Tag Archives: sports injury

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

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

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

Physical vulnerability to concussion mechanics

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

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

Issues with injury recognition and response

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

The 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/

Work Smarter Not Harder!

We have all likely heard the saying, “Work smarter not harder.” While this is generally referenced in an academic setting, it is also very applicable in athletics! One of the benefits to being a runner is that it’s a sport people can participate in at any age and nearly anywhere. Unfortunately, however, anywhere from 65-80% of runners get injured in a given year. A large portion of these injuries are related to overuse.

Recovery

It’s a common misconception amongst runners that the harder you push during your runs, the faster you will be on race day. As a result, the majority or runners overdo their “easy” days. This leaves their legs fatigued and tired going into workouts and races. The majority of fitness is gained during a “workout” day, so overdoing easy days reduces your ability to push hard on workout days. To truly maximize their potential, an athlete must focus on their recovery. Recovery is a broad term that includes a variety of factors such as sleep quality, nutrition, and post run stretching and rehab exercises. Monitoring your heart rate is one way to manage your recovery, reduce overtraining, and limit bone stress injuries. 

Managing Heart Rate

Photograph of a smartwatch reading heart rate
Photo by Brooke Trossen

Heart rate monitors are used by runners to train smarter and ultimately race faster. Resting heart rate and heart rate recovery measurements are indications of how an athlete’s body is responding to stress and exercise long term. Heart rate measurements can be used to guide what the pace of a run should be. Heart rate measurements are commonly separated into five “zones.” On different days of the week and stages in a training cycle, a run should fall into the different zones. It may be beneficial for an athlete to also have a general idea of what their heart rate is at a given running pace. If their heart rate is more than 7 beats per minute above the usual rate, it may be a sign that the athlete has not fully recovered from their last training session and that they should continue with easy days until having another intense session. This is also important for runners since the weather conditions can greatly affect the difficulty of a run. Rather than having a goal pace for a given day, it is better to have a goal range of heart rates to make sure the run is best serving the athletes body. This will enable an athlete to get the appropriate effort in whether it is 70° and sunny or 30° with 20 mph winds.

Monitoring heart rate after exercise can also accurately indicate whether or not an athlete is fully recovered. It is important to note that your heart rate fluctuates, so it is more valuable to observe general trends than it is to overanalyze specific data points. A morning heart rate 5 beats per minute above your usual heart rate may be indicative that your body needs more rest or that you are getting sick. The image below shows a chart with ranges of resting heart rates depending on gender and age.

Chart of healthy resting heart rates for men and women with varying ages.
Photo by Jeremy on Agelessinvesting.com

Minimizing Bone Stress Injuries

Photograph of a stress reaction in the femur of a female runner
Photo by Brooke Trossen

Building a training plan with runs in a variety of zones will help limit overtraining and make the development of overuse injuries less likely. A bone stress injury (BSI) is defined as the inability of a bone to withstand repetitive loading. There are varying degrees of bone stress injuries from stress reactions to complete bone fracture. When performing repetitive motions such as running, micro-cracks form in your bone. These micro-cracks are actually healthy because loading your bones makes them stronger. In the process of remodeling, the micro-cracks are healed. Generally, additional remodeling units can be recruited in response to increase loads. The increase in remodeling units present, decreases the amount of bone mass. This results in a decrease in the ability for the bone to absorb energy and an increase in the number of cracks formed. When insufficient time is given for remodeling, the micro-cracks will begin to accumulate and stress reactions and fractures will form. A stress reaction in the right femur of a female runner is shown in the image above. The white highlights represent inflammation in the bone. 

Although overuse injuries are very common in runners, research shows that the use of heart rate monitors can help regulate recovery and positively influence training plans to limit overtraining. 

Rock on, Dude!

In the rock climbing world, there is not much that people fear more than the sound of a “pop” coming from their fingers. That sound means months of rehab and can keep you off the rock for up to six months [1]. But what exactly is happening when you hear that dreaded sound? The fingers are so small, how can one injury to the fingers be so devastating? Let’s dive in.

