Tag: sports

Ski Racing: Where Champions are Made on the Course and in the Lab

If you have ever watched the winter Olympics, you have probably watched in awe as the alpine ski racers flew down the course. Years of training to perfect technique and build strength are essential for any athlete trying to compete with the best, but in a sport where hundredths of a second can separate first and second place, racers are always looking for ways to shave time. Understanding the forces that slow them down and their relationship to body positioning gives these athletes a competitive advantage.

Photo of Mikaela Shiffrin, a world champion ski racer, in a low tuck position. She is turning around a blue gate racing in the 2022 winter Olympics.
Photo of Mikaela Shiffrin in a low tuck at the 2022 winter Olympics taken by Robert F. Bukaty.

Forces

The figure is a free body diagram of a skier. It shows a stick figure of the skier's body with a gravitational force acting down, a normal force acting perpendicular to the skis, a friction force acting parallel to the skis, and a drag force acting parallel to the path of the skier.
Free Body Diagram of the forces on a skier.

Several forces act on a skier during a race, including gravity pulling him or her down the hill, friction from the snow, and drag. Friction and drag decrease speed. Drag force occurs when an object moves through a fluid. It is a function of the fluid properties, the cross-sectional area of the object, and the object’s surface roughness. In ski racing, the fluid is air. Drag force increases as velocity and cross-sectional area increase.

A diagram of the air flow around a circle. The air flow is shown with arrows pointing in the direction of flow. One arrow strikes the circle at the center. The others bend to move around the circle, this is the attached flow. At the back of the circle, the flow separates and bends into spirals of turbulent wake, creating the low pressure zone.
Diagram of the air flow around blunt objects highlighting pressure drag.

There are two categories of drag. Viscous drag is caused by friction between the air and the body. Skiers decrease this force by wearing smooth suits. Pressure drag occurs because the air stream separates to move around the body. When the air strikes an object, particles build up and compress on the front surface. They are more spread out behind the object, creating a low-pressure zone that induces drag.

Body Position Basics

The drag force has the most significant impact on speed. Ski racing involves adopting a low tuck position to decrease cross-sectional area. In a low tuck, the athletes bend at the waist and knees while tucking their poles beneath their armpits.

A photo of a ski racer in a low tuck position. She is in a wind tunnel wearing full ski racing gear, including a helmet, goggles, speed suit, gloves, poles, boots, and skis.
A figure taken from Brownlie et al. of a ski racer in a wind tunnel.

Athletes also spend time in wind tunnels during the preseason to perfect their body positioning. This testing, however, is time consuming, expensive, and fails to highlight the distribution of flow around the skier’s body. To better understand these forces, several researchers, Elfmark, Asai, and Brownlie, used a mix of wind tunnel testing and computational fluid dynamics to estimate the drag force, visualize air flow, and find the position that minimizes drag.

Ideal Body Position

A figure of a digital skier's body with a plot overlaid. The plot has length along the athlete on the x-axis and drag coefficient on the y-axis. The drag coefficient spikes when moving over the head, at the elbows and knees, and when moving over the thigh.
Figure taken from Elfmark et al. showing how drag force increases along the length of the body.

The data showed that an upright, open body position will increase the drag force, hence the need for a low tuck. Specifically, the head, upper arms, thighs, and lower legs have the largest affect on drag. This is because these are blunt areas on the body that the air stream must separate to move around. The figure shows that the drag force spikes as the air strikes the head, upper arms, and thighs, and around the arm pits. Additionally, Elfmark’s team found that the ideal position was when the knees filled the gap beneath the arm pits. This decreases the need for the air to separate, facilitating a smooth air flow and thus less drag.

Although these results are interesting, they have significant limitations. The tests modeled a static position of the skier, which is unrealistic in a dynamic sport.

How to Optimize Biomechanics Forces of Olympic Giant Slalom Skiers

Giant Slalom skiers skiing down slope in tandem.
Photo GEPA pictures

How to Optimize Biomechanics Forces of Olympic Giant Slalom Skiers

            Do you ever wonder what differentiates a casual skier from an Olympic level skier? The distinction lies in the immense forces these Olympic skiers’ output as they naturally transition from incredibly high speeds to sharp turns on the icy slopes. The four famous alpine skiing events held at the Winter Olympics are the slalom, giant slalom, downhill, and super-G events. In these events the human body is pushed to its limit with skiers experiencing forces of up to 2000N during turns through closely spaced poles and gates [1]. Which is the equivalent of a 440-pound weight laying on top of you. These forces are integral in achieving faster times, better technique, and winning Olympic gold. How can these forces and techniques be optimized for the best possible ski run?

