Finger flexor and extensor muscles load sharing: Effect of the climbing grip technique

Area of Science:

• Biomechanics
• Sports Science
• Musculoskeletal Ultrasound

Background:

• Rock climbing relies on fingertip force from crimp and slope grips.
• Evaluating individual muscle contributions in these grips is challenging.
• Shear Wave Elastography (SWE) offers a non-invasive method to assess muscle stiffness and recruitment.

Purpose of the Study:

• To compare flexor digitorum profundus (FDP), flexor digitorum superficialis (FDS), and extensor digitorum communis (EDC) muscle contraction between crimp and slope grips using SWE.
• To assess the repeatability of SWE measurements in experienced rock climbers during isometric contractions.
• To correlate muscle stiffness with fingertip force exertion in different grip types.

Main Methods:

• Forty-six experienced climbers performed submaximal isometric fingertip force exertions in crimp and slope grips.
• Shear Wave Elastography (SWE) quantified muscle shear modulus for FDP, FDS, and EDC.
• Data was synchronized with fingertip force measurements from a custom ergometer.
• Repeatability of SWE measurements was evaluated using intraclass correlation coefficients (ICC) and standard error of measurement (SEM).

Main Results:

• SWE demonstrated moderate to excellent reliability (ICC: 0.62-0.83) for muscle stiffness assessment.
• The FDP showed greater stiffness in slope grips, while the FDS was stiffer in crimp grips.
• The EDC's stiffness increased with force in both grips, indicating co-contraction, more so in slope grips.
• Muscle recruitment patterns differed significantly between the two grip types, reflecting grip-specific biomechanics.

Conclusions:

• SWE is a reliable tool for assessing functional muscle mechanics in rock climbing grips.
• Grip type significantly influences the recruitment of forearm flexor muscles (FDP and FDS).
• Understanding these grip-specific muscle activations aids in injury prevention and performance optimization for climbers.