Tag: impact

Well, if the Boot Fits! The Effect of Ice Skating Boots on Overuse Injuries in Competitive Figure Skaters

Every 4 years, viewers around the world tune into the Winter Olympics to watch the world’s best athletes compete in events like figure skating. With each passing Olympics, skaters push the limits of what is possible on the ice, always attempting jumps with more revolutions than ever before to impress judges and amaze viewers. However, these high-revolution jumps pose serious risks to the skaters who perform them, mainly in overuse injuries resulting from countless hours of practicing these jumps to perfect them for competition.

Read more: Well, if the Boot Fits! The Effect of Ice Skating Boots on Overuse Injuries in Competitive Figure Skaters

When landing these jumps, skaters’ lower bodies are subjected to large impacts on their joints and bones due to the dissipation of kinetic energy resulting from their rapid rotations while in the air. As the number of jump revolutions increases, so too does the kinetic energy required to successfully perform them as skaters must rotate faster while in the air.

Elite figure skater Amber Glenn performing a Triple Axel, a jump with 3.5 revolutions. Video by FloweringDagwood from Wikimedia Commons.

Additionally, high-rotation jumps place skaters’ completion of rotations closer to the ice, as skaters have less time to complete rotations while in the air. This results in a collision-type impact between the skaters’ landing foot and the ice that shortens how long skaters have to absorb forces from landing their jumps and further increases the impact on their joints and bones. Combined with the sheer number of jumps that skaters perform daily to perfect their skills, these high-revolution jumps greatly increase the risk of overuse injury development in skaters’ lower bodies.

To better preserve skaters’ joint and bone health, researchers have studied how ice skating boots impact skaters’ performance. These boots, which are worn by all skaters regardless of skill level, rise high on skaters’ ankles and are tied like shoelaces around metal hooks mounted on the boot. Tying the laces around these hooks provides extra stability to skaters’ ankles and ensures a secure fit of the boot around a skaters’ foot. A stiff platform runs under the boot and slightly raises the boot’s heel. Finally, a thin metal blade with a jagged pick at the toe of the boot and a rounded edge at the heel is mounted to the underside of this platform.

Image of two figure skates in front of a blue background. The boots of the skates are white and have 4 metal hooks lined vertically by the ankle of the boot and has white laces running through holes on top of the foot part of the boot. A thin brown wooden platform is underneath the boot and forms a slight incline at the heel of the boot. Under the platform is a silver metal blade that connects at the toe, sole, and heel of the boot. The blade has a jagged pick at the toe of the boot and a rounded edge at the heel of the boot. The skates are untied in the image.
Ice skating boots worn by competitive figure skaters. Image by Johannes Robalotoff from Wikimedia Commons.

The most important feature of these boots is their stiffness around skaters’ feet and ankles to serve as braces that protect their ankles from wobbling and losing balance when landing jumps. However, this boot stiffness limits the ability of skaters’ feet and ankles to absorb the impact experienced upon landing jumps. This results in landing forces traveling up the skaters’ lower bodies and mainly impacting their knees, hips, and lower backs.

Therefore, boot models must strike a balance between structural stability and joint mobility, and researchers aim to identify this balance by observing how boot stiffness and fit around skaters’ feet impact their range of motion. Ankle and foot range of motion is important for skaters because it controls which joints are impacted most in skaters’ lower bodies. Studies have found that boots with angled forms and raised heels result in increased ankle range of motion and thus improved force dissipation in skaters’ feet and ankles rather than transferring more of these loads upwards to their knees, hips, and lower backs. Additionally, lightweight boots made of materials like fiberglass, plastic, and soft memory foam absorb a greater amount of the landing force impact than boots made of heavier materials like leather and wood. With these findings, skaters can make educated choices for their ice skating boots that prioritize their long-term joint and bone health, protecting themselves from overuse injuries to prolong their skating careers and get the most benefit out of their daily training.

Featured image by Sandro Halank from Wikimedia Commons.

Does Boxing Headgear Prevent Concussions?

In boxing, behind every punch connecting and glove pushing into a face, there is a complex collection of engineering principles at play that can vibrate a human skull and cause serious neurological damage. The impact of a punch can jolt the brain, causing it to move across the cerebrospinal fluid that it sits in and putting the person at risk. The rotation and rebound of the brain inside the skull from the rapid force applied is what produces concussions in the sport. Theoretically, headgear will reduce the likelihood of a concussion by softening the blows.

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The Invisible Wound: Unlocking the Biomechanics of Wartime Traumatic Brain Injury

For most of history, battlefield medicine was about treating only visible injuries. Cuts, fractures, and shrapnel wounds defined military trauma and critically impacted generations of soldiers. But the wars in Iraq and Afghanistan, characterized by increased use of improvised explosive devices (IEDs) introduced a new and invisible wound known as blast-induced traumatic brain injury (TBI). While more than 75% of these cases are classified as mild TBI, they typically lack visible or physical damage on patients through conventional scans and can lead to debilitating long-term symptoms such as headaches, memory loss, and post-traumatic stress disorder.

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Limiting Repetitive Subconcussive Impacts in Rugby

It is no secret the danger head injuries can pose for player safety in contact sports. While the public is aware of the danger of large hits and concussions, many remain unaware of the danger small blows to the head can have on an individual. Formally, these incidents are known as subconcussive impacts, which are defined as blows to the head that result in mild brain trauma without the presentation of typical concussion symptoms. Recent studies have indicated repetitive subconcussive impacts can lead to cumulative, long-term brain damage. This discovery has been increasingly alarming for rugby players who can average 77 of these impacts per game! With the discovery of this newfound danger, the question must be asked: what is being done to protect at risk rugby players?   

