The laws of physics encompass both the matter and non-matter, and their implications have been very useful to mankind. In this technological era, mankind has relied on science for both efficiency and effectiveness of tools, equipment, and gears. Various materials used for particular functions, from heavy to menial, have been enhanced, improved, and upgraded based on our understanding of their science. In this discussion, we will examine the physics behind basketball shoes. This discussion will focus heavily on the parameters that would greatly enhance the performance of basketball shoes.
The history of basketball shoes was greatly influenced by the successes of activity-specific athletic shoes. Early designs for running shoes featured light and flexible structure, while football shoes were designed with interchangeable spikes for better performance on slippery grass fields. Moreover, the business rivalries of companies producing athletic shoes resulted to the development of technological institutions with the purpose of enhancing athletic shoes (i.e. Nike, Inc., Adidas, Puma, etc.) (Keyser 26-27). For instance, the Nike Flywire Technology was designed to minimize the weight of the shoe without compromising the strength of the upper of a shoe.
After extensive research of studies and reliable sources focusing on the physics of basketball shoes, it was realized that there are three fundamental parameters to consider: (1) traction of the soles, (2) mass of the shoes, and (3) the flexibility of the shoes. In this light, the succeeding parts of this paper will focus on these three parameters, especially on why these parameters are significant in considering the performance of basketball shoes. Moreover, this paper will also examine, based on previous studies, the degree of influence of the three parameters to the performance of the players.
Traction on the Soles
The term traction refers to the ability of materials to “stick” to surfaces, which, to basketball shoes, are significant. The ability of a basketball player to swerve fast to dodge defense, or chase the opponents, relies on the traction supplied by the basketball shoes. The significance of traction is to keep a high mobility especially on a slippery court. In physics, the term traction can be equated to the concept of friction, specifically static friction.
Friction is a force that exists between two surfaces in contact. Microscopic images of even what we can consider smooth surfaces reveal that surfaces are not as smooth as we think. Most surfaces, under microscopic scales, have bumps that intervenes a sliding motion against surfaces. Needless to say, the friction opposes the movement along the surface. The friction that arises from the sliding of surfaces against one another is termed kinetic friction.
However, even when the surfaces are not sliding against each other, a force called the static friction can still arise. Static friction is a force exerted by the surface against an object that opposes the force exerted on the object. In this scenario, the static friction prevents the object from moving. Therefore, we can say that the static friction is a force that needs to be conquered before a motion follows. Moreover, the static friction varies from zero (0) to the maximum value (or maximum limit) depending on the value of the force parallel to the surface (Giancolli 93-94).
Going back to the discussion about basketball shoes, one might see how friction is important during a basketball game. Unlike other sports venue, a basketball court has a slippery surface, which implies the need for shoes to have good traction. Common sense dictates that it is preferable to wear shoes that has the higher chance to prevent the wearer from slipping, especially when the wearer sprints and jumps frequently. Needless to say, shoes with higher traction coefficient should produce a better performance (Wannop S98-S100). In fact, this is exactly the case, as a 20% reduction in traction coefficient from 1.0 to 0.8 translates to a 10% decrease in sprint performance, 5-centimeter decrease in maximum jump height, and 30% decrease in cutting performance. On the other hand, a 20% increase in traction coefficient from 1.0 to 1.2 translates to a 4% increase in cutting performance (Wannop S98-S100).
Moreover, the comparison of three shoe properties (shoe mass, traction of the outsoles, and forefoot bending stiffness) reveals that traction of the outsoles has the most influence on sprint, jump, and cutting performance. Thus, one should prioritize the traction of the outsoles over the two shoe properties when aiming for optimizing the performance (Wannop S98-S100).
Mass of the Shoes
The second parameter we will discuss involves a property of all matter: mass. The mass of the shoes can be easily equated to the difficulty level of the player to move. In other words, the mass, like all matter, defines the force required to lift the object. Obviously, the bigger the mass, the heavier the weight. Note that weight refers to the gravitational force of an object, which can be acquired by multiplying the mass of the object with the acceleration due to gravity. Here on the surface of the Earth, the acceleration due to gravity, denoted as g, is equal to 9.81 meters per second-squared (Giancolli 33).
