In your guys experience, what’s been the best distance (optimal distance) in training, for improving specific endurance for the
100m?
200m?
400m?
If I would have to limit myself to one training distance (not ideal) I’d say on average:
100m for the 100m
200m for the 200m
300-350m for the 400m (cause doing more than 1 rep at 400m at >95% in one training session is impossible for most)
You dont think overdistance works well?
Good question. My eyes are glued to the responses you get.
Over distance training involves the completion of sprint runs over 150-500% of the competition distance.
-Standing 120s and flying 150s for 100m.
-Standing 230s and flying 270s for 200m.
For 400m
- 10 x Flying 100m at 400m race pace rests 3min
- 4 x 200m at 400m pace rests 5min
- 2 x 300m at 400m race pace rest 15min
You wouldn’t do any work around 450-500 for a 400 runner?
I can’t really argue with that. But don’t you think running a 180 is almost a different race? For a non elite athlete, say 4-5x180m could seem like a conditioning run rather than speed endurance.
Or maybe I, for one, could use a lot of endurance training! 
I was speaking for myself. I really like the 180-150-120 15-20min rest for the 100m.
What about 150-120-100-80, more specific to the 100?
And thoughts on doing 250-300 vs. 200-250 for the 200?
80-100m don’t work for me.
Overdistance can surely work and would form part of my program but I interpreted the question as asking for ONE particular distance. In that case I choose the distance (and therefore speed) which is most specific to the event.
Not sure if it’s changed but the great Tony Wells used to advocate race distance + 20%