Course:KIN366/ConceptLibrary/RacquetSports

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Movement Experiences for Children
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KIN 366
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Instructor: Dr. Shannon S.D. Bredin
Email: shannon.bredin@ubc.ca
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Racquet sports are activities that require a handheld apparatus in which individuals aim to strike a ball or object in a specified area of play. There have been various racquet sports developed across the world and adopted by many countries. With many different cultures exposed to some form of racquet sport, there are often modifications that give rise to a similar but new sport. The most popular racquet sports worldwide consist of tennis, badminton, and squash.

History

Table Tennis

Table tennis was a modification of lawn tennis to the dining room with altered equipment to be played after dinner (Olympic.org, 2014). The altered equipment included books that acted as a net, champagne corks as a ball, and cigar box lids as rackets. Modern day equipment include a hollow celluloid ball and wooden or carbon-fibre paddles to be played on a wooden table. There are approximately 40 competitive table tennis athletes worldwide and the greatest popularity of the sport is in China.

Tennis

Tennis was founded in northern France during the Middle Ages where it was played in cloisters and the only racket they had were their hands (Rowley, 2008). This is the only racquet sport that calls their playing apparatus a racket as opposed to a racquet. Rackets were not used until they were developed in the sixteenth century. The modern lawn tennis game was modified in Britain in the 1870s and tournaments were created a decade later. With the creation of the first modern Olympics in 1896, tennis was included for a couple decades before being removed. Men and women played singles, doubles and mixed doubles and court surfaces were changing from the lawn to clay and hardcourts following World War II. 1968 marked the beginning of the Open Era built upon the early tennis pioneers such as Billie Jean King and Rod Laver. Tennis is now one of the fastest growing sports not only in Canada, but also in the world. Canadian statistics from 2010 show that tennis was the sixteenth most popular sport with a participation rate of 2.0% (Canadian Heritage, 2012).

Badminton

Badminton had developed in the 1870s which was a modification of shuttlecock (Cannon, 2009). It was first played in India by the army where the rules were created in Poona. A Badminton Association was formed in 1893 which eventually led to an International Federation being created in 1934. The popularity of badminton was due to the high intensity of play and that it flew under the radar in most cultures which eventually spread to the Middle East and Eastern Asia. In a study conducted by government of Canada, badminton was the eighteenth most popular sport in Canada for children between ages of 5 and 14, with participation at 1.5% in 2010 (Canadian Heritage, 2012).

Squash

Squash was developed by medieval European monks who enjoyed bouncing a ball off a wall which became the basis of the sport (Zug, 2003). The sport had evolved from India’s rubber balls, bamboo racquets, and granite cages to modern glass walls and steel racquets. It is now a popular recreational sport played all across the world but its popularity lies more with the older generation than children.

Racquetball

Racquetball was created in 1950 which was a combination of squash and handball with a smaller racquet with tennis string patterns (United States Racquetball Foundation, 2012). This sport uses a different ball than squash and was a fast emerging sport in the United States in the 1980s. In 1995, there were 24 million players across 91 countries across the world. Like squash, there is more popularity among older adults in comparison to children.

Fundamental Movement Skills

All racquet sports have commonalities amongst them, but the biggest one is the biomechanical strain on the inferior body (Bouché, 2010). These sports require fast footwork and body movements to help execute the sudden acceleration or deceleration of an individual. Movements considered “stop-and-go” motions involve many different fundamental movement skills which is greatly dependent on the age group of children and whether they have developed mature patterns for those skills. The Fundamental Movement Skills that may be exhibited through locomotor skills which moves an individual from one place to another or nonlocomotor skills which alters posture with little or no movement of the lower limbs that plants an individual to one spot (Gabbard, 2012). Locomotor skills include walking, running, or sliding movements while nonlocomotor skills consist of twisting, bending, or swaying. Another category is manipulative skills which are composed of major or minor movements of the hands or feet such as striking or throwing. All these actions produce stress in the vertebrae and the lower limbs that are often overlooked in competition, especially in children (Bouché, 2010).

