Interval purposes (side topic from pg3 of "other than experience" thread) (Read 5518 times)

Going off-topic in the other thread, so I'm bringning it here. I was relating the concept of using relatively short recoveries between intervals when trying to achieve high-end aerobic development. The questions were asked why, what I was trying to acheive, etc etc. So here it goes. There are three basic types of intervals, each with a purpose: 1) 200-400m intervals with long recoveries: The purpose of this workout is to develop raw speed, working on strength, turnover, and fast-twitch muscle coordination. To achieve this, it is important to run each interval as fast as possible. Long recoveries are used to make sure you can run each interval near maximal pace. By definition, these intervals are limited to a max of 400m in length as you can't sustain speed longer than this. If you are prepping for a 800m or 1500/1600m race, you may do 600-800m in this workout though you will likely no longer be at maximal speed, but doing more or a race simulation (ie running 800m at 1500m race pace). These workouts are actually not very fatiguing, because if you accumulate residual fatigue between intervals you can't sustain the speed required in the workout. Of the three types, this will have the fewest number of intervals in a set. 2) 400m-1600m intervals with medium recoveries The purpose of this workout is to go into anaerobic debt on each interval and thereby stimulat building up your anaerobic capacity. This can also help somewhat with strength and speed tolerance. Moderate recoveries (say, 3+min for a 400m etc) are used to allow time to clear the lactic acid from your system and get HR back near baseline in order to be able to repeat the effort in the next interval. Comparing a 400m under this strategy to a 400m under #1 above, the time will be slower. This workout will actually feel much harder on you that #1 above, because you are working your anaerobic system so hard. 3) 400m-3000m intervals with short recoveries The purpose of this workout is to give your body an extended period of time at the very upper limits of your aerobic zone. This is probably also the best way to develop speed tolerance for 5K-10K paced races. This is the only one of the three types where your recovery will be shorter than your intervals. For example, I run 800m intervals in 2:22-2:30 avg depending on conditioning but only jog recover 90sec. Sets will also be longer than the other two types. (I do 8-10X800 or 6-8X1000 typically). The short recoveries bring you back just enough to be able to go out and do the next interval just as fast, or slightly faster than, the previous one (if you lose the ability to hit your target in the middle of the set, start slower the next time!). Using this strategy, you spend the whole workout at a very high aerobic capacity, with each interval inching you closer and closer to anaerobic. Due to the constant demand, this is probably the most demanding of the types. Say you run a 5K in 16:00. While races are always good for development, you will rely heavily on the anaerobic component in the end stages of the race so you expose your body to high-end aerobic effort less than that 17:00. However, say you do 8X800 in 2:30 avg with 90sec recoveries. That workout will take you 32 minutes to complete, and the only time you tap anaerobic is if you try to blow out the last interval fast. You've just gotten yourself nearly twice the amount of time at sustained high-end aerobic effort! Think what that does for your development and the ability to hold high-end aerobic paces in your next race. The bulk of my speed workouts are #3. I will use #2 as a sharpening tool 2-3 times going into a key race under 10K. The only time I have used #1 post-college was when I was picked to run an 800m leg at the USATF Indoor Championships on a distance medley relay team. It only took 3 weeks of doing two #1 workouts per week to find speed I hadn't known I had since high school. #1 gives up its gains in just a few weeks. #2 takes a bit longer. I've successfully continued to gain by #3 for up to 4 months. But they should be ideally applied in the reverse order (#3 followed by #2 then #1 time-wise). When using #3, I suggest those newer to intervals start out at 2 miles of total intervals and work their way up. A well-conditioned and relatively quick runner should be able to get in 4 miles of these intervals in a session (not counting recoveries). When I was peaking out I could get 5 miles of intervals in a workout but I would not recommend that unless you are winning races and runnin 90+ mpw. I have experimented with longer intervals, all the way up to 3200m. 3X3200m with 5min recovery is a great workout but the pace is getting too slow to consider it in any of the groupings above. The two last interval workouts I ran before my 10K PR were 4X2000m then 3X3000m workouts at 10K goal pace. I always dreamed of running 3X5000m with 7min recovery in 16:00 or faster but it never worked out.

Thanks. I just printed that out. That's exactly the stuff I was looking for with my question in the other thread.

Other than the incorrect lactic acid stuff, this post is fantastic. Lactic acid build-up as the source of "the burn" or a source of fatigue is a myth. Lactic acid (or more properly, lactate) in the bloodstream is actually feed back into your body's energy producing cycles as a source of energy. http://www.runningahead.com/forums/post/06f09a8e70584820ba3a033592b4874e#focus http://www.runningahead.com/forums/post/2f607a3c402146dfaaf5bb28082a85f9#focus I say this not to be snarky or pick on your thread, but merely wanted to help avoid continuing to propagate an old running myth. Seriously, though, fantastic stuff on the intervals.

Excellent post...Was curious if you have any kind of formula for rest/recovery times for each interval type? I recently started shortening my recovery times and it seems to have really helped in my last 5k.

Excellent post...Was curious if you have any kind of formula for rest/recovery times for each interval type? I recently started shortening my recovery times and it seems to have really helped in my last 5k.

Except for type 1 intervals in spaniel's great post, I think it's good to start with recoveries equal in duration to the hard part, and shrink the recovery times as you get better. (i.e. if you do 6x800m in 3:00 each, start with a 3-minute recovery). Spaniel also makes a good point in that it's usually better to reduce recovery times as you advance, rather than pile on more reps.

If lactate is clearing between repeats, it means you are going further from the "edge" of high-end aerobic work and are not getting the accumulated time there that you are striving for from the workout. You back way off, then go too fast on the next repeat and overshoot. You want to stay on the edge and utilize the full aerobic value, not toggle between very aerobic and very anaerobic....

Ah...biochemistry. A degree I have wasted. This is spot on accurate. Good post. MTA: In regards to you #3 intervals, those are the type I run the most. I haven't been to a real track in years so I run these on the road, etc. What pace do you normally run those at? I don't want a specific number, but just in relation to 5 or 10k pace. Personally I run some at 5k pace and some at 10k pace. It just depends on how my legs feel on a given day. Do you vary the pace at all? Good post by the way.

Man, I keep thinking "be more clear"... So glucose is broken into 2 pyruvate molecules that can go two ways -- straight into the mitochondria to be metabolized into energy by the use of oxygen, or into lactate. Now, the conversion in the mitochondria is much more efficient but A) requires oxygen, and B) takes longer. The conversion to lactate gives off a small amount of energy much quicker but leaves the bulk of the potential energy from the molecule locked up in the lactate. People who say "but lactate is a fuel!" miss the point of its production. Lactate is not produced in great amounts when oxygen is available -- the body wants to be as efficient as possible. Therefore, if lactate is flooding into the bloodstream then oyxgen is relatively low. True, lactate can be used as a fuel. It is imported back into the cells, lactate dehydrogenase enzyme then converts the lactate back to pyruvate...which is then metabolized using oxygen. The important note here is that, if lactate is only produced in low oxygen environment, it cannot be a substantial fuel source until oxygen levels increase as it requires oxygen to break it down!! However once oxygen levels rise it is easily recycled. This is why I say you are trying to ride that edge and don't want lactate falling too much...If it does, oxygen is going way up, and you aren't riding the line as closely.

Yes, I was not clear and I can see that. Sorry. Hope my biochemical ramblings have cleared that one up!

I appreciate your biochemical ramblings, and between you and Marcus, I now know where to turn when I have questions in that arena.