ESS2003 Kinesiology and Biomechanics II

Laboratory Session 2

Joint Angles in Running

Dr Sharon Dixon

Purpose

To investigate the changes in lower extremity joint angles during the ground contact phase when running with and without heel inserts.

Aims

To obtain mean and standard deviation values for the minimum ankle and knee angles over three consecutive steps when running with and without heel inserts.
To obtain mean and standard deviation values for the maximum negative ankle and knee angular velocities over three consecutive steps when running with and without heel inserts.
To compare subject results to mean group values and values presented in the research literature, highlighting possible factors causing differences.

Data collection.

Video will be collected at 25 Hz viewing the right side of the subject. Subjects will run at 3.4 m/s, (12.2 km/h) with and without heel inserts in their shoes.

Procedures

Load 1 of your running data files

Double click ‘Hu-m-an’ icon on desktop

Click e:

Select [progr~1] [studio~1] [captur~1] [***.avi]

View the video sequence

In VIDEO-MODEL CONTROL window

-play the video sequence

-slow video playback speed by reducing ‘Speed’ to ‘1’

-Using the video controls, advance your video to the frame you want to start digitising from (when the subject is running at constant velocity). Enter this frame number as the ‘start’ frame in the VIDEO-MODEL CONTROL window using the arrow below ‘start’.

-Advance the video to the last frame you want to digitise (you must have at least 3 steps), and enter this number as your ‘end’ frame in the VIDEO-MODEL CONTROL window using the arrows below ‘end’.

-Go to the Utilities menu option – ‘set a new trial sub-sequence’ – yes.

Select model for digitising

-Edit – Trial Set Up

Under ‘List of Trial Set Up Titles’ - Select ‘5 Pt. Lower Limb’

-Load – Yes – Exit

Digitise the running sequence

-Options – Digitise

DIGITISE window will be active

-using the left mouse button, select body landmarks as specified in the DIGITISE window

hip, knee, ankle, heel, toe

-click left mouse button to advance to the next frame

-if an error is made, click ‘re-collect this frame’ to redigitise the whole frame

Continue digitising until all three running steps have been digitised.

When all frames have been digitised, close the DIGITISE window.

View the model

Using VIDEO-MODEL CONTROL window

-play the sequence to view the video and the model simultaneously

-select (tick) +Model

-view the sequence again

Identification of the frames during ground contact

-play the sequence one frame at a time. For each step identify the frame number for each foot strike (the frame just before ground contact), and the frame number for the same foot toe-off.

-input the frame numbers in Table 1

Calculate joint angles during running

When calculating the joint angles note that you are viewing the subject from the left hand side, therefore the angles measured by the software will be the opposite to those measured last week. To calculate the appropriate angles: 360° - angle given by software = appropriate angle

- Calculate - Relative Angles

Select Knee angle

Calculate

In GRAPH DATA CONTROL window

Click ‘Clear/Reset’

Select ‘Knee angle’

- For each step, identify the minimum knee angle during ground contact by clicking on the appropriate points of the graph. Input results in Table 1.

- Calculate - Relative Angles

Select Ankle angle

Calculate

In GRAPH DATA CONTROL window

Click ‘Clear/Reset’

Select ‘Ankle angle’

- For each step identify the minimum ankle angle during the ground contact by clicking on the appropriate points of the graph. Input results in Table 1.

Table 1 – Joint angles at heel strike and during ground contact when running without heel inserts.

Ground contact / Knee angle / Ankle angle
Step / Frame at foot strike / Frame at Toe off / Minimum angle during ground contact (degrees) / Minimum angle during ground contact, (degrees).
1
2
3
Mean
SD

Calculate joint angular velocities

Using the same procedures as described for the calculation of joint angles, determine the knee and ankle joint angular velocity – time histories. For each running step identify the maximum negative joint angular velocities (during ground contact) and complete Table 2. Present the joint angular velocities in degrees/s and radians/s ( radians = 180 degrees).

Similar to above as you are viewing the subject from the left hand side, therefore negative angular velocities are in effect positive and visa versa, e.g. +180 degrees/s in the software is actually -180 degrees/s.

Table 2 – Peak joint angular velocities during ground contact when running without heel inserts.

Ground contact / Maximum negative knee flexion angular velocity / Maximum negative ankle dorsiflexion angular velocity
Step / Frame at foot strike / Frame at toe off / Degrees/s / Radians/s / Degrees/s / Radians/s
1
2
3
Mean
SD

Export angle data

File – Export Graph Data to File

- check path is: e:\hu-m-an\data\Year2\file name

The exported angle data can now be viewed and manipulated in spreadsheet packages such as Excel.

View data in a spreadsheet

For Excel,

Double-click Excel icon.

File – Open

To open your file in c:\hu-m-an\data\Year2

-locate e:\hu-m-an\data\Year2

-Under ‘Files of type:’ select ‘all’ files

-Open your file (OK)

The text import wizard will appear.

- Click ‘delimited’

-Next

-Click ‘space’ as the only delimiter

-Next

-Finish

The columns represent the calculated angles in the same order as they appear in the hu-m-an GRAPH DATA CONTROL window.

Repeat steps 1-10 for your second running video (heel inserts).

Insert the results for running with heel inserts in Tables 3 and 4.

Table 3. Joint angles at foot strike and during ground contact when running with heel inserts.

Table 4. Peak joint angular velocities during ground contact when running with heel inserts.

Ground contact / Maximum negative knee flexion angular velocity / Maximum negative ankle dorsiflexion angular velocity
Step / Frame at heel strike / Frame at toe off / Degrees/s / Radians/s / Degrees/s / Radians/s
1
2
3
Mean
SD

Construct 2 tables (Table 5 and 6) containing the mean data for each subject in your group for running with and without heel inserts.

Construct 1 graph (Figure 7) containing data for your subject, both with and without heel inserts.

Questions

Does the heel insert reduce maximum ankle dorsi-flexion angle for your subject?

What influence does the heel insert have on knee flexion for your subject?

Based on your results, would the use of a heel insert be beneficial for reducing the chance of Achilles tendon injury? Explain your answer.

How do your results compare with those for the rest of your group?

Comment on the reliability and accuracy of your data collection methods.

Suggest statistical methods for investigating the influence of heel inserts for the group of subjects.