Estimation of hand and wrist muscle capacities in rock climbers

Muscle strength in sport climbing: a systematic review and meta-analysis

INTRODUCTION

This study aimed to synthesize the literature comparing muscle strength and endurance characteristics between 1) sport climbers and non-climbing controls; 2) sport climbers at different performance levels; and 3) boulderers and lead climbers.

EVIDENCE ACQUISITION

A systematic literature search (PubMed, Embase and SportDiscus) was performed. Inclusion criteria involved participants aged ≥18, muscular performance measurements and comparisons of either: climbers and non-climbers, boulder climbers and lead-climbers, or climbers of different levels. Meta-analyses comparing grip strength and muscle endurance of the forearm between sport climbers and non-climbers, and finger strength between boulders and lead climbers were conducted providing the standardized mean difference (SMD).

EVIDENCE SYNTHESIS

A total of 960 climbers and 301 non-climbers were included in the study. The data showed: 1) Compared to non-climbers, climbers showed significantly higher grip strength: SMD 1.82 (95% CI 1.23; 2.41, P<0.001) and underarm endurance: SMD 0.70 (95% CI 0.17; 1.24, P=0.01); 2) compared to lead-climbers, boulder climbers showed significantly higher finger strength: SMD 1.08 (95% CI 0.54; 1.62, P<0.001); 3) higher-level climbers showed better finger strength, grip strength, forearm endurance and powerslap when compared to lower-level climbers.

CONCLUSIONS

Climbers had superior grip strength and forearm endurance compared to non-climbers. High-level climbers exhibited better finger strength, grip strength, forearm endurance and powerslap, when compared to lower-level climbers. Finally, boulder climbers exhibited greater finger strength than lead-climbers. These findings expand our understandings of climbers' physical attributes across disciplines and levels.

Development of EMG-based criteria to evaluate the difficulty of realization of sign language: A potential contribution for understanding the negative hand paintings

The sign language uses a combination of complex finger and wrist configurations. The frequency of use of a particular sign is highly dependent on its physiological difficulty. However, no method allows to quantify accurately this difficulty. In the context of paleolithic negative hand paintings this absence of methods is problematic since the hand signs which are painted may be related to a primitive hand sign language. The objective of this study was to develop and validate a method based on electromyography recordings for quantifying sign language difficulty. Electromyography of the six main hand muscles were recorded and analyzed to determine individual muscle activity, summed muscle activity and muscle coactivation. Those results were correlated to subjective scales of difficulties to determine the electromyographic variables and/or the combinations of them which are good candidates for determining hand sign difficulties. Among all variables the summed muscle activities and the thumb muscle coactivation presented the most promising criterion. On the top of that, those criterions presented encouraging correlation with the frequence of occurrence of ten hand paintings of the Gargas Cave which open further studies for analyzing the origin of negative hand paintings.

Neuromechanics of finger hangs with arm lock-offs: analyzing joint moments and muscle activations to improve practice guidelines for climbing

Introduction

Climbing imposes substantial demands on the upper limbs and understanding the mechanical loads experienced by the joints during climbing movements is crucial for injury prevention and optimizing training protocols. This study aimed to quantify and compare upper limb joint loads and muscle activations during isometric finger hanging exercises with different arm lock-off positions.

Methods

Seventeen recreational climbers performed six finger dead hangs with arm lock-offs at 90° and 135° of elbow flexion, as well as arms fully extended. Upper limb joint moments were calculated using personalized models in OpenSim, based on three-dimensional motion capture data and forces measured on an instrumented hang board. Muscle activations of upper limb muscles were recorded with surface electromyography electrodes.

Results

Results revealed that the shoulder exhibited higher flexion moments during arm lock-offs at 90° compared to full extension (p = 0.006). The adduction moment was higher at 135° and 90° compared to full extension (p < 0.001), as well as the rotation moments (p < 0.001). The elbows exhibited increasing flexion moments with the increase in the arm lock-off angle (p < 0.001). Muscle activations varied across conditions for biceps brachii (p < 0.001), trapezius (p < 0.001), and latissimus dorsi, except for the finger flexors (p = 0.15).