Locomotor Skills

Walking

Walking is the basis of movement for all racquet sports. It is the transfer of weight from one foot to the other when transporting the body from one place to another with one foot contacting the ground at all times (Gabbard, 2012). This fundamental movement skill has no major significance in play of racquet sports as athletes would generally walk from one spot to another during their rest intervals. It may seem like an unimportant motor skill in the participation of racquet sports but a mature walking pattern would help the development of other movement skills such as running.

Running

This fundamental movement skill is a basic progression of walking and is defined by a flight phase in which neither leg is supporting the body off the ground (Gabbard, 2012). By the time a child begins to learn a racquet sport, they will be in the process of attaining a mature running pattern. Generally children will have a competent running stride but it will require instruction to achieve sprinting to play any racquet sport well, especially at an elite level. Sprinting is able to generate normal forces comparable to jumping that vary from triple to quintuple the body weight of an individual (Cavanagh, 1980). It was also found that the greatest force used to accelerate is 60% of an athlete’s body weight and the force to decelerate of stop is 80% of the body weight. Racquet sports are considered an anaerobically dominated sport so running is a crucial skill required to be developed by children when they begin a racquet sport in order to generate regular play patterns. There is many starts and stops of play action with the activity reaching vigorous levels of intensity and rest that demonstrate no or low levels of intensity to recover for the next sequence (Girard, 2008). Play action durations in racquet sports range from 2 to 15 seconds on average and the work-to-rest ratio could vary between 1:1 or 1:4 which is entirely sport dependent but the level of competition plays a factor as well.

Tennis is shown to have a significant disparity in pace of play between intermediate and advanced players. Nigg, Luthi, and Bahlsen discovered that there is noticeably more walking than running or hopping in intermediate level players compared to equally amounts of walking, running and hopping in advanced players due to lower work-to-rest ratios (as cited in Bouché, 2010, p. 216).

Badminton is the racquet sport that requires the most running following tennis. This sport requires coverage of an athlete’s side of the court whose dimensions are 6.7meters long by 6.1 meters wide (Mawani, 2003). Other racquet sports such as squash or racquetball are in confined areas that require less running from wall to wall.

Jumping

Jumping is a locomotor skill that produces a force to propel an individual off the ground off one or two feet and land on a single foot or both feet (Gabbard, 2012). Similar to running, children will have most likely developed this motor skill when they begin to partake in racquet sports. The most popular form of jumping in racquet sports is vertical jumping as elevation is essential to the performance of the child. In the process of achieving the vertical jumping skill, children begin with propelling off the ground with two feet and stretches upward to acquire greatest reach. As a child specializes for certain sports, coaches will train them with different jumping tactics for their respective sports. Jumping is mostly seen in tennis and badminton in certain circumstances but all other racquet sports exhibit no vertical component. The standing long jump development is considered irrelevant in racquet sports as it never utilized in any situation.

In tennis, vertical jumping occurs during the service motion, high volleys or smashes. There is also a small vertical jump prevalent to all tennis movements during game action known as a “split step”, which is a jump to keep the player on the balls or toes of their feet to be prepared to move to the next shot. During the service motion, the main focus is not the jumping component as a vertical jump only occurs during weight transfer of a body for the player to reach maximum extension upon contact. During high volleys, especially on the backhand side, a one-foot takeoff may be suggested by coaches if more height is needed. Also, if a ball is hit high behind the athlete that wants to smash, the athlete will shuffle back, takeoff one foot and perform a scissor kick upon contact to gain maximal reach, power and recovery. This movement is also present in badminton for similar reasons. A study by Valiant found athletes who elevate to strike a smash and contacts the ground heel-first or flat-footed, may be withstanding their body weight six fold (as cited in Bouché, 2010, p. 216). On the contrary, if the player lands on the balls of the feet, the player will only stress four times the body weight on the foot and a study found stress placed while running is only double or triple the body weight (Cavanagh, 1980).

Sliding

This fundamental movement skill is sideways movement in which the direction one wants to head is the foot that leads first (Gabbard, 2012). Weight transfers from the lead foot during the movement to the following foot at the conclusion of the action. The lead foot that begins the slide is considered slow but the following foot quickly catches up to the lead foot that is a momentary jump that resembles hovering from one spot to another. Table tennis utilizes this movement the most during the point duration as their playing areas are considerably smaller other racquet sports. Sliding on the actual surface is most commonly present in tennis due to surfaces and the evolution of the game that allows athletes to tolerate such forces on the body. There are variations to the slide, as in badminton there is chasse step in which the racquet foot (leading foot) takes a step quickly followed by the non-racquet foot (following foot) in preparation for a lunge (Mawani, 2003).