            Let’s explore the turn mechanics and forces experienced by giant slalom skiers. Giant slalom was chosen because it combines the quick turns of slalom and the high speeds of the super-G and downhill events [2]. Therefore, it is an adequate choice for investigation. First, we need to understand the forces experienced by a skier during a turn around a gate, which are displayed.

Skier bending down while turning
Forces on alpine skiers (J. Smith representation)

            Skiers experience four basic forces during a turn. They undergo friction forces between the skis and snow and the force of air drag as they blister down the slopes. The force of their body weight due to the constant force of gravity. As well as ground reaction forces (GRFs), which represent the force of the skiers on the ground. These GRFs are highly important as the skier pushes hard against the ground to carve through turns and around the gate. 

            The most important part of the ski turn is the change of direction. Skiers change their direction by digging into the snow while changing the angle of their skies. This causes variability in their outputted forces. Prior to changing direction, skiers output 500N of GRFs, but as they begin to change angle around each gate they skyrocket to 2000N [1]. This is due to the adjustment of ski angle against the direction of motion. The understanding of these forces can be the difference between Olympic gold and last place. 

            These forces are important for the success of the skier as well as their safety. Every skier has different approaches towards their turn around a gate, so it is important to gather data to optimize the success of each ski run. Ski equipment also plays a vital role and could influence ski times, as each skier has difference in preferences for their equipment [3]. 

Understanding these forces are important for the success of the skier as well as their safety. Every skier has different approaches towards their turn around a gate, so it is important to gather data to optimize the success of each ski run. Ski equipment also plays a vital role and could influence ski times. As each skier has difference in preferences for their equipment. Comprehension of these forces play a huge role in enhancing skier safety. Slipping due to high speeds and improper technique can cause crashes and devastating injuries. The goal of this study is to produce a point of fast ski times where safety, equipment, and technique are optimized. There are many unknowns in the optimization of the perfect ski run. With future study of the alpine skiing, skiers and their equipment will continue to develop and their times will become faster. 

References 

[1] Gilgien, Matthias. et al. “Determination of external forces in alpine skiing using a differ- ential global navigation satellite system.” Sensors (Basel, Switzerland) vol. 13,8 9821-35. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3812581/

[2]  Supej, M and Holmberg, H. “Recent Kinematic and Kinetic Advances in Olympic Alpine Skiing: Pyeongchang and Beyond.” Frontiers in Physiology. https://doi.org/10.3389/fphys.2019.00111

[3]  Cross, M. et al. (2021) Force output in giant-slalom skiing: A practical model of force application effectiveness. PLOS ONE 16(1): e0244698 https://doi.org/10.1371/journal.pone.0244698

Which Body Mechanics Help You Jump Higher?

Vertical jumping is an essential aspect of many sports. In volleyball and basketball, for example, jumping higher than your opponent gives you a significant competitive advantage. Volleyball players need to be able to block and spike, while basketball players need to be able to rebound well and finish tough shots over opponents. Most athletes know the basics of jumping, but few know what specific body mechanisms contribute to jump height. This article will discuss four key elements to vertical jump height:

  • Squat depth
  • Non-extension movements
  • Arm swing
  • Toe flexor strength

Understanding the mechanics behind each of these elements can help guide athletes in training regimens to better increase jump height.

Squat Depth

Three illustrations displayed, showing the squat depth at each studied angle.
The different squat depths studied. Taken from Gheller et al. (2014).

It seems obvious that squat depth is a part of jumping, but does the average athlete really consider how deep they squat during a jump? A study was done by Gheller et al. (2014) to determine the optimal squat depth to increase jump height. The depth was measured by the angle of the inside of the knee at the bottom of the squat. Participants were instructed to squat to three different depths, < 90◦, > 90◦, and their own preferred, natural squat depth, before jumping as high as they could. Surprisingly, the squats at < 90◦ produced higher jumps than squats at preferred depth. This is primarily due to these jumps producing the greatest takeoff velocity.

