The Experts below are selected from a list of 7407 Experts worldwide ranked by ideXlab platform

Na Jin Seo - One of the best experts on this subject based on the ideXlab platform.

  • Effects of Sensory Deficit on Phalanx Force Deviation During Power Grip Post Stroke.
    Journal of Motor Behavior, 2016
    Co-Authors: Leah R. Enders, Na Jin Seo
    Abstract:

    The effect of sensory deficits on Power Grip force from individual phalanges was examined. The authors found that stroke survivors with sensory deficits (determined by the Semmes-Weinstein monofilament test) Gripped with phalanx force directed more tangential to the object surface, than those without, although both groups had similar motor deficits (Chedoke-McMaster and Fugl-Meyer), Grip strength, and skin friction. Altered Grip force direction elevates risk of finger slippage against the object thus Grip loss/object dropping, hindering activities of daily living. Altered Grip force direction was associated with altered muscle activation patterns. In summary, the motor impairment level alone may not describe hand motor control in detail. Information about sensory deficits helps elucidate patients' hand motor control with functional relevance.

  • altered phalanx force direction during Power Grip following stroke
    Experimental Brain Research, 2015
    Co-Authors: Leah R. Enders, Na Jin Seo
    Abstract:

    Many stroke survivors with severe impairment can grasp only with a Power Grip. Yet, little knowledge is available on altered Power Grip after stroke, other than reduced Power Grip strength. This study characterized stroke survivors’ static Power Grip during 100 and 50 % maximum Grip. Each phalanx force angular deviation from the normal direction and its contribution to total normal force was compared for 11 stroke survivors and 11 age-matched controls. Muscle activities and skin coefficient of friction were additionally compared for another 20 stroke and 13 age-matched control subjects. The main finding was that stroke survivors Gripped with a 34 % greater phalanx force angular deviation of 19° ± 2° compared to controls of 14° ± 1° (p < .05). Stroke survivors’ phalanx force angular deviation was closer to the 23° threshold of slippage between the phalanx and Grip surface, which may explain increased likelihood of object dropping in stroke survivors. In addition, this altered phalanx force direction decreases normal Grip force by tilting the force vector, indicating a partial role of phalanx force angular deviation in reduced Grip strength post-stroke. Greater phalanx force angular deviation may biomechanically result from more severe underactivation of stroke survivors’ first dorsal interosseous and extensor digitorum communis muscles compared to their flexor digitorum superficialis or somatosensory deficit. While stroke survivors’ maximum Power Grip strength was approximately half of the controls, the distribution of their remaining strength over the fingers and phalanges did not differ, indicating evenly distributed Grip force reduction over the entire hand.

  • Contribution of intracortical inhibition in voluntary muscle relaxation
    Experimental Brain Research, 2012
    Co-Authors: Binal Motawar, Pilwon Hur, James W. Stinear, Na Jin Seo
    Abstract:

    Terminating a voluntary muscle contraction is an important aspect of motor control, and yet, its neurophysiology is unclear. The objective of this study was to determine the role of short-interval intracortical inhibition (SICI) by comparing SICIs during relaxation from a Power Grip versus during a sustained Power Grip at the matching muscle activity level. Right-handed healthy young adults Gripped and relaxed from Power Grip following auditory cues. The relaxation period was determined as the time for the flexor digitorum superficialis (FDS) muscle to reach its pre-contraction baseline level after the cue to relax. SICI during relaxation was obtained at different times into the relaxation period in two separate studies (70, 80, 90 % into relaxation in Study 1; 25, 50, 75 % into relaxation in Study 2). In addition, SICI during sustained contraction was assessed while subjects maintained a Power Grip at the matching FDS EMG levels (obtained during relaxation, for both Studies). Results showed that the mean SICI was greater during relaxation than during sustained contraction at the matching muscle activity level in both Studies (p < 0.05), indicating increased activation of intracortical inhibitory circuits for muscle relaxation. SICI gradually increased from 25 to 50 and 75 % into relaxation (Study 2, p < 0.05), but did not change from 70 to 80 and 90 % into relaxation (Study 1). MEP decreased with progression of relaxation (p < 0.05) in both Studies, reflecting gradual decreases in corticomotor excitability. This work supports the hypothesis that relaxation from a voluntary muscle contraction involves inhibitory activity in the primary motor cortex.