Nonlocomotor Skills

Twisting

Twisting is the most significant nonlocomotor skill in the success of racquet sports. This is influential in power generated by a player and is attained by many elite level players across various racquet sports. This nonlocomotor skill functions with the contortion of the upper body and requires great abdomen strength as well. Many children will not incorporate this early on in racquet sports but as they mature they will become more flexible and begin twisting their body to improve upon their racquet sport.

Bending

Bending is a nonlocomotor skill that helps with preparation and consistency of shot making in racquet sports as this helps with stability of the body. This may include bending of the back or legs with allow for a child to be prepared to play the next shot. This is only essential for participants to be in the “ready position” so they are always prepared for play action.

Swaying

Swaying is the least important nonlocomotor skill as it is not utilized in the point duration of any racquet sport. This skill consists of weight transfer from one foot to the other to exhibit left and right swaying. It is most predominant in tennis during serve receive as it is part of many players’ routines to return serve. Very rarely is there swaying from the toes to the heel of the foot and as a result, front and back swaying is irrelevant in racquet sport.

Manipulative Skills

Throwing

Throwing is the manipulative movement where an individual tosses an object away from themselves into the air (Gabbard, 2012). The underhand throw is most common in all racquet sports and is seen most in tennis. This is proficiently attained around the 7-years-of-age and will be utilized effectively in the respective racquet sports. The underhand throw is only prevalent in tennis during the service toss where a child must toss the ball in the air for the ball to be struck to the other side. A mature tennis underhand throw will require training to master and is very critical in the success of an athlete’s serve. Badminton would only utilize throwing during drill practice and not necessarily match play due to the accustomed rules as well as the use of a birdie instead of a ball. During drills, underhand throws of the birdie will be used to simulate drops and overhand throws also called “dart-throws” simulate smashes (Mawani, 2003).

Ball Bouncing/Dribbling

This manipulative skill involves pushing a ball towards the ground (Gabbard, 2012). When a child drop the ball and it bounces back towards them, the child is inclined to strike the object continuously which would be considered dribbling. This skill is irrelevant to the performance of racquet sports but it is usually a routine many players use in tennis in preparation of a serve. A child will have attained skilled dribbling pattern about 6-years-of-age in which they will dribble the tennis ball before tossing the ball up. They will begin by bouncing the ball three to four times and when they have attained mastery of the skill they may bounce it thirty times like the professionals on the tour.

Catching

Catching is a manipulative skill that requires eye-tracking of an object, stopping the object and maintaining it in the hands (Gabbard, 2012). Catching is not an important skill in play action, it is just effective to catch the ball or birdie in periods of rest. In tennis, if an ineffective toss has been made, then the player has the option of catching the ball and tossing it again. In badminton, the player may want to catch the birdie to speed up the rest period to prepare for the next point.

Striking

Striking is the most important manipulative skill due to the objective of racquet sports being the object in question being hit to the opponents side. It is most commonly performed by the hand, foot, or head with apparatuses such as racquets, paddles or bats (Gabbard, 2012). This manipulative skill has three common movements, either overhead, sidearm or underhand. Squash and racquetball only utilize the sidearm strike while both badminton and tennis use all three motions. Sidearm striking is present when child reaches 3-years-of-age but does not attain a skilled pattern until 5-years-of-age. Badminton, squash, and racquetball all only utilize a 1-arm while performing the sidearm strike due to convenience. It is similar to the sidearm throw as with regard to body positioning and movement. Tennis is the only racquet sport that has the possibility of using a 2-arm striking skill which evolved in the modern era of tennis and the evolution of tennis racket technology. The 2-arm striking skill in tennis is the backhand stroke preferred to be taught by most coaches due to stability and power generated by a player. 1-arm striking skill for a tennis backhand is difficult to attain mastery especially for a child beginning to participate in the sport. Overhead striking in badminton occurs with three shots: the clear, the drop and the smash (Mawani, 2003). While in tennis, overhead striking occurs with serving, smashing and punch volleys. Underhand striking in badminton only occurs with underhand clears and in tennis with desperate lobs.