Non-Extension Movements

Non-extension movements are movements not related to any lower leg extension. In other words, these are movements seemingly unrelated to the core mechanics of the jump. However, some of these movements were found to have a significant impact on jump height. A study was done by Sado et al. (2020) regarding a running jump off one leg, where the amount of mechanical energy generated by various non-extension movements was calculated. This mechanical energy is converted to energy needed to produce higher jumps (Evert). Again, the velocity of the participants’ center of masses was recorded, from which these energies were calculated. During the takeoff phase, 59% of the increase in Evert was found to be due to the rotations of the stance-leg (jumping leg) calf, free-leg thigh, and the pelvis. The free-length thigh was the largest contributor, followed by the stance-leg calf, then the pelvis.

Arm Swing

The arm swing in a jump is intuitive for most people, but it is important to still understand its mechanics to better utilize the mechanism. During a jump, people swing their arms back as they squat down, then swing them back up as the propel vertically. How does this impact jump height? A study was performed by Hara et al. (2006) where participants stood on a force platform and jumped with and without swinging their arms. Every participant’s jump was higher with an arm swing. This is because the ground reaction force from the force platform increased with the swing, meaning the participant had pushed off the ground with greater force. This created a higher takeoff velocity, resulting in a greater height.

Two step-by-step illustrations comparing what jumps with and without an arm swing look like.
Top: a jump without an arm swing. Bottom: a jump with an arm swing. Modified from Hara et al. (2006).

Toe Flexor Strength

Test subject standing on toe grip dynamometer and squeezing the grip bar with his toes.
Toe flexor strength experimental setup. Taken from Yamauchi and Koyama (2020).

Toe flexor strength is rarely considered when jumping, which is why it is important to understand. In this study by Yamauchi and Koyama (2020), participants stood on a toe grip dynamometer and squeezed the grip as hard as possible. The maximum force was recorded, then separately, participants jumped as high as possible. Participants with greater toe flexor strength also had greater jump heights. This is a lesser-known correlation that can help athletes gain a slight advantage over competitors by training their toe flexors.

This is not an all-intensive list of what goes into jumping but knowing how these mechanisms work can still guide an athlete’s training program. In today’s world, sports are so competitive; everyone is always looking for a leg up (pun intentional). Knowing the biomechanics behind jumping can truly lead to better sports performance.

An Exploration Into The Growth Of The Heart As A Result Of Certain Exercise

Have you ever wondered what happens to your heart when you begin to consistently exercise? How does the heart change and why? Well, the answer may not be very complicated.

During intense exercise, our heart is put under stress as it has to rapidly pump blood throughout the body. The heart often responds to this by increasing its size, but it does not do this like our other muscles. The heart has to add mass to its existing cells instead of adding new cells as we only have a limited amount of cardiac muscles; the amount we are born with is all we have. The health of our hearts is important. In the US, heart disease and injury are the number 1 cause of death. So, it is in our best interests to learn more about our health so as to minimize our risks of heart-related ailments.

Results of Marathon training

Studies have been performed to analyze the changes in the heart of people as they were training to run a marathon. The main study that I looked at tracked the heart taking measurements every three months. As a result of marathon training the test subjects’ hearts had increased wall thickness, left ventricle end-diastolic volume, and right ventricle end-diastolic volume. The end-diastolic volume is the amount of blood in the heart while it is full. This is all just to say the heart could pump more blood per heartbeat than before.

This graphic shows that the Left and Right Ventricles of the heart increase in volume as a result of running with the left growing more towards the end of the first year while the right grows more initially. Wall thickness is also shown to increase after the first three months then leaving off.
The result of marathon training on the left and right end-diastolic volume as well as the heart’s wall thickness. (Arbab-Zadeh et al., 2014)

The Result of Constant Swimming… on mice

I could not find a study on how the human heart adapts to constant months of swimming. However, I found a study that does it for mice. Each day, mice were forced to swim 5 hours a day for 6 days a week for 9 weeks. At the end of the experiment, the heart of the mouse that endured swimming was 73% larger in weight than the control group.

I could not find a study on how the human heart adapts to constant months of swimming. However, I found a study that does it for mice. Each day, mice were forced to swim 5 hours a day for 6 days a week for 9 weeks. At the end of the experiment, the heart of the mouse that endured swimming was 73% larger than the control group.

Which Exercise is better for the Heart?

