Biomechanics
ALL WORK CAN BE DONE IN THIS DOCUMENT
This assignment focuses on data collected for walking, running and jumping on a force plate to determine the ground reaction forces (GRF) associated with these activities. The assignment provides experience in interpreting the force-time curve representation from the data collected using the force plate. In class, videos were shown for two former students in an SPSC 3001 class doing these activities. For both the walking and running activities, the participants starts off the force plate and proceeds towards the force plate which captures one foot fall (step). For the vertical jump, the participant starts on the force plate, jumps up and lands back down on the force plate.
You have been provided an excel spreadsheet with pertinent walking, running and jumping trials. Each column of data refers to a specific channel captured by the force plate. You will only be concerned with the first three columns, which are the forces in 3 directions.
| Column | Data | Column | Data |
| 1 | Fx (fore-aft direction) | 4 | Mx (rotation around x) |
| 2 | Fy (medial-lateral direction) | 5 | My (rotation around y) |
| 3 | Fz (vertical direction) | 6 | Mz (rotation around z) |
Question 1: For the walking and running trials determine:
- Peak force (Fx, Fy, Fz) in Newtons (N) an length of activity (in seconds) [4 marks]
| Trial | Fx | Fy | Fz | Trial time |
| Walk |
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| Run |
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- Rate of Loading (Fz) in Newton per second (N/s) [4 marks]
| Trial | F50
(N) |
T50
(s) |
P1
(N) |
T1
(s) |
Loading Rate (N/s) |
| Walk |
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| Run |
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- Rate of Decay (Fz) in Newton per second (N/s) [4 marks]
| Trial | P2
(N) |
T2
(s) |
P50
(N) |
T50
(s) |
Decay Rate
(N/s) |
| Walk |
|
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| Run |
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Reminder of Rate of Loading and Decay
| Loading Rate (R1)
• Find Peak (P1) & first point > 50 (F50+) • Record time of P1 (T1) & time of F50+ (T50+) • F50+ = • T50+ = • P1 = • T1 = • Loading Rate (R1) = (P1 – F50+) / (T1 – T50+)
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Decay Rate (R2)
• Find point after P2 < 50 (F50-) • Record time (T50-) • F50- = • T50- = • P2 = • T2 = • Decay Rate (R2) = (F50- – P2) / (T50--T2)
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Question 2: Discuss the differences in the walking and running performances based on the force loading profiles. [4 marks]
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Question 3: Determine the following for the vertical jump:
- Determine the impulse of the takeoff and the landing. [2 marks]
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- What is the peak force on landing? [1 mark]
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- How much time did the participant spend in the air? [1 mark]
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Question 4 – The following graphs represent the same person performing three vertical jumps: one straight legged at take-off and landing; one with knees bent at take-off but straight on landing; and the third where the knees are bent on both take-off and landing.
Identify which graph represents each of the three jump performances and indicated what features of each graph allowed you to draw that conclusion [6 marks].
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