High Load and Low Load Density Training

by Steve Bechtel

In the old days, we trained “endurance” by climbing easy moves until we got pumped and fell off. For me, this usually involved doing routes on toprope at Fremont Canyon, or traversing a long flagstone wall near the interstate in my hometown of Casper, Wyoming. The problem was this: Eventually, you got good enough that you didn’t fall off as quickly and endurance sessions ended up plateauing because the time available to climb became the big limiter. You can only get so many pitches done in a normal day of climbing. Likewise, skin and sheer boredom became the major factor in the flagstone traverses. How much 5.6 traversing can one person take?

We switched to 4x4s when we learned about them from our friends in Utah, and the pump was so severe that we thought we’d found the motherlode. The problem was that facing the pain became increasingly difficult 8 or 10 or 12 sessions in, and it seemed like we weren’t getting any better. My friend Bobby Model and I did a full 16 sessions (2 per week) of a 4×4 workout only to find that our endurance got worse progressively after about session 8, no matter how loud we cranked the music and no matter how much ephedra we took. 

I don’t believe there is a solid ceiling to one’s endurance like there is with finger strength or power. I knew then, even as I tried to recover from yet another power endurance smoker, that we weren’t quite getting it right. It wasn’t until maybe the early 2000s that we started trying to increase endurance by other methods. It was around this time we learned about managing the density of a training session, and the game changed forever.

Density training is a staple of muscular endurance training. Instead of trying to increase the duration of your session or to add difficulty to the work sets, you instead try to fit more work at the same difficulty into a fixed amount of time. The first step is to figure out how much work you have time to do. In these sessions, I recommend you do boulder problems, though you could conceivably do a weight circuit or series of hangs or some system board work. 

Most climbers are capable of doing as much as 45-60 minutes of climbing in the work sets of these sessions. The set up is simple: warm-up for 10 minutes or so (I like a combination of cardiac output work and climbing), then set a timer for the planned duration, and start climbing boulders. 



I look at density sessions in two different categories: high-load density and low-load density. The high-load density sessions tend to help increase your ability to handle lots of hard climbing or work (glycolytic capacity), where the low-load sessions tend to increase your ability to do harder climbing in endurance situations (aerobic power). These are not discrete adaptations, however, and should be looked at more like a venn diagram, as noted below:


A high-load session might look like this:

30 minutes of as many OS-level boulder problems as possible

rest 10-15 minutes, with mobility work

30 minutes of as many OS-level problems as possible

You’ll see each problem is somewhat difficult, and you need plenty of rest between. Over the course of a training phase, your density will only increase slightly.


A low-load session might look like this:

15 minutes of as many OS-3 or OS-2 

rest 10 minutes, with mobility work

15 minutes of as many OS-3 or OS-2 

rest 10 minutes, with mobility work

(you could also mix in more general training, as indicated below.)

15 minutes of as many rounds as possible:

1x OS-level boulder problems

5x Inverted Row

10x Kettlebell Swings


In low-load sessions the problems should be 2-3 grades below your onsight level. Set firm boundaries here, so you don’t get sloppy toward the end of the workout and start adding in problems that are too easy just to get more mileage. Remember, quality counts.

Track the V grades of the boulders you do. At the end of your planned duration, stop the clock and add up all your numbers. Divide this number by the number of minutes in your session. This will give you a session density number. The goal of these workouts is to push that number higher. Aim to do 4-8 sessions at the most before cycling out and moving on to other training. 

In high-load sessions, you’ll be doing harder problems and will naturally rest more. Over a full training cycle, you might only increase your density by 2-3 problems in an hour…but remember we are looking for long-term benefits, and over several cycles you’ll see a major phase-shift in your anaerobic capacity. 

The magic bullet has nothing to do with whether your gym has a treadwall or a Tension Board or a good autobelay training wall. It has to do with your ability to be consistent, progressive, and dedicated to your training. It is going to take longer than you think, and it is going to be harder than you think.


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