The Effects of Finger Extensor Training on Climbing Performance Compared With Traditional Flexor Training

The Effects of Finger Extensor Training on Climbing Performance Compared With Traditional Flexor Training: A Randomized Control Trial

The purpose of this study, is to assess climbing performance metrics that include max strength testing on a rock climbing hangboard, maximum grip strength, assessment of pain and function using the DASH (disability of the arm, shoulder and hand), and maximum flexor strength and maximum extensor strength in climbers who perform a traditional finger training protocol compared to climbers who train both traditional flexor training protocol and extensor tendons.

Study Overview

• Status: Active, not recruiting
• Conditions: Healthy Adult
• Intervention / Treatment: Other: Traditional Hangboard Protocol; Other: Extensor Tendon Isometric Training

Detailed Description

Hand, forearm strength, and endurance are highly important elements in elite climbers. Constant training is essential, e.g. eccentric-concentric training of finger flexors. Climbers have traditionally trained finger flexor strength for climbing performance, however to our knowledge, no formal protocol exists for training extensor tendons. In a study performed by Devise, finger flexor to extensor strength ratios were found to be 3:1 in non-climbers. In experienced or elite climbers however, the average ratio was 6:1 and as high as 9:1. Upper extremity injuries are most common in rock climbers, with finger injuries being most prevalent. Pulley injuries, consisting of rupture of the A2 or A4 annular pulleys are the most common type of injury. Other finger injuries include tenosynovitis of the flexor tendons, as well as lumbrical muscle tears. The coordinated action of flexor and extensor tendons allows for a wide range of hand movements, including grasping, gripping, and releasing objects, as well as intricate finger movements. The pulleys along the tendons (annular and cruciate) act as fulcrums, increasing the mechanical advantage of the tendons and allowing for efficient flexion. Damage to either flexor or extensor tendons can lead to significant loss of hand function. The purpose of our study, is to assess climbing performance metrics that include max strength testing on a rock climbing hangboard, maximum grip strength, assessment of pain and function using the DASH (disability of the arm, shoulder and hand), and maximum flexor strength and maximum extensor strength in climbers who perform a traditional finger training protocol compared to climbers who train both traditional flexor training protocol and extensor tendons.

• Study Type: Interventional
• Enrollment (Estimated): 36
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Oregon
    • Portland, Oregon, United States, 97215
      • Mazamas

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Adults aged 18 years or older
• Recreational to advanced rock climbers as defined by the International Rock Climbing Research Association (IRCRA) scale
• Climbing experience of at least 1-2 sessions per week for the past 6 months OR a minimum of 2 years of climbing experience
• Ability to commit to two 45-minute training sessions per week for 6 weeks
• Access to a hangboard or fingerboard and appropriate loading equipment
• Ability to provide informed consent
• Willingness to refrain from climbing the day prior to testing sessions

Exclusion Criteria:

• Upper extremity injury (hand, wrist, elbow, or shoulder) within the past 6 months
• Participation in a structured or organized hangboard training protocol within the past 4 months
• Climbing less than 1-2 times per week during the past 6 months and less than 2 total years of climbing experience
• Age under 18 years
• Inability to safely perform maximal isometric finger flexion or extension testing
• Inability or unwillingness to comply with the study protocol

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Maximum Flexor Strength (MFS); Participants assigned to the Maximum Flexor Strength (MFS) group will perform a traditional finger flexor hangboard training protocol twice weekly for six weeks. Training is performed at 70% of maximal finger flexion strength using a standardized work-to-rest ratio. Participants will complete pre-, mid-, and post-intervention testing of grip strength, finger flexion strength, finger extension strength, finger endurance, and self-reported upper extremity function	Other: Traditional Hangboard Protocol; A structured finger flexor strength training protocol performed on a climbing hangboard at 70% of maximal finger flexion strength. Training consists of 5 seconds of isometric loading followed by 5 seconds of rest for 6 repetitions per set, across 6 sets with 3 minutes rest between sets. Training is performed twice weekly for six weeks following a standardized upper extremity warm-up.
Experimental: Maximum Extensor Strength (MES); Participants assigned to the Maximum Extensor Strength (MES) group will perform a traditional finger flexor hangboard training protocol combined with a structured finger extensor training protocol twice weekly for six weeks. Extensor training is performed at 70% of maximal finger extension strength using isometric loading, and will . Participants will complete pre-, mid-, and post-intervention testing of grip strength, finger flexion strength, finger extension strength, finger endurance, and self-reported upper extremity function.	Other: Traditional Hangboard Protocol; A structured finger flexor strength training protocol performed on a climbing hangboard at 70% of maximal finger flexion strength. Training consists of 5 seconds of isometric loading followed by 5 seconds of rest for 6 repetitions per set, across 6 sets with 3 minutes rest between sets. Training is performed twice weekly for six weeks following a standardized upper extremity warm-up.; Other: Extensor Tendon Isometric Training; A structured finger extensor tendon training protocol performed at 70% of maximal finger extension strength using isometric loading. This intervention will be in addition to performing the Finger Flexor Protocol. Training consists of 30-second isometric contractions with 3 minutes of rest between sets for a total of 6 sets per hand. Training is performed twice weekly for six weeks and is completed during rest periods of the finger flexor training protocol
No Intervention: Control; Participants assigned to the control group will continue their usual climbing activities without participation in a structured finger training intervention. Participants will complete pre-, mid-, and post-testing identical to the intervention groups.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Maximal Finger Extension Strength (MES)	Maximum isometric finger extension force for digits 2-5 measured using a VALD strain gauge system with finger loops positioned over the middle phalanx. Three 5-second trials per hand with 20 seconds rest; best of three recorded for each hand.	Baseline (pre-training), 3 weeks, and 7 weeks (post-training)
Maximal Finger Flexion Strength (MFS) on Hangboard	Maximal added load (or total load) for a 7-second hang on a 30 mm hangboard edge using a standardized half/open crimp position. Load increased until participant cannot maintain the full 7 seconds; maximal successful load recorded.	Baseline (pre-training), 3 weeks, and 7 weeks (post-training)
Finger Stamina and Endurance /Time Under Tension (TUT) at 80% of MFS	Stamina assessed as total time under tension while maintaining 80% of calculated maximal finger flexion strength using a Tindeq device and a 20 mm fingerblock. Endurance will be measured by calculating critical force at the completion of the test. Participants alternate 7-second work and 3-second rest cycles while attempting to maintain 80% target force for as many repetitions as possible to calculate stamina (up to 24 cycles). Critical Force will be calculated for each hand at completion of 24 cycles to measure endurance.	Baseline, 3 weeks, and 7 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Finger Flexion-to-Extension Strength Ratio	Ratio calculated from maximal finger flexion strength (hangboard test) divided by maximal finger extension strength (VALD test), calculated for each hand.	Baseline, 3 weeks, and 7 weeks
Disabilities of the Arm, Shoulder and Hand (DASH) Score	Self-reported upper extremity disability and symptoms using the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, a 30-item validated instrument. Each item is scored from 1 (no difficulty/no symptoms) to 5 (unable to perform activity/severe symptoms). The final score is calculated using the standardized formula and converted to a scale ranging from 0 to 100, where: 0 = no disability 100 = most severe disability Higher scores indicate worse upper extremity function.	Baseline, 3 weeks, and 7 weeks