Discussion

Our findings indicate that isometric finger dead hangs with arms fully extended are effective for training forearm force capacities while minimizing stress on the elbow and shoulder joints. These findings have important implications for injury prevention and optimizing training strategies in climbing.

Exploring forearm muscle coordination and training applications of various grip positions during maximal isometric finger dead-hangs in rock climbers

Background

Maximal isometric finger dead-hangs are used in rock climbing to strengthen finger flexors. Although various grip positions are often used when performing finger dead-hangs, little is known regarding how these grip positions can affect forearm muscle activity. Understanding how forearm muscles are recruited during dead-hangs could help foreseeing the potential for training of different grip positions. The aim of the present study was to explore the training applications of the various grip positions by comparing the activity of forearm muscles during maximal dead-hangs in rock climbers.

Materials & Methods

Twenty-five climbers performed maximal dead-hangs in three climbing-specific grip positions: CRIMP, SLOPE, and SLOPER. We recorded the maximal loads used and the sEMG of the flexor digitorum profundus (FDP), the flexor digitorum superficialis (FDS), the flexor carpi radialis (FCR), and the extensor digitorum communis (EDC). Individual and global (sum of all muscles) root mean square (RMS) and neuromuscular efficiency (NME) values were computed. Repeated measures analysis were performed to assess grip differences (p < 0.05).

Results

SLOPER showed the largest maximal load values among the three grip positions (p < 0.001, d ≥ 2.772). Greater global (p ≤ 0.044, d ≥ 0.268), FDS (p ≤ 0.005, d ≥ 0.277), and FCR (p < 0.001, d ≥ 1.049) activity was observed for the SLOPER compared to CRIMP and SLOPE, while EDC (p ≤ 0.005, d ≥ 0.505) showed lower activity in the SLOPER compared to the other two grip positions. SLOPER presented the highest global (p < 0.001, d ≥ 0.629), FDP (p < 0.001, d ≥ 0.777), FDS (only CRIMP vs SLOPER: p < 0.001, d = 0.140), and EDC NME (p < 0.001, d ≥ 1.194). The CRIMP showed greater FDS activity (p = 0.001, d = 0.386) and lower NME (p = 0.003, d = 0.125) compared to SLOPE.

Conclusions

These results revealed that, under maximum intensity conditions, SLOPER could stimulate the FDS and FCR better than the other grip positions at the expense of using greater loads. Similarly, maximum CRIMP dead-hang could better stimulate the FDS than the SLOPE, even when using similar loads.

Clinical management of finger joint capsulitis/synovitis in a rock climber

This case study presents a 23-year-old male recreational rock climber, who climbed an average of 3-4 times per week and presented with finger joint capsulitis/synovitis after increasing his climbing intensity and training from moderate to high over 6 months, which led up to injury. During the exam, the diagnosis was ruled in with clinical orthopedic testing. Additional movement analyses revealed improper gripping mechanics contributing to asymmetric finger loading. A comprehensive rehabilitation program was developed based on the concept of a progressive framework that included unloading of the affected tissues, increasing mobility, improving muscle performance, and correcting suboptimal climbing movements. After 6 weeks, the climber's pain 24 h after climbing, which was rated on a visual analog pain scale (VAS), decreased from 5.5/10 to 1.5/10 and 0/10 at the 12-month follow-up. His patient-specific functional scale improved from 0% at the initial evaluation to 43% after 6 weeks and to 98% after 12 months. His sports-specific disabilities of the arm, shoulder, and hand improved from 69% to 34% to 6% during the initial evaluation, 6-week follow-up, and 12-month discharge. He made a full recovery to his previous grade of V8 bouldering. This is the first case study of its kind to provide a rehabilitation framework for the management of finger joint capsulitis/synovitis in a rock climber.

