As climbers, we all crave the ability to stay on the wall, push through endless sequences, or send that route that makes us suffer. This desire leads us directly to climbing-specific endurance (CSE), a complex and fundamental quality that goes far beyond simply “hanging on.” In this post, we’ll break down what CSE really is, how it manifests in our bodies, and—most importantly—how we can train it intelligently to maximize our performance.

What makes climbing endurance so unique?

Unlike other sports, characterizing climbing effort in traditional bioenergetic terms (like VO2max or lactate) is extremely difficult. Climbing stands out for:

Variable contraction intensity: Not all holds require the same force.
Variable work/rest ratio: There are moments of intense tension followed by brief respites, or even prolonged rests.
Intermittent rest phases: These allow oxidative pathways to try to restore energy, but not always completely.

The key factor is occlusion. When we grip a hold with sufficient intensity (typically between 40% and 75% of our maximal isometric strength), blood flow to the finger flexors is interrupted. This creates “non-oxidative” local conditions, forcing cells to generate energy without oxygen. Recovery between holds is vital to restore those energy substrates, but the effectiveness of this restoration depends on our adaptations.

Endurance is “conditioned strength”

According to experts like González Badillo, endurance is not a separate quality, but the continued and intermittent expression of strength under changing metabolic conditions. Each grip expends energy and generates fatigue, meaning the next grip is not performed under the same initial metabolic conditions.

Therefore, improving endurance involves two fundamental things:

Increasing maximal strength: So you expend less energy on each hold relative to your total capacity.
Improving endurance adaptations: So that recovery between holds is greater and faster.

The components of climbing-specific endurance

CSE manifests using all metabolic pathways, but their prevalence varies according to intensity and work/rest ratio:

Non-Oxidative Phosphagen Component: Dominates at very high intensities, where there is total occlusion and phosphocreatine stores are used for short efforts.
Non-Oxidative Extramitochondrial Glycolytic Component: Comes into play at high intensities that also occlude blood flow, but for somewhat longer efforts, generating waste products like lactate and hydrogen ions.
Fast Oxidative Component (Aerobic Glycolysis): Acts during brief recoveries between high-intensity holds, helping to restore phosphagens.
Slow Oxidative Component: Key at low intensities where there is blood flow, allowing prolonged efforts and more complete recoveries.

Key adaptations we seek with training

To develop each of these components, we need specific metabolic and structural adaptations:

Oxidative adaptations:

Vascular adaptations (angiogenesis and arteriogenesis): Increase the number and thickness of blood vessels, improving oxygen delivery to the muscle when a contraction is released.
Mitochondrial enzyme density: To use more oxygen efficiently.
Hydrogen ion transport capacity: To remove them from the muscle and delay fatigue.
Higher proportion of intermediate muscle fibers: More resistant to fatigue.

Non-oxidative adaptations:

Phosphocreatine and glycogen stores: More “fuel” available.
Glycolytic capacity and amount of glycolytic enzymes: To generate energy quickly without oxygen.
Buffering capacity: To buffer the accumulation of hydrogen ions.
Greater prevalence of fast muscle fibers: Although scarce in the finger flexors, they are important for explosive power.

Directed or special training (climbing)?

While directed training (specific exercises on a hangboard or campus board) offers greater control of intensity, special training (climbing directly) provides greater specificity and works on movement skills, which are fundamental. Current evidence suggests that, in most cases, it is more effective to work endurance by climbing than with directed training, especially for intermediate and lower-level climbers.

Directed training is reserved for when there are limitations (time, facilities) or when special training does not produce the expected adaptations.

Guidelines for developing endurance (directed means)

Here’s a quick guide to orient your training according to the component you want to develop:

1. Non-oxidative phosphagen endurance (and fast oxidative):

Goal: Deplete phosphocreatine stores and rapid regeneration.
Intensity: High or very high (75%-95%).
Contact times: 5-8 seconds.
Recovery: 15-25 seconds between reps; 3-10 minutes between sets.
Sets/Reps: 1-3 sets x 10-20 reps, close to failure.
Frequency: 2-3 times per week.