Adaptations and Modifications

Tennis has recently developed a modified program for the children to be engaged in the sport of tennis to decrease the drop-out rate of children. It is called Progressive Tennis which follows the Long Term Athlete Development (LTAD) model (Tennis Canada, 2011). There are smaller courts, racquets and balls which help retain young children in tennis. This development was created due to tennis rackets being too heavy for children, the courts and nets being too big for them to play on, and the ball travelling too fast to be able to strike. Many tennis programs have adopted this system endorsed by the International Tennis Federation (ITF) and Wilson Tennis equipment to allow for progressions of tennis to be made that adjust to age groups and skill levels.

There are three levels to Progressive tennis which are: Red Tennis, Orange Tennis, and Green Tennis. Red Tennis caters to 6 to 8-year-olds, Orange Tennis caters to 9 to 10-year-olds, and Green Tennis caters to children older than 11-years-old. Table tennis, badminton, squash, and racquetball may have different sized racquets but they are all played on the same court. A couple of these sports in Canada also follow the LTAD model but none have gone to change the equipment to accommodate younger children.

Injuries

Head Injuries

Even though racquet sports are non-contact sports, there are still many situations where injuries are unavoidable. Eye injuries are studied as thoroughly as any other part of the body due to the significance of vision in everyday life (Cullen, 1994). The prevalence of eye injuries are more common in squash and racquetball due to the small court area, the fast-pace ball and racquets swinging about. There is always risk of injury but they are easily avoidable with preparation. In racquetball, only 5% of racquetball injuries are not due to being hit by the ball, and squash injuries not caused by the ball have a 40% occurrence rate. Prevention of these eye injuries is by wearing protective eye wear and has even been made mandatory in some courts.

Lower Body Injuries

Lower body injuries often arise from the elements of the surroundings. Squash and racquetball are generally played on confined playing areas on hardwood with three concrete walls, one glass wall, and the ceiling. Badminton is played on a hardwood or cushioned surface depending on the level of play or the facility provided in an open play area that has enough free space around and above the court which would not hinder play action. Tennis has the most diverse playing surfaces out of all the racquet sports that range from hardcourt to grass to clay, descending from hardest surface to softest surface respectively.

Tennis

Tennis player injuries are usually caused by overuse or acute trauma (Jacobson, Miller, & Morag, 2005). The most common playing surfaces vary across the globe and are dependent on which surfaces are the most affordable to maintain in that geographical location. For example, in North America or Australia, it is most cost-effective to maintain hardcourts due to our climate, economic status and cultural influences. On the contrary, majority of courts in certain countries of Europe are dominated by clay-courts due to climate being suitable to maintain it annually and it is most cost-effective for those countries’ budgets. Tennis courts surfaces are classified into hard, cushioned or soft (Bouché, 2010). Hardcourt surfaces are generally composed of asphalt and concrete topped with weatherproof paint that maintains it year-round. Cushioned surfaces tend to have a hardcourt base below force absorbing materials to finally be topped by acrylic coverings. Soft courts are made up of grass, clay, or artificial turf. Courts are also differentiated between fast and slow surfaces, grass being the fastest surface, then hardcourt, and the slowest surface is clay. There are also slight variations that affect this simple classification since new surfaces such as the artificial turf may replace the faster grass surfaces or there are various types of clay used around the globe as well. Children raised in different regions around the world will be accustomed to varying play surfaces if they are exposed to tennis. This will ultimately result in altered movement experiences for the same age group and each will have their own pros and cons associated with the surroundings. Hardcourt surfaces are known to be harsher and less forgiving on the body than clay courts. Children who mature playing on hardcourts will exhibit more running and shuffling as they attempt to move in the most biomechanically efficient way possible. Adolescents who grow up playing on clay surfaces are accustomed to running and shuffling as well, but they will incorporate more sliding into their court movements due to the clay absorbing force produced by the players (Bouché, 2010). Lower body injuries occur two times more often than upper body injuries which happen as much as upper body injuries (Jacobson et al., 2005). Nigg (2000) gathered outcomes that showed differences in normal forces between various shoes and court surfaces which was dependent on the pairing.