  • phalanx force magnitude and trajectory deviation increased during Power Grip with an increased coefficient of friction at the hand object interface
    Journal of Biomechanics, 2011
    Co-Authors: Leah R. Enders, Na Jin Seo
    Abstract:

    This study examined the effect of friction between the hand and Grip surface on a person's Grip strategy and force generation capacity. Twelve young healthy adults performed Power Grip exertions on an instrumented vertical cylinder with the maximum and 50% of maximum efforts (far above the Grip force required to hold the cylinder), while normal and shear forces at each phalanx of all five fingers in the direction orthogonal to the gravity were recorded. The cylinder surface was varied for high-friction rubber and low-friction paper coverings. An increase in surface friction by replacing the paper covering with the rubber covering resulted in 4% greater mean phalanx normal force (perpendicular to the cylinder surface) and 22% greater mean phalanx shear force in either the proximal or distal direction of the digits (p<0.05; for both 50% and maximum Grip efforts). Consequently, increased friction with the rubber surface compared to the paper surface was associated with a 20% increase in the angular deviation of the phalanx force from the direction normal to the cylinder surface (p<0.05). This study demonstrates that people significantly changed the magnitude and direction of phalanx forces depending on the surface they Gripped. Such change in the Grip strategy appears to help increase Grip force generation capacity. This finding suggests that a seemingly simple Power Grip exertion involves sensory feedback-based motor control, and that people's Power Grip capacity may be reduced in cases of numbness, glove use, or injuries resulting in reduced sensation.

  • Phalanx force magnitude and trajectory deviation increased during Power Grip with an increased coefficient of friction at the hand-object interface.
    Journal of Biomechanics, 2011
    Co-Authors: Leah R. Enders, Na Jin Seo
    Abstract:

    This study examined the effect of friction between the hand and Grip surface on a person's Grip strategy and force generation capacity. Twelve young healthy adults performed Power Grip exertions on an instrumented vertical cylinder with the maximum and 50% of maximum efforts (far above the Grip force required to hold the cylinder), while normal and shear forces at each phalanx of all five fingers in the direction orthogonal to the gravity were recorded. The cylinder surface was varied for high-friction rubber and low-friction paper coverings. An increase in surface friction by replacing the paper covering with the rubber covering resulted in 4% greater mean phalanx normal force (perpendicular to the cylinder surface) and 22% greater mean phalanx shear force in either the proximal or distal direction of the digits (p

Leah R. Enders - One of the best experts on this subject based on the ideXlab platform.

  • Effects of Sensory Deficit on Phalanx Force Deviation During Power Grip Post Stroke.
    Journal of Motor Behavior, 2016
    Co-Authors: Leah R. Enders, Na Jin Seo
    Abstract:

    The effect of sensory deficits on Power Grip force from individual phalanges was examined. The authors found that stroke survivors with sensory deficits (determined by the Semmes-Weinstein monofilament test) Gripped with phalanx force directed more tangential to the object surface, than those without, although both groups had similar motor deficits (Chedoke-McMaster and Fugl-Meyer), Grip strength, and skin friction. Altered Grip force direction elevates risk of finger slippage against the object thus Grip loss/object dropping, hindering activities of daily living. Altered Grip force direction was associated with altered muscle activation patterns. In summary, the motor impairment level alone may not describe hand motor control in detail. Information about sensory deficits helps elucidate patients' hand motor control with functional relevance.

