By Steve Bechtel

If you have been training for climbing very long, you've probably come across the idea of doing some kind of interval in order to help improve your endurance. Even a person that is totally focused on bouldering is going to need to tap into their ability to endure longer durations of power output over a given period of time. Occasionally, we fall into the trap of thinking that bouldering is only about power and strength development. One of the most difficult things for a boulderer to do is to understand that the demands that we are addressing on a spray wall or fixed board are different from the demands that we actually will face outside on the rock.

When we are training for strength or power, we tend to seek out only higher outputs. When we are training for endurance, we too often seek out only fatigue. 

"If doing 30 seconds of climbing followed by 90 seconds of rest is difficult, then it can only be better training if I decide to only rest 60 seconds. And logically, dropping my rest to 30 seconds, will be even more difficult, resulting in even better training." Being more tired at the end of training is better, right?

Just because it is difficult does not make it good training. Does it not seem ironic that we seek out the highest amount of fatigue possible in the least amount of time while training in the gym, only to turn around and carefully avoid fatigue at all costs when we are performing at the crag?

In 2020, we started experimenting with a diminishing interval program. Rather than sticking with a fixed schedule, such as 60 seconds of work followed by two minutes of rest for several rounds, we looked at research that indicated athletes could continue to maintain intensity by dropping the duration of intervals as the session progressed. What research is finding is that maintaining high levels of intensity is as important, if not more important, then high levels of volume in an interval workout.

In my original plan, which was cleverly titled "3:2 Diminishing Intervals," I outlined a simple session structure. In it, a climber would start with three minutes of continuous climbing, followed by two minutes of recovery. We would then reduce the next interval to 2 minutes, followed by one minute 20 seconds of recovery. Following the 3 to 2 ratio, the next set we would move to one minute of activity, followed by 40 seconds recovery, then to 30 seconds of activity, with just 20 seconds of recovery. This last interval would then be repeated until failure to complete the full 30 seconds of activity. It looked like this:





Continuous Climbing



Make this somewhat technical climbing, i.e. repeating boulders, following a marked circuit, etc.

Continuous Climbing



Make this somewhat technical climbing, i.e. repeating boulders, following a marked circuit, etc.

Board Ladders




Board Ladders




Board Ladders



Repeat until failure to complete 30 seconds continuous movement

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Climbers were encouraged to do just one of this series, connected to the end of a normal training session, to begin. We would then move to two of them for a few sessions, and then finally moved to three of them as the main training in an endurance-oriented session.

New Session Structures

I get excited about these things. As soon as I learn something, I want to get it in the hands of climbers as quickly as possible. Although it is probably more prudent to wait and test and slowly filter the information out, I am more apt to shout it from the rooftops when I find something that feels like it works really well. Such was the case with the 3:2 interval.

After the initial article came out, I started testing several variants in actual sessions. I programmed the session as written above a few times, and then I started experimenting with different training modes. What follows are a few ideas on session structure and then I will follow up with some progressions that I have found to work fairly well. As with all of these things, understand that we are way on the front end of research and best practice, and you yourself may be fundamental to leading the climbing community forward in practical application of training ideas. If you’re interested in the idea behind this structure, simply Google “High-intensity decreasing interval training.”

Alternating Non-Specific Exercises Within the Session

I started with the base session structure as follows:


3:00 work / 2:00 rest

2:00 work / 1:20 rest

1:00 work / :40 rest

:30 work / :20 rest (repeated until failure)


You'll recall that in the original training session, the first two groups were done climbing on open holds on a spray wall. The one minute and the :30 intervals were done on a campus board with a kick rail. We worked on these until we got up to three full rounds. This isn't too bad for a lot of climbers, but I, myself, found that my skin started to be as big a limiter as my endurance. So, for a few sessions, I alternated in some rowing on a Concept 2, as follows:

Group 1:

3:00 Climb open / 2:00 rest

2:00 Rowing / 1:20 rest

1:00 Climb open / :40 rest

:30 Rowing / :20 rest (repeated until failure)


Group 2:

3:00 Rowing / 2:00 rest

2:00 Climb Open / 1:20 rest

1:00 Rowing / :40 rest

:30 Climb open / :20 rest (repeated until failure)


This resulted in a whole lot more local fatigue in my arms and back than climbing alone did. Although it was easier on my skin, I felt like it was not as specific to the endurance needs of climbing. One of the things that we keep coming back to is how slow the pace of climbing is and how unlike climbing our non-specific cardiovascular modes can be. 