Ankle injuries occur most often with lateral side-to-side movement and during these movements, the inside edge of the shoe contacts the ground first (Reinschmidt, Stacoff, Steger, & Stüssi, 1996). It was discovered that 15-30% of all injuries in sports that require lateral movement are ankle sprains. Slipping is a major cause of ankle inversion sprains because either the shoe slips on the surface or the foot slips inside the shoe. Slipping between the shoe and the surface occurs when the coefficient of the surface is low and speculation of the foot slipping inside the shoe is that the shoe is tightly gripped to the surface that causes the foot to slip. Tennis game situations also affect the risk of injury as it was found if the lateral movement was in the player’s comfort zone the risk was only 30% but if they were forced to move more abruptly, the risk rose to 42%. Ankle injuries happen more often on hardcourts where players are unable to slide like they do on clay courts, so more aggressive styles of play on hardcourt often lead to more injuries due to the forces applied to the body (Bouché, 2010).

The three most common areas for young tennis players to strain a muscle are the groin, hamstrings, and calf (Jacobson et al., 2005). A muscle or tendon strain in the calf is defined as “tennis leg” and it occurs more often on the inside of the calf. Hamstring tears occur most during fast change in directions such as sprinting towards the net (Bylak & Hutchinson, 1998). To assess this injury is that there is pain and weakness of the tear, which may include inflammation as well. Treating this injury includes use of icing, elastic wraps to support the leg, massage, and anti-inflammatories. Once range of motion has improved, stretching exercises will help flexibility to be followed by strength exercises.

Badminton

The vulnerable part of the body is the Achilles tendon, which can differ in severity from tendinosis to a full-thickness tear (Jacobson et al., 2005). It was found in a study that 92% of minor badminton injuries were related to the lower body, with Achilles tendon ruptures being most prevalent at 34.6% and ankle sprains and fractures at 29.5%. A study found 275 badminton injuries occurring over the course of a single season where there were 2.9 injuries per player per 1000 badminton hours (Bouché, 2010). Men were injured more often than women and there was an average of 0.3 injuries per player. These injuries were then subdivided to find that ¾ of the injuries were due to overuse and ¼ of the injuries were due to acute trauma.

Upper Body Injuries

Upper body injuries are quite similar across all the racquet sports. The most common overuse injuries in the upper body include the rotator cuff, epicondylitis which can involve the inside, outside and back of the elbow (Jacobson et al., 2005). Tennis elbow mainly refers to lateral epicondylitis. Rotator cuff inflammation is caused by repetitive striking and serving (Bylak & Hutchinson, 1998). This injury occurs across the life span but the reasons for this injury differ. The reason why a young child may develop rotator cuff inflammation is that the child is still developing and his shoulder joint is unstable. Assessment of this injury is to test shoulder range of motion, strength of muscles around the shoulder, and how stable the joint is. Treatment of this injury include rest, ice and anti-inflammatories to be followed by exercises a couple weeks later. Traction apophysitis happens less often but it is found in young tennis athletes as well. This injury occurs when child is growing and ossification of the humerus (bone of the upper arm), which causes pressure that leads to possible inflammation. This happens most often during the overhead service motion and it is suggested that the child rest from tennis for a year to prevent overgrowth and impingement of the shoulder.

Sprain or separation of the acromioclavicular joint (located in the front part of the shoulder) is quite common in squash or racquetball if individuals land on the shoulder or collide into the wall at the acromioclavicular joint (Cullen, 1994). It must be assessed by a doctor or physiotherapist with the possible use of machines like X-rays. To treat this injury, a sling may be placed to support the arm and to keep it from moving about as well as ice to reduce inflammation. When it is healed to the point when it can be moved, rehabilitation exercises that focus on the upper back may be conducted.

Shoulder impingement occurs often when there is repeated swinging of the racquet above shoulder height which has a greater increased risk if there have been past rotator cuff injuries. Pain in the shoulder happens more at night and this injury may be discouraging for young children to endure sport. Assessment will be made in the upper arm and if there is weakness, the shoulder may be impinged. Best form of treatment is rest and anti-inflammatory drugs for the pain.

