Running and multisport watches normally have a “lap”
How to mark a “lap” in the Workout app
While tracking a workout with the Workout app on your Apple Watch, double-tap the screen to highlight a segment. A summary will appear and you can continue to sweat and mark segments and laps if you wish.
Note: Things are a bit different with swim workouts as the screen locks automatically. In Pool Swim workouts, your watch keeps track of the number of lengths you do (based on the pool length you enter at the start); It also automatically splits your workout into sets based on each time you stop at the pool side for more than ten seconds. There is no way to add segments to an Open Water Swim workout.
How to see your laps (and other segments)
To view your segment divisions, open the “Fitness” app on your iPhone and select your workout when you are done. Tap on ‘Segments’ and you will see a numbered list and all associated statistics.
Why segments matter
Average workout stats – like running pace and bike speed – and individual mile splits aren’t worth much unless you’re just doing a slow, steady workout (or, I think, mile repetitions). For example, if you do a mile warm-up, run a mile and a half, and then a half mile cooldown, the bit that matters most is between mile 2 and mile 3.5, but neither the average run speed nor the mile split in the Fitness app will tell you how fast you did it.
However, if you’re using the lap feature on your watch, you can warm up your half mile, double tap to hit lap, run a mile and a half, double tap to get back on lap, then cool down. Then, when you view the workout in the Fitness app on your iPhone, it will be split into three segments: your warm up, your workout, and your cooldown.
And you can’t just track running and cycling. If you’re doing some High-Intensity Interval Training or CrossFit-style circuits, you can mark each lap.