Hi I have difficulty to improve.
i have never run before, however I walked (10km 40:46 20km 95 and 50km 3:58) 18 years ago
Recently I run marathon in 3:24 meaning slower than I used to walk. Recently i walk 10km under 47min.
I am 49 years old. In my opinion there is no problem with any programm as they do not improve our muscles.
I think we need combination of targerted weight training and specific running to improve speed.
I have found that my speed range have been dramaticaly reduced.
I can run 5min a 1km pace almost forever, and founding 4:40 pace is very hard to sustain even for 2km.
Simply just running afert 45 vill get you fit but very slow.
I have started running hills and short intervals. Instead 12km steady I run 30sec fartlek.
I have noticed my speed slowly improving.
Happy running