Most effective way to improve threshold?

Probably by doing a weekly workout at LT pace, which is basically 109% of your current 5k race pace per mile. Do long sets of 1ks, 1200's, 1600's, with fairly short break.

Train right around that pace.

If you mean the point when the anaerobic system has to kick in because the aerobic system can't keep up, that's done with paces much slower than 5/10k race pace, more like half marathon pace or even slower than that. Two reasons: faster paced workouts' stimulus will be split between the aerobic and anaerobic systems; and we can handle more work at a slower pace, which means that we begin to cycle through muscle fibers and use/train faster twitch fibers more aerobically.

steeper wrote:

If you mean the point when the anaerobic system has to kick in because the aerobic system can't keep up, that's done with paces much slower than 5/10k race pace, more like half marathon pace or even slower than that. Two reasons: faster paced workouts' stimulus will be split between the aerobic and anaerobic systems; and we can handle more work at a slower pace, which means that we begin to cycle through muscle fibers and use/train faster twitch fibers more aerobically.

It sounds like you're talking about the somewhat undefined "aerobic threshold" where blood lactate concentration is around 2mmol/liter.

I assume the OP means the maximum steady state pace, where lactate concentration would be around 4mmol/liter. That's faster than half marathon pace. Closer to 10 miler pace.

The most time-effective way to improve threshold is to run 20-25 mins at LT pace (the pace you can sustain for around an hour, which is approximately equal to 5k pace + 30 secs per mile, 10k pace + 20, or marathon pace - 20).

Another good way to do threshold work is to run shorter intervals at the same pace but with some rest (about 1 min rest for every 5 minutes of running). This method lets you put in a higher volume of work at the pace. It's relatively easy to do 5 x 10 mins at LT w/ 2 min rest, but 50 mins straight at LT would almost be a race.

steeper wrote:

If you mean the point when the anaerobic system has to kick in because the aerobic system can't keep up, that's done with paces much slower than 5/10k race pace, more like half marathon pace or even slower than that. Two reasons: faster paced workouts' stimulus will be split between the aerobic and anaerobic systems; and we can handle more work at a slower pace, which means that we begin to cycle through muscle fibers and use/train faster twitch fibers more aerobically.

Huh?

First, the "anaerobic" system is always working--yes even as you sit and read this. Your first sentence reads as if you think it is "on/off" when it is more of a continuum.

The next part is confusing. You state above that the anaerobic system has to kick in and then you say that the faster paced workouts will be split between aerobic and anaerobic.

The last part has me a little confused. If you run long enough then Type I fibers will fatigue and Type IIs will be recruited. Or you can run faster (around 75% VO2max) and recruit Type II fibers and train them.

The exact pace is going to vary. Let's say one's pace at LT is 7min/mile. That person probably runs the half just a bit slower than that and a 10K a little faster than that. You have a choice.

1) You can run a little faster than 7 min/mile but for a shorter period of time or

2) You can run a little slower for a longer period of time.

I have seen results doing both as the "area under the curve" in terms of acidity and lactate could be pretty damn close.

It is also worth noting that LT pace is a bit of a moving target and not as finely tuned as one thinks. Let's say you go into a lab and get LT measured (or ventilatory threshold if you get it measured that way) and it comes out to be 7 min/mile it could be a little faster or slower a few days later using the same testing procedures. So get in the ball park.

I use the following workout as a favorite (got it first from David Martin--who consulted with Seb Coe).

Warmup

20 min at LT (for me I use a target pace of 15sec/mile slower than current 10K race pace)

5 min easy jogging

20 min as above

Why 15 sec/mile: in lots of lab tests of myself and elite runners, that is about where LT pace fell (at least using the criteria of the lab for selecting LT pace).

My guess is that if I am in pretty good shape that is close to my half-marathon pace.

Using the above (and a few variants in terms of time of each rep but getting in 40-45 minutes per week) I have seen LT pace improve--yes, testing again back in the lab. Gosh, it was great having access to the lab...

800 dude wrote:

steeper wrote:

If you mean the point when the anaerobic system has to kick in because the aerobic system can't keep up, that's done with paces much slower than 5/10k race pace, more like half marathon pace or even slower than that. Two reasons: faster paced workouts' stimulus will be split between the aerobic and anaerobic systems; and we can handle more work at a slower pace, which means that we begin to cycle through muscle fibers and use/train faster twitch fibers more aerobically.

It sounds like you're talking about the somewhat undefined "aerobic threshold" where blood lactate concentration is around 2mmol/liter.

I assume the OP means the maximum steady state pace, where lactate concentration would be around 4mmol/liter. That's faster than half marathon pace. Closer to 10 miler pace.

No, I'm not talking about the "aerobic threshold" and a blood lactate concentration varies widely among people for any of the thresholds. I am simply stating that you do not have to train right at the threshold to improve it. Training just below is at least just as effective and perhaps more so for the reasons I gave.

Yes, I know the anaerobic system is always contributing energy however, it's contribution is relatively little at a pace below the threshold. For the sake of discussion, let's say it's 50/50 aerobic/anaerobic at threshold. That means if a training run is done at the threshold, 50% of the stimulus goes to improving the aerobic and 50% goes to improve the anaerobic. That is not as effective to improve the aerobic system as a run at something like 60/40 and that can be run twice as long. The height of the threshold, is it not determined most by the ability of the aerobic system?

Yes, if running faster, you can also recruit the type II fibers. But they would be working with less oxygen and not be transitioned to type IIa from type IIb. If improving the threshold is the goal, you'd want to transition as much type II to be type IIa. However, like you point out Seb Coe, his training was geared to the 800-1500 events and it was important for him to still have a diverse spectrum of type II fibers.

So it always comes back to 'what is the goal?' I just wanted to answer the OP's question of the most effective way to raise the threshold.