Discussion: track or terrain?

I see many people on AP logging interval training on the road or on a track. Ignoring the navigational side of orienteering training for a moment, with the goal of becoming a faster runner for orienteering, is it better to run interval training on a track or road, or is it better to run fartlek style training or intervals in the the woods and other off-road terrain?

Why choose? I think there's a lot to be said for running fast on all surfaces. For most people, track training is the best way to get in true interval work because it enforces a discipline of staying right at the pace where maximum VO2 adaptations are made. That said, if that's the only fast running you do, you might find yourself hitting the ground more often than you like in the woods. I like to run intervals (typically uphill) in the woods with a map (e.g., this) to practice moving hard while reading and not killing myself.

staying right at the pace where maximum VO2 adaptations are made

You are talking about maintaining a specific optimum HR, right?

There's a safety/injury issue if you try doing at least the faster end of the range of things people call intervals in terrain in that it's hard to run all out on uneven footing without a high risk of falling and hurting yourself or turning an ankle. It's therefore probably somewhat important that Eric typically does his intervals uphill, since it's much harder to hurt oneself running uphill (things come at you slower and you have less momentum if you do fall plus a shorter distance to fall before hitting the ground). I suspect when Eric doesn't run terrain intervals uphill he runs them in very runnable terrain with generally good footing. Depending on how often you do orienteering races or race-like technical training, I'd say there may be a place for training the ability to run quickly through less runnable woods but this probably ought to be separate from interval training, i.e. the main point would be to work on the skill of running fast in terrain rather than any physiological training effect.

A good variety of everything is good. Uphill, downhill, or flat and road, trail, or wood.

In my experience with injury, I would save the fast downhill running for race settings only.

Just about all the woods in St. Louis could be categorized as reasonably open. That said, a couple points:

1) Intervals are not "all out", they should be run at 98% VO2Max. At that pace you should still have enough composure to keep your footing and dodge the odd branch. Keeping your HR that high in light/medium green woods is very difficult, simply because you can't keep your legs going fast enough without getting caught on stuff.

2) While blasting over really loose terrain is begging for disaster, running very fast off trail is a skill that should be developed in training, not competition. One drill I like is to set a series of 800m (or so) legs where the first part of the leg is on trail. I run the trail portion at tempo pace and then try to maintain the same speed as I leave the trail (which pushes it up into the range of true speedwork, that is 105-110% VO2Max). This matters for the same reason speedwork (as opposed to interval training) matters on the track. The timing of the neural firings is different and you have to get the muscles used to moving at that speed for them to become efficient.

I like a mix of both track and open grass to do intervals on. There's different running form used on both. For pure speed results, running on a track with other people (running clubs) is best. There is training in running form when doing track intervals and different muscle groups involved. However, the harder surface of the track and the pounding from going fast can be harder on the body too. The older I've gotten, the less I've gone to the track to train. Some of that also has to do with the extra effort involved in getting to a track after work to train with others. I've found that the speed training translates to gains in very open woods and when one hits a road or field for part of a leg. It takes regular training to get the results. Once speed has been achieved, changing the mix of weekly training to more terrain running gets your running in the woods form and strength better.

Just to be clear, when ebuckly says intervals should be run at 98% of VO2Max, he is using a very specific definition.

In one commonly used scheme, intervals are supposed to be done near the VO2MAX, while 'threshold runs' are done at a slower pace, near the so-called lactate threshold, and 'repeats' are done at a higher pace above VO2Max. Each type of training is intended to have specific physiological effects. Of course, many people deviate from these definitions.

My coach was always saying: "Where are you doing your orienteering races? That's the place you need to do your intervals."
The surface you will orienteer most often on, or the surface of the race you want to focus on, that's the surface you want to do your intervals and reps.

Yes, I am using the very specific definition of "intervals" that is commonly applied to the workouts pioneered by Bannister and popularized by the success of Zatopek. The importance of this region just below VO2Max can't be overstated. This is where you maximize your cardiovascular improvements WITHOUT trashing your skeletal muscles in the process. The workouts are designed to improve the heart, not the legs (although the skeletal muscles will make adaptations, too).

Many runners miss the importance of keeping these efforts below VO2Max and run them too hard. The result is that their legs are dead for a few days. Not a big deal if you are running 5-6 hours a week, but a real problem if you have a more serious training schedule. Because these are sub-maximal efforts, I've found that they can be nicely combined with work in the terrain provided you can keep the pace right. I would not recommend running intervals in the terrain until you've done enough of them on the track that you can run them accurately by "feel". A rule of thumb suggested by Alan Lawrence is that you should be able to consistently run them within 4 seconds per 400m. I think that's a bit generous as the physiological effect of a quarter in 90 seconds is quite different from one in 82, but the idea is sound - when you can run them within a few seconds per lap without looking at your watch, you're ready to take the workout off the track.

I did the Attackpoint 1600m Time Trial Challenge and when I logged my results the little vdot link appeared next to the item.

Look at that! It automatically calculates proper pacing for Easy, Threshold or Interval training.

I presume that 98% V02 Max pace on the track is faster than a 98%VO2 Max pace in the woods, right?

Assuming the computed pacing chart is applicable only to training on the track, how would I translate the paces for running in terrain?

I suppose that I could sustain the desired pace on the track for a bit and then record my average HR. Then I could match the track "pace" by running at a similar HR out in the woods, albeit at a slower speed. Am I on the right track?

That's what we do. Seems like a reasonable approach.