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  • 1
    Language: English
    In: Medical & biological engineering & computing, 2020-08-17, Vol.58 (10), p.2531-2549
    Description: 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. The extensor carpi radialis (ECR) and the extensor digitorum communis (EDC) were studied as representative of wrist and finger extensors. Ten participants performed isometric extension force-varying contractions in different postures on an ergometer recording resultant moment. The joint angle, the myotendinous junction displacement and activation were synchronously tracked using motion capture, ultrasound and electromyography. Muscle force was estimated via a musculoskeletal model using the measured joint angle and moment. The force-length-activation relationship was then obtained by fitting a force-length model at different activation levels to the measured data. The obtained relationships agreed with previously reported data regarding muscle architecture, sarcomere length and activation-dependent shift of optimal length. Muscle forces estimated from kinematics and electromyography using the force-length-activation relationships were comparable, below 15% differences, to those estimated from moment via the musculoskeletal model. The obtained quantitative data provides a new insight into the different muscle mechanics of finger and wrist extensors. Graphical abstract By combining in vivo data (kinematics, dynamometry, electromyography, ultrasonography) during isometric force-varying contractions with musculoskeletal modelling, the force-length-activation relationships of both finger and wrist extensors were obtained. The results provided a new insight into the role of hand extensors in the generation and control of hand movements.
    Subject(s): Biomechanics ; Biomedical and Life Sciences ; Biomedical Engineering and Bioengineering ; Biomedicine ; Computer Applications ; Engineering Sciences ; Human Physiology ; Imaging ; Mechanics ; Original Article ; Radiology
    ISSN: 0140-0118
    E-ISSN: 1741-0444
    Source: Business Source Ultimate
    Source: Academic Search Ultimate
    Source: Alma/SFX Local Collection
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  • 2
    Language: English
    In: Journal of sports sciences, 2017-08-18, Vol.35 (16), p.1643-1651
    Description: This paper investigates how tennis players control stroke-induced vibration. Its aim is to characterise how a tennis player deals with entering vibration waves or how he/she has the ability to finely adjust them. A specific experimental procedure was designed, based on simultaneously collecting sets of kinematic, vibration and electromyographic data during forehand strokes using various commercial rackets and stroke intensities. Using 14 expert players, a wide range of excitations at spectral and temporal levels were investigated. Energetic and spectral descriptors of stroke-induced vibration occurring at the racket handle and at the player's wrist and elbow were computed. Results indicated that vibrational characteristics are strongly governed by grip force and to a lower extent by the racket properties. Grip force management drives the amount of energy, as well as its distribution, into the forearm. Furthermore, hand-grip can be assimilated to an adaptive filter which can significantly modify the spectral parameters propagating into the player's upper limb. A significant outcome is that these spectral characteristics are as much dependent on the player as on the racket. This contribution opens up new perspectives in equipment manufacture by underlining the need to account for player/racket interaction in the design process.
    Subject(s): Biomechanical Phenomena ; Biomechanics ; Elbow - physiology ; Electromyography ; Engineering Sciences ; Equipment Design ; Forearm - physiology ; grip force ; Hand Strength - physiology ; Hand-tool interaction ; high-resolution method ; Humans ; Male ; Man-Machine Systems ; Mechanics ; shock propagation ; Sports Equipment ; Tennis ; Tennis - physiology ; Vibration ; Wrist - physiology ; Young Adult
    ISSN: 0264-0414
    E-ISSN: 1466-447X
    Source: SPORTDiscus with Full Text
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  • 3
    Language: English
    In: Journal of sports sciences, 2019-04-18, Vol.37 (8), p.886-894
    Description: 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.
    Subject(s): Arm - physiology ; arm power ; Biomechanical Phenomena ; Biomechanics ; Electromyography ; Fingers - physiology ; grip types ; Hand Strength - physiology ; Humans ; Life Sciences & Biomedicine ; Male ; Mechanics ; Mountaineering - physiology ; Muscle Contraction - physiology ; Muscle Fatigue - physiology ; Muscle, Skeletal - physiology ; Physics ; Pull-up training ; Resistance Training ; Science & Technology ; Sport Sciences ; sport-climbing ; Task Performance and Analysis ; Young Adult
    ISSN: 0264-0414
    E-ISSN: 1466-447X
    Source: Web of Science - Science Citation Index Expanded - 2019〈img src="http://exlibris-pub.s3.amazonaws.com/fromwos-v2.jpg" /〉
    Source: SPORTDiscus with Full Text
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  • 4
    Language: English
    In: European journal of applied physiology, 2017-09-20, Vol.117 (11), p.2309-2320
    Description: 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.
