Happy New Year all. Marathon runner here. Sometimes I think I am overdoing it with the intense workouts, like with intervals in particular, especially if I do them the same week as a challenging hill run. I often feel very exhausted and a little too sore by the end of a week like this, almost to the point that I come close to injuring myself.
This leaves me wondering if hill runs, in particular, hill sprints, can replace interval runs done on a flat surface? Do hill sprints(run up hill at max or near max speed for 10 to 12 sec, walk down hill during rest, rest for a minute) have the same benefits as interval runs performed on flat areas? I used to do intervals for about 15 minutes, 30 sec fast/30 sec rest. Hill repeats I often do for 20 minutes as part of a longer run(though not a "long" run).
I'm thinking of replacing flat intervals with hill sprints once a week, plus hill repeats once a week(or alternatively, a long run through a hilly area). Is this a good idea? Any recommendations?