yees wrote:
You can´t really run too slow at all. Fast workouts are meant to be fast, all others are pretty easy.
Even at pro level, cyclists, swimmers, xc skiers, train plenty at heart rates around 110 or even less, down to 100.
I read a book by Lasse Viren´s coach, and the one line I pick up the most is "easy pace is enough" when it comes to developing the lowest area of base endurance. I think he also mentioned a HR of 100 as some kind of a limit.
As some sort of corroboration of this, I did no running at all for four months this winter, just a brisk walk (slowest around 8 min/km, quickest around 6:30 min/km) more or less every day of about 14km average. Thus Zone 1 training, occasionally up in Zone 2. Quite hilly routes, but nothing extreme. After 5-6 runs over 3 or 4 weeks, and no intervals, I ran a comfortable 35:30 for a 10km, which is essentially the same shape as I was in last time I raced.