7-Day Training Load & Exercise Load graphs relationship. Are they wrong?

You need to have sufficient recovery between exercises, otherwise the Exercise Load starts cummulating (see the rising green graph after the ~10 days of training). So what the watch tells you, means that the Training Load rises so, that the productivity of the training starts dropping. In other words - overtraining, and the need for more (or better) recovery. However, in your case the drop is only brief (around 28th), and the effectivity seems to be still ok.

Thank you for great explanation! So does it mean that the numbers from the blue graph (training load) are not just simply added to the black graph and there is more calculations needed inside the device and the device itself is actually way smarter than the user. I started running again 3 weeks ago after 1 month of injury. Did a simple training - every Mon, Wed and Fri ~5 km and recovery in between these exercises. My body feels fine and can feel I am getting fit again. One think I found however is that 2 months ago the watch suggested me new Lactate threshold value and I just simply accepted it. However I think the new value is way off (after one + year of +- similar LTR value it suddenly dropped by 8 Hrm without any reason so I think the watch was also calculating HR zone, training load and many other things incorrectly. I set the LTR value back to what it was 2 months ago and will do the Lactate test and will see if fitness stats gets more accurate. 

If you have doubts about the LT the watch measures, have it measured in a lab, to be sure. The LT estimate from the watch, is finally just an estimate, and may indeed differ from the reality, especially if the conditions during the Guided Test were no ideal. Read more about it here:

How Is Lactate Threshold Measured by My Garmin Device? 

The black dot value is the sum of the training load of all exercises done over the last 7 days. This means that the Training Load of your training of today should be fully added to the today's value of the black dot but at the same time the exercise load of the training done exactly one week before is subtracted from today's black dot value. Nothing more, nothing less if it comes to the calculations of the 7-day training load.

Example: your exercise on 25-Jan was slightly higher than the one at 18-Jan. The difference between the 25-Jan and 18-Jan exercise load will be the increase in value of the 25-Jan black dot value.

If it comes to the adaptation of the green bar, then there is an algorithm behind it which we users cannot see.

Remarks: all exercises should be registered with the same Garmin device, otherwise the exercise load will NOT be included in the 7-Day Training Load despite the exercise load being visible as a blue bar in the upper graph

scusate ma a me dopo 2 mesi di carico acuto alto (somma EPOC 7gg sempre superiore alla barra verde ottimale), il fitness ossia la barra verde, rimane sempre costante....... in pratica non si alza mai....