To start the discussion:
- Do you run a 5K tune up race all out?
- VO2max pace is more likely your 3K pace than 5K pace, unless you are elite.
- It is not so obvious that 5x1000m w/rest is easier than a 5K w/no rest.
- Can you actually draw a line between LT and VO2max? Can you draw a line anywhere?
A 5K tune up race likely improves both LT and VO2max.
A continuous 5K would accumulate more lactate than a 5x1K with full recovery -- so would be a better stimulus to make adaptations to deal with higher levels of lactate, by minimizing, or tolerating lactate accumulation, i.e. it is an LT workout. A 10 mile or half-marathon, is run at a slower pace where lactate accumulation is delayed. It's also be an LT workout but it's a different stimulus.
Presumably, classic VO2max training has already developed the VO2max, at the point in a training when you do 5K tune up racing, so the purpose and benefit of the 5K tune up is more LT than VO2max.