  • Altered phalanx force direction during Power Grip following stroke
    Experimental Brain Research, 2015
    Co-Authors: Leah R. Enders
    Abstract:

    Many stroke survivors with severe impairment can grasp only with a Power Grip. Yet, little knowledge is available on altered Power Grip after stroke, other than reduced Power Grip strength. This study characterized stroke survivors’ static Power Grip during 100 and 50 % maximum Grip. Each phalanx force angular deviation from the normal direction and its contribution to total normal force was compared for 11 stroke survivors and 11 age-matched controls. Muscle activities and skin coefficient of friction were additionally compared for another 20 stroke and 13 age-matched control subjects. The main finding was that stroke survivors Gripped with a 34 % greater phalanx force angular deviation of 19° ± 2° compared to controls of 14° ± 1° ( p  

  • altered phalanx force direction during Power Grip following stroke
    Experimental Brain Research, 2015
    Co-Authors: Leah R. Enders, Na Jin Seo
    Abstract:

    Many stroke survivors with severe impairment can grasp only with a Power Grip. Yet, little knowledge is available on altered Power Grip after stroke, other than reduced Power Grip strength. This study characterized stroke survivors’ static Power Grip during 100 and 50 % maximum Grip. Each phalanx force angular deviation from the normal direction and its contribution to total normal force was compared for 11 stroke survivors and 11 age-matched controls. Muscle activities and skin coefficient of friction were additionally compared for another 20 stroke and 13 age-matched control subjects. The main finding was that stroke survivors Gripped with a 34 % greater phalanx force angular deviation of 19° ± 2° compared to controls of 14° ± 1° (p < .05). Stroke survivors’ phalanx force angular deviation was closer to the 23° threshold of slippage between the phalanx and Grip surface, which may explain increased likelihood of object dropping in stroke survivors. In addition, this altered phalanx force direction decreases normal Grip force by tilting the force vector, indicating a partial role of phalanx force angular deviation in reduced Grip strength post-stroke. Greater phalanx force angular deviation may biomechanically result from more severe underactivation of stroke survivors’ first dorsal interosseous and extensor digitorum communis muscles compared to their flexor digitorum superficialis or somatosensory deficit. While stroke survivors’ maximum Power Grip strength was approximately half of the controls, the distribution of their remaining strength over the fingers and phalanges did not differ, indicating evenly distributed Grip force reduction over the entire hand.

  • phalanx force magnitude and trajectory deviation increased during Power Grip with an increased coefficient of friction at the hand object interface
    Journal of Biomechanics, 2011
    Co-Authors: Leah R. Enders, Na Jin Seo
    Abstract:

    This study examined the effect of friction between the hand and Grip surface on a person's Grip strategy and force generation capacity. Twelve young healthy adults performed Power Grip exertions on an instrumented vertical cylinder with the maximum and 50% of maximum efforts (far above the Grip force required to hold the cylinder), while normal and shear forces at each phalanx of all five fingers in the direction orthogonal to the gravity were recorded. The cylinder surface was varied for high-friction rubber and low-friction paper coverings. An increase in surface friction by replacing the paper covering with the rubber covering resulted in 4% greater mean phalanx normal force (perpendicular to the cylinder surface) and 22% greater mean phalanx shear force in either the proximal or distal direction of the digits (p<0.05; for both 50% and maximum Grip efforts). Consequently, increased friction with the rubber surface compared to the paper surface was associated with a 20% increase in the angular deviation of the phalanx force from the direction normal to the cylinder surface (p<0.05). This study demonstrates that people significantly changed the magnitude and direction of phalanx forces depending on the surface they Gripped. Such change in the Grip strategy appears to help increase Grip force generation capacity. This finding suggests that a seemingly simple Power Grip exertion involves sensory feedback-based motor control, and that people's Power Grip capacity may be reduced in cases of numbness, glove use, or injuries resulting in reduced sensation.

