Over-Under workouts teach you to recover while still running fast, turning your body into a machine that recycles fatigue into energy.
- Lactate isn’t just waste; it’s a potent fuel if you know how to use it.
- Over-Unders alternate moments of accumulation (above threshold) with moments of clearance (just below).
- This workout improves your ability to handle pace changes in a race without “blowing up.”
- It’s tough: it requires mental strength, pacing, and knowing your limits.
There is a precise moment in every race or hard workout when you feel the “low fuel” light come on. Your legs get heavy, your breathing gets shallow, and your instinct screams one thing: slow down.
Usually, when this happens, we are forced to slow down drastically or stop to recover.
But what if you could recover without slowing down—or rather, by slowing down just a tiny bit, staying at a pace that others consider “fast”?
Welcome to the magical (and painful) world of Over-Under workouts.
Let’s be clear: this isn’t for someone who started running yesterday. It’s for those who want to shave precious seconds off their personal best, for those who want to understand how their engine works under the hood.
It is the art of dancing on the razor’s edge of your anaerobic threshold, jumping back and forth, to teach your body a fundamental lesson: fatigue can be recycled.
Running Fast Isn’t Enough: You Must Teach Your Body to “Eat” Lactate
For years we were told that lactic acid (or rather, lactate) was the “bad guy.” The thing that made your legs seize up.
The truth, as often happens in physiology, is more nuanced. Lactate is a byproduct of intense effort, yes, but it is also a readily available energy source for muscles.
Imagine your body as a bathtub.
When you run slow, the tap is open a little and the drain is clear: the water level (lactate) stays low.
When you run fast, you open the tap all the way. If the drain isn’t big enough, the tub overflows. And you stop.
Classic training (intervals with standing recovery) teaches you to tolerate a full tub. Over-Under training, on the other hand, teaches you to widen the drain. It teaches you to clear the fluid while the tap is still open almost to the max.
The Science of Over-Unders: Accumulate and Clear on the Move
This theory has a noble father: physiologist George Brooks, who formulated the “Lactate Shuttle Theory.” Brooks demonstrated that lactate can be moved from the cells that produce it to those that can use it as energy.
Over-Unders exploit this very mechanism.
Here is how they work:
- Over: You run for a short period slightly above your anaerobic threshold. Here you produce more lactate than you can clear. The tub fills up.
- Under: You run for a period slightly below your threshold. Warning: this is not jogging! It is a sustained, challenging, but sustainable pace. In this phase, you teach your body to take that excess lactate and “burn” it to keep running.
It is a balancing act. You are telling your body: “Hey, we’re full of waste, clean it up! And do it while we’re running at a 6:25/mile pace.”
Why This Workout Raises Your Threshold More Than Classic Intervals
In classic intervals (e.g., 1000 meters hard, 2 minutes rest), passive recovery causes your heart rate to drop and allows lactate to decrease naturally. It’s great for aerobic power, but it doesn’t simulate race reality.
In a 10K or half marathon, you don’t stop to rest. If there’s a hill or you surge to pass someone, you go into the “red zone” and then have to recover while running.
Over-Unders accustom the body and mind to manage that discomfort.
Physiologically, you improve the ability of lactate transporters (MCT proteins) to move fuel where it’s needed.
Mentally, you learn that the burning in your legs isn’t a signal to “stop immediately,” but something you can manage by breathing and focusing, without crumbling.
Note: To do this workout, you need a clear idea of your threshold. If you don’t know it and want to estimate it, you can use a field test (20–30 minutes at a constant hard effort), power data/critical power, or a lab test; the Conconi test can give indications but isn’t always reliable for everyone.
The Practical Workout: 3 Blocks of “Over-Under”
Ready to suffer (intelligently)? Here is a classic Over-Under session.
Warm-up:
- 15-20 minutes of easy running.
- Some strides to wake up your legs.
The Main Set:
The goal is never to stop during the block.
- Perform 3 or 4 repetitions of the following continuous block:
- 2 minutes “OVER”: Run about 10-15 seconds per mile faster than your threshold pace (10K pace or slightly faster). You should feel fatigue accumulating.
- 2 minutes “UNDER”: Switch directly (without stopping!) to a pace about 15-20 seconds per mile slower than your threshold (Half Marathon pace). You should feel like you are “floating”: it’s hard work, but you feel control returning.
If you are a beginner: Do just one continuous 12-minute block (3 cycles of 2+2) and then recover with 3 minutes of jogging. Repeat 2 times.
If you are advanced: You can try doing 20 minutes continuously alternating 2′ and 2′ without stopping.
Cool-down:
- 10 minutes of very slow running to return to calm.
It’s Hard, But It’s What Makes You Switch Gears in a Race
The first time you do this workout, the 2 minutes “Under” will seem too fast to recover. You’ll want to stop. Don’t.
That is where the magic happens. Hold on, breathe, relax your shoulders.
When you have to tackle a hill in a race or respond to a friend’s surge, you will thank those minutes spent floating on the threshold. Because you will know that you can go “over,” and then come back “under,” without ever shutting down the engine.