For kick detection the apple watch needs to see two things:
1) Accelerometer goes to 0 at the start and end of the rep.
2) Watch hand position changes.
#1 is easy since you start the set at 0 and then go back to 0 when you stop swimming.
#2 The watch assumes you are either in streamline or using a board in front of you. In order to record the end, you need to drop your watch hand by your side for 5 seconds.
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