Footprints In The Sand Inquiry Activity 2E Activity Objectives: Working in collaborative groups, students will be able to: assume assigned roles to complete a given task examine the various parts of the gait cycle through an interactive lab and report their findings using charts, graphs, and simple calculations generate a hypothesis to be investigated determine accuracy of hypotheses by analyzing data collected present and support findings to the class describe how the different variables affect gait Activity Description: By performing the lab, students will determine the effects of different variables on gait cycle by measuring and calculating the following: base of support, line of progression, and foot angle. This lab uses the materials from Footprints in the Sand. Activity Background: As students discovered in the previous lab, Footprints in the Sand, everyone s footprints are unique. This uniqueness can be explained by examining base of support and foot angle. Base of support refers to the distance between parallel lines intersecting the midpoint of each heel print (Figure 1). Base of support is a primary indicator of a person s overall stability and balance. In order for a person to remain stable, their body s center of mass must fall within the base of support. Examining an individual s base of support can be useful in prescribing therapy to correct gait abnormalities, diagnosing balance disorders, and preventing falls in the elderly. Foot angle can also be useful when examining an individual s gait. Foot angle refers to the angle formed by the intersection of the line of progression and a second line, which is drawn through the midpoint of the heel and the space between the first and second tarsal. Gait Parameters Figure 1 Line of Progression Base of Support Foot Angle Activity Overview 1
In this lab, students will introduce common variables and determine if these variables significantly impact base of support and/or foot angle. Some factors that can affect the base of support and foot angle measurements include: wearing shoes with high heels and/or thick soles, increasing weight load/distribution, visual impairments, and the use of ambulatory devices. These variables can be simulated in the classroom using easily attainable materials. For instance, when studying the potential impact of high heeled or thick - soled shoes, you should instruct students to perform the lab while wearing shoes with a heel at least 2-3 in height or with a minimum sole thickness of 2. When studying weight load/distribution, have students wear a backpack weighted heavily with textbooks. Students should be monitored to assure that they are not adding excessive weight for their frame which could result in injury. You may want to ask students to wear the backpack on their back, in a frontal position simulating the weight distribution found during pregnancy, or on a single shoulder. To mimic a visual impairment, instruct students to wear a blindfold as they perform the lab. When studying the effects of ambulatory devices, students should perform the lab while using a cane or a walker. The tested variables should cause changes in base of support and foot angle measurements. After collecting the measurements with the applied variables, students will compare these results with those previously obtained in the original Footprints in the Sand lab. The original measurements should have been within the normal range of gait values. See Table 1 below: Table 1 Normal Gait Values Base of Support Foot Angle 7-9 cm 10-14 degrees After students have analyzed their data, the class will share their findings and compare them with others obtained during the lab. Students should be encouraged to examine why certain variables impact base of support and foot angle more than others. Guide students to explore different scenarios where these variables are present and how they can significantly impact a person s mobility. Base of Support/Foot Angle Background: Shoe Characteristics: Heel Height & Sole Thickness: Natural gait, also referred to as barefoot gait, is nearly unattainable while wearing shoes due to the many accommodations the body must make in order to maintain its equilibrium. In fact, certain shoes may be hazardous to your health due to the increased risk of falls 2
and other injuries associated with them. This makes proper footwear selection a vital part of maintaining mobility for all people. However, because of the complications that could arise from a serious fall, this issue can become one of life or death for the elderly. High - heeled shoes, with a heel height greater than two inches, can cause the most dramatic change to an individual s normal gait. When barefoot, the upright position of the body is perpendicular to the floor creating a 90 angle. By adding heel height, that angle is drastically changed causing the body to compensate by altering a number of things such as the position of the center of mass, base of support, and other parameters of the gait cycle. In addition, high - heeled shoes also render the normal heel to toe strike pattern found in natural gait impossible, creating a more flat - footed step pattern. Consequently, wearers of these shoes develop a cautious or unsteady gait characterized by shortened step lengths, slower velocity, and a smaller base of support in response to the disruption of their usual walking style. Similarly, thick - soled shoes can create observable changes to the gait cycle. Due to the restriction of normal foot flexibility caused by these shoes, a direct correlation has been made between sole thickness and instability. As sole thickness increases, instability