So, as I may have mentioned before,

[zoidberg]

this is going to be The Summer of Speed. I have a plan for weekly speedwork plus a long run because I want to improve my half time for this fall.

My question is, will it screw up my training if I do my long runs on a trail?

I would also like to improve trail running a little, and there is a 2 mile loop trail really near my house. I was thinking of doing my long runs there for some diversity.

[taratru]

I can't see why it would hurt. It will be a nice break from the speed.

[zoidberg]

I don't know, I thought maybe doing my long run on a trail (which would be much slower) would be counter-productive to my goal of getting faster on the road.

I have no idea, I don't really know anything about training.

[clseale]

I think there's a place for trail running. I think it can be a nice break, & I think it can strengthen things that road running will not, but I wouldn't do ALL of my long runs on the trail. I used to use trails as a nice 5 mile easy run on Saturdays before my Sunday long runs. As you get closer to your half, I would make sure to maybe alternate long runs between trails & road.