Background: Male, 34 years old. 12 Stone in weight, running around 50 + /- 10 miles per week. I can comfortable run at 730 - 8minute mile pace over distance, recently completing the Berlin Marathon doing such a pace.So my endurance baseline if you will is good. However, my 10k run time l struggle to get under 45mins, no matter what method l train - fartlek, weighted endurance etc. PFT / BPFA / BFT (Whatever its called this week) around 10mins. I would really like to get my 10k under 40mins, and PFT back to around 930 or less. The problem l have is that my breathing and heart rate go of the scale when doing the shorter distances, lve tried Powerbreath with not much of a result. Ive had asthma testing, and came back negative. Does anyone else recognise this format, and how have you got around it?