Tag Archives: sports

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.

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.

Oops I Did It Again: The Biomechanics Behind Repetitive Ankle Injuries

Ankle injuries – either sprains or fractures – are one of the most common sports traumas plaguing the US today. Sprains are overextensions or tears in ligaments.  Fractures, on the other hand, are broken bones.

Here, we will focus on sprains of which there are three grades. To help visualise a sprain, think of a Fruit By the Foot (the gummy fruit snack you may have eaten as a child). A Grade 1 sprain involves stretching like if you were to pull on either end of the fruit rope and small tears start to develop along the middle. A Grade 2 sprain develops when the tear is larger and originates from a side; a grade 3 sprain is a complete tear into two pieces.

A Little Background

The ankle joint, also known as the talocrural joint is a synovial hinge joint that mainly moves in dorsiflexion and plantarflexion 1. If you were sitting on the ground with both legs extended in front of you, dorsiflexion is the movement of your foot upwards toward your shin, and plantarflexion is the action associated with pointing your toes moving away from your body.

Video Explanation of Ankle Movements in Dorsiflexion and Plantarflexion

Sprains & Pains

The most common type of ligament injury are lateral ankle sprains or inversion sprains where the ankle joint over rotates in the outward direction, especially an inversion while in plantarflexion 2. Exercises that include running, jumping, and/or cutting put the athlete’s ankle at high risk for sprains. This is especially seen in soccer, football, basketball and volleyball players.

Depiction of ankle position with an inversion sprain. Light purple items are bones and have rectangular callouts, while red items are ligaments with circular call outs. Labeled items include: Tibia, Fibula, Talus, Cuboid, and Calcaneus bones as well as the ATFL, PTFL, and CFL (ligaments).
Figure 1 – Left Foot/Ankle in an over-rotation with main bones (in square callouts) and ligaments (in circle callouts) identified

Figure 1 above shows an ankle in the common and compromising position of an inversion sprain. The circled ATFL, PTFL, and CFL are ligaments in the joint, namely the Anterior Talo-Fibular ligament, the Posterior Talo-fibular ligament, and the Calcaneofibular ligament respectively. Additionally, the boxed call outs are bones in the foot.

Numbers show that close to 70% of patients that had experienced a lateral ankle sprain in the past repeated the same injury to their ankle1.

What is the medical explanation behind repeated ankle injuries?

One study by Doherty et al. followed emergency room visits for ankle injuries and found that 40% of patients with ankle sprains had to seek medical treatment for another ankle injury within the year. Yet, another statistic found that over half of people who experience ankle sprains don’t even go to a hospital.

Ankle sprains are sometimes deemed as a “walk-off injury“, or one that hurts momentarily but just needs a few minutes before resuming activity. However, many people suffer from prevalent and reoccurring ankle sprains. Officially dubbed Chronic Ankle Instability or Sprained Ankle Syndrome, this condition is characterised by a host of symptoms including pain, swelling, perceived and actual instability, balance issues, and joint weakness. Chronic Ankle Instability, or CAI more commonly, can also cause a decrease in physical activity, changes to walking or running form, onset arthritis, and problems with knees and hips due to overcompensation1.

The tried-and-true course of action to prevent CAI is efficient rehabilitation. A study showed that if the patient recovers fast enough, the body won’t change movement patterns.

Problem: Altered Movement Patterns

The changing of movement patterns in the ankle joint, or arthrokinematics1 is one of the main factors that contributes to CAI. The brain, like a protective mama bear, trains the body to operate (walk, run, jump) in a different manner to protect the strained ligaments. Over time, muscle memory kicks in and the compensation for ankle mobility becomes your new normal. This adoption of an incorrect form of walking, running, jumping, etc. can backfire and translate to repeated ankle injuries. This muscle memory has been identified as a neurosignature2 from Melzack’s neuromatrix of pain theory; however, this pain theory also describes how elimination of the pain, stress, or chronic symptoms associated with an ankle sprain can prevent reoccurrence – elimination, that is, through efficient rehab.

Solution: Efficient Rehabilitation

A quick recovery can be achieved through various muscle strengthening exercises from a licensed physical therapist or “ankle disk training,” which basically consists of a flat board mounted on a semi-circle. By standing on this unbalanced board, stability can be practiced as well as specific ligament targeting to build muscle. A more serious solution of ankle surgery showed a 90% success rate of mediating mechanical instability, but this is not a widely-practiced nor traditional treatment plan for CAI3. In fact, ankle taping and/or lace-up 3 bracing when exercising proved most helpful in preventing over rotations of the lateral ligaments.

