high Stress after Sport

Stress is measured through heart rate variability. https://support.garmin.com/en-US/?faq=WT9BmhjacO4ZpxbCc0EKn9 

It could be that your heart rate isn’t steady. It could also be that the heart rate monitor in your watch is causing the issue. Make sure the sensors are clean and the watch is snug.

This is very much normal. It's an indication of EPOC.

"Here's a cool fact: The same thing happens to your body after exercise. Similar to how a car’s engine remains warm after being turned off, once a workout is over and you’re back in your daily routine, your body’s metabolism can continue to burn more calories then when at complete rest. This physiological effect is called excess post-exercise oxygen consumption, or EPOC. Also known as oxygen debt, EPOC is the amount of oxygen required to restore your body to its normal, resting level of metabolic function (called homeostasis). It also explains how your body can continue to burn calories long after you’ve finished your workout."

Agree - this is pretty much the pattern you should be seen. Stress should be high after a workout, and gradually decline in the hours after a workout.

When it remains high (especially overnight) is when you should be more concerned - either a sign that you are overtraining and need to schedule additional recovery, or perhaps that your body is fighting an illness.

It's pretty normal. I prefer to look at the body battery thing with the stress data. It gives a lot of insights which I actually know. :)

Here is my graph from 29, 30, 31 of August and 1st of September.

29 Aug. I went to bed at 4a.m and woke up at 7 and brought a team mate to a MTB race. I didn't do anything heavy or stressing, but due to not enough sleep, body felt its stress. Garmin advising me to sleep.

30 Aug. Some sleep gave me some recovery but I didn't sleep well again. At 5  a.m. we went for a bike ride and rode till the midnight, more than 300 kilometers. No stres data was recorded as it doesn't record during activities. Garmin advising to slow down. :)

31 Aug. Fairly active and hard work day. Body battery was 0 the whole day and heavy stres. Garmin advised to sleep again.

1st of Sept. I had some deep sleep and my body battery increased with stress levels going down. Actually, some of that stress is due to work environment. Garmin said congrats, 

It's normal that stress levels increase after tiring activities. And it takes some time until fully recovered from it.

thank you all for your answeres !!!  they have been very helpful