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Maximal Finger Flexion and Extension Strength	Change from baseline to 7 weeks in maximal finger flexion strength (hangboard) and maximal finger extension strength (VALD).	Baseline to 7 weeks

Collaborators and Investigators

• Sponsor: April Henderson
• Investigators: Principal Investigator: Chuck Ruot, PhD, Hardin-Simmons University

Publications and helpful links

General Publications

• Valenzuela M, Launico MV, Varacallo MA. Anatomy, shoulder and upper limb, hand lumbrical muscles. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025. Available from: https://www.ncbi.nlm.nih.gov/books/NBK534876/
• Colzani G, Tos P, Battiston B, Merolla G, Porcellini G, Artiaco S. Traumatic extensor tendon injuries to the hand: Clinical anatomy, biomechanics, and surgical procedure review. Journal of Hand and Microsurgery. 2016;8(1):2-12. doi:10.1055/s-0036-1572534
• Johnson MA, Polgar J, Weightman D, Appleton D. Data on the distribution of fibre types in thirty-six human muscles: An autopsy study. Journal of the Neurological Sciences. 1973;18(1):111-129. doi:10.1016/0022-510X(73)90023-3.
• Salonikidis K, Amiridis IG, Oxyzoglou N, Giagazoglou P, Akrivopoulou G. Wrist flexors are steadier than extensors. International Journal of Sports Medicine. 2011;32(10):754-760. doi:10.1055/s-0031-1280777.
• Hägg GM, Milerad E. Forearm extensor and flexor muscle exertion during simulated gripping work: An electromyographic study. Clinical Biomechanics. 1997;12(1):39-43. doi:10.1016/S0268-0033(96)00049-6.
• Lum D, Barbosa TM. Effects of isometric strength training on strength and dynamic performance. International Journal of Sports Medicine. 2019;40(6):363-375. doi:10.1055/a-0863-4539.
• Vigouroux L, Quaine F, Labarre-Vila A, Moutet F. Estimation of finger muscle tendon tensions and pulley forces during specific sport-climbing grip techniques. Journal of Biomechanics. 2006;39(14):2583-2592. doi:10.1016/j.jbiomech.2005.08.027
• Leung J. A guide to indoor rock climbing injuries. Current Sports Medicine Reports. 2023;22(2):55-60. doi:10.1249/JSR.0000000000001036
• Philippe M, Wegst D, Müller T, et al. Climbing-specific finger flexor performance and forearm muscle oxygenation in elite male and female sport climbers. European Journal of Applied Physiology. 2012;112:2839-2847. doi:10.1007/s00421-011-2260-1
• Saul D, Steinmetz G, Lehmann W, Schilling AF. Determinants for success in climbing: A systematic review. Journal of Exercise Science and Fitness. 2019;17(3):91-100. doi:10.1016/j.jesf.2019.04.002.
• Devise M, Pasek L, Goislard De Monsabert B, Vigouroux L. Finger flexion to extension ratio in healthy climbers: A proposal for evaluation and rebalance. Frontiers in Sports and Active Living. 2023;5:1243354. doi:10.3389/fspor.2023.1243354.

Helpful Links

• Critical Force Calculations
• Emil Abrahamsson No Hangs Protocol Warm up Routine

Study record dates

Study Major Dates

• Study Start (Actual): November 11, 2025
• Primary Completion (Estimated): April 4, 2026
• Study Completion (Estimated): April 6, 2026

Study Registration Dates

• First Submitted: February 11, 2026
• First Submitted That Met QC Criteria: February 11, 2026
• First Posted (Actual): February 17, 2026

Study Record Updates

• Last Update Posted (Actual): February 18, 2026
• Last Update Submitted That Met QC Criteria: February 15, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: 202532

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data (IPD) will not be shared. All data are coded by participant number and stored on a secure, password-protected computer accessible only to the research team. Due to the small sample size and the potential for re-identification based on detailed performance and training data, IPD sharing is not planned. Only aggregate, de-identified results will be reported in publications and presentations.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No