>General Running>Why I *LOVE* 400's (for the most part)
400 meter repeats, due in large part to the utter simplicity of being exactly one lap of an outdoor track, are a staple of many training programs whether for high school middle distance runners or adult marathoners. I cannot tell you how many 400s I've run in my life, except to say too many. I also tend to think they are one of the most overrated and potentially dangerous workouts out there. Here's why: for most of us they are too short to be an effective VO2max workout, and they are too long to be a pure speed workout.
For pure speed, I think it is important that the reps be under 60 seconds in duration--otherwise you accumulate too much lactate and instead of a speed maintenance session you wind up having a pretty deep effort. And depending upon what phase of training you are in, accumulating lactate can have some pretty negative results on aerobic capacity--that's right you'll actually get slower not faster at 5k on up if you run too many short fast reps. This is especially true for runners without a huge aerobic base. So unless you are an elite athlete who can turn 400s in around 60, 400s are too long for pure speed. For me, 300's with full recoveries are as long as I ever go for pure speed reps.
For VO2Max, or interval speed (what most people think of when they say speedwork) you will improve most rapidly with intervals of 2 to 6 minutes in duration. This makes 400's a bit too short or on the very low end of the spectrum for most of us. And even if 400s fall within the 2:00 - 6:00 minute range for you, I still think they are short enough that there is too much of a chance of running them too hard and going anaerobic--with the same negative results as above.
The most effective running intensity to improve your VO2 max is 95 percent to 100 percent of your current VO2 max. Well-trained runners can run at VO2 max pace for about eight minutes. Ninety-five percent to 100 percent of VO2 max coincides with current 3,000 meter to 5,000 meter race pace. This typically coincides with an intensity of approximately 94 to 98 percent of maximal heart rate or 93 to 98 percent of heart rate reserve. Running your intervals at this pace or intensity is part of the optimal strategy to improve your VO2 max.
I Pace. The next important training velocity is the one that stresses and improves V02max V02max-interval (I) velocity. The intensity here should be equal to vVO2max- I believe most people should shoot for 98% - 100% of HRmax, rather than always demanding a 100% value, if using heart-rate as a guide. This is suggested because if maximum heart rate coincides with a pace of 6:00 per mile, for example, then certainly 5:50 or any pace faster than 6-minute pace will also elicit maximum heart rate, but is too fast for the purpose of the training session -- optimum result with the least possible stress. No single run, which makes up a series of Intervals, should exceed 5-minutes.
The stimulus to improve your VO2 max is provided by the amount of time you accumulate during a workout in the optimal intensity range of 95 percent to 100 percent of VO2 max. This has implications for how best to structure your VO2 max sessions. Consider two workouts that each include 6,000 meters of intervals—one of 15 x 400 meters, the other of 5 x 1200 meters. When you run 400-meter repetitions, you’re in the optimal zone for perhaps 45 seconds per interval. If you do 15 repetitions, you would accumulate just over 11 minutes at the optimal intensity. When you run longer intervals, you are in the optimal intensity zone much longer. During each 1,200-meter interval, you would be in the optimal intensity zone for three to four minutes, and would accumulate 15 to 20 minutes in that zone during the workout. This would provide a stronger stimulus to improve your VO2 max.
In this way, time dictates the workout. Going for over five minutes results in too much blood lactate accumulation, so avoid mile repeats if your interval pace is above a five-minute mile. You might find you can schedule at most three times around the track in a single bout; so be it.
Note, though, that five-minute bouts are excellent to achieve prolonged running at VO2max. You should run these often in your sessions regardless of how far you get. Rely on the feeling of stress you experience, and not on a pre-determined distance goal over a certain time.
Here's a sample workout for a runner at 6:00/mile interval pace (:90/400m):
six 2:00 runs with 1:00 recoveries;
eight 1:00 runs with: 30 recoveries;
eight: 30 runs with: 15 recoveries.
This totals 24:00 at interval pace and 12:00 easy, for a 36:00 session. The time spent at VO2max is comparable to a workout of three- and five-minute runs with longer recoveries.
As discussed in common training mistake #1, to improve your VO2 max you need to accumulate time running at, or close to, your current VO2 max. Your aerobic system, however, doesn’t reach VO2 max as soon as you start an interval. It can take up to a minute for your cardiovascular system to work at its maximal capacity. If you run intervals of 400 meters or less, therefore, you will not accumulate much time in the optimal intensity range. The best way to rack up time at VO2 max over the course of a workout is to run intervals of two to six minutes duration.
Training principle #2 - Specificity of training. The system which is stressed is the one which stands to benefit from the stress. While training for one particular sport usually has little or no beneficial effect on your ability to perform a second sport, in some cases there may actually be a detrimental effect.
A common trend in European athletes are high rep 400's that is 15-25x400m at 10,000m pace. Is this more effective than say 8x1000m? Well the 400's (if run in a controlled manner) don't leave you as taxed, yet you can cover a great distance at or near race pace. It is hard to cover the same distance at the same pace in 800-1600m reps hence the value.
gimme some sugar, baby
Roads were made for journeys...
But point #8 about them being safe--I don't think you can really compare 100s or 200s with 400s. They are for different purposes, at least in my mind. And even when you are doing 100s or 200s for pure speed, these should not be sprints. I think that's a major misconception. The type of pure speed that a distance runner needs is more like mile pace to 3k pace. So if you need to do 400s to slow yourself down to mile or 2 mile pace then you're still taking on too much injury risk, imo. This is another reason why I do most of my pure speed sessions (strides) on the roads by time as well. I do 8 x 20 seconds on / 40 seconds off or 6 x 30 seconds on / 1 minute off on a flat stretch of road. That way I can focus on hitting the right effort (i.e. quick but not a sprint), for that amount of time.
Jake, you are awesome. I'll probably have to wait till the weekend to read this, but I look forward to it!