The lactic acid produced during anaerobic training may inhibit the aerobic muscle enzymes necessary for building an aerobic base. In time, this may force more anaerobic metabolism and less aerobic function.
Source:
http://www.championseverywhere.com/why-you-dont-do-anaerobic-during-the-aerobic-phase/
During strength work I feel the burn, so am I fucking up my training? I know Coe did circuits & weights but he might just be a freak of nature.
There are so many different opinions on how to maximize performance, you have the late Frank Horwill who was basically HIIT daily, to Coe who was somewhere between Frank and the late Arthur Lydiard.
I was thinking of doing the Kettlebell routine, 'Simple & Sinister' but now I might just do some basic work that doesn't get me breathing hard.