

Saturday, January 26, 2008

Anaerobic Threshold

Anaerobic threshold, also called lactate threshold, is the point at which one's muscles produce the same amount of lactate as they are able to export to the liver. It's the major factor in determining one's ability in races between 15 minutes and 75 minutes long (those interested in ultras must wonder how many more posts before I get to their realm). Despite some literature (again I'm picking on Daniels), there is no such thing as a "lactate turnpoint," a velocity above which lactate is formed in sharply larger amounts, nor is there one pace corresponding to the threshold. Rather, running at any pace, there is a time after which lactate is formed faster than it is removed; runners seem to be able to learn when they've reached this point - it's when they first think about quitting and when they're tempted to switch from taking a breath every four steps to every other step.

Training to improve lactate threshold involves both increasing the rate of removal (via lactate tolerance training) and training to decrease lactate production at a given pace. The latter is accomplished by frequently running at that pace as long as is comfortable.

Anaerobic threshold is pace training. It's really that simple.

One of the most convenient things about the time at which the threshold is reached is that it is generally 1/3 to 1/2 the of the distance one could race at that pace. This allows one to write workouts fairly easily. For example, a 10K runner would try to run 2-3 miles at 10K pace. The limit is probably reached at the marathon, as an hour of running at this effort level is rather stressful. [I have to admit here that, training for a 100 mile race, I have a fondness for 33 mile long runs.]

Anaerobic threshold effort level is about 80% (8 miles in 60 minutes for someone capable of running 8 in 48 as a race). According to the Gardner-Purdy tables, one should be able to run 15 repetitions at this pace with two minute rest intervals. This obviously doesn't apply to long distances. 15 is a maximum; the last few would be beyond the anaerobic threshold and would feel much harder. 9-10 reps is reasonable. This corresponds well with some common workouts: 5 minute milers run 8-10x 400 meters in 75 seconds and 2:50 marathoners run 9x 1 mile in 6:30 (which is about an hour total). These interval workouts are generally avoided by all but beginning marathoners who need to learn pace, as they could run the 9 miles without the rests.
For the record, 5K runners do repeat 600s, 10K runners do 800s, half- marathoners do 1000 meters.

Daniels' idea of "cruise intervals," repeats of 2-3 miles with minimal recovery, is largely meaningless. If one is a marathoner trying to run at pace for 10-12 miles and can't finish the workout, one frequently finds that a short rest doesn't decrease one's heart rate very much and one can try again to get in the mileage. In my own workouts, occasionally I will run repeats that look like these, but they're generally at a much faster pace and are an attempt to get in as many miles as possible at that faster pace.


I saw Kurt linked to this site, but not under "Blogs I read." I think that's very funny. I'm thinking of having a category of "Blogs I Don't Read."

The 5 Fab Fifties is about to get some press. I'll be sure to link to it, if I can.

I was asked about coaching. I love coaching; whether or not I'm good at it is debatable. One of the greatest comments I've ever heard was, "You can always tell Quick's runners. They're covered in blood and have mischievous grins."

I was going to go to the Winter Carnival 1/2-marathon this morning, but decided I'd end up racing when I wasn't planning on it. It was only a mile from where I did run. If I'd had info about the 5 Fab Fifties to hand out, I'd've been shilling.


aharmer said...

Steve, the trail is in fantastic shape. You can go with or without snowshoes...without snowshoes you'll want a traction device of your choice. We'll see what happens in the next couple days, could be wild weather.

One question on your post. Daniels' cruise intervals are limited to 5:00 in duration at tempo pace. When you mentioned 1-2 miles was that a typo or did he publish additional info I haven't seen? Hope to see you Saturday.

SteveQ said...

Adam, I'll have to recheck Daniels. I do recall he had a 5:1 work to rest ratio and maybe I had a set rest interval in mind and worked backward. The 2-3 miles at 10K is also probably too hard for anaerobic threshold.

SteveQ said...

I rechecked Daniels. His book (second edition) has workbouts of up to 15 minutes. Table 3.2 lists threshold times for 400, 1200 and mile, but he never mentions 400s again (at a 5:1 work:rest ratio, they'd be annoying, if not impossible); the chapter on threshold says typical runs are a mile with one minute rest or two miles with two minutes - having 5 min./mile in mind.