the movement of the soft palate during snoring, where a piece of wood was used to simulate the hard palate and a piece of leather simulated the soft palate. The leather and wood were attached to each other inside of a rigid tube that was connected to a pump (meant to model the lung inspiration).

During inspiration, the leather flap oscillated until it reached its full amplitude. Upon reaching the maximum amplitude, the leather flap hit the wall of the tube and created a noise known as palatal “flutter”. This palatal flutter is the most common method of noise production in humans: snoring.

Is Snoring Something to Be Concerned About?

Young woman waking up in the morning, appearing tired.
Photo by Kinga Cichewicz on Unsplash

Approximately 44% of men and 28% of women are habitual snorers.

Snoring can be a symptom of obstructive sleep apnea, a condition distinguished by snoring and breathing that is labored by repetitive and obstructive gasps.

The fragmented sleep resulting from sleep apnea can lead to decreased energy and poor attention and concentration. Sleep apnea can also be related to vascular issues like hypertension and its prevalence appears to increase in people over 65 years of age.

What Are Some Remedies to Snoring?

Remedies for snoring range from noninvasive devices to invasive surgical procedures.

The surgical option to remedy snoring involves removing a portion of the vibratory tissue from the back of the upper airway. For those people wanting to avoid surgery, non-invasive solutions include the use of nasal strips to lift and open the nasal passages; experimenting with sleep positions other than sleeping on the back; or using oral appliances and nasal continuous positive airway pressure (nCPAP) to prevent the tongue and soft palate from collapsing into the upper airway. Losing weight, avoiding smoking and alcohol can also help to reduce snoring.

There are also resources for snoring in kids, as well as additional home remedies and surgical information regarding snoring.

Below is a great animated video which gives an introductory explanation to snoring.

The Ship of Pearl – Jet Propulsion in the Chambered Nautilus

In the aptly titled poem The Chambered Nautilus, Oliver Wendell Holmes Sr. praises the eponymous cephalopod for its elegant shape and vibrant colors. The ship of pearl, as Wendell calls it, might not be the swiftest vessel; but Thomas R. Neil and Graham N. Askew’s research indicates that the chambered nautilus might be among the most energy efficient ships in the seven seas.

The Nautilus pompilius is constantly moving to depths up to 700 m. At such depths, oxygen concentration decreases significantly: only 30% of that available at the surface. In such harsh environments, the nautilus must find a way to use its oxygen reservoir most efficiently while still being able to carry out metabolic functions. As such, the nautilus has adapted to use jet propulsion in a most efficient manner.

Jet propulsion mechanism of the chambered nautilus
modified from Neil & Askew, Royal Society Open Science (2018)

Jet propulsion in the nautilus is achieved by the simultaneous contraction of the head retractor and funnel muscles (shown in diagram above). The compression of the mantle cavity causes a pressure difference with its surroundings, resulting in a jet of water being expelled from the mantle cavity via the funnel. The nautilus uses its flexible funnel to control its swimming direction as shown in the video. Slower swimming is powered by rhythmic contractions of the funnel flaps that generates a wave that travels along the funnel wings. This produces a unidirectional flow across the gills. Although jet propulsion is less efficient than undulatory swimming (think of the swimming motion of a ray), the Nautilus converts chemical energy into hydrodynamic work for motion more efficiently than fellow cephalopods such as the squid and even salmons (at lower speeds).

 

In their study, Neil and Askew used particle image velocimetry (PIV) to study the wake of the nautilus’s jet. PIV consists of spreading particles of aluminum oxide in a water tank and shinning a laser on them. As the nautilus moves, the particles in the tank move with the jet. A high-speed camera is used to take multiple pictures of the floating particles and the relative position of these between snapshots is used to determine a velocity profile of the nautilus’s water jet.

Nautilus and its jet wake as seen in PIV
Photo by: Simon and Simon Photography, University of Leeds. Taken from Greenwood, The New York Times (2018)

 

 

 

 

 

The results from the study show that the whole cycle propulsive efficiency and thrust generation are related to the swimming orientation of the nautilus. The propulsive efficiency ranged between 30% and 75% for posterior-first swimming and 48% to 76% for anterior-first swimming (orientations defined in diagram above). Moreover, efficiency increases with greater speed in posterior-first orientation but decreases in anterior-first. This might have to do with energy losses associated with the re-orienting of the funnel that turns back on itself to move in the anterior orientation. Moreover, at low speeds, the nautilus spends more time jetting water than refilling, resulting in a lower jet speed but overall more efficient propulsion.

Although not covered in their research, Neil and Askew’s findings about jetting duty cycles and efficient propulsion at low speeds could be potentially applied to the design of more efficient hydrojets to be used in underwater vehicles. Engineering seeks to imitate nature’s most intelligent designs; and as Wendell puts it in his work, the nautilus proves to be a truly awe-inspiring creature worthy of imitation.

Will Removing Headgear Make Boxing Safer?

Our brains are made of a very soft material but luckily our skulls provide the brain protection from the outside world. However, during violent movements the brain is free to move inside the skull and collide with the skull. This impact can cause injury to the brain, known as a concussion, that can lead to various symptoms depending on severity. A 2014 paper by McIntosh et al. researched the biomechanics of concussions for Australian football players. Their research showed that a linear acceleration of 88.5 g to the head results in a 75% likelihood of a concussion. A g is the unit of acceleration and a single g is equivalent to the force of gravity at the Earth’s surface.

A very serious long-term effect of brain injury is Chronic Traumatic Encephalopathy known as CTE. Additional reading on CTE can be found here. Proper care must be taken to ensure the long-term health of contact sport athletes. Some contact sports utilize protective equipment such as helmets or mouth guards. However, the world of amateur boxing went a very different route to prevent brain injuries. An article by the New York Times reviews the International Boxing Association’s (A.I.B.A.) decision to remove headgear from international, male boxing competitions. In 2016, Olympic boxers entered the ring without headgear for the first time since 1984 according to the article. Apparently, this seemingly counterintuitive decision makes boxing safer. A cross-sectional study by the A.I.B.A. Medical Commission found there were more stoppages, caused by hard hits to the head, in fights with headgear. In fact, the data suggests that boxing without headgear lowers the chance of a stopped fight by 43%.

The A.I.B.A. claims that headgear did little to prevent brain injuries, however, there is counter research that refutes the A.I.B.A.’s claim. For example, a study by McIntosh and Patton researched the capability of A.I.B.A.-approved headgear to protect against injury. A glove was mounted to a driver and a Hybrid III head was used to record the head accelerations at different contact points and speeds. According to this study, head accelerations were significantly reduced by the headgear.

Boxing glove on piston delivering punch to a crash test dummy head
Modified from McIntosh & Patton, British Journal of Sports Medicine 2015

Headgear by no means prevents all concussions, for example, when the glove speed reached 8.34 m/s in the previously mentioned McIntosh and Patton study. Without headgear, the head experienced 133 g from a punch to the side of the head and 131 g from a punch to the front center of the head. With headgear, the head experienced 86 g from the lateral punch and 88 g from a punch to the front center of the head. The results showed there is a chance those with headgear could develop a concussion. However, without headgear, a concussion is guaranteed.

Headgear will not prevent all concussions but it can significantly decrease the chances of getting one. At some point, the force will surpass the protective capability of the headgear. Both sides of the argument present interesting and compelling data. In short, boxing is a contact sport. There will most likely always be a chance the athletes could develop brain injury.  In order to ensure the safety of the athletes, it is important to make decisions based on their health with definitive proof it protects them. The video below shows different sides to the debate.