Are 12x400m intervals the best workout for runners?

Why nobody cares about a 40-degree Fahrenheit day

Quick recap because... this isn't 'Breaking Bad' and you don't have time to watch all five seasons:

• 🌡️ Nobody gives a 🤬 about a 40-degree Fahrenheit day.

• 🏃🏽‍♀️This workout will improve your 800m, 5k, 10k, half and full marathon times - guaranteed

• 📋 Workout Of The Week

• 🧘🏽 Fix tight hips with this

• 🛑 On Delaying Gratification

Awesome, that’s done. If you’ve got 4.49 minutes, read on to get better at DIY running.

🌡️ Nobody gives a 🤬 about a 40-degree day.

I rarely watch or read things more than once. Too much life to be lived. For some reason, I’ve watched all five seasons of The Wire five times. Yes I’m that guy screaming how The Wire is the greatest show ever… right ahead of Breaking Bad.

Fun random fact — I got into distance running while living in Baltimore, where The Wire was filmed, and I ran my first half marathon through a lot of the east Baltimore neighbourhoods. I also didn’t start watching The Wire until after I moved out of Baltimore… who does that?!

For runners, the line “Nobody gives a f*ck about a 40-degree day” from one of the characters, Stringer Bell, rings both true and false. We've all experienced those 40-degree morning runs - not blazing hot, but not bone-chilling either. Just... there.

Like paint drying. BTW - This metaphor only works in 40 degrees Fahrenheit, which is 5 degrees Celsius. Sorry for the confusion, international crowd. 🙏

Anyways… On the surface, a 40-degree F day seems like the running sweet spot. Cool enough for comfort but not frigid enough to require dressing up like the Michelin Man. A Goldilocks temperature. Perfect race day weather to run your best time. But, how often do we look back and reminisce about those quintessentially meh 40-degree runs? Probably about as often as we fondly recall our last dentist visit.

Nope, our memories latch onto the extremes like a hangry runner bonking mid-marathon. The grueling summer sessions where the humid air hung heavy and drenched shirts clung to our backs. Or those bitter winter miles where each breath seared our lungs and icicles formed on our eyelashes like Jack Nicholson at the end of The Shining.

But the 40-degree F days? They fade into the background, like the flashback scene in the movies.

Here's the thing, though: Without those overlooked 40s acting as palate cleansers between running's highs and lows, the extremes would lose their punch. We'd be depleted, lacking the small reprieves that keep us going.

Those forgotten 40-degree days are the gentle lulls that give our running journey its rhythm. The cool-down miles let us reset before the next push, with well-timed rests, preventing us from burnout. “It’s not a party if it happens every night” © The Postal Service.

Next time you go for a boring AF 40-degree run, don't just go through the motions. Savor each moderate, beautifully ordinary stride like tasting your favorite gel after craving it for 45 minutes.

Nobody giving a 🤬 about 40-degree days? For runners, those could be the most important 🤬s of all. Unless you like heatstroke or hypothermia—in which case, do you my friend. DO YOU!

🏃🏽‍♀️Are 12x400m intervals the best workout for runners?

Looking for a cheat code to get pretty fit without suffering? Welcome to the easiest of the hard workout sessions for runners: the 12x400 interval workout. This routine is a favorite of mine because it boosts your VO2 max, improves your running economy, which is your body's ability to use oxygen as the main fuel source for as long as possible, and prepares your body for the harder and longer work later in the season.

Whether you're training for a 5K, 10K, half or even a full marathon, 12x400 intervals done at the right pace and time of the season might help you hit your goals. Let’s get into why this workout will give you the business and how you can make it part of your training right now.

Finding the Physiological Flow

The best part about the 12x400 workout? The symmetrical flow state. By the fourth or fifth interval, many runners, Mike Trees and myself included, tend to hit a rhythm that feels almost magical. It makes a tough workout feel like a breeze. The perfect lap-balanced flow keeps you motivated and focused, making each stride feel smooth and effortless.

Compared to longer intervals like 5x1 mile, 12x400s are easier to handle mentally. Shorter distances and frequent breaks make it feel less daunting. Each 400-meter interval is followed by a rest of two to one ratio.

This rest is critical as it helps you recover quickly, keep your heart rate elevated (what we want) and maintain high intensity throughout the session. It’s a great way to transition from easy runs to speed work.

Watch, listen and read about the best vo2max-improving interval session for runners

📋 Workout Of The Week: 12x400s with half rest @ current 5k fitness

Since I devoted a whole episode to one workout (my favorite!), why not actually give you a detailed step by step of how to do it.

12 x 400m Interval Workout

What is it?

• 12 x 400m repeats with very short 2:1 rest in between.

• Designed to boost running economy, VO2 max, and race pacing.

• You are running this at your current 5k fitness, aka current threshold — Not your goal time for an upcoming race.

• Don’t know your current 5k fitness? Do a 5k time trial, race or park run! Don’t want to suffer that long, do a 1 mile or 3k race or take your latest race from the last 4-6 weeks and plug it into the Vdot calculator.

Why it's Important?

• Builds Speed and Endurance: Helps you run faster for longer.

• Enhances Running Economy: Makes running more efficient, saving oxygen.

• Improves Vo2 Max: Your Vo2 Max fitness can help you run everything from the 100m to marathons and ultras. I give this workout to all my runners that I coach in the early part of a race build and it gets them ready to handle whatever race they have coming up.

How to do it?

• Warm-Up (10 mins): Easy jog + dynamic stretches/strides.

• Main Set:

  • Intervals: 12 x 400m at current 5k fitness (not goal race pace in the future)
    Example: For me, I run this in 80-84 seconds

  • Effort Level: Challenging but doable, around 85-90% effort.

  • Rest: Rest should be about half of what it took you to run the interval. Walk/jog slowly to recover but be ready to start as the time will sneak up on you.
    Example: For me, my rest is between 40-42 seconds

• Cool-Down (10 mins): Easy jog + strides or sprints if on a track.

Things To Remember

• Tips:

  • Consistent Pacing: Keep each 400m at the same pace.

  • Use RPE: Aim for 7-8/10 effort at the end. Never touch 9 or 10 out of 10.

  • Monitor Recovery: If the intervals start feeling hard, don’t increase rest. Slow down your intervals until it feels like a 7/10 again.

• Traps to Avoid:

  • Starting Too Fast: Start slower, finish strong. The first few should feel relatively easy with a low ish heart rate.

  • Skipping Warm-Up/Cool-Down: Prevents injury and aids recovery.

  • Ignoring Form: Maintain good form, so you know you aren’t redlining and going too fast.

  • Inadequate Rest: Consistent rest periods are key. Too little or too much rest can mess with your workout, causing you to lose the specific adaptation you need and possibly wasting your time.

  • Suffering Is Not The Point: Jack Daniels says if you start too fast or max out your heart rate in VO2 max workouts, you won’t get the full benefits.

🧘🏽 5-minute Hip Mobility Warm-Up For Runners

While I could go on and on about strength training for runners (I love it), most people ignore hip mobility.

Fun story — I had some calf issues early on in my endurance sport/distance running career when I tried to ramp up the volume. I went to a physical therapist, and they did some testing of my hip mobility, and flat-out said, “Dude, you have very tight hips. If you loosened these up, you would unlock some free speed”. Say no more; I focused on moving forward combined with a full range of motion strength training, and my hips have never felt better.

Learn how to fix tight, achy hips and prevent injury here with 1% Better Runner friend Dr. Whitt Fit.

🛑 On Delaying Gratification

Stop sacrificing 100% input of yourself for the short term fleeting gains.

Instead, optimize for operating at 80% over the next fifty years.