That might depend on your current needs and the track session you are doing.

If you need to improve your running ability at VO2max then 2 to 5 min intervals of the appropriate speeds would help you quickly. Maybe as quickly as 5 weeks but probably nearer 10 weeks.

If you already have a large spread between your ability at VO2max and LT, then short track intervals probably won't help as quickly as LT intervals will.

An example, I recently did some lab testing and found that my LT is 91% of my V02max. The doctor said that indicates that I've done a lot of training at LT and in order to improve my running, I need to raise my ability to run at my VO2max. So in my case, I'll be doing at least 6 weeks of sessions aimed at increasing my ability to run near VO2max and then may move to longer LT intervals on the track (or road) afterwards.

if you're running once a week it's going to take a very long time to gain any fitness

I run 6 days a week.

I mean if I add a day of speed work which i have never done in my 10 years in Tri. How long until I should see an increase run speed

---

Yellowfin Endurance Coaching and Bike Fits
USAT Level 1, USAC Level 3

I think the previous reply was taking in to account you run more than once a week but if you are only doing one speed work session per week it still will take a long time to see marked increases in speed.

a long time.

i don't think you're really asking the "right question."

If your running six days a week I would say at least one speedwork session (400's, 800's etc...) and one tempo session per week is going to be required to see noticeable improvement and even then its going to take time and consistency.

Provided the stimulus is higher than the previous, you are still going to see adaptations to the change in 5 to 6 weeks.

At what degree is noticeable is a matter of opinion.

It also depends on the type of speed work vs the length of the races you do. And while running 6 days per week is great, how many miles does that come out to per week?

You could also try 2 weeks of speed work and then maybe 4-6 weeks of slow easy and repeat.

IME after running 5-6 days/wk, ~60km/wk, all easy with some strides and/or hill sprints for several weeks in the context of Tri training, adding a track/track-like workout per week I see an increase in run speed en 3-6 weeks.
For example using a progression like 12x400x200 > 8x600x300 > 6x800x400 > 5x1000x400 > 4x1200x400 > 3x1600x400 work intervals around 3-5k pace with slow jog active recovery, I start to feel better the week of 6x800 and I can ran a decent-for-me 5-10k instead of the 3x1600, which I don't like very much, BTW.

---

Ale Martinez
www.amtriathlon.com