  • Phalanx force magnitude and trajectory deviation increased during Power Grip with an increased coefficient of friction at the hand-object interface.
    Journal of Biomechanics, 2011
    Co-Authors: Leah R. Enders, Na Jin Seo
    Abstract:

    This study examined the effect of friction between the hand and Grip surface on a person's Grip strategy and force generation capacity. Twelve young healthy adults performed Power Grip exertions on an instrumented vertical cylinder with the maximum and 50% of maximum efforts (far above the Grip force required to hold the cylinder), while normal and shear forces at each phalanx of all five fingers in the direction orthogonal to the gravity were recorded. The cylinder surface was varied for high-friction rubber and low-friction paper coverings. An increase in surface friction by replacing the paper covering with the rubber covering resulted in 4% greater mean phalanx normal force (perpendicular to the cylinder surface) and 22% greater mean phalanx shear force in either the proximal or distal direction of the digits (p

Laurent Vigouroux - One of the best experts on this subject based on the ideXlab platform.

  • Handle Shape Affects the Grip Force Distribution and the Muscle Loadings During Power Grip Tasks.
    Journal of Applied Biomechanics, 2015
    Co-Authors: Jeremy Rossi, Benjamin Goislard De Monsabert, Eric Berton, Laurent Vigouroux
    Abstract:

    The objectives of this study were to investigate the effect of handle shape on the Grip force distribution in the hand and on the muscle forces during maximal Power Grip tasks. Eleven subjects maximally grasped 3 handles with different external shapes (circular, elliptic, and double-frustum). A handle dynamometer, equipped with both a force sensor and a pressure map, was used to record the forces exerted at the hand/handle interface. The finger and wrist joint postures were also computed from synchronized kinematic measurement. These processed data were then used as input of a biomechanical hand model to estimate muscle forces. The results showed that handle shape influences the maximal Grip force, the Grip force distribution, and the finger joint postures. Particularly, we observed that the elliptical shape resulted in a 6.6% lower maximal Grip force compared with the circular and double-frustum handle. Concomitantly, the estimated muscle forces also varied significantly according to the handle shape, with up to 48% differences for the flexor digitorum superficialis muscle for example. Interestingly, different muscle coordination strategies were observed depending on the handle shape, therefore suggesting a potential influence of these geometrical characteristics on pathological risks such as tendonitis.

  • Quantification of Hand and Forearm Muscle Forces during a Maximal Power Grip Task
    Medicine and Science in Sports and Exercise, 2012
    Co-Authors: Benjamin Goislard De Monsabert, Jeremy Rossi, Eric Berton, Laurent Vigouroux
    Abstract:

    GOISLARD DE MONSABERT, B., J. ROSSI, E. BERTON, and L. VIGOUROUX. Quantification of Hand and Forearm Muscle Forces during a Maximal Power Grip Task. Med. Sci. Sports Exerc., Vol. 44, No. 10, pp. 1906-1916, 2012. Purpose: The aim of this study was to estimate muscle and joint forces during a Power Grip task. Considering the actual lack of quantification of such internal variables, this information would be essential for sports sciences, medicine, and ergonomics. This study also contributed to the advancement of scientific knowledge concerning hand control during Power Grip. Methods: A specially designed apparatus combining both an instrumented handle and a pressure map was used to record the forces at the hand/handle interface during maximal exertions. Data were processed such that the forces exerted on 25 hand anatomical areas were determined. Joint angles of the five fingers and the wrist were also computed from synchronized kinematic measurements. These processed data were used as input of a hand/wrist biomechanical model, which includes 23 degrees of freedom and 42 muscles to estimate muscle and joint forces. Results: Greater forces were applied on the distal phalanges of the long fingers compared with the middle and the proximal ones. Concomitantly, high solicitations were observed for FDP muscles. A large cocontraction level of extensor muscles was also estimated by the model and confirmed previously reported activities and injuries of extensor muscles related to the Power Grip. Quantifying hand internal loadings also resulted in new insights into the thumb and the wrist biomechanics. Output muscle tension ratios were all in smaller ranges than the ones reported in the literature. Conclusions: Including wrist and finger interactions in this hand model provided new quantification of muscle load sharing, cocontraction level, and biomechanics of the hand. Such information could complete future investigations concerning handle ergonomics or pathomechanisms of hand musculoskeletal disorders.

