12 x 400m + 2 x 2K
12 x 400m + 2 x 2K
Intensity — 400s @ 3K, 2Ks @ 15K
Recovery — 200m after each rep. 3’ - 5’ after the 12th 400m rep.
Exertion — 8/10
Context & Details
Repeat quarters at 3K race pace is what I call a “Gold Standard” workout.
The reason is 3K race pace correlates closely with the laboratory measure known as VO2 Max. Compact and highly intense sessions at this effort level significantly upgrade many key performance variables including running economy, fatigue resistance, vVO2 Max, aerobic power, and Lactate-Threshold Velocity.
As I’ve presented it, the best way to progress the 12 x 400m portion of the session is as follows:
First stabilize the running of all reps at a runner’s 3K Date Pace, without concern for the duration of the recovery interval.
Once a runner can perform all the 400s at 3K Date Pace then seek to advance all the recovery intervals down to only 45 - 60 seconds — this may take 2 - 4+ runnings of the workout to realize.
Next, systematically work backward from rep #12, then #11, then #10, etc. to intensify the 400m reps to 3K Goal Pace. This should be done while keeping the recovery intervals declined at 50 - 6t0 seconds.
When the runner can perform all 12 of the 400m reps are 3K Goal Pace on only 45 - 60 seconds recovery then they’re ready to run a big personal best!
This may take 8 - 12 runnings of this session to advance a runner through this progression. You could do it every 7 - 14 days depending on your particular athlete’s preparation timelines.
With that explained, then what’s the purpose of adding 2 x 2,000m at 15K race pace at the end of the session?
Answer: It’s an “Aerobic Flush.”
15K race pace is my definition of a runner’s true Lactate Threshold. Brief repeat bouts (60” - 10’) at these speeds can create strong oxidative recovery signaling which promotes an immediate “flushing” of metabolic waste products out of the bloodstream through slightly elevated respiration and heart rate. The trick is for the athlete to go by effort, not pace, on the flushes. The #1 goal of 2K flushes is to springboard recovery, not further exhaust the runner.
What typically happens in this scenario is the first 2K flush feels hard (and is pretty slow) — and that’s OK. Running 12 x 400m at 3K on short recoveries sharply disturbs the body’s homeostasis. The 2K flushes are designed not to be a training stimulus but create an environment that will optimize the recovery and regeneration process after the series of hard quarters. The second 2K flush is usually better. How the runner feels and the time on the stopwatch typically both improves.
Aerobic flushes don’t need to be 2,000m in length to be effective. If you’re working with younger or lower volume athletes, after a highly taxing workout performing 4 - 8 x 200m of Aerobic Flushes followed by 200m jog gets the job done as well.