    Subject(s): Adult ; Biomechanical Phenomena ; Biomedical and Life Sciences ; Biomedicine ; Contraction ; Coordination ; Electromyography ; Finger ; Fingers - innervation ; Fingers - physiology ; Force ; Hand ; Hand modelling ; Human Physiology ; Humans ; Isometric Contraction ; Kinematics ; Life Sciences ; Male ; Muscle contraction ; Muscle Strength ; Muscle tensions ; Muscle, Skeletal - innervation ; Muscle, Skeletal - physiology ; Nervous system ; Neural control ; Occupational Medicine/Industrial Medicine ; Original Article ; Redundancy control ; Sports Medicine ; Variance analysis ; Wavelet-based intermuscular coherence ; Wrist
    ISSN: 1439-6319
    E-ISSN: 1439-6327
    Source: Alma/SFX Local Collection
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  • 5
    Language: English
    In: Scientific reports, 2019-12-18, Vol.9 (1), p.19357-11
    Description: 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.
    Subject(s): Biomechanical Phenomena ; Biomechanics ; Electrodes ; Engineering Sciences ; Female ; Force ; Hand Strength - physiology ; Humans ; Male ; Mechanics ; Models, Biological ; Multidisciplinary Sciences ; Muscle, Skeletal - physiology ; Muscles ; Posture ; Regression Analysis ; Science & Technology ; Science & Technology - Other Topics ; Wrist ; Wrist - physiology ; Wrist Joint - physiology ; Young Adult
    ISSN: 2045-2322
    E-ISSN: 2045-2322
    Source: Nature Open Access
    Source: Academic Search Ultimate
    Source: Web of Science - Science Citation Index Expanded - 2019〈img src="http://exlibris-pub.s3.amazonaws.com/fromwos-v2.jpg" /〉
    Source: PubMed Central
    Source: Web of Science - Social Sciences Citation Index – 2019〈img src="http://exlibris-pub.s3.amazonaws.com/fromwos-v2.jpg" /〉
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  • 6
    Language: English
    In: Journal of sports sciences, 2012-04-01, Vol.30 (7), p.669-677
    Description: The aim of this study was to understand how the commonly used climbing-specific grip techniques and hold depths influence the finger force capacities. Ten advanced climbers performed maximal voluntary force on four different hold depths (from 1 to 4 cm) and in two force directions (antero-posterior and vertical) using three grip techniques (slope, half crimp and full crimp). A specially designed platform instrumented with a 6-degrees-of-freedom (DoF) force/torque sensor was used to record force values. Results showed that the maximal vertical forces differed significantly according to the hold depth and the grip technique (ranged from 350.8 N to 575.7 N). The maximal vertical forces increased according to the hold depth but the form of this increase differed depending on grip technique. These results seemed to be more associated with finger-hold contact/interaction than with internal biomechanical factors. Similar results were revealed for antero-posterior forces (ranged from 69.9 N to 138.0 N) but, it was additionally noted that climbers have different hand-forearm posture strategies with slope and crimp grip techniques when applying antero-posterior forces. This point is important as it could influence the body position adopted during climbing according to the chosen grip technique. For trainers and designers, a polynomial regression model was proposed in order to predict the mean maximal force based on hold depth and adopted grip technique.
    Subject(s): Adolescent ; Adult ; Biological and medical sciences ; Biomechanical Phenomena ; crimp grip ; finger forces ; Fingers - physiology ; Forearm ; Fundamental and applied biological sciences. Psychology ; Hand ; Hand Strength - physiology ; hold depth ; Humans ; Life Sciences ; Male ; Movement - physiology ; Muscle Contraction - physiology ; Physical Exertion - physiology ; Posture ; Regression Analysis ; slope grip ; Sport climbing ; Task Performance and Analysis ; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports ; Young Adult
    ISSN: 0264-0414
    E-ISSN: 1466-447X
    Source: SPORTDiscus with Full Text
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  • 7
    Language: English
    In: Journal of sports sciences, 2017-06-18, Vol.35 (12), p.1155-1164
    Description: The aim of this article is to characterise the extent to which the dynamic behaviour of a tennis racket is dependent on its mechanical characteristics and the modulation of the player's grip force. This problem is addressed through steps involving both experiment and modelling. The first step was a free boundary condition modal analysis on five commercial rackets. Operational modal analyses were carried out under "slight", "medium" and "strong" grip force conditions. Modal frequencies and damping factors were then obtained using a high-resolution method. Results indicated that the dynamic behaviour of a racket is not only determined by its mechanical characteristics, but is also highly dependent on the player's grip force. Depending on the grip force intensity, the first two bending modes and the first torsional mode frequencies respectively decreased and increased while damping factors increased. The second step considered the design of a phenomenological hand-gripped racket model. This model is fruitful in that it easily predicts the potential variations in a racket's dynamic behaviour according to the player's grip force. These results provide a new perspective on the player/racket interaction optimisation by revealing how grip force can drive racket dynamic behaviour, and hence underlining the necessity of taking the player into account in the racket design process.
