Introduction to Sports Biomechanics: Analysing Human Movement ...

INTRODUCTION TO SPORTS BIOMECHANICS
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intervals (rows) i+1 and i−1, respectively. As before, the denominator in the
equation (2∆t) is the time interval between times (rows) i+1 and i−1 and
is 0.04 s. Tabulate your knee angular acceleration data in a new column in
your Excel worksheet. Note that we cannot estimate the angular accelerations
at the first and last instants of the knee angular velocity–time series (and, therefore,
not at the first two and last two time instants of the knee angle–time
series).
(c) Plot the time-series graphs of knee angle, angular velocity and angular acceleration.
Do the time-series patterns basically agree with the qualitative patterns for
running from Figure 3.10? Explain your answer. Does the angular acceleration–
time series graph look sufficiently ‘smooth’ to justify our assumption about the
knee angle data being noise-free? Comment on your findings.
Hint: You may wish to reread the section in Chapter 3 on ‘The geometry of angular
motion’ (pages 93–6) and consult your answer to Study task 4 in that chapter before
undertaking this task.
5 Carry out an experiment to determine the volume of (a) a hand, (b) a forearm
segment. You will need a bucket or similar vessel large enough for the hand and
forearm to be fully submerged. You will also need a bowl, or similar vessel, in which
the bucket can be placed, to catch the overflow of water; and calibrated containers
to measure the volume of water. Repeat the experiment at least three times and then
calculate the mean volume and standard deviation for each segment. How reproducible
are your data?
Hint: You may wish to reread the subsection on ‘Body segment inertia parameters’
(pages 137–9) before undertaking this task.
6 (a) Plan an experimental session in which you would record an essentially twodimensional
sports movement, such as a long jump, running or a simple gymnastics
vault. You should carefully detail all the important procedural steps,
including the use of skin markers (see Table 5.1 and Box 6.2).
(b) If you have access to a suitable video camera, record several trials of the movement
from one or more performers; if not, download a suitable running
sequence from the book’s website.
(c) If you have access to a video digitising system, then digitise at least one of the
sequences you have recorded. If you have access to analysis software, then plot
stick figure sequences and graphs of relevant kinematic variables, which should
have been established by a qualitative analysis of the movement similar to that
performed in Study task 2. If you do not have this access, you can download
stick figure sequences and graphs of kinematic variables from the book’s website,
but you will still need to justify which variables are of interest.
(d) Write a short technical report of your study in no more than 1500 words. Focus
on the important results.
Hint: You should reread the subsection on ‘Two-dimensional recording procedures’
(pages 126–30) before undertaking this task.
7 (a) A shot is released at a height of 1.89 m, with a speed of 13 m/s and at an angle
of 34°. Calculate the maximum height reached and the time at which this