Bstarr,
Great to hear you are enjoying the book! I look forward to hearing about your results.
Yes, 30-35 minutes pf Zone 1-2 appears to be the “maximum effective dose” for many aerobic training benefits. However, that duration does not capture the full spectrum of the specificity behind training. “Benefits” are almost always event specific. A 3-hour bike ride is really a minimum aerobic requirement for 70.3 training, but completely unnecessary for Olympic training. A 2-hour run is a minimum long aerobic run for Marathon training, but overkill for 10K training.
So, to answer your direct question, if I were to do a back-of-the napkin minimum weekly Zone 1-2 aerobic run workout by distance, it would be the following:
(run only)
5K – 45 minutes
10K – 1 hour
HM – 1.5 hours
Marathon – 2 hours
Sprint – 1 hour
Olympic 1.5 hour
70.3 – 2 hours
IM – 2 hours
David