How Rate of Force Development and Strength Define Elite Sport Climbers
Upper body rate of force development and maximal strength discriminates performance levels in sport climbing.
Stien, N., Vereide, V. A., Saeterbakken, A. H., Hermans, E., Shaw, M. P., & Andersen, V. (2021). Upper body rate of force development and maximal strength discriminates performance levels in sport climbing. PLOS ONE, 16(3), e0249353. https://doi.org/10.1371/journal.pone.0249353
As rock climbing garners more attention on the competitive stage, athletes and coaches seek a deeper understanding of the physical traits that separate elite climbers from others. A 2021 study has shed light on two crucial factors, maximal force output and the rate of force development (RFD), which differentiate climbers. In this blog, we’ll walk through the study's methods and results, focusing specifically on the grips, testing positions, and measurements that reveal what makes elite climbers unique.
Purpose and Methodology of the Study:
This study involved 57 male climbers grouped by self-reported climbing skill levels: intermediate, advanced, and elite. Researchers aimed to determine if and how maximal force and RFD could distinguish these groups through a series of tests that closely simulate climbing-specific movements.
The researchers assessed each climber’s isometric pull-up performance using a 23 mm deep climbing-specific hold designed to mimic the demands of real climbing holds. This setup provided consistent measurements across groups while reflecting the actual forces experienced in climbing.
Test Positions and Grip Specifications:
To capture climbing-specific performance accurately, the study used a standardized testing position that included the following elements:
Grip Type:
All participants used a half-crimp grip on the hold. This grip type is common in climbing and involves flexing the fingers at the PIP joint.
The half crimp grip on a 23 mm hold is challenging but accessible across skill levels, allowing for a fair comparison.
Body Position and Angle:
The isometric pull-up was performed with a 90-degree elbow angle, a position relevant to climbing moves where the arms must pull forcefully against small holds.
A static rope attached to the climber's harness ensured that participants maintained a fixed angle, allowing for consistent and accurate force measurements.
Stabilization and Setup:
To eliminate variability, participants used chalk, and the hold was brushed regularly to ensure consistent friction.
This controlled environment aimed to reduce external factors and focus on each climber’s raw strength and explosive capacity.
Measurements and Data Collection:
With these standardized conditions, researchers used a force sensor system connected to the climber’s harness to capture precise force output data. The following measurements were taken:
Maximal Force Output:
This value, measured in Newtons (N), represents each participant's peak force during a maximal effort pull.
The maximal force was captured as the highest force reached during a sustained pull-up, generally held for 3 to 5 seconds.
Rate of Force Development (RFD):
RFD, or the speed at which force was generated from the onset of contraction, was measured across absolute and relative periods.
Absolute RFD was recorded at 50, 100, 150, 200, and 250 milliseconds after the force initiation. This measured how quickly each climber could generate force in the early contraction phases.
Relative RFD was measured at 25%, 50%, 75%, and 95% of the time to peak force, reflecting how RFD varies proportionately to the time needed to reach maximal contraction. This allowed researchers to account for the differing time climbers needed to generate peak force.
Normalized RFD:
To isolate the RFD component from overall strength, RFD was also normalized to each participant’s peak force output, a measure that adjusted for differences in maximal force capacity.
Consistency and Reliability Checks:
Each climber was allowed three attempts, with feedback provided between attempts. The best performance was recorded, and reliability was confirmed through intra-class correlation (ICC) and coefficient of variation (CV) values.
Results and Data Insights:
Maximal Force Output by Group
Elite Climbers: Produced an average maximal force of 2519 N (about 566.19 lb), significantly higher than the advanced and intermediate groups.
Effect sizes indicated significant differences between elite and intermediate (ES = 1.77) and elite and advanced (ES = 1.78) groups.
Intermediate and Advanced Climbers: These groups showed no significant difference in maximal force output, averaging 1166 N (262.08 lb) for intermediate and 1272 N (286.02 lb) for advanced.
Rate of Force Development (RFD) in Absolute and Relative Time Periods
The study demonstrated distinct RFD values across absolute and relative timeframes, highlighting the quick force production essential for elite climbing.
Absolute Periods (in lb/s after conversion):
50 ms RFD:
Elite: 1457 N/s (327.55 lb/s)
Advanced: 799 N/s (179.62 lb/s)
Intermediate: 801 N/s (179.93 lb/s)
100 ms RFD:
Elite: 1928 N/s (433.43 lb/s)
Advanced: 1146 N/s (257.57 lb/s)
Intermediate: 1069 N/s (240.27 lb/s)
150 ms RFD:
Elite: 2236 N/s (502.67 lb/s)
Advanced: 1495 N/s (336.06 lb/s)
Intermediate: 1364 N/s (306.58 lb/s)
Relative Periods:
25% of Time to Peak Force:
Elite: 1719 N/s (386.45 lb/s)
Advanced: 952 N/s (213.97 lb/s)
Intermediate: 747 N/s (167.89 lb/s)
50% of Time to Peak Force:
Elite: 2555 N/s (574.39 lb/s)
Advanced: 1272 N/s (286.02 lb/s)
Intermediate: 1092 N/s (245.61 lb/s)
75% of Time to Peak Force:
Elite: 2889 N/s (649.47 lb/s)
Advanced: 1562 N/s (350.94 lb/s)
Intermediate: 1426 N/s (320.45 lb/s)
95% of Time to Peak Force:
Elite: 2807 N/s (631.04 lb/s)
Advanced: 1548 N/s (347.77 lb/s)
Intermediate: 1426 N/s (320.45 lb/s)
Time to Reach Peak Force
Elite climbers also reached peak force more quickly than advanced climbers, demonstrating an additional element of speed:
Elite Mean Time to Peak Force: 2065 ms
Advanced Mean Time to Peak Force: 1495 ms
This faster time to peak force reflects the elite climbers’ capacity for rapid force generation, which is critical in competitive climbing.
Training and Practical Takeaways:
Focus on Relative RFD for Consistent Performance:
The study found relative RFD measures were more consistent and reliable, particularly for elite climbers. For athletes and coaches, training should include exercises to improve RFD within relative timeframes, ideally at 75% and 95% of peak force times.
Training for Early-Phase RFD:
Elite climbers distinguished themselves with higher RFD at early phases (50–150 ms), indicating their explosive strength. Training to improve force output within the first 150 ms of movement can benefit climbers aiming to advance to elite levels.
Strength as a Foundational Attribute:
With maximal force outputs well above those of intermediate and advanced climbers, elite athletes show the importance of a strong strength foundation, primarily through climbing-specific holds. Progressive overload and maximal strength training targeting upper body and finger flexor strength can improve climbing performance across skill levels.
Assessment and Monitoring:
Relative RFD measurements provide a better indicator of progression, especially for elite climbers. Coaches can use these findings to design testing protocols that monitor improvements in RFD, ensuring that climbers are developing the explosive strength needed for competitive climbing.
This study highlights that reaching elite levels in climbing demands more than strength alone.
Rapid force production, consistent relative RFD, and refined control over explosive power set elite climbers apart.
For climbers seeking to elevate their performance, incorporating RFD-focused training and strength testing into their regimen can make a significant difference.