THRESHOLD THOUGHTS by Nick Arndt


In the 6-week build-up to November 2018’s Indianapolis Monumental Marathon (my debut marathon), I ran 34 total sub-6min miles. Very unimpressive, in my opinion.

I had a decent aerobic base, having just won the North Face Endurance Challenge 50K in Wisconsin, mid-September. However, even with a road marathon looming, I still continued to train mostly on trails, and wasn’t dedicated to a specific marathon plan. I trained my own way, yet still managed a 2:31:47 (5:47/mi), for which I am proud of! However, I knew I was just scratching the surface of my potential.

Fast forward to today, having just nailed another treadmill tempo session. Per usual, thoughts were bouncing around in my head and I thought I’d put some of them to paper.


Currently, I’m in the process of finishing up the first six weeks of my 18-week Indy Mini (13.1mi) training block. It’s the first absolutely specific training block I’ve ever attempted, so I’m very eager to see the end results. So far, I’ve run 52 total sub-6min miles. And, after some basic math, I will show up to the starting line in May having run around 200 total sub-6min miles! Such a stark contrast.


What actually is “tempo”? Or, “threshold”? Well, simply put, it’s the pace at which a runner (trained, rested, and psyched up) can maintain for about an hour. For some, it’s around 10K race pace. For world-class elites, it’s about their half-marathon race pace.

At rest, all humans produce about a millimole of blood lactate and, constantly, we are clearing it. The blood sends it to the liver and the liver turns it back into carbohydrate fuel for the body to use. Now, when we start to run, our body produces more and more of this lactate. At some point, we reach a certain speed and the body can’t clear the lactate as fast as it’s being produced. The lactate-clearing demand is just too much. That specific point is called your “lactate threshold”. Usually, this effort is around 85 – 88% of maximum heart rate.

So, what’s being measured is not the “production” of lactate, but rather the “accumulation” of lactate.

As for training, spending time at that threshold is very important! NOT beyond it. And, NOT below it. At it. The way to improve any bodily function is to stress that specific function. Basically, training at your lactate threshold improves your endurance!


I don’t know my limits. All I’m trying to do is outwork my potential. I’m just out here trying to hit splits. That’s my damn job. Times don’t lie. If I show up to a session and don’t hit splits, it’s a failed session, a waste of time.

Right now, I’m hitting splits. It all feels appropriate. I can feel myself getting fitter each and every day. Training is hard. But, I’ve found a rhythm, a rhythm I’ve been seeking all my life. This, this is what fitness feels like. This is why I run. Staring at the basement wall, dripping sweat, this is what I do. I’m a Lone Wolf training in the Adirondack tundra.


Six weeks down. Twelve to-go.

#RoadTo67

Published by Nick Arndt

Running on dirt, rocks, and pavement in the Adirondack Mountains...

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