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The Biomechanical Blueprint: How Cheetahs’ Bodies Are Engineered for Speed

The cheetah (Acinonyx jubatus) is the fastest land animal on earth reaching speeds of over 60 miles per hour (29 m/s). The cheetah is native to Africa and parts of the Middle East and is a predator of the impala, along with several other prey animals of the Savannah and Middle East. The biomechanics of the cheetah can help us understand how to create such high speeds in biological organisms and how to protect the body against high acceleration and decelerations.

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Wreckage Before the Real Crash: The Biomechanics of Crash Test Dummies

Every 25 seconds, someone is killed in a car accident, resulting in more than 1.25 million deaths worldwide each year.

Two fully assembled crash test dummies seated in car awaiting testing
Photo by Wikimedia Commons, Dynamic Test Center

As a result, dummies are an important tool used in many safety tests for car crashes, and they help to inform many design decisions for automobile manufacturers. Since these dummies are used to assess human behavior in many types of situations involving collisions, swerving, and other performance measures, the primary goal for dummy creators is to imitate human response as closely as possible using artificial means.

Read more: Wreckage Before the Real Crash: The Biomechanics of Crash Test Dummies

Therefore, biomechanics plays an integral role in dummy design, from choosing materials that accurately reflect limb stiffness, to assembling ball-and-socket joints that sever when undergoing a certain threshold stress or strain. There are many techniques that researchers use – from computational models to in-field testing – to ensure these dummies reflect the parameters and properly inform the design decisions they are a part of.

Cross section diagram of dummy illustrating the assembly of different body parts
Photo by National Highway Traffic Safety Administration

      Manufacturers routinely spend millions of dollars each year to develop and fine-tune the dummies (or more technically known as anthropomorphic test devices or ATDs) that they implement in their testing procedures. Its history can be traced all the way back to 1949, where the US Air force implemented a dummy for test ejection seats, while they were first implemented commercially by General Motors more than 30 years later. They have undergone many advancements in terms of their accuracy and manufacturing efficiency, arriving at the now ubiquitous Hybrid-III model, which resembles a 50th percentile adult “family man” male that is used in almost all testing simulations. Although many cadever models have been explored, these artificial models offer the most consistent and reliable solution to testing needs, which involves blunt head-on crashes, various types of rollovers, and other rear-based and side-based collisions. By equipping dummies with different kinds of sensors, primarily consisting of MEMs accelerometers and other force transducers, dummies provide predictive power on the impact of different simulation parameters on driver safety and other outcomes.

Demonstration of the head drop test set-up described in the main text body
Photo by National Geographic on Youtube


            Dummy performance analysis can be found both in creation of the dummies, ensuring the dummies have the correct human mechanical properties, and in dummy testing, anticipating damages in crashes. Both see a heavy cross-section in biology and mechanics, best illustrated by the head-drop test in the initial development stage. Here, a dummy head undergoes a drop from a predetermined height, and sensing systems ensure the model has optimal weight and damping properties in comparison to in vivo concussion testing. This way, when the commonly used QMA Series 3 DoF Force Transducer later measures neck whiplash force (the most common cause of car crash injury), testing models can be confident such data will reflect real-world collisions. These kinds of before and after tests are used in all parts of the dummy, from parts as large as the lower back, to parts as small as the hinge joint in a finger knuckle. Such precision is needed in all areas to increase the predictive power of dummies, since details like Young’s Modulus (a measure of stiffness) in the chest area affects steering wheel impact displacement, while the coating paint consistency affects the skin abrasions associated with friction and rubbing. Each part of the dummy is crafted meticulously, and as such, the manufacturing and design process of the dummies involves a fast knowledge of physics, biology, and everything in between. Some additional overviews and readings can be found here and here.

Too Tall to Run: How a Giraffes Height Affects their Locomotion

Seeing a giraffe for the first time, one is amazed by their long necks and long legs, but do you ever wonder how their long skinny legs can support their large body mass as they move about? Studies have shown that a giraffe’s legs undergo a large ground reaction force when walking freely and an even larger ground reaction force when moving at a faster speed than walking.

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A striking difference: How combat sports affect bone density

We have all seen it before, whether it is in Hollywood depictions, or watching competitors in the Ultimate Fighting Championship, there is always a sense of awe when watching humans strike and break surfaces with astounding force. Whether it is breaking bricks, a baseball bat or their opponents, the physiological phenomena that allows these athletes to perform such feats results from years of dedicated practice and study. By continuously placing their bodies under immense stresses and impacts, the actual composition and density of the athlete’s bones adapt to provide increased strength and durability. In practice this is done by repetitively striking a hard surface, such as a wooden planks, or a punching bad, with increasing force for a prolonged period of time. Although the practice of bone hardening has roots as ancient as the martial arts themselves, the scientific study of the phenomena has only occurred in the past few decades. So how do these athletes develop exceptionally strong bones?

Continue reading “A striking difference: How combat sports affect bone density”

We have all seen it before, whether it is in Hollywood depictions, or watching competitors in the Ultimate Fighting Championship, there is always a sense of awe when watching humans strike and break surfaces with astounding force. Whether it is breaking bricks, a baseball bat or their opponents, the physiological phenomena that allows these athletes to perform such feats results from years of dedicated practice and study. By continuously placing their bodies under immense stresses and impacts, the actual composition and density of the athlete’s bones adapt to provide increased strength and durability. In practice this is done by repetitively striking a hard surface, such as a wooden planks, or a punching bad, with increasing force for a prolonged period of time. Although the practice of bone hardening has roots as ancient as the martial arts themselves, the scientific study of the phenomena has only occurred in the past few decades. So how do these athletes develop exceptionally strong bones?

Continue reading “A striking difference: How combat sports affect bone density”

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

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.

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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.

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