Changes of agonist and synergist muscles activity during a sustained submaximal brake-pulling gesture

We analyzed the time course of changes in muscle activity of the prime mover and synergist muscles during a sustained brake-pulling action and investigated the relationship between muscle activity and braking force fluctuation (FF). Thirty-two participants performed a continuous fatiguing protocol (CFP) at 30% of maximal voluntary contraction (MVC) until failure. Surface electromyography was used to analyze root mean square (RMS) values in the flexor digitorum superficialis (FD), flexor carpi radialis (FC), extensor digitorum communis (ED), extensor carpi radialis (EC), brachioradialis (BR), biceps brachii (BB), and triceps brachii (TB). The FF and RMS in all muscles increased progressively (P<0.01) during the CFP, with sharp increments at time limit particularly in FD and FC (P<0.001). The RMS of the FD and FC were comparable to the baseline MVC values at time limit, in comparison to the other muscles that did not reach such levels of activity (P<0.003). The three flexor/extensor ratios used to measure coactivation levels decreased significantly (P<0.001). In contrast to RMS, MVC was still depressed at the minute 10 of recovery. The results suggest that the time limit was mainly constrained by fatigue-related mechanisms of the FD and FC but not by those of other synergist and antagonist muscles.

Effects of Forearm Compression Sleeves on Muscle Hemodynamics and Muscular Strength and Endurance Parameters in Sports Climbing: A Randomized, Controlled Crossover Trial

Purpose: Wearing compression garments is a commonly used intervention in sports to improve performance and facilitate recovery. Some evidence supports the use of forearm compression to improve muscle tissue oxygenation and enhance sports climbing performance. However, evidence is lacking for an effect of compression garments on hand grip strength and specific sports climbing performance. The purpose of this study was to evaluate the immediate effects of forearm compression sleeves on muscular strength and endurance of finger flexor muscles in sports climbers.

Materials and Methods: This randomized crossover study included 24 sports climbers who performed one familiarization trial and three subsequent test trials while wearing compression forearm sleeves (COMP), non-compressive placebo forearm sleeves (PLAC), or no forearm sleeves (CON). Test trials consisted of three performance measurements (intermittent hand grip strength and endurance measurements, finger hang, and lap climbing) at intervals of at least 48 h in a randomized order. Muscle oxygenation during hand grip and finger hang measurements was assessed by near-infrared spectroscopy. The maximum blood lactate level, rate of perceived exertion, and forearm muscle pain were also determined directly after the lap climbing trials.

Results: COMP resulted in higher changes in oxy[heme] and tissue oxygen saturation (StO₂) during the deoxygenation (oxy[heme]: COMP –10.7 ± 5.4, PLAC –6.7 ± 4.3, CON –6.9 ± 5.0 [μmol]; p = 0.014, η_p² = 0.263; StO₂: COMP –4.0 ± 2.2, PLAC –3.0 ± 1.4, CON –2.8 ± 1.8 [%]; p = 0.049, η_p² = 0.194) and reoxygenation (oxy [heme]: COMP 10.2 ± 5.3, PLAC 6.0 ± 4.1, CON 6.3 ± 4.9 [μmol]; p = 0.011, η_p² = 0.274; StO₂: COMP 3.5 ± 1.9, PLAC 2.4 ± 1.2, CON 2.3 ± 1.9 [%]; p = 0.028, η_p² = 0.225) phases of hand grip measurements, whereas total [heme] concentrations were not affected. No differences were detected between the conditions for the parameters of peak force and fatigue index in the hand grip, time to failure and hemodynamics in the finger hang, or performance-related parameters in the lap climbing measurements (p ≤ 0.05).

Conclusions: Forearm compression sleeves did not enhance hand grip strength and endurance, sports climbing performance parameters, physiological responses, or perceptual measures. However, they did result in slightly more pronounced changes of oxy [heme] and StO₂ in the deoxygenation and reoxygenation phases during the hand grip strength and endurance measurements.

Retrospective Analysis of Functional Pain among Professional Climbers

Climbing became one of the official Olympic sports in 2020. The nociplastic pain mechanism is indicated as important in professional sports. Functional pain, which has not been examined in climbers until now, can be an example of nociplastic pain. This study aimed to determine functional pain locations in climbers according to gender and dominant climbing style. Climbers (n = 183) and healthy subjects (n = 160) completed an online survey focused on functional pain occurrence in the head, spine, and upper limbs. The logistic regression showed that climbing predisposes one to functional pain at: Gleno-humeral joint (odds ratio (OR): 3.06; area under the curve (AUC): 0.635), elbow (OR: 2.86; AUC: 0.625), fingers (OR: 7.74; AUC: 0.733), all (p < 0.05). Among the climbers, the female gender predisposed one to pain at: GHJ (OR: 3.34; AUC: 0.638), thoracic spine (OR: 1.95; AUC: 0.580), and lumbosacral spine (OR: 1.96; AUC: 0.578), all (p < 0.05). Climbing predisposes one to functional pain development in the upper limb. While the male climbers mainly suffered from finger functional pain, the female climbers reported functional pain in the GHJ and the thoracic and lumbosacral spine. Further studies on functional pain occurrence are recommended.

