Course:KIN355/2020 Projects/Acceleration

Defining the Concept and Its Importance

Newton’s three laws of motion can be used to explain the foundation of how objects move; this is applicable to human movement. Newton’s second law states that the acceleration of an object is produced by the amount of force placed on an object divided by the mass of that object or the time rate of change of velocity (Hewitt, 2019). Acceleration includes changes in speed and/or direction (Hewitt, 2019). In relation to movement experiences, acceleration is the ability to generate speed or force from a still or moving position (Lockie, Murphy, Knight, & Jonge, 2011).

Acceleration is proportional to the force applied to the object (Gagen & Getchell, 2013). This means that the more force is applied to an object, it increases the rate of velocity change. An example of this could be a child kicking a soccer ball. The more force produced into the ball, the further the ball will travel. Acceleration is also inversely proportional to the mass of the object (Gagen & Getchell, 2013). This means the lighter an object is, the more acceleration it can have. An example of the inversely proportional relationship would be pushing someone on a swing. It is easy to push a child fast on a swing due to their small mass. However, pushing an adult on the swing with the same amount of force would result in little to no acceleration of the person.

Newton’s second law of acceleration is a concept that occurs daily without consciously thinking about it. The concept of acceleration can be confusing to understand. As a child begins to crawl, they start slow and progress. As a child becomes more proficient, they are able to accelerate quickly from a still position as well as change their speed and direction. The child is unaware that they are learning about acceleration and how crucial it is when moving. This process applies to other developmental milestones and movement experiences. Acceleration is an important concept when discussing running, particularly in sports such as soccer or football where there are frequent stop-and-go actions. Most sports do not allow the participant to reach their maximum speed because they are short-duration sprints (Lockie et al., 2011). Due to the short duration, accelerating faster than the competitor may determine who gets to the ball first and score.

For child educators and coaches, teaching their students and players about acceleration can help them further understand movements. Coaches should teach their athletes about acceleration to improve stride frequency and reduce contact time later on as they develop (Lockie et al., 2011). With proper acceleration training, athletes will be able to perform at higher levels than before. Educating children about acceleration and deceleration can help prevent injuries and help with fundamental aspects of movement.

Role in Childhood Development and Contemporary Considerations

Acceleration is an important concept when discussing sport performance, proficiency and development. Regardless of the sport or age of the person, an athlete must apply the law of acceleration in all movements in order to perform at the highest level. Thus, the demand for speed and force production is needed to maximize their performance. Children incidentally start to learn the fundamental application of acceleration when generating a force from a still or moving position (Lockie, Murphy, Knight, & Jonge, 2011). Newton’s second law of acceleration can be used to discuss the proficiency of movements and proper developmental progression. For a child to run proficiently, they can use the foundation of acceleration to reduce their contact time with the ground and/or increase the force produced in their legs (Lockie et al., 2011). In summary, they need to reduce the time spent accelerating or increase the amount of force produced.

When discussing proper development, children learn motor milestones by progressing through stages. They begin at the emerging stage and finish at the accomplished stage when they have mastered the skill (Bredin, 2020). When children start doing an action such as throwing a ball, they typically only apply force through the flexion and extension of their elbow (Gagen & Getchell, 2013). Therefore, applying force from the arm does not allow the ball to move very far. As the motor milestone develops to further stages, the child changes their form to keep up with the demands (Gagen & Getchell, 2013). They will learn to wind up their arm, add a step and rotate their torso to increase the acceleration of the ball (Gagen & Getchell, 2013). The progress through the stages of development allows for the incidental learning of proper biomechanics and the application of acceleration.

One contemporary issue impacting children’s learning of acceleration is the amount of time spent sitting. In Canada, school-aged children report spending up to 8 hours a day in front of a screen (Alberta Health Services, 2020). As a result of increased sedentary activities, children are spending less time experimenting with their movement. Exploration during youth has major implications on a child’s development. The exploration of different movement techniques allows for the development of critical thinking skills. This can be applied in situations where you want to maximize performance using acceleration (Bredin, 2020). Coaches and teachers need to provide different sizes, weights and materials of equipment for their students to use. This allows children to learn how they need to adapt their movements in different situations and how the law of acceleration changes when weight or force application changes.