In short, players wearing a lighter pair of shoes exert less effort to move than players wearing a heavier pair of shoes. According to Fuller (419), the inertial difference of a lighter shoe from a heavier shoe, if we consider the effort of players to accelerate with and against gravity with each stride, implies that a decreased muscular effort must have a greater running performance. Most studies also agree that lighter pair of shoes results to a greater performance compared to heavier pair of shoes.
However, it is notable that most studies consider light shoes to have a mass below 440-460 grams per pair while heavy shoes are those that have a mass above 440-460 grams per pair. Another notable fact is that most studies see no difference in running economy between light shoes and barefoot (Fuller et al. 419-420). Moreover, a 160-gram difference in mass per pair, or higher, results to no significant changes in performance, which implies that two pairs of shoes with a mass difference almost equal to this value must cause similar performance on running and jumping. Moreover, mass of the shoes had the least notable difference in the performance relative to the traction of the soles and the forefoot bending stiffness (Wannop S98-S100).
Flexibility and Support
Flexibility of the shoes is one parameter that should be considered for both comfort and performance. Although this parameter can be easily studied by relating the anatomical biological mechanism of running and jumping, the effect of the flexibility of a shoe on the performance can also be explained by concepts in physics. During running and jumping, the human body relies on the forces distributed along the important parts of the feet. To push the body onwards, first the heel contacts the surface in a supinated position, with the lateral part of the heel in direct contact. The foot pronates until the entire foot is in contact to the ground and in a neutral position for the leg to shift. Gradually, the foot supinates until the heel releases contact to the surface, and the swing forces a toe-off (Dutra 37-38).
Needless to say, the flexibility of the shoes can be influential since the actual mechanism of running involves flexing and contracting of foot muscles. To support the force during the first contact of the heel and the ground until its release from contact, most insoles of basketball shoes are designed with materials, such as rubber foam and memory foam (Dutra 37-38). A notable design consideration features the backside part of the upper of the shoes. Most shoe designs for basketball shoes have a high upper but has a dip on the backside. The reason for this lower backside is to prevent the shoes from limiting the plantar flexion. In fact, a lower backside was shown to produce a better jumping performance than a higher backside (Blache, Beguin & Monteil 48-50). Moreover, the stiffness of the forefoot also increases the running and jumping performance of the player. Note that the stiffness of the forefoot should significantly improve running especially during the toe-off stage. Indeed, increasing the forefoot bending stiffness was associated with a 1.0% increase in the sprinting performance, and a 1.7% increase in the cutting performance (Wannop S98-S100). As for the jumping performance, having a stiff upper of a shoe was correlated with a better jumping performance relative to its flexible upper of a shoe counterpart, except for those that are considered light shoes (Blache, Beguin & Monteil 48-50).
Summary
Works Cited:
Blache, Y., A. Beguin, & K. Monteil. “Effects of various parameters of basketball shoeson vertical jumping performance: A case study.” Science & Sports, 26.1 (2011): 48-50. Print.
Dutra, Tim. “Athletic Foot Types and Deformities.” Athletic Footwear and Orthosesin Sports Medicine. Eds. Matthew B. Werd & E. Leslie Knight. New York, NY: Springer, 2010. Print.
Fuller, Joel T. et al. “The Effect of Footwear on Running Performance and RunningEconomy in Distance Runners.” Sports Medicine, 45.3 (2014): 411-422. Print.
Giancolli, Douglas C. Physics: Principles and Applications. 7th Ed. Glenview, IL: Pearson Education, Inc., 2014. Print.
Keyser, Amber J. Sneaker Century: A History of Athletic Shoes. Minneapolis, MN: Lerner Publishing Group, Inc., 2015. Print.
Wannop, John William. “Influence of basketball shoe mass, traction and bending stiffness on athletic performance.” Footwear Science, 5.1 (2013): S98-S100. Print.
