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.

Influence of Pedal Interface During Pedaling With the Upper Versus Lower Limbs: A Pilot Analysis of Torque Performance and Muscle Synergies.

Pedaling is a physical exercise practiced with either the upper or the lower limbs. Muscle coordination during these exercises has been previously studied using electromyography and synergy analysis, and three to four synergies have been identified for the lower and upper limbs. The question of synergy adaptabilities has not been investigated during pedaling with the upper limbs, and the impact of various modalities is yet not known.

The effect of trapeziometacarpal joint passive stiffness on mechanical loadings of cartilages.

Hypermobility of the trapeziometacarpal joint is commonly considered to be a potential risk factor for osteoarthritis. Nevertheless, the results remain controversial due to a lack of quantitative validation. The objective of this study was to evaluate the effect of joint laxity on the mechanical loadings of cartilage.

Pull-Up Performance Is Affected Differently by the Muscle Contraction Regimens Practiced during Training among Climbers.

Sport climbing performance is highly related to upper limb strength and endurance. Although finger-specific methods are widely analyzed in the literature, no study has yet quantified the effects of arm-specific training. This study aims to compare the effects of three types of training involving different muscle contraction regimens on climbers' pull-up capabilities.

Finger flexion to extension ratio in healthy climbers: a proposal for evaluation and rebalance.

Introduction: Finger strength is a key factor in climbing performance and is highly dependent on the capacity of the finger flexor muscles. The majority of finger-specific training therefore focuses on improving such capabilities by performing finger flexion contraction during hanging exercises on small holds. However, greater strength in the finger flexors causes an imbalance with the extensor muscle capacities.

Assessing climbers' pull-up capabilities by differentiating the parameters involved in power production.

This study explored the capabilities of sport climbers to pull up with arms. The methodology aimed at assessing (i) concentric capabilities of arm muscles, (ii) body coordination skills (iii) characteristics of energy storage and (iv) capabilities to resist fatigue. Twenty-eight climbers were tested and the force exerted was recorded during three pull-up exercises: jump tests (with or without coordination, or preceded by an eccentric phase), incrementally weighted pull-ups and maximum number of pull-ups.

Electromyography-informed musculoskeletal modeling provides new insight into hand tendon forces during tennis forehand.

Lateral epicondylitis, also known as tennis elbow, is a major health issue among tennis players. This musculo-skeletal disorder affects hand extensor tendons, results in substantial pain and impairments for sporting and everyday activities and requires several weeks of recovery. Unfortunately, prevention remains limited by the lack of data regarding biomechanical risk factors, especially because in vivo evaluation of hand tendon forces remains challenging.

Influence of Force-Length Relationship and Task-Specific Constraints on Finger Force-Generating Capacities.

Grip strength loss in extended and flexed wrist postures has been explained by reduced force-generating capacities of extrinsic finger flexor resulting from non-optimal length, owing to the force-length relationship. Recent works suggested that other muscles, especially wrist extensors, participate in this grip strength loss. The objective of this study was to clarify the role of the force-length relationship in finger force production.

Relationship between trapeziometacarpal joint morphological parameters and joint contact pressure: a possible factor of osteoarthritis development.

The trapeziometacarpal (TMC) joint is the one of the hand joints that is most affected by osteoarthritis (OA). The objective of this study was to determine if specific morphological parameters could be related to the amount of pressure endured by the joint which is one of the factors contributing to the development of this pathology. We developed 15 individualized 3D computer aided design (CAD) models of the TMC joint, each generated from the CT scan of a different participant.

Evolution of muscle coordination and mechanical output following four weeks of arm cranking submaximal training.

Unlabelled: Muscle synergies is extensively studied to understand how the neuromusculoskeletal system deals with abundancy. The synergies represent covariant muscles that acts as building blocks for movement production. Nevertheless, little is known on how those synergies evolve following training, learning and expertise.

The effect of index finger distal interphalangeal joint arthrodesis on muscle forces and adjacent joint contact pressures.

