Today I did a long run with a marathon training group. We did about half, then took a 5-10 minute break (not my choice), then headed back out to complete the rest of the run.
Is there any detriment to training to include a break in a long run? I would think that by running the entire time, it would help with endurance, but we stopped because some people weren't doing the full distance, and some people had to go to the bathroom, get a drink, etc.
It won't make much difference unless you were running faster than "easy" pace.
I don't think that there is a real detriment to it, but when I'm in a marathon training block I try to keep the stops to a minimum on the long run. Even when you're cruising along at easy pace for your 20 milers I think there is something to be said for getting your body used to staying in constant motion (or as close to constant as realistically possible considering traffic, etc). The elapsed time for breaks for bathrooms and fuel can add up over the course of a 2+ hour run and that's just rest time that you simply won't get in a marathon. Just a personal opinion though.
If you're not doing marathon specific training though and the long run is just an extra workout, I say rest on. I can't see a 5 to 10 minute break really making much of a difference for a long run at normal pace.
Running stores have these types of runs. It keeps the slower runners motivated, and let's everyone catch up. And, it gives a chance for some to move on for the rest of the run while some beginners call it a day and hope to gradually build each week or so.
I would not recommend doing this very often on long runs if you are a sub 3 hr marathoner.
Most of the people that do these breaks are 4 hour + marathoners, and their goal is really just to finish.
I'll go out for a 32km run and around 20km stop at my parents for some Devonshire Tea, 15 minutes later I'm out the door again, happy as a pig in shit.
I was running some hard 15-16 mile trail races a few years ago. Didn't have anything to do one weekend so I went to a club run that was 25k. We were stopping all the time as the lead group to make arrows with sticks so the other runners didn't miss some turns. We also stopped about halfway for a few minutes for refreshments. I was far more wiped out after this run because I was used to getting done in a couple hours and this took about 2:45 (3 minutes slower per mile) I got dehydrated and didn't eat enough for the time it took.
A couple weeks later I had a great race on a hard 16 mile trail so it may even help.
You could just consider it 2 X 10 mile with 4 minute recovery. You could also keep running short loops until they got going again and get in an extra mile.