Activities Based on the Running Data for Subject Paul
Motion and force data was taken for subject Paul as he ran steadily in a straight line at
the Chapin Gait Analysis Center. The data is in an Excel spreadsheet file,
PaulRun1AA.xls. A video and two animations of her motion are also available. The
video is on the file PaulRun1.mpg. A stick figure animation showing recorded force
vectors is on the file PaulRun.mov.
Conceptual Activities:
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 Paul running on file PaulRun1.mpg. Next observe the stick
figure animation of the motion on file PaulRun.mov. Locate any times when both feet of
his feet are off the ground simultaneously. What percentage of the time is this? Describe
his motion when neither of his feet is touching the ground.
3. Compare the running motion with walking motion by looking at the animation on
file PaulWalk.mov. When are the 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 PaulRun.mov. Describe what happens to
the direction and magnitude of the force vector as Paul 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 when Paul is
running. Now create the corresponding graph for walking from the data on file
PaulWalk3AA.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 Paul 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 Paul as
a function of time.
4. What is the maximum downward force exerted by each foot on the plate as it strikes
the floor? What is the maximum upward force exerted on each foot by the plate as the
foot lifts from the floor?
5. Using Excel’s chart wizard, make a graph of the motion of the sensor attached to
Paul’s right wrist versus time. Compare this to the graph of the motion of the sensor
attached to Paul’s right elbow versus time. What can you say about Paul’s arm motion
during the run?
6. Make a graph of the motion of the sensor attached to the right side of his head versus
time. Compare this graph to the motion of the sensor attached to the right shoulder.
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.