How Reliable Are Finger Strength Tests? New Climbing Research Explains
Are Your Finger Strength Tests Reliable? New Research on Finger Strength and Endurance in Climbers
INTRO
When you think about testing your finger strength, do you consider how reliable the data is? A recent study evaluated the reliability and validity of climbing-specific finger strength and endurance tests. In this blog, we’ll break down what they found and how it applies to your training.
WHY TESTING RELIABILITY MATTERS
If we track finger strength, endurance, and fatigue, our tests must be consistent and repeatable. Otherwise, we’re just guessing. This study examined whether different testing setups changed results and whether some methods were more reliable.
The key research questions:
Does fixing the arm position (arm fixation, AF) improve reliability?
How well do these tests predict climbing ability?
Can we confidently use these tests to track progress in training?
WHAT THEY TESTED
The researchers used a 3D force-measuring system to test finger strength and endurance under two different conditions:
With Arm Fixation (AF): Shoulder at 90° flexion, elbow at 90°, and forearm locked in place.
Without Arm Fixation (No AF): Shoulder at 180°, elbow fully extended, relying on body weight to generate force.
Participants performed maximal strength tests, a 30-second all-out test, and an intermittent endurance test, measuring peak force, rate of force development, and fatigue resistance.
RESULTS & FINDINGS
Does Fixing the Arm Improve Reliability?
Yes—and this is important. Testing with AF (bent arm position) had better reliability (ICC = 0.94) compared to the straight-arm position (ICC = 0.88). This means it produced more consistent and repeatable results, which is essential for accurately testing finger flexor muscle strength.
However, climbers produced significantly lower forces in the bent-arm AF position (62N, or 13.94lbs less on average). This suggests that while the straight-arm position may have more ecological validity (meaning it looks and feels more like real climbing), it also allows for greater upper body involvement, making it less of a pure test of finger flexor strength.
Which Test Correlates Best With Climbing Ability?
The maximal strength test WITHOUT AF correlated best with sport climbing (r² = .48) and bouldering (r² = .66) and is likely due to climbers being more coordinated in that position.
The all-out test (30s max effort) also showed a strong relationship, especially with bouldering ability (r² = .58).
This makes sense—climbing movements rarely isolate the finger flexors. The higher forces in the straight-arm position probably reflect the additional involvement of the shoulder and arm muscles rather than just finger strength.
Does Endurance Testing Matter?
Intermittent tests (8s contraction, 2s rest) were highly reliable, but the fatigue index (decline in force over time) did not correlate with climbing ability.
This suggests that maximal force matters more than endurance for distinguishing climbing ability.
WHAT THIS MEANS FOR CLIMBERS
1. The Bent-Arm Test is More Accurate for Finger Strength
If you want to truly assess finger flexor muscle strength, the bent-arm position, or others in which the upper extremity is minimized from producing force, is more reliable. It removes upper-body compensation, making it a more isolated and repeatable test.
2. The Straight-Arm Test is More Climbing-Specific
If you aim to assess climbing performance rather than just finger strength, the straight-arm position better mimics real-world climbing demands. However, because it allows more involvement from other muscle groups, it’s not a pure measure of finger flexor force production.
3. Maximal Strength is a Better Predictor Than Endurance
This study supports what many coaches already suspect—maximal finger strength is the best predictor of climbing ability, not endurance tests. To track progress, focus on maximum force output rather than fatigue rates.
4. Use Reliable, Repeatable Testing Methods
Choose a consistent grip and edge depth—variation changes force output.
Compare force numbers over time, not one-off tests—day-to-day fluctuations exist.
Use an objective tool like a strain gauge (Tindeq Progressor)—hanging tests have too many variables.
RECAP
If you’re tracking finger strength, ditch unreliable testing methods and focus on tests that actually correlate with climbing performance.
The Bent-Arm Test (AF) is best for measuring finger flexor strength.
The Straight-Arm Test (No AF) better represents climbing-specific demands but involves more upper-body muscles.
Measure peak force, not endurance decline—strength is the better predictor.
Standardize your test setup—so you can reliably track progress.
FINAL THOUGHTS
This study highlights a simple but essential takeaway: test specificity matters. If you’re using a strain gauge like the Tindeq Progressor, consider which position best suits your goals—the bent-arm position for accuracy or the straight-arm position for climbing-specific validity.
Citation for Further Reading:
Michailov, M. L., Baláš, J., Tanev, S. K., Andonov, H. S., Kodejška, J., & Brown, L. (2018). Reliability and validity of finger strength and endurance measurements in rock climbing. Research Quarterly for Exercise and Sport, 89(2), 246-254. https://doi.org/10.1080/02701367.2018.1441484