As a review of hand anatomy, direct your attention to the graphic on the right. There are two main tendons that run up each finger to allow the fingers to produce the curling motion. In order to keep these tendons close to the bones to provide for maximum torque,

Diagram of the hand showing the tendons and pulleys
Anatomy of the hand [2]
they are held by pulleys. The pulleys are the culprits of the “pop” when grabbing tiny holds. Without these pulleys, the tendons would “bowstring” and pull away from the axis of rotation of the finger and thus decrease the strength of the system [2]. The important pulleys in climbing are the A2 and the A4, as they are fibro-osseous pulleys (connect bone to bone) and are stiffer than the A3 and A5[3].

In climbing, there are two main hand positions when grabbing

The open hand position
The open hand position [2]
holds: Open-hand and crimp. The open-hand grip relies heavily on the forearm muscles, while the crimp puts a significantly higher strain on the skeleton. The crimp is incredibly dangerous, as it puts three times the force being applied to the fingertip on the A2 pulley [4]. A common mistake I have noticed for newer climbers is to crimp everything as the big muscles in the upper arm and back are much stronger than the forearms. Putting all the weight on the skeleton and big muscles allows you to skip over the limiting factor of weaker forearms. This allows climbers to pull on smaller holds and climb harder routes. New climbers are not as aware of the dangers and they get excited

hand in the crimp position
Hand in the crimp position [3]
to send harder and harder routes, but this reinforces the bad habit of crimping which will eventually get you injured. Of course, sometimes crimping is unavoidable when the holds are very small, but it is best to avoid it as much as possible.

 

So how strong are these pulleys? In a study performed with recently deceased cadavers, the A2 pulley resisted up to 408 N, which is 91 pounds [5]. This was determined by removing the bone from the hands and pulling on the pulleys until they broke. Based on another study in live humans, the force applied to the A2 pulley was extrapolated to be around 373 N with 118 N applied to the fingertips [4]. This extrapolation was based on a controlled environment. It is easy to see that a pulley could be loaded with much more force than that if a climber’s foot slips mid- move or if you catch a hold with fewer fingers than you mean to. It was also

Me crimping as hard as I can because I'm weak
Me crimping as hard as I can because I’m weak

found that the bowstringing in the intact A2 increased by 30% throughout a warm-up process [4]. This clearly shows the importance of a good warm-up.

Sources and extra reading:

[1]https://theclimbingdoctor.com/pulley-injuries-explained-part-2/

 

[2]https://theclimbingdoctor.com/pulley-injuries-explained-part-1/

[3]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3371120/

[4]https://www.sciencedirect.com/science/article/pii/S0021929000001846

[5]https://journals-sagepub-com.proxy.library.nd.edu/doi/pdf/10.1016/0266-7681%2890%2990085-I

 

Ankle Sprains: An Epidemic in the World of Athletics

Have you ever been out running on a gorgeous fall day, only to have the run cut short by a painful misstep on a tree root covered by leaves? I have, and let me tell you – it’s awful! And even if you aren’t a runner, according to the Sports Medicine Research Manual, ankle sprains are a common, if not the most common, injury for sports involving lower body movements. Now, the solution to preventing this painful and annoying injury could be as simple as avoiding tree roots and uneven ground, but the real problem behind ankle sprains deals with the anatomy of the ankle.

The ankle is made up of many ligaments, bones, and muscles. However, when sprained, it is the ligaments that are mainly affected. Connecting bone to bone, ligaments are used to support and stabilize joints to prevent overextensions and other injuries. The weaker a ligament is, the easier it is to injure. There are three main lateral (outer) ligaments supporting the ankle joint that can become problematic: the anterior talofibular ligament, the calcaneofibular ligament and the posterior talofibular ligament. According to a study from Physiopedia, these lateral ligaments are weaker than those on the interior (medial) of the ankle, with the anterior talofibular ligament being the weakest.

