I want to give some information about what can happen in an athlete of top level. I'm speaking about Stefano Baldini.
We use a test (Faraggiana-Gigliotti) consisting in 6 x 2000 even pace in crescent times, covering every possibility of marathon pace. For example, for Baldini, 6:15 - 6:10 - 6:05 - 6:00 - 5:55 - 5:50, with recovery time very short (only what we need for taking blood from the ear). After the last, we use 1200m free, at max speed, for controlling the level of lactate that the athlete can reach.
Every 2000m is at even pace, using an "acustic rabbit", able to send a beep every 25m (we have cones every 25m on the track) at the programmed speed.
In this way, using always the same speeds, we can test the improvement of the athlete in his SPECIFIC MARATHON ENDURANCE, that is clear when, for the same speed, the level of lactate is lower.
As Marathon is a problem of fuel, and we have to reduce the consumption of glycogen at marathon pace in order to last longer, when the lactate is lower, the athlete is more RESISTANT AT HIS MARATHON PACE.
We use this type of test about every 4 weeks, normally 4 times during the preparation of the race (last time about 10 days before the race).
Till 5 years ago, we didn't use the last test of 1200m. We added this distance in order to investigate how much glycogen the athlete had yet in his tank. HIGHER IS THE LEVEL OF LACTATE, MORE RESERVES THERE ARE IN THE TANK.
We use this test with all the best marathon runners that we follow.
Very interesting thing is to see, in longitudinal way, what happens with an athlete that, in 5 years, is able to improve his time of 3-5 minutes.
About Baldini, for example, when he ran his first Marathon in 1995 (2:11 in Venice), he had a steady state around 2 mmol/l (where physiologists normally say that there is the Aerobic Threshold). At that time, he did 6x2000 from 6:20 to 6:00, having lactates of :
1.7 (6:20) - 1.9 (6:15) - 2.0 (6:10) - 3.2 (6:05) - 4.4 (6:00).
His average in the race was 3:06 /km, that is around 2 mmol.
In 1996, Baldini won World Half Marathon Championships, after working for about two months for improving his AnT. At that time, he was able running at 2:53 pace having 4.2 mmol (and was his HM pace).
He spent 45 days in preparing NY Marathon, but was not able to individuate to speeds very close, where having a personal steady-state. His values were :
1.7 (6:15) - 2.1 (6:10) - 2.5 (6:05) - 3.4 (6:00) - 4.3 (5:55) - 5.6 (5:50).
In the race, he dropped out after 27 km, nervously empty.
He spent all winter in preparing London Marathon '97, and his last test was very different :
1.6 (6:15) - 1.9 (6:10) - 2.0 (6:05) - 2.1 (6:00) - 3.2 (5:55) - 4.8 (5:50) - 7.3 (3:21 on 1200m)
So, it was possible to identify a special Aerobic Threshold from 3:05 to 3:00, without variations of lactate. He was able running 2:07:57.
During the last period, he became more "marathoner". His best shape was this year, in London, when he was 2nd in 2:07:56 overtaken by Abera only during last 5 meters.
He was able running about 2:06, and only the tactic of the race didn't permit to run so fast. Instead, during World Championships, his shape was not the same.
Before London, the last test had these results :
1.5 (6:15) - 2.0 (6:10) - 2.5 (6:05) - 2.4 (6:00) - 2.6 (5:55) - 4.5 (5:50) - 8.6 (3:15 on 1200m).
In this case, is possible to identify a special Aerobic Threshold from 3:02.5 to 2:57.5, but the level of lactate is no more 2 mmol, but about 2.5.
If the lactate level is higher, is because the athlete is using more glycogen at that speed. But, if his endurance for marathon is OK, and the size of his tank is the same of 4 years before, this is possible only because he is able to use a higher percentage of the lactate that he can produce running, so is clear that there is a "shuttle" effect, only after some year of specific training.
So, we can say that "fibres must learn to use their lactate for improving their aerobic capacity", like a "turbo" for an engine of a car.
I think that this attitude, naturally, is the big difference between african and white runners. The AnT in kenyans is very higher than in a European runner, and they are able to use their lactate for producing energy in a higher percentage than european runners.