bme lab report 2

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University Of Connecticut *

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3600

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Mechanical Engineering

Date

Dec 6, 2023

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pdf

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17

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Uploaded by KidMoonBee21

Rojas 1 Lab 1: Balance Control Testing with Sports Helmets Written by: Isabella Rojas Group Members: Adam Badgley, Victoria Ballestas, Diego Melendez BME 3600 Lab Section 001L Group 1
Rojas 2 Table of Contents Title Page: ........................................................................................................................................ 1 Table of Contents: ............................................................................................................................ 2 Introduction: ..................................................................................................................................... 3 Methods: .......................................................................................................................................... 4 Results: ......................................................................................................................................... 5-7 Discussion: .................................................................................................................................. 8-10 Conclusion: .................................................................................................................................... 11 References: ..................................................................................................................................... 12 Appendix: ................................................................................................................................. 13-17
Rojas 3 Introduction This second Biomechanics lab was on nonlinearity of human balance during two different positions on a force platform: quiet standing and lifting the subject’s dominant leg, in this case my right leg, in my frontal plane. We did this to understand the interaction of movement of body balance and center of pressure (COP), which are major components of human balance. We come to learn how to determine the influence of COP on body balance during the different static postures and wearing different sports helmets, including the helmets designs of football. Baseball, softball, and hockey. For many years, there have been increasing rates of Traumatic Brain Injuries (TBI) in sports-related activities, especially in children and young adults. TBI usually results from a violent jolt to the head or body causing a wide range of physical and psychological effects. To prevent TBI, good balance is needed to not only decrease the risk of falling, but to also recover rapidly when someone is about to fall. This lab aims to analyze the balance control of the human body and to also measure the effects of various sports helmets on body balance and center of pressure (COP). As much as the helmet protects the head from a direct hit, it also affects an athlete's balance because of its weight and overall structure. As a biomedical engineer, more information about balance and COP in circumstances with different sports helmets would help with better design of sports gear so athletes can play safer with an improved biomechanical performance.
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Rojas 4 Methods This lab consisted of a few pieces of equipment and materials: - AMTI force platform Accusway RS-232 - AMTI Netforce version 3.5.2 software - BioAnalysis version 2.3.1 software - Nike Pro Gold TCF 10 Batter’s Baseball Helmet - Riddell Revolution Speed Football Helmet - Natural Grip Two Tone with Mask Softball Helmet - Bauer 9900 Hockey Helmet In the beginning, my height and weight were measured and taken using a scale and tape measure. Their gender, level of activity, and leg dominance were recorded as well. The subject then performed the quiet standing on the force platform with no helmet. In quiet standing, the subject stands with their feet around hip distance apart with their hands by their sides, and looking straight at the wall that has a big black X mark. The subject stays in that position for 20 seconds while the person at the computer is gathering the net force and taking the measurements. After the measurement is complete, the subject steps down from the platform and has a resting time of about 15 seconds. Next, the subject stood on one leg on the force platform with their right leg raised in the frontal plane, approximately 30 degrees from their standing position. The subject maintains this position for 20 seconds again while the measurements are being taken and then they step down from the platform. The quiet standing and raised leg positions were performed four more times each while the subject was wearing a football helmet, a baseball helmet, a softball helmet, and a hockey helmet. After finishing and getting the statistics, the subject’s comfort level with each helmet was recorded on a paper for later reference.
Rojas 5 Results Table 1: Subject Body Measurements Subject Name Isabella Rojas Height [in.] 63 Weight [lbs.] 130 Gender Female Exercise Level Low Hand Dominance Right Table 2: Comfort Level of Each Helmet Helmet Design Comfort Level (0-10) where Higher is the Most Comfort Football 2 Baseball 8 Softball 8 Hockey 6 Table 3: Data for Subject’s Quiet Standing No Helmet Football Baseball Softball Hockey Avg Displacement along X [cm.] 0.287 0.295 0.198 0.343 0.617 Avg displacement along Y [cm.] 0.457 0.511 0.513 1.12 0.744 Avg. radial displacement [cm.] 0.574 0.648 0.587 1.217 1.021 SD-Major Axis of 95% ellipse 0.325 0.478 0.645 1.212 1.021
Rojas 6 SD-Minor Axis of 95% ellipse 0.549 0.513 12 0.5 0.538 Avg. velocity [cm/sec] 21.763 26.091 23.317 26.03 22.921 Length [cm.] 36.281 43.492 38.875 43.404 38.219 Table 4: Data for Subject’s Right Leg Raised No Helmet Football Baseball Softball Hockey Avg Displacement along X [cm.] 0.518 0.64 0.447 0.973 0.594 Avg displacement along Y [cm.] 0.851 1.029 0.599 1.361 0.813 Avg. radial displacement [cm] 1.082 1.3 0.815 0.795 0.45 SD-Major Axis of 95% ellipse 0.892 0.892 0.709 0.904 0.556 SD-Minor Axis of 95% ellipse 0.861 1.146 0.582 1.41 0.841 Avg. velocity [cm/sec] 64.282 71.811 49.012 60.594 61.326 Length [cm.] 107.15 91.146 81.676 100.998 102.23 Figure 1: Overlaid 95% Ellipse of Quiet Standing
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Rojas 7 Figure 2: Overlaid 95% Ellipse of Right Leg Raised
