Lower treshold power, what?

In my fitness signature I can see my lower treshold power rising at same when the peak power is gradually going down. Based on brief discription of LTP IN the glossary, it is very hard to interprete the development. Any chance to get some information about the actual meaning of LTP curve and changes in it?

LTP generally rises with lower training load. It will generally level out or perhaps even decline with rising high/peak training loads.