Leg workouts are less likely to cause soreness that impedes subsequent training compared to HIIT.

“And even though the previous day I may have taken a three hour weight vested hike, never are my legs so sore from that long slow endurance work, because it is long and slow, that I'm unable to train legs. Contrast that with a, say, high intensity interval training workout, which comes later in the week, and my legs might be sore.”