Rojas 8 Discussion After conducting the experiment there were some very interesting results. In this lab, a force platform was used to measure body balance under different helmet conditions. Several factors of this measurement would help in determining which helmet gave the best balance control and which helmet was the worst. The variables under consideration are the length of COP, 95% Ellipse Area, and average velocity, whose larger values indicate worse balance. On the other hand, the more circular the 95% ellipse is, the better a person can recover from a potential fall. In almost all cases, the quiet standing provided better balance than raising a leg which is to be expected as during this the subject has a larger base, which leads to better control. In terms of length of COP during quiet standing, the hockey helmet had the lowest value of 38.219 cm while the football helmet had the highest value of 43.492 cm. This also correlates with the hockey helmet having the lowest velocity of 22.921 cm/sec and the football helmet having the highest velocity of 26.091 cm/sec. This would suggest that the hockey helmet provides the best balance among the four helmets tested. This was shocking since the subject believed this helmet was not the most comfortable, and also hockey helmets are known to be helmets that need more improvement. Because of this, we can also suggest that in the experiment, there may have been errors, possibly from the subject having overall poorer balance than normal and wobbling on the force platform, for example. However, something fascinating was that the results were the opposite for the 95% Ellipse Area where the baseball helmet had the lowest area of 0.432 cm 2 while the softball helmet had the highest area of 1.305 cm 2 . This could be because the subject rated baseball helmets as the most comfortable of the four helmets tested and in this context it provided better balance support.
Rojas 9 A similar correlation was observed in the length of COP while raising a leg where the baseball helmet had the lowest length of 81.676 cm whereas the hockey helmet had the highest length of 102.23 cm. The baseball helmet also had a lower length than the no helmet control situation which had a COP length of 107.15 cm. With this, we can say the baseball helmet helped increase balance control during this dynamic motion. Standing on one leg is way harder than just standing still as the whole force of the body rests on a smaller area, hence why there was a significant difference in the two balance results. Looking at the velocity, the baseball helmet had the lowest velocity of 49.012 cm/sec which was unexpected as this was one the most comfortable helmets for the subject due to its weight and tight fitting. In this case, the weight of the helmet might have stabilized the body and prevented it from shaking too much. Football had the highest velocity of 71.811 cm/sec while raising the leg which means that it decreases balance during this situation. The baseball helmet also had the lowest 95% Ellipse Area of 1.176 cm 2 whereas the softball helmet had the highest area of 3.720 cm 2 . This factor shows the negative way the softball helmet affects balance in this scenario with this subject. A variety of factors like level of exercise, gender, and overall build may have affected the results. The subject had a low level of exercise but a person who exercises more would perform better in the balance tests because their muscles are more trained which would give different results. Gender would also have an impact on balance since male and female subjects would have many physiological differences. Lastly, the way a person's body mass is distributed would affect their balance results by a lot and they might need different types of helmets to counteract that aspect.
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Rojas 10 Looking at the data, improvements on the helmets could be made by having more even mass distribution of the helmet. Also, the physical differences between male and female bodies should be taken into account while designing the helmet. As for sources of error, the angle between the legs during the leg-raising situation is never measured and was mostly entrusted to the intuition of the subject. This could mean that it was not consistent during all the measurements. Moreover, there was no break between trials which means the subject could have been fatigued during the later part of the experiment which affected the results. This could have also biased the comfort rating and made the helmets that were tested later (like the football helmet) seem worse.
Rojas 11 Conclusion Overall, it could be said that the baseball helmet affected balance the most during quiet standing while the softball helmet affected balance the most when raising a leg. The experiment could have been improved by doing more trials with each helmet because the subject was a little nervous and unsure of how good her balance was and it would also provide more data to make better conclusions. The leg-raising portion of this experiment could also be repeated with the subject’s hands being free to move. This is said because in most real-life situations, the hands are used to support us in balancing and would give a more accurate to-life picture of the effect of various helmets on balance.
Rojas 12 References BME 3600 Biomechanics. (2023). Lab #2 Balance control testing with sports helmets. Lab Handout Lee, Chia-Hsuan, and Tien-Lung Sun. <Evaluation of Postural Stability Based on a ForcePlate and Inertial Sensor during Static Balance Measurements - Journal of PhysiologicalAnthropology.= BioMed Central, BioMed Central, 13 Dec. 2018, https://jphysiolanthropol.biomedcentral.com/articles/10.1186/s40101-018-0187-5 . Quijoux, Flavien et al. <A Review of Center of Pressure (COP) Variables to QuantifyStanding Balance in Elderly People: Algorithms and Open access Code*.= Physiologicalreports. 9.22 (2021): https://physoc.onlinelibrary.wiley.com/doi/full/10.14814/phy2.15067 Traumatic Brain Injury.= Mayo Clinic, Mayo Foundation for Medical Education andResearch, 4 Feb.2021, https://www.mayoclinic.org/diseases-conditions/traumatic-brain-injury/symptoms-causes/ syc-20378557 .
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Rojas 13 Appendix BioAnalysis Data: Quiet Standing with No Helmet Right Leg Raised with No Helmet
Rojas 14 Quiet Standing with Football Helmet Right Leg Raised with Football Helmet
Rojas 15 Quiet Standing with Baseball Helmet Right Leg Raised with Baseball Helmet
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Rojas 16 Quiet Standing with Softball Helmet Right Leg Raised with Softball Helmet
Rojas 17 Quiet Standing with Hockey Helmet Right Leg Raised with Hockey Helmet