At first, it is. You’re cruising, latching one hold after another without breaking a sweat. But halfway up, you start to slow. Your forearms are burning. Your elbows begin to wing desperately upward. The moves aren’t getting any harder—and you climb this grade in the gym all the time—but you’re running out of gas. Your fingers are peeling open and no hold feels good enough to pause on. By the three-quarter mark, you can see the anchors but you just can’t hold on anymore: Your tank is empty.

Sound familiar? You could be dealing with a case of poor local endurance.

Types of Muscular Endurance

Sports researchers talk about several different types of endurance, but the types you’ll hear about most in climbing are “local endurance” and “power endurance.” Power endurance is the ability to execute many big, demanding moves in a row. Local endurance is the ability to keep going at a moderate level of difficulty without getting tired. It means that when you encounter a big hold or a section of moderate climbing in the middle of a route, your body will be able to rest and recover. By the time you get to the next crux, you’ll have the energy to power through.

What is ARC Training?

Local endurance is one of the fundamental building blocks to address when you first start climbing or after you’ve taken a long break. One of the best ways to build it is by ARC training.

ARC stands for Aerobic, Respiration, and Capillarity. In other words, ARC training should improve your aerobic fitness, strengthen your respiratory system, and increase the spread of your forearm capillaries (the tiny blood vessels that deliver oxygen to your muscles). The result: better efficiency on the wall, less forearm burning, and more time before fatigue.

You might think you’re training endurance when you spend two hours at the climbing gym and tick off a bunch of routes or boulders. But the walls of most gyms are shorter than what you’ll find outside, and every time you sit back to lower, you’re taking a significant rest. Because of those rests, taking turns at the gym is more of an interval workout than an endurance workout, no matter how long you’re there. It’s like doing sprints, whereas ARC training is like going for a 2- to 5-mile jog. Like running, ARCing may feel difficult at first, especially if you haven’t been doing much endurance training. The good news: It will become much easier over time.

The 10 Rules of ARC Training

ARC training is best done for four to six weeks at the beginning of a new training cycle, or whenever you start to feel like your endurance on moderate terrain is lacking. Your goal is to spend 15 to 45 minutes on the wall at a time, two to four times per week. During your ARC training cycle, keep these fundamentals in mind.

1. Warm Up First

Before starting the stopwatch on your ARC session, do some dynamic stretches, light shoulder engagement, and a few boulder problems or routes, resting between each. These should be at least two grades below your onsight level, i.e. the hardest grade you can do without falling on your first try.

2. Stay Off the Steeps

For your ARC session, stick to terrain that’s dead-vertical or just slightly overhanging.

3. Keep it Cruiser

Your goal is a low-intensity endurance workout; ARC train on the same grades you warm up on.

4. Stay on Route

Climb existing boulder problems or roped routes rather than grabbing holds at random. That way you’re still training technique and efficiency.

5. Downclimb

Lowering off routes or jumping off boulders gives your arms a rest, cutting into your endurance gains. The more time you spend on the wall, the better.

6. Work Up to It

Your first goal is to spend 15 minutes on the wall without touching the floor. Not there yet? Try three sets of 5 minutes to start, then two sets of 10 minutes the next week.

7. Take Long Rests

Rest as many minutes as you’re on the wall. Doing three sets of 5 minutes? Rest 5 minutes between each set. Two sets of 10 minutes? Rest 10 minutes in between.

8. Maintain Good Form

Your goal is to achieve a light burn in your forearms that you can maintain for your whole session. If you begin to need more rest between moves or your form starts to suffer, pause until you feel recovered. Then resume climbing at an easier grade.

9. Pair it With Strength Training

If you can send 5.12, long sections of 5.8 will feel easy no matter how little endurance training you’re doing. Getting stronger should be a priority: On the days you aren’t ARCing, go bouldering, do some conditioning, or hangboard to strengthen your fingers.

10.  Increase Duration, Not Intensity

As your ARC training becomes easier, go for longer (up to 45 minutes at a time) or add another set (up to three sets of 30 minutes). But don’t make the routes harder—stay about two grades below your onsight level for the best results.

All articles are for general informational purposes.  Each individual’s needs, preferences, goals and abilities may vary.  Be sure to obtain all appropriate training, expert supervision and/or medical advice before engaging in strenuous or potentially hazardous activity.