Discussion
1. Compare the results of the 2 running shoes, how will you interpret the results?
Peak Pressure
Pressure Time Integrals
Maximum Force
Li Ning Brand Running Shoe
Mean: 223.125
Mean: 24.935
Mean: 239.637
S.D.: 13.98125
S.D.: 1.115
S.D.: 3.771
Asics Brand Running Shoe
Mean: 229.91
Mean: 27.598
Mean: 243.506
S.D.: 15.86
S.D.: 1.561
S.D.: 5.897
Based on the gathered data, the previous table shows the mean and standard deviation of two running shoes with respect to their attributes i.e. peek pressure, pressure time integrals and maximum force. From the illustration in the table, it is found out Asics Brand Running Shoe exceeds Li Ning Brand Running Shoe in terms of their mean with respect to the attributes. In peak pressure Asics receives a mean of 229.91 against 223.125 of Li Ning. With regards to the pressure-time integrals, Asics Brand Running Shoe gathers a mean of 24.935 and Li Ning Brand Running connects a 27.598 mean. In terms of the maximum force, Li Ning gathers a mean of 239.637 and 243.506 for Asics.
Actually, the result of mean alone cannot show if Asics Brand Running Shoe dominates Li Ning Brand Running Shoe in terms of their performance since also have to include the discrepancies between these means i.e. standard deviation. In order to evaluate the difference of two running shoes, the use of Coefficient of variation statistic should be use.
Then we have,
x 100%
For peak pressure (Li Ning Brand Running Shoe)
x 100%
x 100%
CV= 6.27%
For Pressure Time Integrals (Li Ning Brand Running Shoe)
x 100%
x 100%
CV=4.47%
For Maximum Force (Li Ning Brand Running Shoe)
x 100%
x 100%
CV=1.57%
For peak pressure (Asics Brand Running Shoe)
x 100%
x 100%
CV= 6.9 %
For Pressure Time Integrals (Asics Brand Running Shoe)
x 100%
x 100%
CV=5.6%
For Maximum Force (Asics Brand Running Shoe)
x 100%
x 100%
CV=2.42%
With these results, we may say Asics Brand Running Shoe is more variable than Li Ning Brand Running Shoe with respect to the three attributes i.e. peek pressure, pressure time integrals and maximum force. Actually, high plantar pressures can results to damage and injury of someone’s’ foot (1980). Thus, based on these results, Li Ning Brand is recommended to be use since it has small amount of pressures compared to Asics Brand.
2. Why do we measure plantar pressure in running? What is its importance in the
biomechanics of running?
Foot-ground structures exist in many diverse forms. Most of the time, the structure is floor mat or a shoe, and occasionally it is a carpet-like fabric, such as an Astroturf, giving a specific biomechanical distinctiveness to assist one perform efficiently. Thus, the measurement of plantar pressure in running can create a vital role in improving performance and functionality; it also helps to prevent injury, and reduction of discomfort.
According to (1990), human movement usually involves frequent loading at the foot-floor structure, ensuing in force diffusion throughout the human feet and headed for the upper extremities. Proper cushioning anticipates this impact forces and protects the musculoskeletal system from possible injury. Apparently, (1980) verified that high plantar pressures have also been linked to foot pain and discomfort. (1986) performed a study to compare the effectiveness of reducing plantar pressure using seven different materials. A similar comparison study, related to flooring conditions on standing tolerance, was reported by (1988). However, as the types of insoles and foot-floor interfaces on the market increase in number, such comparisons become almost impossible to perform and somewhat meaningless.
Measurement and analysis of high amplitude and short duration impacts typically occurring during locomotion are not straightforward. Mechanical tests and subject tests have been used to evaluate the cushioning properties of sports footwear. In mechanical testing, the shock attenuating capacity of a running shoe is quantified by dropping an instrumented weighted missile on the heel and fore part of the shoe ( 1988). Actually, purely mechanical measurements are certainly not suited to make predictions with regard to the influence of shoe construction on the loading of the body during running. Typically, the simulation of the foot inside the shoe and the kinematic adaptations of the runner cannot be undertaken sufficiently well and, generally, most researchers have a preference for controlled subject tests to supplement data obtained from mechanical impact testers.
3. What are the implications of the findings?
With regards to the findings in the study, comfortable shoes with fewer pressures to be used like Li Ning Brand are relatively the important thing to consider in biomechanics of running. Comfort is a multifaceted entity. Also, discomfort and comfort measures are a complex mapping to the sensation or perception domain. A participant’s inability to differentiate fatigue and discomfort further complicates the issue (1995). Hence, it is more appropriate to split the material-comfort mapping from materials to perceived cushioning and then from perceived cushioning to comfort, discomfort, or fatigue. This is clear from the (1995) and (1991) studies, in which the duration effects of foot-floor interfaces on whole-body discomfort were different. Duration effects are primarily a result of the body forces (or more appropriately, the body deformations) rather than the “applier,” the foot-floor interface. The foot-floor interface is somewhat static, and the material to perceived cushioning mapping should also be static.
4. What are the limitations of this study?
It is no doubt an interesting exercise to evaluate commercially available products and to place them on a comfort-compression, tiredness-hardness, or similar type of map. However, technological improvements, such as advances in composite materials, can alter significantly the physical or mechanical characteristics of products and alter the position of a product on such a map. Product and usability testing are important for product-evaluation purposes and best-in-class assessments, but they do not explain the underlying causes of “good” or “bad” products or perceived feelings of the wearer, which are the most important elements in designing products right the first time. It would be better to develop an acceptable and relevant characterization procedure that can provide a means to improve wearer comfort and also reduce fatigue and injury during activity. Such an approach will allow designers and developers of products to understand which particular cushioning characteristics are perceived by humans in any given activity being performed. For example, in high-loading situations such as running, do people perceive the shock absorption property? In other situations, such as standing, do people sense the hardness or compression property of the material?
5. You are free to discuss any other issue you think is important.
Footwear can be designed to enhance the performance of all sports involving locomotion and dynamic foot-ground interaction. Shoe characteristics such as traction, stability, flexibility and weight can all be modified towards that goal. Much attention has also been focused on the protective role of footwear in helping to prevent either acute injury or chronic damage to the body during sporting activities. Although sometimes the professional elite performer may place slightly more emphasis on performance rather than safety features of footwear, for the majority of sports participants the protective function of sports shoes becomes increasingly important. A mixture of protective features for sports footwear, geared towards the specific demands of each sport, is often required.
Adequate and durable cushioning systems in the shoe are necessary for safe participation in sports such as distance running where the lower limbs need to be protected from repetitive impact loading. For many team sports the body must also be protected against less frequent but more severe impact forces of jump landings, and high shear forces generated during sudden stops and turns. In this latter case, compliant and shock absorbing shoes are essential but it is also necessary to have lateral stability and optimal traction. This combination of cushioning protection and support of the foot during forward and lateral dynamic maneuvers presents a difficult challenge for sports shoe design engineers.
On the other hand, the fit of the shoe and the amount of pressure the foot is exposed to at its plantar and dorsal surfaces are additional factors that may be associated with the long-term overloading and damage of the foot. Clearly there is a need for sufficient characterization and subsequent improvement of the safety aspects of sports shoes. There are some standard mechanical techniques available to examine sports shoe properties but there is a growing trend to combine such information with biomechanical measurements on subjects wearing the footwear during typical sporting maneuvers.
Credit:ivythesis.typepad.com
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