Distal interphalangeal joint arthrodesis is a frequent surgical operation performed to treat severe arthritis. Nevertheless, the angle selected when fusing the joint is arbitrarily chosen without any quantified data concerning its mechanical effects, thus preventing the optimal choice for the patient. In the current study, we realized an experiment and developed a numerical model to investigate the effect of fusion angle on the biomechanics of adjacent non-operated joints.

Effects of Different Hangboard Training Intensities on Finger Grip Strength, , and .

Climbing-specific training programs on hangboards are often based on dead-hang repetitions, but little is known about the real intensity applied during such effort. The aim of this study was to quantify and compare the effects of different training intensities (maximal, high submaximal, and low submaximal intensities) on the fingers' physiological capabilities using a hangboard fitted with force sensors. In total, 54 experienced climbers (13 women and 41 men) were randomly divided into four groups, with each group following different training intensity programs: maximal strength program performed at 100% of the maximal finger strength (MFS; F100), intermittent repetitions at 80% MFS (F80), intermittent repetitions at 60% MFS (F60), and no specific training (control group).

Subject specific muscle synergies and mechanical output during cycling with arms or legs.

Background: Upper (UL) and lower limb (LL) cycling is extensively used for several applications, especially for rehabilitation for which neuromuscular interactions between UL and LL have been shown. Nevertheless, the knowledge on the muscular coordination modality for UL is poorly investigated and it is still not known whether those mechanisms are similar or different to those of LL. The aim of this study was thus to put in evidence common coordination mechanism between UL and LL during cycling by investigating the mechanical output and the underlying muscle coordination using synergy analysis.

Unusual rupture of the middle finger flexor digitorum superficialis tendon in a climber: Biomechanical analysis.

Sport climbing is increasingly popular and consultations by climbers in hand surgery departments are on the increase. The pathologies related to this sport concern essentially the pulley system, tendons being rarely affected. We report the case of a male climber who presented an atypical rupture of the flexor superficialis tendon in his left middle finger sustained when using an atypical climbing grip technique: the "hook grip".

Performance Assessment for Rock Climbers: The International Rock Climbing Research Association Sport-Specific Test Battery.

Purpose: To examine the validity and reliability of a battery of 10 measures designed to assess the key physiological parameters for successful rock climbing performance.

Methods: In phase 1 of the research, an expert panel, using the Delphi method, established a 10-item test battery based on the key determinants of climbing performance. In phase 2, the tests were assessed for validity and reliability to examine their suitability as sport-specific measures of rock climbing performance.

Mechanical performance comparison of two surgical constructs for wrist four-corner arthrodesis via dorsal and radial approaches.

Background: Four-corner arthrodesis, which involves fusing four carpal bones while removing the scaphoid bone, is a standard surgery for the treatment of advanced stages of wrist arthritis. Nowadays, it can be performed using a dorsal approach by fixing a plate to the bones and a new radial approach is in development. To date, there is no consensus on the biomechanically optimal and most reliable surgical construct for four-corner arthrodesis.

Modelling force-length-activation relationships of wrist and finger extensor muscles.

The wrist and finger extensors play a crucial role in the muscle coordination during grasping tasks. Nevertheless, few data are available regarding their force-generating capacities. The objective of this study was to provide a model of the force-length-activation relationships of the hand extensors using non-invasive methods.

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.

The impact of hand proportions on tool grip abilities in humans, great apes and fossil hominins: A biomechanical analysis using musculoskeletal simulation.

Differences in grip techniques used across primates are usually attributed to variation in thumb-finger proportions and muscular anatomy of the hand. However, this cause-effect relationship is not fully understood because little is known about the biomechanical functioning and mechanical loads (e.g.

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 New Echocardiographic Tool for Cardiac Output Evaluation: An Experimental Study.

Background: The correlation between cardiac output (CO) evaluated by echocardiography and CO measured by thermodilution (COth) varies according to different studies. A new transthoracic echocardiography (TTE) tool allows automatic calculation of the subaortic velocity time index (VTIauto) and CO (COauto). The main objective was to evaluate the correlation between COth and COauto in an anesthetized, ventilated piglet hemorrhagic shock (HS) model.