  • Quantification of Hand and Forearm Muscle Forces during a Maximal Power Grip Task
    Medicine and Science in Sports and Exercise, 2012
    Co-Authors: Benjamin Goislard De Monsabert, Jeremy Rossi, Eric Berton, Laurent Vigouroux
    Abstract:

    AB Purpose: The aim of this study was to estimate muscle and joint forces during a Power Grip task. Considering the actual lack of quantification of such internal variables, this information would be essential for sports sciences, medicine, and ergonomics. This study also contributed to the advancement of scientific knowledge concerning hand control during Power Grip. Methods: A specially designed apparatus combining both an instrumented handle and a pressure map was used to record the forces at the hand/handle interface during maximal exertions. Data were processed such that the forces exerted on 25 hand anatomical areas were determined. Joint angles of the five fingers and the wrist were also computed from synchronized kinematic measurements. These processed data were used as input of a hand/wrist biomechanical model, which includes 23 degrees of freedom and 42 muscles to estimate muscle and joint forces. Results: Greater forces were applied on the distal phalanges of the long fingers compared with the middle and the proximal ones. Concomitantly, high solicitations were observed for FDP muscles. A large cocontraction level of extensor muscles was also estimated by the model and confirmed previously reported activities and injuries of extensor muscles related to the Power Grip. Quantifying hand internal loadings also resulted in new insights into the thumb and the wrist biomechanics. Output muscle tension ratios were all in smaller ranges than the ones reported in the literature. Conclusions: Including wrist and finger interactions in this hand model provided new quantification of muscle load sharing, cocontraction level, and biomechanics of the hand. Such information could complete future investigations concerning handle ergonomics or pathomechanisms of hand musculoskeletal disorders. (C)2012The American College of Sports Medicine

  • Characterisation of forces exerted by the entire hand during the Power Grip: effect of the handle diameter
    Ergonomics, 2012
    Co-Authors: Jeremy Rossi, Eric Berton, Laurent Grélot, Charlie Barla, Laurent Vigouroux
    Abstract:

    The objective of this study was to analyse the effect of the handle diameter on the Grip forces exerted by the hand during a maximal Power Grip task. A handle ergometer, combining six instrumented beams and a pressure map, was used to determine the forces exerted by the palm side of the hand regrouping data from 10 anatomical sites (fingertips, phalanges, thumb, palm…). This methodology provided results giving new insight into the effect of the handle diameter on the forces exerted by the hand. First, it appeared that the relationship between the hand length/handle diameter ratio and the maximal Grip force fit a U-inverted curve with maximal values observed for a handle diameter measuring 17.9% of the hand length. Second, it was showed that the handle diameter influenced the forces exerted on the anatomical sites of the hand. Finally, it was showed that the handle diameter influenced the finger force sharing particularly for the index and the little fingers. Practitioner Summary: This study analysed the e...

  • Characterisation of forces exerted by the entire hand during the Power Grip: effect of the handle diameter
    Ergonomics, 2012
    Co-Authors: Jeremy Rossi, Eric Berton, Laurent Grélot, Charlie Barla, Laurent Vigouroux
    Abstract:

    The objective of this study was to analyse the effect of the handle diameter on the Grip forces exerted by the hand during a maximal Power Grip task. A handle ergometer, combining six instrumented beams and a pressure map, was used to determine the forces exerted by the palm side of the hand regrouping data from 10 anatomical sites (fingertips, phalanges, thumb, palm...). This methodology provided results giving new insight into the effect of the handle diameter on the forces exerted by the hand. First, it appeared that the relationship between the hand length/handle diameter ratio and the maximal Grip force fit a U-inverted curve with maximal values observed for a handle diameter measuring 17.9% of the hand length. Second, it was showed that the handle diameter influenced the forces exerted on the anatomical sites of the hand. Finally, it was showed that the handle diameter influenced the finger force sharing particularly for the index and the little fingers. Practitioner Summary: This study analysed the effect of the handle diameter on the Grip forces exerted by the hand during a maximal Power Grip force. This study showed that measurement of the totality of the forces exerted at the hand/handle interface is needed to better understand the ergonomics of handle tools. Our results could be re-used by designers and clinicians in order to develop handle tools which prevent hand pathologies.