Another contemporary issue that children are facing is sport specialization occurring at an early age (Smucny, Parikh, & Pandya, 2015). Many children are signed up for after school sports programs such as soccer. In these types of programs, children are learning how to kick or throw a ball at different distances, but they are not taught using varying ball sizes. Part of learning about acceleration is how movement changes when the mass of the object changes. Children now specialize in their preferred sports early in their youth and don’t get the chance to experiment with different sports and different equipment. Early sport specialization in structured development prevents children from developing all-around skills and coordination (Smucny et al., 2015). If they are unable to learn about the concept of acceleration in all different sport contexts, this prevents them from fully understanding the law of acceleration and its applications in movement development and proficiency.

Practical Applications

Go-Go-Stop

Acceleration is an important locomotor skill to develop, as it's transferrable to many sports such as soccer, football and rugby. Acceleration in these types of sports can be characterized by abrupt and shortchanges in velocity, changes which require adjustments in foot placement, stride rate, and stride length (Lockie et al., 2011). As such, the purpose of the game Go-Go-Stop is to facilitate improvement in the rate of change in velocity within short periods of time, in a fun and engaging way. Go-Go-Stop is appropriate for children 3-12 years of age, and the minimum number of players needed to play is three. As long as the space is appropriate it can be played indoors or outdoors. The space should be reasonably large and open, approximately the size of a gymnasium, which is typically about 15.2m by 25.6m. However, the size of the space is also dependent on the number of children, therefore, can be modified to best fit the number of children playing. If there are too many players to play safely in the space, you can also divide into smaller groups and play multiple rounds. There is no equipment required. The only tool that will be needed is a loud voice. When giving out instructions, clearly define the playing area with a designated starting line and finish line. Instruct all players to line up at the starting line, and have the instructor stand at the finish line with their backs facing the start line. The instructor is the Go-Go-Stop commander. When they say “go”, players may begin to run and make their way towards the finish line. When the instructor says “slow,” players must slow down and may move only at a walking pace. Finally, when players hear the “stop” command, they must come to a complete stop and freeze in the position they are in. The instructor will then turn around. If they see any player moving, that player must return to the starting line. All players must remain frozen until the next “go” command. Play continues in this manner until someone reaches the instructor at the finish line. The player who tags the instructor then becomes the new Go-Go-Stop commander and the game begins again. Note, the instructor may use “go”, “slow”, and “stop” at any point and in any order in which they choose, meaning they are not required to stick to the same “go”, “slow”, and “stop” sequence. Go-Go-Stop can be modified to further develop or focus on specific movement areas. Variations include adding new commands such as “right” and “left”. This allows children to explore the concept of space awareness and gives them an opportunity to work on accelerating in different directions. Moreover, instead of walking and running, instructors may get the children to squat jump forward on the “go” command and drop down on their tummies on the “slow” command – movements which work on force production. Greater force production can lead to greater stride length, thus improving speed at which one is able to accelerate (Dawes & Lentz, 2012).