MBboard: Validity and Reliability of a New Tool Developed to Evaluate Specific Strength in Rock Climbers

In the present study, we analysed the validity and reliability of a new tool designed to assist the measurement of maximal upper-limb strength in rock climbers in a specific way, named MBboard. The MBboard consists of an artificial small climbing hold affixed to a wooden board, which is connected to any cable-motion strength equipment to determine the maximum dynamic strength (MBboard-1RM). Ten male rock climbers (Rock Climbing Group, RCG = 10) and ten physically active men (Control Group, CG = 10) performed, on three separate occasions, a familiarization session with procedures adopted during MBboard-1RM testing and two experimental trials (i.e., test and retest) to determine the construct validity and reliability of the MBboard during unilateral seated cable row exercise. In the first trial, the electromyographic activity (EMG) was recorded from the flexor digitorum superficialis. The self-reported climbing ability was also recorded. The RCG had superior performance (i.e. 37.5%) and EMG activity (i.e. 51%) in MBboard-1RM testing when compared with the CG (p < 0.05). There was a significant correlation between the MBboard-1RM results and climbing ability (r > 0.72, p < 0.05). Intraclass correlation coefficient analysis revealed good reliability within trials (ICC > 0.79, p < 0.05). These findings suggest that the MBboard is a valid and reliable tool to assess rock climbing-specific maximal strength. The validity of MBboard-1RM appears to be related to the finger flexor muscles activation, probably reflecting the specific adaptations resulting from long-term practice of this sport discipline.

Complex couplings between joints, muscles and performance: the role of the wrist in grasping

The relationship between posture, muscle length properties and performance remains unclear, because of a lack of quantitative data. Studies on grasping tasks suggested that wrist position could favour the extrinsic finger flexor in regards to their length to maximise grip force performance. The present study aimed at providing quantitative evidence of the links between wrist posture, muscle capacities and grip capabilities. It combines experimental measurements and a musculoskeletal model including the force-length relationship of the four prime muscles used in grasping. Participants exerted their maximum grip force on a cylindrical dynamometer in four different wrist postures, including one freely chosen by participants (spontaneous). A musculoskeletal model computed the muscle force level and length from motion capture and muscle activation. Results revealed that participants exerted maximum grip force spontaneously, with a loss of force when using other postures. At muscle force and length level, grip force variation seems to be associated with all the muscles under study. This observation led to a first quantitative link between power grip, posture and muscle properties, which could provide more insight into neuromechanical interaction involved when grasping. The design of ergonomic devices could also benefit from this quantification of the relationship between wrist angle and muscle length properties.

Acute effects of kinesio taping on muscular strength and endurance parameters of the finger flexors in sport climbing: A randomised, controlled crossover trial

Kinesio taping (KT) is a commonly used intervention in sports and, recently, KT has become popular among athletes competing in sport climbing and bouldering events. However, evidence on the effect of KT on grip strength and endurance is still controversial. Therefore, the purpose of this study was to evaluate immediate effects of KT on muscular strength and endurance of the finger flexor muscles in sport climbers. Twenty recreationally-trained active sport climbers (10 men, 10 women) aged 28.5 ± 10.6 years performed one familiarisation trial and subsequently, in a randomised crossover design, two test trials either with (TAPE) or without (CONTROL) KT over the finger flexor muscles. Test trials consisted of three performance measurements (hand grip strength and endurance, finger hang, and lap climbing) at intervals of 48 h in a randomised order. We observed no significant differences in the parameters of hand grip peak force, fatigue index, finger hang time, lap climbing distance and time, or maximum blood lactate values after lap climbing between the TAPE and CONTROL trials (p > 0.05). The participants' climbing ability was significantly correlated with the intra-individual performance changes between the TAPE and CONTROL conditions for the fatigue index (r = -0.598, p = 0.005), but not in any of the other performance-related parameters. Therefore, KT over the finger flexor muscles neither enhanced hand grip strength and endurance nor the sport climbing performance parameters of finger hang, lap climbing distance and time, and maximum blood lactate values after lap climbing.