While both exercises can promote heart health. For a person who wants to get serious about their heart, running is better for the heart. A study, by Currie, Katharine D et al. in 2018, was done comparing the heart of Olympic-level runners and swimmers. While the sizes of the hearts of the athletes were almost identical. The runners had a lower resting heart rate as a result of larger pumping volume. This may have to do with the fact while someone is swimming their body is horizontal so the heart does not have to pump blood up against gravity. More studies should be done to see the direct impact of swimming on the heart. In the end, both exercises are beneficial to our heart’s health.

Jumping into Better Bone Health: Impact Exercise and Your Bones

When exercising for overall health, the general public tends to disregard the importance of bone health. Often the focus is on consuming milk or calcium rich foods, but are there certain exercises that can increase bone health? Studies show that the presence of impact in exercise plays a major factor.

As we age, everyone loses bone mineral density, which is a determining factor in bone strength and stiffness [1]. Decreasing bone mineral density can lead to bones that easily break and fracture, and will, in extreme cases, result in the disease osteoporosis. Women are at a higher risk of osteoporosis because they lose more bone mineral density as they age due to the process of menopause [2]. Increasing bone mineral density at younger ages can ensure that even with the inevitable bone loss, peoples’ bones are still strong.

Bone mass as a function of age (Wikipedia Commons).
Simone Biles Back Band Handspring on Beam. (KSN: Tokoyo Olympics).

Adding high impact activities into one’s exercise routine can increase bone mineral density and prevent weak bones from developing. When athletes engage in high impact activities, the forces from the impact induce small strains in their bones. Strain in bones causes bone growth which increases the bone mineral density of the impacted bones, therefore making them stronger [3]. When gymnasts perform back handsprings or flips, or when volleyball players jump high into the air to spike the ball, they load their bones with high forces. A study done on college athletes showed that gymnasts and volleyball players had significantly higher bone mineral density than swimmers, which is considered a low-impact sport. Additionally, the swimmers did not vary much from the non-athlete group signifying that rigorous exercise is not enough to increase bone health without the presence of impact. The gymnasts also had higher levels of bone mineral density in their arms than all groups, because they were the only sport that induced significant strain in their arms [3].

There are many types of impact sports, from cross country to gymnastics. All impact sports increase bone mineral density in their participants, but the sports that involved the highest loads such as jumping increased bone mineral density more than medium impact sports [4][5]. Running is a great pastime for overall health but if bone health is a priority more focus should be given to even higher impact activities. Like any other type of workout plan, consistency is key. College athletes show significant increases in bone mineral density from the pre-season to the post-season, meaning that they often lose bone during their time off working out.

Long Jumps and Plyo Jacks (Verywell Fit).

It is still unclear what precise frequency of bone impact or amounts of strain optimize bone growth. Higher levels of load generally led to stronger bones, but obviously there is a limit to the amount of load bones can take without breaking. What is the optimal amount of strain to put bones under to produce the strongest possible bones? This is still up for debate, but it is well established that only activities with impact play a role in increasing bone strength. If you’re an avid swimmer or cyclist, consider adding running or some jump squats into your cross training to keep bones strong and healthy.

Works Cited

16 Mar. 2022

[2] Nazarian, Ara, et al. “Tensile Properties of Rat Femoral Bone as Functions of Bone Volume Fraction, Apparent Density and Volumetric Bone Mineral Density.” Journal of Biomechanics, vol. 44, no. 13, Sept. 2011, pp. 2482–88. DOI.org (Crossref), https://doi.org/10.1016/j.jbiomech.2011.06.016.

[3] Fehling, P. C., et al. “A Comparison of Bone Mineral Densities among Female Athletes in Impact Loading and Active Loading Sports.” Bone, vol. 17, no. 3, Sept. 1995, pp. 205–10. DOI.org (Crossref), https://doi.org/10.1016/8756-3282(95)00171-9.

[4] Carbuhn, Aaron F., et al. “Sport and Training Influence Bone and Body Composition in Women Collegiate Athletes.” Journal of Strength and Conditioning Research, vol. 24, no. 7, July 2010, pp. 1710–17. DOI.org (Crossref), https://doi.org/10.1519/JSC.0b013e3181d09eb3.

[5] Dook, Jan E., et al. “Exercise and Bone Mineral Density in Mature Female Athletes:” Medicine amp Science in Sports amp Exercise, vol. 29, no. 3, Mar. 1997, pp. 291–96. DOI.org (Crossref), https://doi.org/10.1097/00005768-199703000-00002.

Do your Foot Arches make you more or less likely to be injured?

