Good afternoon, and welcome back.

In last week’s newsletter, I talked about the specifics of hill sprints, and the features that make it such a potent stimulus. Interestingly, on my podcast with pro runner, Emily Venters, she talked about her training and how she uses uphill running for entire workouts, specifically her threshold workouts.

This weeks podcast is with special guest, Andy Jones. This might be the greatest podcast I’ve ever recorded. What’s more, Dr. Jones has a book coming out entitled “Faster” which will (or is?) be available for preorder very soon. If you read this newsletter, then buy this book. It will literally be the best book about running ever written, and I know for a fact that it won’t have any gimmicks. All facts. Evidence based.

On this week’s newsletter, I’m going to talk about double threshold training, and why it might or might not be a good option for you.  

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If you haven’t heard of Double Threshold Training, that’s okay! I will explain it very simply here. Marius Bakken published a series of articles on his website regarding this method on January 23, 2022. The primary thesis is that training should revolve around threshold intensity, and that the best way to increase one’s anaerobic threshold, the intensity beyond which fatigue increases exponentially, is to run at that threshold for as much as possible.

This should be done via “blocking” or “clustering” the threshold days on the same day e.g., Double Threshold.

Now, some other minor suggestions from the original publication, though it has been updated and adapted with AI, are to have high mileage, train at altitude, do strength work, and add an “X” session once a week that’s more intense, i.e., hill sprints to fill in any holes in the training.

Typically, the intensities should be done “just below” actual threshold to preserve the wear and tear on the system. In science terms, this is individualized, but Bakken recommends somewhere around 3.0 mmol. In elite runners, this may be hard as they may peak at 5.5mmol if they’re highly trained. We can talk more about this later, but it has to do with their maximal lactate steady state and accumulation rate, VLaMax. Listen to my podcast on it if you haven’t…  It’s deep. In short, it’s hard to have high peak lactates and very fast anaerobic thresholds because your anaerobic threshold is dependent on your ability to shuttle and consume lactate. If lactate consumption/clearance is fast, then it’s hard to accumulate it.

There are some other features that are talked about in much less detail. One of which is that the sessions should ideally be done on the treadmill. Bakken argues that this puts less wear and tear on the body and is a consistent stimulus. I definitely agree with the latter, though I don’t have any evidence to counter the former [1]. Most studies show the two are comparable from a biomechanical standpoint. Bakken also argues that there are a few papers showing that treadmills have lower vertical oscillation, which is how much you bounce up and down. I was curious about this so I tested it, and he’s actually right, though the difference, in my opinion, isn’t meaningful. 

For example, I did two 25 minute tempo runs at 5:28 pace and 5:27 pace about 2 weeks apart. The vertical oscillation outdoors was 10.5 cm and the vertical oscillation indoors was 10.4 cm. My data technically supports his… but… I’d say not in a meaningful way. The ground to contact times were 208 on the treadmill and 212 on the track. So yes, it’s different, but marginally.

A second piece that’s rarely talked about is that Bakken recommends using the warmup and workout heart rate as red, yellow, or green lights for progression. For example, if the warmup heart rate was “low”, the workout lactate was low, and the heart rate was relatively higher, then he knew he had to increase the duration of the reps. Conversely, if he couldn’t push his HR up during an individual rep (I am currently experiencing this as mine have been sitting at 160), then he would just cut the workout by the 3^rd or 4^th rep.

It works. I currently have a preliminary data on a cohort of double threshold runners vs. traditional single daily runners performing higher intensity training, and the threshold runners did have significantly faster threshold speeds.

Interestingly, they also had slower race times. Why? Hard to say. It’s possible that the double threshold training increases their AT so close to their VO2max, around 90-91% that they’re basically racing even 5ks at their AT. Conversely, in the HIIT group, they’re probably closer to 85-87%, and likely have a higher D’ (critical power term) that lets them kick and push harder. basically they have a bigger reserve to kick with that makes a difference in the course of something like a 5k.

The thing about threshold training is that in most studies it increases threshold intensity and running economy. The problem is that it often neglects to increase VO2max. Take the paper below that compared different training paradigms [2].

Table 1. Findings from Stöggl T and Sperlich B (2014) 

The polarized mode had the best results regarding VO2, but runners were actually less efficient compared to the threshold condition. The threshold exercise actually lowered the VO2max. This makes sense and corroborates older findings in elite distance runners whereby marathoners had lower VO2maxes than milers. Makes sense though. They don’t train at VO2max!

I will say that this study used a 5:2 or 4:1 work to rest ratio for the threshold exercise which is on the lower end. 

Bakken argues that Double T prevents the muscles from spasming and accumulating too much muscle tone from the fatigue earlier in the day. I haven’t seen enough evidence on this, and while the inability of a muscle to relax is literally the definition of fatigue, I’m less inclined to believe it has to do with tone, and more inclined to believe it just lets you recover. It would be really hard to do 20 x 1k, but if you split it into two sessions, it allows you to rehydrate, refuel, and let the central nervous system recover. Frankly, I think preventing a substantial rise in core temp by rehydration and refueling on carbs might be the two most important elements.

The thing to remember is that fatigue is a two headed monster. The more fatigued you get, the more force you come into the ground with, the more lateral motion you have in unnecessary muscles, and the more your VO2 starts to spiral upwards and out of control. By splitting the session, you ensure this doesn’t happen. You are basically hitting a hard reset before the second session.

Having done it for a few builds now, I can only speak anecdotally, but it has improved my speed at lactate threshold. I started doing 1ks at 10.9 mph with a lactate of 4.7 mmol and now I am doing 1ks at 11.1 mph with a lactate of 4.6 mmol. This is all done on the same treadmill, in the same room, on the same day each week.

It can improve your speed at threshold. Whether that makes you a faster racer depends on what else is included in your training. If threshold work replaces VO2max training, speed, or race-specific sessions, you may improve your laboratory numbers without improving your race times.

1.) If possible, use the same treadmill every time. This makes the speed, grade, and environment more consistent.

2.) Perform longer reps in the morning and shorter reps in the afternoon. For example:

Morning:

• 6 x 5 minutes with 1 minute rest
• 5 x 2 kilometers with 1 minute rest

Afternoon:

• 10 x 3 minutes with 1 minute rest
• 10 x 1 kilometer with 1 minute rest
• 20 x 400 meters with 30 seconds rest

3.) Stay slightly below threshold. The goal is to accumulate time, not produce the highest lactate possible. Lactate should remain relatively stable, and the final rep should look like the first.

4.) Separate the sessions by at least six hours. Between workouts, eat carbohydrates, replace fluids and sodium, and get off your feet. This may be the most important part of the entire method.

5.) Start with one double-threshold day per week. Do not jump immediately to the two-day Norwegian schedule. First, prove that you can recover from one.

6.) Keep some faster running in the program. Threshold training may improve your threshold without improving VO2max, top-end speed, or your ability to race above threshold. This is why many Norwegian programs include one harder “X” session each week.

I like it. I think it works. There’s no concrete data on this, but most of the pros are doing it and having success. At the very least, it might be something to try. I am.

Cheers,

Dr. E

References 

1.         Van Hooren, B., et al., Is Motorized Treadmill Running Biomechanically Comparable to Overground Running? A Systematic Review and Meta-Analysis of Cross-Over Studies. Sports Med, 2020. 50(4): p. 785-813.

2.         Stöggl, T. and B. Sperlich, Polarized training has greater impact on key endurance variables than threshold, high intensity, or high volume training. Frontiers in Physiology, 2014. Volume 5 - 2014.

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