I do like alternating in nonspecific work like this, but just rowing might not be the best mode. It tends to feel a little harried.

A better option will probably be to do a full block of the intervals with just climbing and board work. The second set can be done on an air bike or a rowing machine. Then, if you do a third block, you can switch back to climbing. This seems to have all of the benefits of the original session I listed out above, but is a lot more manageable.

Longer Durations and Their Effects

We are always forced to make assumptions. We are always forced to make compromises. With that in mind, I am keeping with the 3 to 2 ratio of work to recovery when I am testing all of these sessions. One of the interesting experiments I did was to extend the working time we started with. Instead of beginning with a three minute interval of open climbing, I played around with starting at a much longer, eight minute intervals. The set structure looked like this:


8:00 work / 5:20 rest

6:00 work / 4:00 rest

4:00 work / 2:40 rest

3:00 work / 2:00 rest

2:00 work / 1:20 rest

1:00 work / :40 rest

:30 work / :20 rest (repeated until failure)


I ended up having to do much easier work in the first intervals. This was more an extensive endurance intensity, probably around 50% of max. I tried to do most of it on established yet easy problems with reasonable downclimbs, and few shakeouts. It seemed like I got far more fatigued than in the shorter sessions, which is expected, but the recovery between seemed like it needed to be much much longer. I routinely recovered 20 minutes between series and could only do two in a day. 

Looking back, I see that the total climbing time is close to 25 minutes in the interval, and my session times routinely pushed against two hours. Although there may be cases where this volume of training would be appropriate, it was clear that this is beyond what I needed for the projects I had in mind. Also, chasing the clock was a bit stressful, and it felt like I got done with the sessions without doing much more than moving around on easy ground. I am always reluctant when I think about developing endurance only on simple moves and big holds as that is almost never where we end up in the performance environment.

Extended Sessions and Combos

One of the things I focused on up to this point is trying to keep the sessions within a practical duration for training. Climbers' abilities to recover between sessions, and their need for specific duration vary quite a bit. It's not uncommon to run into high-level climbers that will do 10 or more pitches per day. Before you ramp up and start doing higher-than-ever volumes, the very first thing you, yourself, need to do is consider what you actually have been doing in your training. Just because some elite climber that you saw on YouTube is training four hours a day doesn't mean that you can quickly adapt to that size of a program.

In general, longer training sessions are primarily aimed at creating greater capacity. This means that if you're pumping out low on a route, losing power, or just feeling the effect of specific exercises, longer sessions might not be the best way to improve. When we want to go long, I feel like a broader approach to training is appropriate. What I mean here is that doing five or six or seven sets of the intervals above will probably be less effective than combining them with other exercises, or doing more targeted training, such as simply bouldering hard several days per cycle.

We can only move the needle so far with a given session. 

Once again, it is important to remember that the regularity of addressing these energy system demands is more important than how hard you go on any individual workout. Honestly, if you don't feel like you can go through at least 4 to 6 weeks of an endurance build, it's probably better to spend your time elsewhere. The adaptations that endurance training requires are big, and they don't happen overnight.


Steve is the founder of Climb Strong, and is proud to be the worst coach on the Climb Strong team. A climber for nearly 40 years, he has traveled to globe bouldering, sport climbing, and doing first ascents of some of the world's biggest walls. 

At one point, Steve and his friend Todd seemed to find new crags every month, but none were the "Heart of Gold." Between climbing days, he still searches out, and occasionally finds, amazing new zones in the hills near his home. 

He is cofounder of the Performance Climbing Coach organization, and is the author of several books on training for climbing. He lives in Lander, Wyoming, with his wife Ellen, and children Sam and Anabel.



1 Comment

  1. Jerry Kripal on July 22, 2023 at 11:19 am

    Love your articles, books & podcast interviews!
    You might want to fix this typo:
    climber for nearly 40 years, he has traveled to globe bouldering, sport

    change “to” to the

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