Lateral epicondylitis (tennis elbow) is caused by wrist snapping that results in pain in the outside of the elbow which happens during sidearm striking of the ball. Signs of this injury would be weakness and pain in the outside of the elbow as well as decreased range of motion of the wrist. Treatment for this injury includes rest, anti-inflammatories and stretching exercises. It is suggested that young children take anti-inflammatories for a short term, approximately a week to 10 days (Bylak & Hutchinson, 1998). If progress is shown without the injury resurfacing, then it may be possible for the athlete to return to play with no pain. Tennis elbow occur more often in males because more males use a one-handed backhand which puts more strain on the elbow than a two-handed backhand.

Wrist tendonitis may also happen in elite level players as they attempt to add extra spin to the ball or conduct a bad technique while swinging. Assessment of wrist tendonitis is easy to detect with pain on contact of the wrist, swelling, and pain on the front of the forearm. Treatment includes rest, ice and modification of swing technique but anti-inflammatories maybe be helpful too. If the player can still participate taping may be a useful temporary solution.

Recommendations

The best method to avoid injury is to maintain a healthy balance between training, competition and rest since most injuries happen because of overuse. With regards to the lower body and feet, cushioning of the front and back of the foot will help dampen the forces absorbed by the body and finding the right pair of shoes to match court surface and playing style as well (Bouché, 2010). Shoes used to play on low friction courts such as clay courts should have more traction to be able to grip the court better and shoes on courts with high friction should have less traction to compensate for sliding. Use of insoles that prevent sliding inside the shoe are suggestion to minimize injury due to shoe design. Ankle braces, high cut shoes and taping are effective preventive measures to decrease the chance of ankle injuries (Reinschmidt et al., 1996).

References

Bouché, R.T. 2010. Racquet Sports: Tennis, Badminton, Squash, Racquetball, and Handball. Werd, M.B. & Knight, E.L. Athletic Footwear and Orthoses in Sport Medicine, 215-223. doi:10.1007/978-0-387-76416-0.

Bylak, J. & Hutchinson, M.R. 1998. Common Sports Injuries in Young Tennis Players. Sports Medicine, 26(2), 119-132. doi: 10.2165/00007256-199826020-00005.

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Cannon, J. (2009). The Oxford Companion to British History: Badminton. Retrieved from http://www.oxfordreference.com.ezproxy.library.ubc.ca/view/10.1093/acref/9780199567638.001.0001/acref-9780199567638.

Cavanagh, P.R., & Lafortune M.A. 1980. Ground Reaction Forces in Distance Running. Journal of Biomechanics, 13(5), 397-406. Retrieved from http://ac.els-cdn.com.ezproxy.library.ubc.ca/0021929080900330/1-s2.0-0021929080900330-main.pdf?_tid=a2b26c7e-bf8d-11e4-9cca-00000aacb35d&acdnat=1425157757_31bd9199cba95205c504923340f0430a.

Cullen, P. & Silko G.J. 1994. Indoor Racquet Sports Injuries. American Family Physician, 50(2), 374-80, 383-4. Retrieved from http://web.a.ebscohost.com.ezproxy.library.ubc.ca/ehost/detail/detail?sid=253385c3-64a8-48ad-89bf-df6008cac53f%40sessionmgr4003&vid=0&hid=4109&bdata=JnNpdGU9ZWhvc3QtbGl2ZSZzY29wZT1zaXRl#db=mnh&AN=8042573.

Gabbard, C.P. (2004). Lifelong Motor Development (6th Ed.). San Francisco: Pearson Education, Inc.

Girard, O., & Millet, G.P. 2008. Neuromuscular Fatigue in Racquet Sports. Neurologic Clinics, 26(1), 181-194. Retrieved from http://www.sciencedirect.com.ezproxy.library.ubc.ca/science/article/pii/S073386190700134X.

Jacobson, J.A., Miller, B.S., & Morag, Y. 2005. Golf and Racquet Sport Injuries. Seminars in Musculoskeletal Radiology, 9(4), 346-358. Retrieved from https://www-thieme-connect-com.ezproxy.library.ubc.ca/products/ejournals/pdf/10.1055/s-2005-923379.pdf.

Mawani, A. (2003). Badminton 2000: A Guide to Teaching Badminton. Burnaby: Arif Mawani.