An image depicting the various ligaments of the ankle, both lateral and medial.
Anatomy of the ankle, highlighting the lateral and medial ligaments

The next question that has to be asked is why are these ligaments so much weaker than other ones? The answer to this question is based on their physical make up. Ligaments are made of soft tissue that has various collagen fibers running parallel to each other throughout it. The more fibers there are, the more structure and rigidity there is. Think of the fibers as a rope: The rope can stretch to a certain point, but once it hits that point it will snap and break. But if you have a thicker rope (such as the medial ligaments), it becomes much harder to break.

The ligaments on the outer part of the ankle have fewer collagen fibers than those on the inside of the ankle. Thus, when the ankle is moved in an awkward position, it is more likely that the lateral ligaments will break.

Once you sprain your ankle, the focus turns to treatment. Treatment will differ slightly for every individual depending on the severity of the ankle sprain. The simplest way to treat a sprained ankle is to follow the RICE (Rest, Ice, Compression, Elevation) method. Other forms of treatment include taping the ankle or using a brace to restrict movement and to add support and extra stability. Wearing proper footwear is another way that one can prevent and help treat a sprained ankle, as certain shoes are specifically designed to help avoid such injuries. To prevent future ankle sprains, exercises are recommended to help strengthen and stabilize the joint and surrounding ligaments and muscles.

For more information on ankle anatomy and sprains, check out these articles on BOFAS and SPORTS-Health.

Attempting to “Knock Out” the Causes of Concussions

This image displays a human head experiencing impact to the forehead region.
This image is licensed under CC BY-SA 3.0 .

Approximately every 15 seconds, a traumatic brain injury occurs in the U.S. A concussion is a form of mild traumatic brain injury produced by a contact or inertial force to the head (or neck) area. A concussion causes the brain to rapidly move around inside the skull, harming natural brain function. According to the Brain Injury Research Institute, roughly 1.6 to 3.8 million concussions occur each year in the U.S., resulting from both recreation and sports related incidents. In fact, brain injuries cause more deaths than any other sports injury.

The high incidence of concussions has made the injury subject to several biomechanical studies in recent years. Kinematic, or motion-based, parameters of the head are used as common indicators to predict brain injury as they are suggestive of the brain’s response to force. Early efforts focused on the linear acceleration of the head during concussion as the primary prediction factor of the injury. The peak linear acceleration of the head is correlated to the peak pressure within the brain, and an increase in pressure within the brain can cause neurological damage. Modern sports protection equipment, including ice hockey helmets, maintain performance standards based on the peak linear acceleration experienced by the head during impact. However, linear acceleration does not entirely reflect the risk of concussion and rotational acceleration of the head must be considered. A shear force acts in a parallel direction to a surface or cross section. Shear forces and subsequent strains in the brain are correlated to peak rotational acceleration of the head. Brain tissue is one of the softest bodily materials and deforms quickly to shear forces. Therefore, rotational acceleration of the head is a common catalyst of severe concussion.

This image presents two human skull and brain combinations. The left skull has red horizontal arrows pointing to the brain to depict the linear acceleration of the head during a concussion. The right skull has red arrows acting in a circular manner around the head to represent rotational acceleration acting on the brain during concussion
This image is licensed under the Creative Commons Attribution 2.5 Generic License. Changes were made to the image in the form of text and red arrows.

A 2015 study introduces the addition of the brain deformation metric maximum principal stress (MPA) in order to aid in connecting kinematics and injury during concussion prediction.  The study used Hybrid III crash test dummy head forms to examine the result of varying forms and severities of impact. Each head form was equipped with nine single-axis accelerometers to study the acceleration of the head and hyperelastic models were used to study brain tissue deformation.

The results of the study revealed the existence of significant correlations between linear acceleration, rotational acceleration and maximum principal stress of brain matter, emphasizing the importance of considering several kinematic parameters in predictive concussion studies. Results of the study exemplified the magnitude of accelerations experienced by the head during concussion: the head forms experienced an average linear acceleration of approximately 40.62g and an average rotational acceleration of approximately 3388 rad/s2, which is equal to about  539 rev/s2. The extent of brain injury is revealed through the immensity of the accelerations experienced during impact.

