I was doing a 5x1k workout, felt pretty good after the 5th so I kept going and ended up doing 7. Is there a point of diminishing returns for this workout? Would I have been better off sticking with 5 intervals and picking up the pace slightly? I'm trying to get in good 5k shape if that matters.
That's great, the sort of session you're doing it's arguably better to get in more volume at a relatively high intensity than less volume at an even higher intensity given your goal is to improve your race-specific endurance
Assuming the 1k's are slower than 5k effort - absolutely.
If you are running 7x1k at 5k effort, then you need to realize that is quite the effort regardless of how much rest you may be taking.
The biggest risk of moving up from 5 to 7 is that you increase the risk of injury and if fatigue carrying over to subsequent workouts. But if your mileage is in the mid-50s or above range, you should be able to handles 7 x 1000 without any significant increased likelihood of adverse effects. If you are much below 50, I would limit it to 5-6 intervals.
Appreciate all the feedback. I'm only running around 35 mpw right now and hadn't considered how that might play into it but it makes sense. I've got a couple easy days before I run a tempo on Thursday and if that doesn't feel good I guess I'll have my answer.
You are better sticking with a planned workout.
Shorten the recovery time next time. When I'm at the stage of a training cycle in which I am doing 5x1km intervals weekly I will begin with 2:30 recovery and shorten the recovery every week. I know I'm ready when I can perform the workout with 60 seconds recovery.
I think is fine if late in the season. However, if you are in anything but the later parts of the season I would hesitate against this. More reps at a slower pace early on will be better for you.
I don't know about that, some people run 8 x 1000m with 3'rest a bit faster than 5km race pace. If the guy is in good aerobic condition then the 3min rest really does miracles. In my case I can do them in about 3:02 and still only average 3:06 in the 5km.