Activities Based on the Running Data for Subject Maira
Motion and force data was taken for subject Maira as she ran steadily in a straight line
at the Chapin Gait Analysis Center. The data is in an Excel spreadsheet file,
MairaRun3AA.xls. A video and two animations of her motion are also available. The
video is on the file MairaRun3.mpg. A stick figure animation showing recorded force
vectors is on the file MairaRun3.mov. A stick figure animation showing the paths of
various body parts is on the file MairaRun3_contrails.mpg.
Conceptual Activity:
1. Stand up and walk steadily in a straight line for a few steps. Now run in a straight
line. Describe some similarities and differences between walking and running base on
your experience.
2. Observe the video of Maira running on file MairaRun3.mpeg. Next observe the stick
figure animation of the motion on file MairaRun.mov. Locate any times when both feet
of her feet are off the ground simultaneously. What percentage of the time is this?
Describe her motion when neither of her feet is touching the ground.
3. Compare the running motion with walking motion by looking at the animation on
file MairaWalk.mov. Are there ever times when both feet are off the ground while
walking? Are your observations from the animations consistent with your own
personal experience?
4. Observe the stick figure animation on file MairaRun.mov. Describe what happens to
the direction and magnitude of the force vector as Maira steps on a force plate. Try to
develop a qualitative explanation for why the force vector changes direction as it does.
5. As a follow-up to the previous question, plot the x-coordinate versus time for the
right heel. Describe the motion suggested by this graph. What does the graph suggest
about the x-component of the velocity for the heel? How does it change over the course
of a step? Is the qualitative change in x-component of velocity consistent with the
observed change in direction of the force vector?
6. Make a graph of the z-component of force on the foot versus time. Now create the
corresponding graph for walking from the data on file MairaWalk3AA.xls. Compare
the graphs noting similarities and differences.
7. Summarize similarities and differences between walking and running, based on your
observations and analysis of the animations and data.
Analytical Activities:
1. Develop a spreadsheet that can estimate instantaneous velocity from the position
data for any selected body part.
2. Identify times when Maira has completely lost contact with the ground. Make plots
of the z-coordinate versus time for some selected body parts. Create a mathematical
model for the motion during one of these time periods. You might use the Trendline
tool in Excel. Do the motions of any part correspond to ideal projectile motion?
3. Plot the magnitude of the total floor force as a fraction of total body weight on Maira
as a function of time.
Synthetical Activities:
1. Explore the difference in foot motion between walking and running. You can do this
qualitatively first, by looking at the stick figure animations. A more quantitative
approach would involve plotting the heel and toe coordinates as functions of time.
From the graphs, can you identify times when only a heel or toe is in contact with the
floor? When both are in contact with floor? From your data can you tell which touches
the floor first: heel or toe? Is it the same for walking and running? Write an essay
summarizing your discoveries about the similarities and differences in foot motion
between walking and running.