2. Non-oxidative glycolytic endurance (and fast oxidative):

Goal: Glycolytic capacity, buffering capacity, efficient O2 use.
Intensity: Medium-high (around the occlusion threshold ~70-75%).
Contact times: 8-12 seconds.
Recovery: Very short (0.5-2 seconds) between reps; incomplete (WTx2-4) between sets.
Sets/Reps: 4-8 sets x 4-12 reps, always to failure or very close.
Frequency: 2-3 times per week.

3. Fast oxidative endurance (and non-oxidative glycolytic):

Goal: Improved reoxygenation, arteriogenesis, oxidative efficiency.
Intensity: Medium-high (above occlusion threshold ~70%).
Contact times: 8-12 seconds.
Recovery: Moderate (3-10 seconds) between reps; incomplete (WTx1-3) between sets.
Sets/Reps: 3-6 sets x 3-6 reps, with moderate margin to failure (25-50% in the first set).
Frequency: 2-4 times per week.

4. Slow oxidative endurance:

Goal: Increase oxidative enzymes, mitochondrial density, angiogenesis.
Intensity: Low or medium-low (20-40%), below occlusion threshold.
Contact times: 8-16 seconds (preferably closer to 16 seconds).
Recovery: 4-8 seconds between reps (half the work time); sufficient between sets (work time).
Sets/Reps: 5-10 sets x 5-10 reps, with high total volume (>20 minutes) and far from failure.
Frequency: 2-5 times per week.

Endurance training with special means (climbing)

When training by climbing, intensity is controlled subjectively, but it’s key to consider the work/rest ratio. A scale from 1 (very easy) to 5 (at the limit) helps categorize:

Level 5 (Boulder): Maximal intensity, cannot let go with one hand. Phosphagen metabolism dominates.
Level 4 (Very hard route): No real rests possible, only micro-rests. Above occlusion threshold. Non-oxidative glycolysis dominates.
Level 3 (Moderate route): Short rests possible. Uses non-oxidative glycolytic and slow oxidative.
Level 2 (Easy/moderate route): Comfortable rests, steady state possible. Slow oxidative component dominates.
Level 1 (Very easy route): Can be sustained for a long time without fatigue.

Some examples of special training:

Max endurance with variable intensity: Simulates a real route with hard (level 4) and easy (level 1-2) sections.
Max endurance at “constant” intensity (Supra OTZ): Traverses of homogeneous high intensity (level 4), to failure.
Submax endurance in blocks (Supra OTZ): Circuits of very hard boulders (level 4.5-5), with little margin to failure and incomplete rests.
Submax endurance in medium intensity traverses (Sub OTZ): Traverses of homogeneous moderate intensity (level 3-3.5), with small rests per move.
Submax endurance in low intensity traverses (Continuity / Steady State): Very long traverses of low intensity (level 1-2.5), shaking out on each move to maintain blood flow.

BFR: A complementary tool

Blood Flow Restriction Training (BFR), though with little evidence yet in climbing, is a promising tool. It involves partially restricting blood flow (40-60% of occlusion pressure) to simulate high-intensity conditions with lower efforts. This can enhance strength, hypertrophy, and angiogenesis adaptations, and is especially useful for finger injury rehab. It is considered a complement, not a main strategy.

Conclusion

Endurance in climbing is a multifaceted skill that requires strategic training adapted to the unique conditions of our sport. Understanding the metabolic components and the adaptations we seek is key to designing effective programs. Whether through directed means for precise intensity control or, preferably, by climbing for greater specificity, the path to greater endurance lies in intelligent planning and conscious progression. So, grab those holds and train smart!

Beyond Strength: Unlocking Your Endurance in Climbing