Save trimmed activity as...

You should save each part as its own activity if you want to compare them like that.

You can split it into a multisport activity. They will be separate activities but all under the same multisport "umbrella" activity and it will be hard to compare them as they will be listed inside the multisport activity.

As e7andy wrote, convert the activity to multisport. If you do not know how, click the Edit icon (pencil at top right), and then scroll down:

Thanks a lot! Can I copy the whole activity as a new activity? Real Save as?
Any suggestion how to compare? Only save each activity (interval, 1 km run) as unique activity.

No, it will have the same id so you must change the id of the fit file to be able to upload it again. You can do that in https://gotoes.org/strava/Combine_GPX_TCX_FIT_Files.php or with Fit File Repair Tool. I believe both needs a premium version so you need to buy them.

Thanks all.

merapi said:

Any suggestion how to compare?

You do not need to save the individual legs of the multisport activity separately in order to compare them. You can compare them directly in Garmin Connect. Open the main Activities page, select the sport in order to have each leg listed separately, then select the legs you want to compare (up to 4), and click the Compare button at the top.

And BTW, for the future, it may be easier to set up the auto-lap to 1km, and then reviewing the Laps table - you can sort it by any column, which makes it then easy to compare the individual laps. In this way, it saves you the work with the manual splitting of the 1km laps.

You all are very kind. I try to describe the whole training. It is dragonboating. E.g.

Training on Sunday - heating 5 minutes, improving start paddling sequence (25 strokes) with light paddling between, 2x full 200 m sprint with light paddling between, 1 km intervals, 1 km light paddling improving techniques, 1 km full power, light paddling.

Next training will be different.

After some time I would like to compare all 200 m sprints from different trainings.

Should I start activity before each step or should I record one activity and edit it later?

I really appreciate your help. I am real beginner.

Astrux showed it will work to log it as a multisport activity. Start the first activity normally. When you start the next part you switch to the next activity which can be of the same type. And so on. 

Use a hot key to switch activity and automatically create a multisport activity. 

Sorry for "stupid" question. Hot key on Fenix 6 or in connect?