Shark Attack

Acceleration can be improved through improved stride length. To improve stride length, one must focus on exerting a greater amount of force into the ground at foot strike (Dawes & Lentz, 2012). Greater force generation requires strengthening the hip flexors and quadricep muscles. The hip flexors play an essential role in forward hip movement from an extended to flexed position, reloading the hip for subsequent ground contact (Dawes & Lentz, 2012). Quadricep muscles pull the legs forward for fast burst of running, and work in conjunction with the hamstrings to coordinate running movements. The hamstring muscles also play a major role in decelerating the lower leg in preparation for ground contact (Dawes & Lentz, 2012). As such, the purpose of the game Shark Bait is to engage these muscles to enhance one’s ability to generate force into the ground at foot strike, from a still and a moving position. Shark Bait also encourage kids to discover their true top speed and explore the concepts of effort awareness and relationship awareness. The target age groups are between 6-8 years old and 9-12 years old. These are the childhood years where children are mature enough to practice proper technique and form, as well as develop muscular strength. This game requires an open space, with a minimum vertical distance of 25m. Therefore, as long as the space is appropriate, this game can be played indoors or outdoors. The only equipment required are pinnies for half of the group. A minimum number of six children is best when playing Shark Bait. This ensures each child gets an adequate amount of rest between running periods. Have all the children group into pairs, designating one child to be the “shark” and the other to be the “fish”. Then instruct all the children to line up in two lines; one line consisting of all the “sharks”, and the other line consisting of all the “fish.” Have the “shark” line start 2-5m further back than the “fish” line, and hand each “fish” a pinny – having them tuck the pinny in the back of their pants, just enough so that it stays in place and there is a tail sticking out. The pinnie will act as the “tail” of the “fish.” The game can either start on the instructor’s “go” command or the “fish’s” first move. Upon command, the “fish” will begin to run, trying to avoid getting caught by the “shark,” who’s goal is to catch the “fish” and grab its “tail.” Note, to emphasize safety, instructors should remind children to not push other children while trying to grab the “tail.” The duration of the game or number of rounds played is up to the instructor. Shark Bait can be modified to focus on specific movement goals or to offer advanced variations to further challenge each child. For example, we can further engage the hip flexors, quadriceps and hamstring muscles by having the kids start in different positions; such a laying down on their tummies or starting on one knee. This enhances the development of force production so that it’s more explosive. Another option is adding a right or left turn into the running route. This introduces the concept of space awareness and emphasizes the effects change in direction can have on velocity. Furthermore, instructors can alter the running route by making it uphill. It can be fairly difficult to have poor form when running uphill. The hill provides a natural driving-forward lean seen during acceleration, as such can be beneficial when focusing on proper technique and form. In addition, uphill running offers a greater strength and cardiovascular component. Lastly, by increasing the running distance, children can focus on learning to increase their stride length, without decreasing the stride rate (Dawes & Lentz, 2012).

Summary

Part of Newton's Second Law, acceleration is the change rate of an object's velocity to time. Once the child begins to crawl, they are usually unaware that they are learning about acceleration and how crucial it is when moving. Coaches should teach their athletes about acceleration to improve pace frequency and reduce contact time later on as they develop. Some contemporary issues, such as being sedentary and early sports specialization, prevent children from developing all-around skills and coordination. Different games such as Go-go-stop and Shark Attack can help them learn about acceleration.

References

Active Children. (n.d.). Retrieved October 17, 2020, from https://myhealth.alberta.ca/Alberta/Pages/sedentary-behaviour-guidelines.aspx

Bredin, S (2020). Module 1: Play. KIN 355 Movement Experiences for Young Children, School of Kinesiology, University of British Columbia

Bredin, S (2020). Module 4: Developing Fundamental Movements. KIN 355 Movement Experiences for Young Children, School of Kinesiology, University of British Columbia

Dawes, J., & Lentz, D. (2012). Methods of Developing Power to Improve Acceleration for the Non-Track Athlete. Strength & Conditioning Journal, 34(6), 44–51. https://doi.org/10.1519/SSC.0b013e31827529e6

Hewitt, P. (2019). Focus on Physics: Quickly Teaching Speed, Velocity, and Acceleration--Part 2. The Science Teacher, 086(07). doi:10.2505/4/tst19_086_07_18

Linda Gagen & Nancy Getchell (2008) Applying Newton's Apple to Elementary Physical Education, Journal of Physical Education, Recreation & Dance, 79:8, 43-51,  doi:10.1080/07303084.2008.10598231

Lockie, R. G., Murphy, A. J., Knight, T. J., & Jonge, X. A. (2011). Factors That Differentiate  Acceleration Ability in Field Sport Athletes. Journal of Strength and Conditioning Research, 25(10), 2704-2714. doi:10.1519/jsc.0b013e31820d9f17

Smucny, M., Parikh, S. N., & Pandya, N. K. (2015). Consequences of Single Sport  Specialization in the Pediatric and Adolescent Athlete. Orthopedic Clinics of North America, 46(2), 249-258. doi:10.1016/j.ocl.2014.11.004