The topic of threshold has, perhaps, been discussed ad nauseam at this point, so let's move on to another workout of choice: In/Out 400's and In/Out 800's. Warning: While seemingly entirely different from LT training, the In/Out workout is actually another way to target and improve lactate threshold, and a particularly more effective way to do so especially for race distances half marathon and shorter, so really I just tricked you into reading even more about lactate threshold.
For most of us we think of the tempo run or the LT run as the definitive workout to do to improve our lactate threshold, though there's more than one way to skin a cat (more vegan friendly and less gruesomely stated, more than one road can lead to Rome). So the intention of these in/out workouts is to improve our lactate threshold, though it's a different approach than a continuous run. There are a number of reasons why it's actually a more preferred method of improving threshold (in my opinion). Here are a few reasons:
1. While stressing the cardiovascular system in the same way a continuous effort LT run can, the in/out workout also allows us to get some work at race pace, which is beneficial from a neuromuscular standpoint. Practice at the pace we race while still improving LT. The overall in/out workouts average LT pace, but unlike an LT run, you learn race pace. This is an important skill. To race your best you need to know pace.
2. In/out workouts teach and reward discipline with pace. Discipline is almost everything in running. If you don't execute the in/out paces appropriately, the workout will likely blow up. This is not unlike a race. Getting the in right is as important as the out. The entire workout requires discipline to know your body, to know pace, and to show the ability to display discipline for multiple 400's. This is a skill that carries over into racing and every other aspect of training.
3. The in/outs teach you how to switch gears and adjust speeds on the fly (while not the exact same way, many races, especially championship track races, are run in this way). A foot race is a competition woman vs. woman, and while knowing pace is important, racing and beating the field is almost always the objective (especially in cross country).
4. In/outs teach you how to recover with running. Most of us associate intervals with a set number of reps with specific walking/jogging rest, but the in/outs train us to actively recover while running, rather than standing around. You can't stop and rest during a race, so we like that aspect of this workout for that reason.
5. Most importantly, and rather than writing my own specific thoughts, here's straight from the mouth of a highly respected coach and exercise physiologist, Steve Magness (as also said by world class coach, Renato Canova) -
"We tend to attack this (threshold) problem by continually doing threshold or tempo runs to slowly improve our ability to get rid of the lactate. The first drawback with this method is that it does little to teach the body to clear lactate at faster race paces. The second issue is that, when doing tempo runs, lactate clearance is relatively constant so the body is never stressed to the degree that it needs to be to figure out a faster way to get it out of there.
To get around these shortcomings, two workouts can be used. Both work on the principle that instead of keeping lactate steady, it should undulate (editors note: like in/outs!), meaning that a segment of faster running to increase lactate production should be followed by a slower segment that allows for clearance of the previously produced lactate to take place....Alternations consist of a continuous run where segments of slightly faster running are alternated with periods of slightly slower running. For half marathon and shorter races, the goal is to have one segment at race pace and one slightly slower than a traditional tempo pace."
This is why we do the in/outs. Personally I'd like to think we are ahead of the curve in this regard. The continuous tempo run has value, but especially for the half marathon and under, we need to train our bodies to more quickly process and clear lactate from the blood, and science shows us that in/outs are the best way to do that.
In conclusion, in and outs. They are neat.
- Pete Cushman