10x400

How fast?

a speed that allows you to hit all ten within a second of each other, not a speed that will leave you crawling for the last 8.

my coach calls this type of workout an "aerobic strength" workout

Erm, all of them? And, more importantly, who cares?

Your body doesn't just switch systems on and off. When you're walking you still using some anaerobic energy. Likewise when you're sprinting you'll still be utilising some aerobic energy.

Stop over thinking. Spend more time running your 10x400m than worrying about which energy system is being used.

Your legs

It works your aerobic system almost maximally, because by the 2nd or 3rd rep your heart is pounding, and a minute isn't long enough.

And it works your lactate production and utilisation, and also lactate tolerance near the end, which should be obvious if you have run it.

There's a place for it in everyone's schedule once in a while, if you race anywhere between 800 and 5000.

How much rest? Active or passive?

I run 10x400/100jog frequently. Besides 5km-HM races my only "workout". Pace is ~5k pace-du-jour and I jog the 100 in ~33-35 secs. I started running 4 years a go and the 1500m will become my best event -- eventually.

Here is one sample heart rate/pace diagram

http://artsandcrafts.prior-i.de/images/cpr_sport_running_2009-08-18_10x400-100_Diagramm.png

(I run 5k in 17:30-17:00 PB)

For me it is a "VO2max"-workout in the sense that I measure my training by the time spent with

- runs (solid effort or medium)

- long runs (not much)

- tempo runs (HM pace to 1h pace)

- VO2max (10x400/100)

- leg speed (I should do more)

I have more of these heart rate charts, but not on this computer. Other diagrams show an even nicer upward-wave-like heart rate. I also have the splits of each workout since I started doing them in oct. 2008 (when I read the Cabral/Hadd thread).

I consider myself "fast-twitch" in the 60:40 sense of that thread and it was once very funny to destroy my slow-twitch clubmate of 2-minute-better-10k-ability ;)

A sample workout end of march was:

1:23.44 1:22.82 1:23.27 1:21.88 1:21.10 1:20.81 1:20.45 1:18.60 1:21.70 1:25.35

0:31 0:33 0:34 0:33 0:33 0:33 0:35 0:35 0:35 0:27

(hand-timed, the overly precise times are only for the sake of a better average calculation.)

Ran a not all-out 17:18 in the roads a week later.

So my answer is "VO2max workout".

LoL wrote:

10x400 with say, a minute recovery

what energy system would this be working? Thanks.

All of them.

Who knows? I can tell you what a thousand other coaches and runners could tell you:

It's a classic speed workout. It's also a good workout to estimate what you're capable of in the mile. (4 x your avg time, assuming you stay consistent.)

The damn thing works, I can tell you that.

eurodonkey wrote:

It works your aerobic system almost maximally, because by the 2nd or 3rd rep your heart is pounding, and a minute isn't long enough.

If this is true you're going too fast, this should happen around rep 5-6

twice a runner wrote:

It's a classic speed workout.

nope

wellnow wrote:

All of them.