Name: ___________________________
Date: ________
Biomechanics
KIN 346
Stride Length – Stride Frequency – Velocity
Information: Basic kinematic descriptors of running gait are stride length and stride frequency. During locomotion, a
stride is defined as the time between two consecutive specific discrete events. For example, a stride is often defined
as the time between two consecutive right heel strikes. Stride Length (SL) is defined as the distance traveled during
a stride and Stride Frequency (SF) is defined as the rate of completing the stride. SL has units of distance per stride
(e.g., m/st) while SF has units of strides per time (e.g., st/s). The product of SL and SF is running velocity. As a
person runs faster, he/she can choose to increase either SF or SL.
Purpose: Understand how SF and SL change over different speeds of locomotion.
Instruments:
Part 1: Videos, stop watch
Part 2a: Treadmill, stop watch
Part 2b: tape measure, stop watch, chalk
Methods:
Part 1
 Download the video (‘running at different speeds’).
 Record SF for each speed by timing how long it takes to complete 20 strides.
 Read ‘What stride rate should I use?’
Part 2a
 Instruct how to use the treadmill.
 One person will need to run while another measures SF.
 The person running will select a comfortable running speed.
 Once the speed is selected, the person measuring will time how long it takes to complete 20 right foot
strikes. Be sure to count the very first foot strike as ‘0’ as the timer starts and then stop the timer when
you count to ‘20’ foot strikes.
 Record the running speed.
 Repeat for at least four different running speeds.
Part 2b
 Mark the beginning and ending point for a 50 foot run course.
 Run the 50 feet in as constant a speed as possible.
 Start your watch at the beginning of the run and stop it at the end of the run.
 Count your strides (each right foot strike = +1) during the run.
 Record the number of strides completed to the nearest ½ stride.
 Repeat procedures for at least four different running speeds.
Name: ___________________________
Date: ________
Analysis
Part 1
 Calculate SL for each speed (knowing SL x SF = Speed)
 Plot SL vs. Speed and SF vs. Speed
Part 2a
 Calculate SF by dividing 20 by the time to complete the 20 strides.
 Convert the running speed to feet/s.
 Calculate SL by dividing running speed by SF.
 Plot velocity vs. SF and velocity vs. SL
Part 2b
 Calculate your average velocity: v = Δd/Δt
 Calculate your frequency of strides: Stride Frequency = SF = (number of strides)/(time)
 Calculate the length of stride: SL = v/SF
 Plot velocity vs. SF and velocity vs. SL
Name: ___________________________
Date: ________
Part 1
Trial
Treadmill Speed
(mph)
Treadmill Speed
(feet/s)
Time to complete 20
strides
SF
(strides/s)
SL
(feet/stride)
Treadmill Speed
(mph)
Treadmill Speed
(feet/s)
Time to complete 20
strides
SF
(strides/s)
SL
(feet/stride)
SF
(strides/s)
SL
(feet/stride)
1
2
3
4
5
6
7
8
9
Part 2a
Trial
1
2
3
4
5
6
Equations:
 1 mph = 1.467 feet/s
 SF = (20 strides) / (time to complete 20 strides)
 SL = velocity /SF *Use feet/s units for velocity
Part 2b
Trial
Time
Number of
strides
1
2
3
4
5
6
Equations:
 Displacement = 50 feet
 Velocity = 50 feet / time)
 SF = (number of strides) / time
 SL = velocity / SF
Velocity
(feet/s)
Name: ___________________________
Date: ________
Speed (feet/s)
Speed (feet/s)
SF (strides/s)
SL (feet/stride)
Treadmill Running – Part 2a
SL (feet/stride)
Treadmill Running – Part 2a
Speed (feet/s)
Speed (feet/s)
SF (strides/s)
Speed (feet/s)
SL (feet/stride)
Overground Running – Part 2b
SL (feet/stride)
Overground Running – Part 2b
SL (feet/stride)
SF (strides/s)
SL (feet/stride)
Treadmill Running – Part 1
SL (feet/stride)
Treadmill Running – Part 1
Speed (feet/s)