Picture showing what a flat foot, normal foot, and high arched foot and what the footprint looks like

Have you ever wondered how your arch type may affect your everyday life especially in physical activities such as running or playing sports? Well it turns out that without taking precautions, a higher arch or a flat foot may cause you to more likely be injured! People have all different types of arches, and each foot can be affected differently based on the type of arch.

Different arch types and properties of each (ShutterStock)

Arches are important because they provide impact absorption and stability in the push-off phase in walking or running. Usually there are patterns of types of injuries that may occur based on the type of arch a person has. The injuries may be similar for different types of activities, but the location of the injury may vary. Running is one of the most popular activities for Americans to do and it is estimated that about “one-half to two-thirds of runners will sustain an injury”. This is a very high number so it is important to understand some of the biomechanics behind why this may be happening.

An image showing the gait cycle of the leg swinging forward and stepping.
A man walking, showing the stages of the gait cycle (Taken by Kirker et al. 2016)

The dynamics of the foot cannot be studied without talking about the biomechanics of the leg as well. The main period that is studied to understand the biomechanics of the foot is called the gait cycle, which is the period of time for two steps to happen where the foot makes contact with a surface and the limb swings forward as shown in the image. When moving faster or running, the foot pronates (weight more on the inside of the foot) and supinates (weight more on the inside of the foot) differently and the pressure shifts medially.

Arch types affect where the pressure shifts on the foot. In the article by Rodgers, the collected research shows that high arches are more rigid, and there tends to be more pressure concentrated beneath the heel and forefoot. Low arches are usually associated with flexibility, where the pressure is spread out more including the area of the midfoot. The most common methods for determining the pressures in the feet are by having subjects stand on force plates and this was the method used by Rodgers.

An image showing the process of determining what arch type people have and choosing a shoe based on this arch type.

Various studies came to a few conclusions about injuries based on arch type. The types of injuries in people with high arches tend to be bone or lateral ankle injuries based on the biomechanics that most of the pressure on the foot is in the front and back of the foot mainly when running or walking. The injuries that usually occur to people with low arches tend to be related to soft tissues and knee pain because of how the pressure is more evenly distributed through the foot, especially in the middle of the foot. While many of the results conclude that there is a correlation with injury type and arch type, the main conclusion was that people with high or low arches generally have a higher risk of injury than people with normal arches. The most common injuries seen are overuse injuries and pain to the knee. Luckily, there is technology within shoes that is specifically designed to mimic pressures on a regular foot. Choosing the right shoe based on arch type is important to preventing injuries when doing strenuous activities!

Guide to finding the right shoe based on arch type (taken from Thomas 2019)

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?

Taekwon-Do Grandmaster Rhee Ki Ha breaking a solid concrete block with a punch
Courtesy of: Oakville Today

One of the most important aspects of bone hardening is increasing bone mineral density by continuously loading and unloading bones, as well as contracting the surrounding muscles consistently and for a prolonged period of time. It is particularly interesting to study how the typical bone mass gain that occurs during the adolescents is affected by sports that are high-impact and place great stress on one’s bones. Studies show that adolescents who participate in combat martial arts had significantly higher bone material density in their hands, arms, and legs than comparable adolescents who did not. Since the development of bone mass and structure is most significant during adolescence, the potential to increase the bone mineral density is greatest during this time.

However, as with most things there is a Ying to every Yang in the world of increasing the bone mineral density. The difficult and complex movements required to “harden” one’s bones make the athlete more susceptible to sustain a severe injury in training or competition. As it is typical to experience pain throughout the process of developing bone material density, the development and progression or micro-fractures and injuries can be ignored or mistakenly thought of as typical training pains. This results in there being a fine line between strengthening bone and causing injury to oneself.

Anderson Silva after suffering a gruesome leg injury.
Courtesy of: Lanna MMA

There are other benefits to increasing one’s bone mineral density outside the realm of combat sports. By engaging in high-impact activities during one’s adolescence into adulthood, one can decrease the risk of developing osteoporosis by having increased their bone mineral density. This further supports the reasoning to stay active and healthy to ensure a longer and healthier life.

Whether it is breaking boards to entertain sports, or fighting on the world’s premier combat stage, having strong and healthy bones is an essential aspect of being an athlete in high-impact combat sports. This is achieved through generating increased bone mineral density and is the result from years of dedicated practice and time. All in all, the difference it makes is rather striking.

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.