To start with I think I'd prefer the 7 mile run incorporating the hills rather than straight reps.
Can use the early miles as warm up and take the hills at any pace you want to. If I were to do reps I'd personally find it hard to do them at a pace that wouldn't be damaging if I was coming back from an injury. On the downhill sections make sure you slow your pace down as well and don't let the hill carry your speed. I find this hurts my legs as well if I'm not in complete control. I prefer to use it as a breather and get ready for the next section.
As Fuggan said though, always good to mix it up as well and rep sessions up steep inclines are good but if you're sprinting it can be hard work on the muscles.
Can use the early miles as warm up and take the hills at any pace you want to. If I were to do reps I'd personally find it hard to do them at a pace that wouldn't be damaging if I was coming back from an injury. On the downhill sections make sure you slow your pace down as well and don't let the hill carry your speed. I find this hurts my legs as well if I'm not in complete control. I prefer to use it as a breather and get ready for the next section.
As Fuggan said though, always good to mix it up as well and rep sessions up steep inclines are good but if you're sprinting it can be hard work on the muscles.