Eric Berton - One of the best experts on this subject based on the ideXlab platform.

  • Handle Shape Affects the Grip Force Distribution and the Muscle Loadings During Power Grip Tasks.
    Journal of Applied Biomechanics, 2015
    Co-Authors: Jeremy Rossi, Benjamin Goislard De Monsabert, Eric Berton, Laurent Vigouroux
    Abstract:

    The objectives of this study were to investigate the effect of handle shape on the Grip force distribution in the hand and on the muscle forces during maximal Power Grip tasks. Eleven subjects maximally grasped 3 handles with different external shapes (circular, elliptic, and double-frustum). A handle dynamometer, equipped with both a force sensor and a pressure map, was used to record the forces exerted at the hand/handle interface. The finger and wrist joint postures were also computed from synchronized kinematic measurement. These processed data were then used as input of a biomechanical hand model to estimate muscle forces. The results showed that handle shape influences the maximal Grip force, the Grip force distribution, and the finger joint postures. Particularly, we observed that the elliptical shape resulted in a 6.6% lower maximal Grip force compared with the circular and double-frustum handle. Concomitantly, the estimated muscle forces also varied significantly according to the handle shape, with up to 48% differences for the flexor digitorum superficialis muscle for example. Interestingly, different muscle coordination strategies were observed depending on the handle shape, therefore suggesting a potential influence of these geometrical characteristics on pathological risks such as tendonitis.

  • Quantification of Hand and Forearm Muscle Forces during a Maximal Power Grip Task
    Medicine and Science in Sports and Exercise, 2012
    Co-Authors: Benjamin Goislard De Monsabert, Jeremy Rossi, Eric Berton, Laurent Vigouroux
    Abstract:

    GOISLARD DE MONSABERT, B., J. ROSSI, E. BERTON, and L. VIGOUROUX. Quantification of Hand and Forearm Muscle Forces during a Maximal Power Grip Task. Med. Sci. Sports Exerc., Vol. 44, No. 10, pp. 1906-1916, 2012. Purpose: The aim of this study was to estimate muscle and joint forces during a Power Grip task. Considering the actual lack of quantification of such internal variables, this information would be essential for sports sciences, medicine, and ergonomics. This study also contributed to the advancement of scientific knowledge concerning hand control during Power Grip. Methods: A specially designed apparatus combining both an instrumented handle and a pressure map was used to record the forces at the hand/handle interface during maximal exertions. Data were processed such that the forces exerted on 25 hand anatomical areas were determined. Joint angles of the five fingers and the wrist were also computed from synchronized kinematic measurements. These processed data were used as input of a hand/wrist biomechanical model, which includes 23 degrees of freedom and 42 muscles to estimate muscle and joint forces. Results: Greater forces were applied on the distal phalanges of the long fingers compared with the middle and the proximal ones. Concomitantly, high solicitations were observed for FDP muscles. A large cocontraction level of extensor muscles was also estimated by the model and confirmed previously reported activities and injuries of extensor muscles related to the Power Grip. Quantifying hand internal loadings also resulted in new insights into the thumb and the wrist biomechanics. Output muscle tension ratios were all in smaller ranges than the ones reported in the literature. Conclusions: Including wrist and finger interactions in this hand model provided new quantification of muscle load sharing, cocontraction level, and biomechanics of the hand. Such information could complete future investigations concerning handle ergonomics or pathomechanisms of hand musculoskeletal disorders.