    Subject(s): Biomechanical Phenomena ; Equipment Design ; Grip force ; Hand Strength ; hand-tools interaction ; Humans ; phenomenological model ; Sports Equipment ; Tennis - physiology ; tennis racket ; vibration
    ISSN: 0264-0414
    E-ISSN: 1466-447X
    Source: SPORTDiscus with Full Text
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  • 8
    Language: English
    In: European journal of applied physiology, 2014-12-17, Vol.115 (5), p.947-957
    Description: Purpose This study investigated the hand and wrist muscle capacities among expert rock climbers and compared them with those of non-climbers. The objective was to identify the adaptations resulting from several years of climbing practice. Methods Twelve climbers (nine males and three females) and 13 non-climber males participated in this study. Each subject performed a set of maximal voluntary contractions about the wrist and the metacarpo-phalengeal joints during which net joint moments and electromyographic activities were recorded. From this data set, the muscle capacities of the five main muscle groups of the hand (wrist flexors, wrist extensors, finger flexors, finger extensors and intrinsic muscles) were estimated using a biomechanical model. This process consisted in adjusting the physiological cross-sectional area (PCSA) and the maximal muscle stress value from an initial generic model. Results Results obtained from the model provided several new pieces of information compared to the analysis of only the net joint moments. Particularly, the capacities of the climbers were 37.1 % higher for finger flexors compared to non-climbers and were similar for finger extensor and for the other muscle groups. Climbers thus presented a greater imbalance between flexor and extensor capacities which suggests a potential risk of pathologies. Conclusions The practice of climbing not only increased the strength of climbers but also resulted in specific adaptations among hand muscles. The proposed method and the obtained data could be re-used to optimize the training programs as well as the rehabilitation processes following hand pathologies.
    Subject(s): Adolescent ; Adult ; Biomechanics ; Biomedical and Life Sciences ; Biomedicine ; Electromyography ; Engineering Sciences ; Female ; Fingers - physiology ; Hand - physiology ; Hand modeling ; Hand Strength - physiology ; Human health and pathology ; Human Physiology ; Humans ; Life Sciences ; Male ; Mechanics ; Mountaineering - physiology ; Muscle capacities ; Muscle Strength - physiology ; Muscle, Skeletal - physiology ; Occupational Medicine/Industrial Medicine ; Original Article ; Physical Endurance - physiology ; Sport climbing ; Sports Medicine ; Tissues and Organs ; Training ; Wrist - physiology ; Young Adult
    ISSN: 1439-6319
    E-ISSN: 1439-6327
    Source: Alma/SFX Local Collection
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  • 9
    Language: English
    In: International journal of sports physiology and performance, 2021-03-02, Vol.16 (9), p.1-1252
    Description: To examine the validity and reliability of a battery of 10 measures designed to assess the key physiological parameters for successful rock climbing performance. 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. A total of 132 rock climbers, from 7 countries, volunteered to take part in the study. Each climber visited their nearest laboratory on 3 separate occasions in order to enable the required tests and retests to be completed. A minimum of 7 days was allowed between visits. The 10 tests established for phase 2 were designed as sport-specific measures of flexibility, strength, power, and endurance. Results indicated that, while reliable, the flexibility and strength tests were only partially successful in differentiating across climber abilities. The power and endurance tests, however, performed well with regard to validity and reliability, with the finger hang and powerslap tests being most strongly correlated with performance ability (P 〈 .0005 to P 〈 .002). The authors' data suggest that climbing may require a threshold level of flexibility and strength for successful performance, beyond which further improvements may not be required. In contrast, the finger hang and powerslap tests were not only reliable measures but also differentiated between climber abilities from lower grade to elite levels.
    Subject(s): Flexibility ; Rock climbing ; Validity
    ISSN: 1555-0265
    E-ISSN: 1555-0273
    Source: SPORTDiscus with Full Text
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  • 10
    Language: English
    In: Journal of applied biomechanics, 2011-08, Vol.27 (3), p.173-180
    Description: The objective of this study was to identify the impact of modifying the object width on muscle and joint forces while gripping objects. The experimental protocol consisted to maintain horizontally five objects of different widths (3.5, 4.5, 5.5, 6.5, and 7.5 cm) with a thumb-index finger grip. Subjects were required to grasp spontaneously the object without any instruction regarding the grip force (GF) to apply. A biomechanical model of thumb-index finger pinch was developed to estimate muscle and joint forces. This model included electromyography, fingertip force, and kinematics data as inputs. The finger joint postures and the GF varied across the object widths. The estimated muscle forces also varied significantly according to the object width. Interestingly, we observed that the muscle force/GF ratios of major flexor muscles remain particularly stable with respect to the width whereas other muscle ratios differed largely. This may argue for a control strategy in which the actions of flexors were preserved in spite of change in joint postures. The estimated joint forces tended to increase with object width and increased in the distal-proximal sense. Overall, these results are of importance for the ergonomic design of handheld objects and for clinical applications.
    Subject(s): Adult ; Computer Simulation ; Female ; Finger Joint - physiology ; Fingers - physiology ; Hand Strength - physiology ; Humans ; Life Sciences ; Male ; Models, Biological ; Muscle Contraction - physiology ; Muscle, Skeletal - physiology ; Physical Exertion - physiology ; Task Performance and Analysis
    ISSN: 1065-8483
    E-ISSN: 1543-2688
    Source: SPORTDiscus with Full Text
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