This image presents a side view of the skull that presents all organs as semi-transparent, enabling viewers to effectively see the inner-workings of the head.
“Years in the making: How the risk for Alzheimer’s disease can be reduced.” (2018)

When determining the probability of concussion, it is limiting to utilize just one parameter. Instead, several parameters and the relationship between each must be considered. Additionally, factors like sex-specific characteristics and under-reporting of injury have been proven to affect the severity of brain injury through study.  While brain injury can never be fully avoided, these studies can help to make equipment more protective and reduce injury.

Interested in reading more?

Neuroscience, Biomechanics & the Risk of Concussion in Developing Brains

Additional Sources:

Biomechanics of Concussion

Brain Injury Prediction

Concussion in Female Collegiate Athletes

Tearing and repairing the meniscus

How does someone go from being the youngest NBA MVP one year to barely making headlines the next? Ask Derrick Rose. After being named the youngest MVP in the NBA, Derrick Rose tears his ACL the next year and then tears his right meniscus twice in the span of three years. Knee injuries have not been kind to Derick Rose, but how does one tear their meniscus and how does it get repaired?

The meniscus is shown in Figure 1.

Showcases the location of the meniscus in the knee. Gives the user an image of how the meniscus works, and where it is located.
Figure 1

According to Sports Health, the meniscus is a type of cartilage that provides cushioning between the bones in the knee. The meniscus main role is to absorb shock and the impact on the leg and knee when it is in motion. It allows for stability and smooth motion between the joints.

In a game of basketball, one of the biggest sports in the United States, there is plenty of running, jumping to shoot the ball into the basket, jumping up to catch a rebound, and doing sharp cuts during the game to shake off a defender. All these movements cause high loading on the knee, and if there is an over-rotation on the knee during these movements, then it can cause a tear in the meniscus. The video below shows when Derrick Rose tore his meniscus.

In the video, it shows Derrick Rose doing a relatively easy movement, he plants his foot in order to change direction to chase after the ball. It is a non-contact movement, but due to an awkward landing on his foot, he gets injured and misses games for the rest of the season.

When the meniscus is torn, there are two options in terms of healing the tear. The options are getting the meniscus removed or getting it repaired. Both options have their own recovery time. If you get the meniscus removed, then the recovery time would be from four to six weeks. However, there are setbacks to getting the meniscus removed such as leading to early arthritis. If the meniscus is repaired, then the timetable to return to play is around six months. According to USA Today , he chose to get the meniscus repaired in order to not have future complications around his knee, which is why he had to sit out for the rest of the season. Going this route also gave Derrick Rose the chance to return to his playing form before injury. According to Stein, 96.2% of athletes that undergo meniscal repair go to pre-injury level of activity after the repair, which is good news for Derick Rose.

However, Derrick Rose tore his meniscus again the following season in 2015. He would then have surgery to remove the damaged part of the meniscus and would return in a couple of weeks. This would then be his third surgery to repair his knee, and his surgeries must have an effect on his playing performance. After these surgeries, the world waits to see if Derrick Rose can reach MVP status again during his career. It would be tragic to see that these knee injuries would ruin someone’s career.

Sources and Additional readings:

General information about the meniscus

Meniscal Injuries in the NBA

Injuries in the WNBA

What is Tommy John surgery?

Baseball card of Tommy John for the Los Angeles Dodgers
From Zellner, “A History and Overview of Tommy John Surgery,” Orthopedic & Sports Medicine Specialists

In July of 1974, Tommy John, pitcher for the Los Angeles Dodgers, felt a twinge in his throwing arm, and could no longer pitch. Dr. Frank Jobe tried a new kind of surgery on John’s elbow, and after missing only one season, Tommy John returned to the mound in 1976 and continued pitching until 1989.

How?

