2025-02-03

The Science of Assessing Your Specific Climbing Endurance

Climbing

Training

Endurance

Assessment

Performance

As climbers, endurance is that elusive quality that allows us to redpoint long routes, overcome endless sequences, and stay on the wall when fatigue sets in. But how do we truly measure our specific climbing endurance (SCE) objectively and precisely? Unlike grip strength, where peak force has been established as a reference, the assessment of endurance has been a constant area of debate in scientific literature.

In this post, we'll explore the complexity of SCE, the proposed tests that have emerged, and, most importantly, how a new paradigm allows us to differentiate its components for smarter and more effective training.


Why Is Climbing Endurance Challenging to Measure?

Specific climbing endurance is unique because it can't be characterized with global parameters like in other sports. It involves the ability to repeatedly exert effort to grasp a hold and progress to the next, in a context of:

  • Intermittent contractions.
  • Variable and indeterminate intensity.
  • Effort-to-rest intervals that are usually disproportionate toward effort.

This intermittence is key: the recovery periods, however brief, allow oxidative pathways to sustain the high-intensity efforts demanded by non-oxidative energy pathways during the contraction phases.

Scientific literature has explored various ways to measure it, from intermittent or sustained contractions on specific holds or dynamometers to climbing simulations on treadwalls, bouldering circuits, campus boards, or standardized routes. Local oxygen uptake has even been measured with NIRS, and the critical force model has been introduced. However, consensus has been difficult to reach.


The Problem of Specificity vs. Reliability

One of the great dilemmas in assessing SCE is the tension between specificity (how closely the test resembles actual climbing) and reliability/validity (whether the test consistently measures what it's supposed to measure).

  • Tests that attempt to replicate climbing (such as on-climb tests) tend to be more specific but have shown low reliability, as movement efficiency influences the results too much, and this improves with test repetition.
  • On the other hand, analytical tests (isolating the grip movement) may be less specific but are often more valid and reliable.

The New Paradigm: Differentiating the Components of Endurance

A key study by Maciejczyk et al. (2022) has revolutionized the assessment of specific endurance by introducing the notion of differentiating its components. Instead of a one-dimensional measurement, it's recognized that endurance comprises various metabolic elements. The authors propose that tests, while they should reflect the load characteristics of climbing, shouldn't completely replicate real climbing in its intermittence and intensity. Instead, their parameters should be adjusted to specifically assess the capacity one wants to measure.

This study identified the contribution of different metabolic pathways (anaerobic alactic from phosphocreatine, anaerobic lactic glycolytic, and aerobic) in three key tests:

Test ANA ALAC (PCr) ANA LAC (GLUC) AE
30″ All-out Test 62.4% 18.2% 19.4%
60% Continuous Test 54.2% 17.7% 28.1%
60% Intermittent Test 8:2 27.2% 12.9% 59.9%

These three tests demonstrated reliability and correlation with climbing performance (0.81 for the all-out, 0.71 for the continuous, and 0.41 for the intermittent).


Proposed Component-Based Tests (according to Maciejczyk et al. 2022 and adaptations)

Based on this new approach, we can use a battery of tests to assess different components of endurance:

1. For the Non-Oxidative Component (Phosphagen and Anaerobic Glycolysis Pathways)

  • 30” All-out Test (with sensor):

  - Protocol: Apply maximum voluntary and unilateral force on a 23 mm edge for 30 seconds.   - Indicator: Average force exerted during the test / body weight.   - Characteristics: Very relevant for performance. Positive validity with performance. Very high reliability (ICC=0.921). Very low specificity. Not recommended for beginners or children.

  • 60% MVC Sustained Test (without sensor):   - Protocol: Hang continuously from a 23 mm edge at 60% of your maximum voluntary contraction (PF of the edge), measuring time to failure.   - Indicator: Force-time integral relative to your body weight.   - Characteristics: Very relevant. Positive validity. Very high personal reliability. Very low specificity. Safe for any population.

2. For the Fast Oxidative Component (Phosphocreatine Repletion)

  • 60% MVC Intermittent Test (without sensor):   - Protocol: Hang intermittently (7 seconds of effort: 3 seconds of rest) from a 23 mm edge at 60% of your maximum voluntary contraction (PF of the edge), measuring total time to failure.   - Indicator: Force-time integral relative to your body weight. This test measures the capacity of the oxidative system to replenish phosphocreatine stores and support high-intensity contractions.   - Characteristics: Very relevant for sport climbing performance. Limited but positive validity. Very high reliability (ICC=0.907). Medium specificity (replicates intermittence, but constant intensity). Safe for any population.

3. For the Slow Oxidative Component (Prolonged Efforts)

  • Critical Force Test (with sensor):   - Protocol: Perform 24 repetitions of 7-second all-out contractions and 3 seconds of rest, unilaterally on a 20 mm sensorized edge.   - Indicator: Average of the minimum forces exerted in the last three stages / body weight. This test measures the oxidative capacity of slow-twitch fibers to sustain very prolonged efforts over time.   - Characteristics: A priori, low relevance for sport climbing due to low intensity, but has shown high validity (correlates positively with performance). Very high reliability (ICC=0.848). Very low specificity (long-duration all-out test). Not recommended for beginners or children, and psychologically very demanding.

Important Methodological Considerations

  • Voluntary Application vs. Hangs: The Maciejczyk et al. study used the voluntary application of force, which can generate fluctuations and a delay in force application compared to hangs, where force stabilizes more quickly. Our proposed protocols aim to use hangs for greater stability and reliability.
  • Occlusion Threshold: Although it's argued that at 60% MVC blood flow is fully occluded, studies like Bergua et al. (2020) place this threshold between 55-75% MVC (with an average of 65.6 ± 8.9%). Considering a slightly higher intensity (70-75%) could increase the test's validity.

Conclusions and Next Steps

Assessing specific climbing endurance is complex, but with the right approach, we can obtain very valuable data. The paradigm of Maciejczyk et al. (2022) allows us to go beyond a simple measure of "stamina" to differentiate the metabolic components that contribute to our endurance.

By using tests with high reliability and validity, adjusting methodologies (like using hangs for greater stability), and always considering the climber's safety and level, we can transform our understanding of endurance. Thus, we'll stop guessing and start training with the precision that science offers us, boosting our performance on the vertical!

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