Nigg B.M, & Reinschmidt, C. 2000. Current issues in the design of running and court shoes. Sportverl Sportschad, 14(3), 71–81. Retrieved from https://www-thieme-connect-de.ezproxy.library.ubc.ca/DOI/DOI?10.1055/s-2000-7866.

Olympic.org. (n.d.) Table Tennis Equipment and History. Retrieved from http://www.olympic.org/table-tennis-equipment-and-history?tab=history.

Reinschmidt, C., Stacoff, A., Steger, J., & Stüssi, E. 1996. Lateral stability in sideward cutting movements. Medicine & Science in Sports and Exercise, 28(3), 350-358. Retrieved from http://ovidsp.tx.ovid.com.ezproxy.library.ubc.ca/sp-3.14.0b/ovidweb.cgi?QS2=434f4e1a73d37e8c51a25e56007803d597ee41ed1a5d72e7da0bcce981bfc0780043382bd88dd6085ca0e39d033bf8f545f871e13a6244207cf76090cef9dc5ba456e638ad9d992e1f76354755fce53b3ed5ba81aa63ff0cf54c4b349bead5430c2382c4038e8ce526366aaecfac69e73490b1c3d7ec64cbb8bc0b86270b197a3720af118e41c9226d9babe44b3f20ca724257e3b1246d5b883a32f64d8648979a5091887e8e9ce760719f7cc8c5bed9c6eda059d43d744edda84f22e50af26541c33d9e93c2e8f91e442e228b768ae305dd69409a4449c230a94c0556240aa8227ef11cdddd47863969d0af5324f3a6a79b6ab66991316f0d6b3ff4e83f381f72d350a4541b07ab0694a7817dbc830d5c78f46f604e46df202f777576ce9df286c1d04e7298e103d52e8116c285ac3d31d5239a016ccd5ab72bac9706a41d10b57261ec446a4a3e25ccf15dfda2ddcbc37c921b1e3e7a459486c9b8225e437333c0826fae270577f61688d3621cf7cd54151104e03251e5e1d196177908c37fee2a2b9c880323e9733fcf03086a000777e190eac371ec1c577630aa8bc8d9c2b7a81830018cc24e3df084d9acd894c7d9321d3d205ec02f5da0a6e87b5c6be0b3d608f57c2aaccfc9bb6f2f4896b677e1efebc5211fb4810b6fa9ead26f3f02963501d5d3ec27c22bd63b7f59d8fee10acda12763dd0c45aa73bec3cc615bb037a22227be7f895775fff5f2b12b0aa92bb5b8771434940b875ed7bf8a9109da80f74df1bcc22800a3dd630da71250f7db489721aeda99ef753d605466704be383d1d6b356b1fd72693735f62b366c525b1cf2493a6a8ed7ee177eb4a94b158b49fc346c15c7617aad06156547db258b33f7f96887850fc2325e01990ff349daac673f6037c5bc68a81cbcd8c28b2ba2f9a6f2328bb0cfe1d28cf9002a98bef233c932f057435888#103.

Rowley, Alison. (2008). Oxford Encyclopedia of the Modern World: Tennis. Retrieved from http://www.oxfordreference.com.ezproxy.library.ubc.ca/view/10.1093/acref/9780195176322.001.0001/acref-9780195176322-e-1565?rskey=G11tYE&result=3#acref-9780195176322-section-6125.

Tennis Canada. (2011). Tennis Fundamentals. Retrieved from http://www.tenniscanada.ca/tennis_canada/Contents/TPA/Resources/Text/English/FUNdamentalsEntireProgramupdated.pdf. United States Racquetball Museum. 2012. A Brief History of Racquetball. Retrieved from http://racquetballmuseum.com/history.html

Zug, James. 2003. Squash: A History of the Game. Kirkus Reviews, 71(11), 384. Retrieved from http://web.a.ebscohost.com.ezproxy.library.ubc.ca/ehost/detail/detail?vid=1&sid=93cc0955-7ed1-471f-bd0e-934379d19a15%40sessionmgr4004&hid=4109&bdata=JnNpdGU9ZWhvc3QtbGl2ZSZzY29wZT1zaXRl#db=a9h&AN=9941056.