The surgery which bears Tommy John’s name is by now a common buzzword in the baseball community. Over 500 professional and hundreds of lower level players have received this treatment, but even the most avid fan may still be unsure what it means.

Tommy John surgery is the colloquial name for surgery on the Ulnar Collateral Ligament (UCL). This ligament is vital to the elbow, especially in the throwing motion. Injury to the UCL accrues over time; fraying and eventual tearing occurs after repeated and vigorous use. Baseball pitchers, throwing around 100 times per game and at speeds upwards of 100 mph, put themselves in danger of UCL injury.

Location of the Ulnar Collateral Ligament in the human arm, shown on a baseball pitcher.
Image from Wikimedia Commons.

Tendons in the elbow joint, with the Ulnar Collateral Ligament marked
Image from Wikimedia Commons

What can be done when a player injures his or her UCL?

Prior to 1974, not much. Ice and rest, the most common suggestions, would do little to improve serious UCL damage. A “dead arm” spelled the end of a player’s career. Dr. Jobe would change that. 

Jobe removed part of a tendon from Tommy John’s non-pitching forearm and grafted it into place in the elbow. John’s recovery required daily physical therapy before slowly starting to throw again.

Since Jobe’s pioneer surgery on Tommy John, most patients undergo a similar kind of reconstruction procedure. A tendon from either the forearm (palmaris longus) or the hamstring (gracilis), is looped through holes drilled in the humerus and ulna, the bones of the upper arm and inner side of the forearm. In some modern cases, the hope is to repair the UCL with a brace that lets it heal itself rather than total replacement. This allows for faster recovery time because the new blood vessels that have to form in traditional ligament replacement are unnecessary. In either case, athletes recovering from UCL surgery, a procedure which itself takes less than two hours, typically require at least a year to restore elbow stability, function, and strength.

Some misconceptions about Tommy John surgery exist. One 2015 study found that nearly 20% of those surveyed believe the surgery increases pitch speed. However, increase in pitch speed may be affected more by the extensive rehabilitation process rather than the new tendon itself.

The study also found that more than a third of coaches and more than a quarter of high school and collegiate athletes believe the surgery to be valuable for a player without an injured elbow. This perception of Tommy John surgery makes it seem like a superhuman kind of enhancement, as if out of The Rookie of the Year, or worse, it becomes like a performance enhancing drug. In reality, a replacement UCL at best replicates normal elbow behavior. A procedure capable of creating a superhero might be attractive, but for now, Tommy John surgery just helps players get back in the game.

 

For further information:

 

How Many MLB Players Have Had Tommy John Surgery?

What Makes Someone More Likely to Tear Their UCL?

It takes a lot to make a professional athlete collapse to the ground during a game. After throwing a pitch on September 14, 2019, Toronto Blue Jays pitcher Tim Mayza knelt on the side of the mound while clutching his arm, expecting the worst. The next day, MRI revealed that what he had feared: Mayza had torn his Ulnar Collateral Ligament (UCL).

player following through after throwing baseball
Photo by Keith Johnston on Unsplash

Because of UCL reconstruction, or Tommy John, surgery, this injury is no longer the career death-sentence that it once was, but there is still a long road ahead for Mayza. He probably will not pitch in a game again until 2021. Sadly, this injury is only becoming more and more common among MLB pitchers. In the 1990s, there were 33 reported cases of UCL tears by MLB pitchers. In the 2000s, this number more than tripled to 101. From 2010 to the beginning of the 2015 MLB season, 113 UCL reconstruction surgeries had already been conducted. It has become so common that surgeons have called it an epidemic, and researchers in the US and abroad are attempting to find a way to combat this increase.

Digital image of elbow joint, with a small, red tear in the UCL
Orthopaedic and Neurosurgery Specialists, 2019

The UCL connects the ulna and humerus at the elbow joint, and its purpose is to stabilize the arm. During the overhead pitching motion, the body rotates in order to accelerate the arm and ball quickly, putting a large amount of stress on the UCL. In fact, according to a study by the American Sports Medicine Institute, the torque, or twisting force, experienced by the UCL during pitching is very close to the maximum load that the UCL can sustain.