increases as well. Due to the density of thick soles, the added weight to the foot can also cause a dragging effect, further increasing the risk of falling for the wearer. Increasing Rear Weight Load: Studies have shown that students who routinely carry a backpack weighing 25% or more of their total body weight shown signs of increased muscle stress and equilibrium problems while simply walking around. Excessive amounts of added weight causes the body to compensate by altering its natural alignment causing the wearer to become unbalanced and at a greater risk of falling. It should also be noted that students who carry backpacks weighing 15% or less of their body weight experienced relatively minor disturbances in their balance. In addition to weight recommendations for backpacks, recommendations for proper positioning are equally important for students. Backpacks should always be worn snugly on both shoulders in order to distribute the weight evenly across the upper back. Backpacks that hang lower than the mid-back cause unnecessary pressure on the wearer s muscles due to the increased pulling on the shoulders. Similarly, individual s who wear their backpacks over one shoulder experience the pull created by the uneven weight distribution. The unnatural posture created by this pull can curve the spine and causes undo strain on the upper back, shoulders, and neck. Prolonged wear in this position can ultimately lead to functional scoliosis. 3
Increasing Frontal Weight Load: Excessively overweight individuals and pregnant women, due to their awkward weight distribution, tend to walk with an increased foot angle. This angle, also referred to as out-toeing, produces a distinct walk similar to the waddle of a duck. This waddling gait helps these individuals maintain their balance by increasing the base of support in order to accommodate for the change in their center of mass. The greater foot angle also contributes to the maintenance of their balance by helping them support their additional weight as they move. Visual Impairments: When left uninstructed, visually impaired children tend to develop an usual walking pattern. This awkward gait, which some refer to as blind gait, is characterized by shortened step length, extreme out toeing creating a waddling effect, wide base of support, and flat footed steps. This gait develops out of the individual s need to search out the terrain, avoid hazards, and maintain their balance. Without the visual ability to emulate the normal walking patterns of others they see, these individuals must be trained to use assistive devices and other techniques in order to correct these gait abnormalities. Activity Materials: (per group) 2 meters dark colored butcher paper Talcum powder to fill a shallow tray Shallow tray Masking tape Protractor Meter stick Calculator Blindfold Backpack weighted with books Shoes of varying heel height/sole thickness Ambulatory device (cane, walker) Activity Management Suggestions: You may wish to assign different variables to the student groups to ensure all variables are tested. After students have been assigned a variable, review the process they will need to follow in order to correctly form, test, and reject or accept their hypothesis. You may want to stimulate hypothesis formation by having a brief group share session where students discuss the possible effects of the variables on gait. Allow students to work with a partner to complete lab. 4
Modifications: For students needing more assistance: Group these students with peers who can assist them during the lab. For highly able students: Allow these students to work on the extension activity after completion of lab. Extensions: Students can investigate if any changes are present in the base of support and foot angle of various people outside the classroom. Individuals selected for this investigation should have one of the compromising variables listed above such as the routine use of an ambulatory device or a visual impairment. Activity References Used: Van Hook, F.W., Demonbreun, D., Weiss, B.D. (2003). Ambulatory Devices for Chronic Gait Disorders in the Elderly. American Family Physician. 67(17) 17-24. Whittle, Michael. (1991). Gait Analysis An Introduction. Oxford: Butterworth-Heinemann Ltd. Nawata, K., Nishihara, S., Hayashi, I., and Teshima, R. (2005). Plantar Pressure distribution during gait in athletes with functional instability of the ankle joint: preliminary report. Journal of Orthopaedic Science, (10), 298-301. Broch, NL, Wyller, T, Steen, H. (2004). Effects of Heel Height and Shoe Shape on the Compressive Load between foot and base. Journal of the American Podiatric Medical Association, 94(5), 461-469. Robbins, S, Waked, E, Krougilicof, N (2004). Improving Balance. Journal of the American Geriatrics Society, 46(11) 1363-1370. Robbins, S, Waked, E, Krougilicof, N (1997). Foot Positioning awareness in younger and older men: The influence of footwear sole properties. Journal of the American Geriatrics Society, 45(10, 61-66. Joyce, B, Kirby, RL (1991). Canes, Crutches, and Walkers. American Family Physician, 43(2), 535-542. Foti, T, Bagley, A, Davids, J (1997). Biomechanical Alterations in gait during pregnancy. Retrieved June 2, 2005, American Society of Biomechanics. Website: http://asb-biomech.org/onlineabs/abstract97/50/ Buckley, J, Heasley, K, Twigg, P, Elliot, DB (2005). The effects of blurred vision on the mechanics of landing during stepping down by the elderly. Gait & Posture, 21(1), 65-71. http://www.wayfinding.net/gaithome.htm http://www.icpa4kids.com/pediatric_chiropractic_articles_backpack_re search.htm http://www.physics.ubc.ca/~phys438/reports/waddle.pdf 5