Punch like a nerd: Utilizing Biomechanics in Boxing Form

Why we punch and how we do it

You and I are living creatures. Every living creature on Earth has some means of self-preservation, and while society and technology have advanced humans far beyond the norms of the animal kingdom, deep down at our core is the self-preserving instinct known as “fight or flight”. When the moment arises that flight is not possible, that unarmed self-defense is the only option, a human will most likely throw a punch. Unless you are trained in a combat sport or a style of self-defense, that punch will likely be inefficient and ineffective. I’m here to break down, with biomechanics, the most effective way to throw that punch.

This diagram shows 4 main punches in boxing. This blog will focus mainly on the cross, hook, and uppercut. Photo from neilarey.com

In boxing, that sport that deals with punching a good bit, there are three main types of punches: straight (jab/cross), hook, and uppercut. As pictured above, the three motions have varying paths traveled by the fist and they engage different muscles in different ways.

“Hold on a minute, why not throw a karate chop or a big ol’ open hand slap?” A study was done to answer this question, where untrained men and women hit a target with an open hand, a karate chop and a closed fist. For each of the techniques they calculated the effective mass, which measures the impact the target experiences. The results showed that while the open hand slap and karate chop had similar effective masses, the closed fist punch had an effective mass that was more than double the other techniques. So, unless you’re a black belt in karate with a mean karate chop, let’s stick to punching if the need arises.

Which punch to utilize

Now that you have decided that the first step is to clench your fist and rear up for a punch, how exactly do you do that? Biomechanical studies have shown for low-level boxers the cross, which is a straight punch with the dominant hand, generates noticeably more punching force. When elite level boxers such as Olympic athletes are observed, however, all three techniques produce extremely similar punching forces. This suggests that for the average untrained human, the most effective and efficient punch to use is going to be the cross.

While it is not the most scientific diagram, this graphic gives some biomechanically sound tips on how to throw an effective straight cross. Photo from The Art of Manliness.

But why is the straight cross generating more force in amateur boxers, and how can elite boxers generate high forces with the other techniques? It’s all answered by biomechanics.

Each punch is unique in how force is generated due to the motion of our bodies and the muscles each motion uses. For example, elite level boxers generate much more of their punching force from extension of their back leg and the extension of their elbow when throwing the cross. This is similar to how a baseball pitcher generates force by driving off the mound with their back leg in their throwing motion. When throwing hooks and uppercuts, elite boxers tend to utilize their hip rotation much more than lower-level boxers, who rely on their shoulder motion. All of this leads to the fact that while you’re throwing your fist at a target, most of the power comes from your waist and legs, so mixing a leg day into your workout schedule could be beneficial.

Sources and Further Reading

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.

The Benchmark of Upper Body Strength: Injury Prevention During the Bench Press

Who wouldn’t want to look like Captain America? This common desire to attain a strong Herculean physique, either for athletics or aesthetics, has led many ambitious men and women to weightlifting. An egotistical motivation puts these people at risk of injury, however, as they sacrifice proper form to achieve their next personal best. The bench press is one example of an effective but potentially dangerous lift.

This upper body exercise requires an individual to lie flat on a bench while repeatedly lowering and pressing a straight bar loaded with weights on each end. The hands evenly grip the bar slightly wider than shoulder width apart with the feet remaining flat on the ground and the arms fully extended. During the eccentric (or lowering) phase, the bar is brought in contact with the lower chest. The bar is then pressed up until the arms are once again fully extended (concentric phase).

Recreational weightlifters commonly use a wider grip on the bar, believing that this will increase activation of the chest muscles and allow them to mimic Terry Crew’s version of the Old Spice Man. One study performed on 12 powerlifters, however, found that the prominent muscles used during the lift, such as the pectoralis major, triceps brachii, and anterior deltoids (i.e. chest, triceps, and shoulders), experienced similar electromyographic activity despite varying hand spacing.

Diagram of a human upper body muscular system.
Image by OpenStax from Wikimedia Commons.