Performing pull-ups with small climbing holds influences grip and biomechanical arm action

Pull-ups are often used by sport-climbers and other athletes to train their arm and back muscle capabilities. Sport-climbers use different types of holds to reinforce finger strength concomitantly. However, the effect of grip types on pull-up performance had not previously been investigated. A vertical force platform sensor measured the force exerted by climbers when performing pull-ups under six different grip conditions (gym-bar, large climbing hold, and four small climbing holds: 22mm, 18mm, 14mm, and 10mm). The electromyography of finger flexors and extensor muscles were recorded simultaneously. The maximal arm power and summed mechanical work were computed. The results revealed that the number of pull-ups, maximal power, and summed mechanical work decreased significantly with the size of the climbing hold used, even if no differences were found between a large climbing hold and a gym-bar. Electromyography of the forearm muscles revealed that the use of a climbing hold generated finger flexor fatigue and that the level of cocontraction was impacted by the different segment coordination strategies generated during the pull-ups. These findings are likely to be useful for quantifying training loads more accurately and designing training exercises and programs.

Effects of hand configuration on muscle force coordination, co-contraction and concomitant intermuscular coupling during maximal isometric flexion of the fingers

PURPOSE

The mechanisms governing the control of musculoskeletal redundancy remain to be fully understood. The hand is highly redundant, and shows different functional role of extensors according to its configuration for a same functional task of finger flexion. Through intermuscular coherence analysis combined with hand musculoskeletal modelling during maximal isometric hand contractions, our aim was to better understand the neural mechanisms underlying the control of muscle force coordination and agonist-antagonist co-contraction.

METHODS

Thirteen participants performed maximal isometric flexions of the fingers in two configurations: power grip (Power) and finger-pressing on a surface (Press). Hand kinematics and force/moment measurements were used as inputs in a musculoskeletal model of the hand to determine muscular tensions and co-contraction. EMG-EMG coherence analysis was performed between wrist and finger flexors and extensor muscle pairs in alpha, beta and gamma frequency bands.

RESULTS

Concomitantly with tailored muscle force coordination and increased co-contraction between Press and Power (mean difference: 48.08%; p < 0.05), our results showed muscle-pair-specific modulation of intermuscular coupling, characterized by pair-specific modulation of EMG-EMG coherence between Power and Press (p < 0.05), and a negative linear association between co-contraction and intermuscular coupling for the ECR/FCR agonist-antagonist muscle pair (r = - 0.65; p < 0.05).

CONCLUSIONS

This study brings new evidence that pair-specific modulation of EMG-EMG coherence is related to modulation of muscle force coordination during hand contractions. Our results highlight the functional importance of intermuscular coupling as a mechanism contributing to the control of muscle force synergies and agonist-antagonist co-contraction.

A scaling method to individualise muscle force capacities in musculoskeletal models of the hand and wrist using isometric strength measurements

Because the force-generating capacities of muscles are currently estimated using anatomical data obtained from cadaver specimens, hand musculoskeletal models provide only a limited representation of the specific features of individual subjects. A scaling method is proposed to individualise muscle capacities using dynamometric measurements and electromyography. For each subject, a strength profile was first defined by measuring net moments during eight maximum isometric contractions about the wrist and metacarpophalangeal joints. The capacities of the five muscle groups were then determined by adjusting several parameters of an initial musculoskeletal model using an optimisation procedure which minimised the differences between measured moments and model estimates. Sixteen volunteers, including three particular participants (one climber, one boxer and one arthritic patient), were recruited. Compared with the initial literature-based model, the estimated subject-specific capacities were on average five times higher for the wrist muscles and twice as high for the finger muscles. The adjustments for particular subjects were consistent with their expected specific characteristics, e.g. high finger flexor capacities for the climber. Using the subject-specific capacities, the model estimates were markedly modified. The proposed protocol and scaling procedure can capture the specific characteristics of the participants and improved the representation of their capacities in the musculoskeletal model.