Nice try Sage wrote:
Here is the answer:
5 x 1k @ 5k Goal Pace with 1k recovery at goal place + 40 seconds or less
if your 5k goal is 15:00 than goal pace is 3:00
So your workout would be 5 x 1k @ 3:00 with a 1k in 3:40 for recovery between repeats.
After completing this workout, next time reduce the pace on your 1k recovery by 5 seconds (3:35 instead of 3:40).
Once you can do this workout with the recoveries at about 20 seconds slower than the repeats you'll be able to race the 5k at goal pace.
Benefits:
This is a continuous run, it has an element of lactate threshold (recoveries) and VO2 max (repeats) and will actaully help you lower both. Also helps with lactate clearance and tolerance.
So you are saying that when you are in 15:00 5k shape you are doing hard kilos in 3:00 and doing "cruise" recovery kilos in 3:20....for 10k straight...total time would be 31:40...as a 10k fartlek? That would be very hard for a 15:00 5k runner in my opinion. Very good session - it is like Renato's alternating kilos (although he does them at marathon goal pace) or Run With The Best "floats."
Like I mentioned before (perhaps misinterpreting the OP), if you can do a tempo run as well during the week I would've suggested a different workout. The one "speed workout" only definition is too vague.