Although hand spacing does not significantly affect muscular activity, it can lead to injury. A review of several studies on the effects of hand grip found that a grip width greater than 1.5 times biacromial width, or shoulder width, naturally resulted in shoulder abduction, or rotation away from the body’s centerline, greater than 45°. As this angle increases, shoulder torque increases, causing potential injuries. For instance, the inferior glenohumeral ligament, a ligament restricting translational motion in the anterior direction at the shoulder’s ball and socket joint, may tear as abduction increases, causing instability at that joint. Repetitive cycles with this wider grip may also cause acromioclavicular joint (AC Joint) osteolysis – chronic destruction of the bone tissue at the joint between the clavicle and acromion.

Diagram of shoulder joint.
Image by OpenStax College – Anatomy & Physiology from Wikimedia Commons.

Aside from a wide grip, injuries also commonly stem from over-training and using excessive weight. Research on 18 male college students demonstrated that repeating the bench press motion with high frequency until failure resulted in a significant increase in the medial and lateral force exerted on the elbow joint, which could result in injury over time. Furthermore, performing the bench press with heavier loads could result in a sudden rupture of the pectoralis major. At the bottom of the eccentric phase as the bar touches the chest, the muscle fibers are simultaneously lengthening while also contracting, which increases the risk of muscle tear in this region.

Unlike Captain America, people cannot instantly acquire strength or build muscle. Muscular development and improving one’s bench press require time, patience, and proper form. To learn more about injury prevention or variations of the bench press, check out the video below or read these papers by Bruce Algra and JM Muyor.

Sources can be found below:

The Affect of Grip Width on Bench Press Performance and Risk of Injury

The Effects of Bench Press Variations in Competitive Athletes on Muscle Activity and Performance

Elbow Joint Fatigue and Bench-Press Training

An In-Depth Analysis of the Bench Press

 

Using K-Motion Technology to Achieve the Perfect Baseball Swing

The question on every baseball player’s mind is: besides more practice, how can I improve my batting skills?

Most people would assume it comes down to practice and strength training, but according to Joe Lemire, a sports reporter at SportTechie, the answer actually lies in the biomechanics of the swing. An in-depth description of the intricacies of the biomechanics that are involved in a baseball swing can be found in David Fortenbaugh’s dissertation here.

A photo of a baseball player mid-swing, making contact with the ball in a game.
Photo by Chris Chow on Unsplash

Many professional baseball teams and some training facilities, including Driveline Baseball in Seattle, have turned to using a K-Motion vest to record and analyze different aspects of a baseball swing. This wearable technology started as an analysis for golf swings, but the technology has now been implemented in baseball. Initial installations of this technology were much more expensive and not portable, but engineers have found ways to translate these technologies into wearable devices that can be used in more natural situations.

Prior methods of swing analysis left many unanswered questions and didn’t provide athletes with proper information for improvement. The K-Motion vest collects data on the speed and bend in a player’s torso and pelvis, and the rotation of their body. The portability of the vest allows for it to be used in game-like scenarios and provide useful information. The data that can be extracted from the K-Motion vest can be used to fix mechanical flaws in a player’s swing.

A photo of a man wearing the K-Motion vest, showing that a sensor sits on the top of the spine and at the tailbone.
Photo from Lemire, SportTechie 2018 (Courtesy of K-Motion)

The K-Vest uses four different sensors to measure the rotational velocities of the torso, hips, lead arm, and bottom hand. The four sensors are placed above the elbow on the lead arm, on the back of the lead hand, on the tailbone, and on top of the thoracic spine. The velocities are compiled into a graph, and the peak velocity of each sensor can be analyzed to track the transfer of energy throughout the swing. Through use of the K-Vest, they have found that to elevate one’s hitting ability comes down to the transfer of energy from pelvis and torso rotation to their arms and wrists.

In order to fix the mechanics of a swing, the system has to obtain an understanding of what a good swing is by compiling data from a variety of professional players. On the graph produced with each swing, the range for pro hitters is displayed to give the user an idea of how they compare. Some more information about the kinematic analysis of the data can be found here.

An example of the data that the user receives from the system and how it can be used to improve a player’s swing can be seen in this video:

Though already proven useful in baseball and golf, people are finding that it can also be useful in volleyball, running, skiing, and other forms of physical activity. The use of this technology has become much more common as professional players have found the feedback to be constructive.

For more information about this technology, check out K-Motion’s website, and see here how it’s being used in golf.

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.