The Waterboy wrote:
I think ideally people would want to do singles because of the higher aerobic benefit. The only problem is that most people have school or jobs so they run beforehand and then after to fit in enough training time, but if they had the option I believe they'd limit it to one run
I don't think so. I think that if they had the option they'd run for as long as they felt beneficial to get their optimal benefit (aerobic or otherwise) and then also add a second run.
At least if they were smart....