Speed and agility testing

Testing the top speed of an athlete is important in many sports. To able to accurately measuring a 10-20 m flying sprint is therefore useful. There are also many events where start, stop, and turn agility is important, for example, football (both kinds), basket, tennis, etc. The shuttle is, therefore, also a handy test. This post gives you some tips on using Instant finish for testing and what accuracy you can achieve.

Flying sprint

This is best run with two devices and Start Sender. Since the distance seldom is over 30 m, you can run it in direct mode without an external network.

For the start sender device, you can use the following settings:

Start setup
Start sender mode: Direct
Start mode: Starter
Start clock: Motion or Human

For the finish device, the following is recommended. Auto finish is convenient if you are running multiple tests and want to save all in one list.

Start setup
Start mode: Start Sender
Start sender mode: Direct

Finish setup
Finish mode: Instant
Save time on: Motion or Human
Start detecting after: 1
Stop after pass: 1
Reset at first pass: Off
Lap sound: Voice
Auto finish: On

Shuttle Tests

For the shuttle tests, it is usually enough with one device aimed at the finish line. The shuttle usually involves several passes, so you should set Stop after to an appropriate number. Some tests are also run with a flying start, and here the Reset clock at first pass setting comes in handy.

Start setup
Start mode: Starter or Self
Start clock: Hand

Finish setup
Finish mode: Instant
Save time on: Motion or Human
Start detecting after: 1
Stop after pass: 1-3
Reset at first pass: On or Off
Lap sound: Voice
Auto finish: On

There is a large number of different agility and shuttle tests available. A comprehensive list can be found here. Some examples of how they can be implemented in SprintTimer are given below. Others can be set up following the same procedures.

Reset on firstStop on
20 Yard Agility (Soccer)On2
Pro Agility (5-10-5)Off2
505 Agility testOn1
Agility T-TestOff1
3-cone drill (NFL)Off2
10 x 5m ShuttleOff5
Arrowhead Agility (SPARQ Soccer)On1

Accuracy

When using motion detection there are two main causes of errors: When and where the detection first reacts to the motion and what part of the body (arms or torso) that hits the zone first. The latter is a problem shared with physical timing gates.

Human detection works a little differently. It uses all video frames where there is a human present and calculates the best estimate of when he passes the midline. For a modern fast iPhone/iPad it can be more than 10 detections even on a fast pass. The uncertainty instead comes from calculating the body shape.

To test the accuracy, I set up a tripod with two iPhones (11pro and 12pro) aiming at the same finish line. One was running both motion and human detection; the other was running Photo finish as reference. Both devices were connected to the same start sender device. I ran in front of the camera 15 times and in the graph below I have plotted the difference between the detection time and the photo finish.

Both detection methods exhibit both an offset (i.e. the average is not 0) and a spread. For motion detection the offset is 0.03 s and the spread is about +-0.03 s. For the human detection the offset is 0.01 s and the spread +-0.01 s. For a flying sprint (which is the most accuracy critical) is the offset less important since it will be the same at both ends. Looking at the spread we can see that human detection is a little more consistent.