Recently, many studies have investigated factors that could make pitchers more susceptible to UCL injuries, with a hope of identifying ways to prevent them. One of the biggest findings has been the correlation between UCL tears and pitch velocity. According to a study from the Rush University Medical Center, there is a steady increase in the frequency of UCL tears as max velocity increases. This makes intuitive sense, as more torque would be required to accelerate a baseball to the higher velocities. While this finding does have a very strong correlation, it does not help the players avoid injuries. Pitchers are unlikely reduce their velocity because it would also decrease their effectiveness, so another answer must be found.

The University of Michigan conducted another study, and found that, in addition to velocity, the number of rest days between appearances decreased by just under a full day for pitchers who later needed Tommy John surgery. While this does not seem like a large number, starting pitchers typically only receive 4 days of rest between starts, so the extra .8 days is equivalent to a 20% increase in rest time.

Because of these findings, the MLB has increased the max roster size from 25 to 26 for the 2020 season, with the hope that teams will use the extra player to reduce the frequency that each pitcher is used. In addition, pitch counts in Little League Baseball have had a positive effect on youth injuries. This can be explored further here. This discovery has already made a tangible impact on Major League Baseball, and hopefully more findings will reduce the rate of UCL tears in the future.

What an Optimized Running Gait Can Do for You

Running is one of the oldest and most common forms of exercise, but there are many ways that running mechanics vary from person to person. Identifying the different running gaits is important so that their efficiencies and effects on the body can be analyzed. Injuries in runners are common and having an understanding of how different gaits apply stresses on the body differently can be used to educate runners on how to run in a way that will reduce the risk of injury.

Running with poor mechanics can lead to overuse injuries, which are more common than acute injuries in serious runners. The majority of these injuries occur in the leg either at or below the knee and include patellofemoral pain syndrome (PFPS) and medial tibial stress syndrome (shin splints). Running gait analysis can be used to identify the poor mechanics and the potential risks associated with the mechanics. Further studies have grouped the variations so that the effects of similar gaits can be identified. Extensive analysis has led to the identification of several potential variations in running gait.

A study at Shanghai Jiao Tong University‘s School of Mechanical Engineering determined the effects of step rate, trunk posture, and footstrike pattern on the impact experienced by the runner. Data was collected by instructing runners to run with specified gait characteristics. Sensors made used to make sure that the gait was correct and the impact forces on the running surface were measured. This study showed the lowest impact was experienced with a high step rate, a forefoot strike pattern, and an increased anterior lean angle. Limiting the impact reduces the effects of the loading. As a result, running with these gait characteristics reduces the risk of knee pain and stress fracture in the tibia.

Runner on treadmill with attached sensors following instructions to modify gait
from: Huang, Xia, Gang, Sulin, Cheunge, & Shulla, 2019

While the most important factor in this analysis is how forces are translated through the body, this is difficult to measure directly. The technology does not exist to measure these forces accurately and noninvasively. Since invasive techniques would not allow the person to run normally, indirect ways of measuring this data have been developed. One of these alternatives involves collecting kinematic data which can be used to calculate the forces and observe different gait patterns. They do this by recording high speed video of runners. Usually, photo reflective stickers or LEDs are fixed to critical points of motion so that the motion of these points relative to each other can be plotted and analyzed. This data can be used to develop algorithms that describe different gaits.

Running gait does not only affect risk of injury, but also efficiency. Kinematic studies have shown that as running speed increases, a runner’s gait changes to accommodate this change in speed. One change in the gait was the foot strike pattern changed from rear foot to forefoot. This motion shortens the gait cycle and increases the step rate. However, when the runners ran at their top speeds for an extended period of time, their mechanics broke down and some of the gait characteristics that increase injury risk became pronounced. Because of this tendency, incremental training with focus on proper mechanics is necessary to reduce injury risk.