  • Quantification of Hand and Forearm Muscle Forces during a Maximal Power Grip Task
    Medicine and Science in Sports and Exercise, 2012
    Co-Authors: Benjamin Goislard De Monsabert, Jeremy Rossi, Eric Berton, Laurent Vigouroux
    Abstract:

    AB Purpose: The aim of this study was to estimate muscle and joint forces during a Power Grip task. Considering the actual lack of quantification of such internal variables, this information would be essential for sports sciences, medicine, and ergonomics. This study also contributed to the advancement of scientific knowledge concerning hand control during Power Grip. Methods: A specially designed apparatus combining both an instrumented handle and a pressure map was used to record the forces at the hand/handle interface during maximal exertions. Data were processed such that the forces exerted on 25 hand anatomical areas were determined. Joint angles of the five fingers and the wrist were also computed from synchronized kinematic measurements. These processed data were used as input of a hand/wrist biomechanical model, which includes 23 degrees of freedom and 42 muscles to estimate muscle and joint forces. Results: Greater forces were applied on the distal phalanges of the long fingers compared with the middle and the proximal ones. Concomitantly, high solicitations were observed for FDP muscles. A large cocontraction level of extensor muscles was also estimated by the model and confirmed previously reported activities and injuries of extensor muscles related to the Power Grip. Quantifying hand internal loadings also resulted in new insights into the thumb and the wrist biomechanics. Output muscle tension ratios were all in smaller ranges than the ones reported in the literature. Conclusions: Including wrist and finger interactions in this hand model provided new quantification of muscle load sharing, cocontraction level, and biomechanics of the hand. Such information could complete future investigations concerning handle ergonomics or pathomechanisms of hand musculoskeletal disorders. (C)2012The American College of Sports Medicine

  • Characterisation of forces exerted by the entire hand during the Power Grip: effect of the handle diameter
    Ergonomics, 2012
    Co-Authors: Jeremy Rossi, Eric Berton, Laurent Grélot, Charlie Barla, Laurent Vigouroux
    Abstract:

    The objective of this study was to analyse the effect of the handle diameter on the Grip forces exerted by the hand during a maximal Power Grip task. A handle ergometer, combining six instrumented beams and a pressure map, was used to determine the forces exerted by the palm side of the hand regrouping data from 10 anatomical sites (fingertips, phalanges, thumb, palm…). This methodology provided results giving new insight into the effect of the handle diameter on the forces exerted by the hand. First, it appeared that the relationship between the hand length/handle diameter ratio and the maximal Grip force fit a U-inverted curve with maximal values observed for a handle diameter measuring 17.9% of the hand length. Second, it was showed that the handle diameter influenced the forces exerted on the anatomical sites of the hand. Finally, it was showed that the handle diameter influenced the finger force sharing particularly for the index and the little fingers. Practitioner Summary: This study analysed the e...

  • Characterisation of forces exerted by the entire hand during the Power Grip: effect of the handle diameter
    Ergonomics, 2012
    Co-Authors: Jeremy Rossi, Eric Berton, Laurent Grélot, Charlie Barla, Laurent Vigouroux
    Abstract:

    The objective of this study was to analyse the effect of the handle diameter on the Grip forces exerted by the hand during a maximal Power Grip task. A handle ergometer, combining six instrumented beams and a pressure map, was used to determine the forces exerted by the palm side of the hand regrouping data from 10 anatomical sites (fingertips, phalanges, thumb, palm...). This methodology provided results giving new insight into the effect of the handle diameter on the forces exerted by the hand. First, it appeared that the relationship between the hand length/handle diameter ratio and the maximal Grip force fit a U-inverted curve with maximal values observed for a handle diameter measuring 17.9% of the hand length. Second, it was showed that the handle diameter influenced the forces exerted on the anatomical sites of the hand. Finally, it was showed that the handle diameter influenced the finger force sharing particularly for the index and the little fingers. Practitioner Summary: This study analysed the effect of the handle diameter on the Grip forces exerted by the hand during a maximal Power Grip force. This study showed that measurement of the totality of the forces exerted at the hand/handle interface is needed to better understand the ergonomics of handle tools. Our results could be re-used by designers and clinicians in order to develop handle tools which prevent hand pathologies.

Jeremy Rossi - One of the best experts on this subject based on the ideXlab platform.

  • Handle Shape Affects the Grip Force Distribution and the Muscle Loadings During Power Grip Tasks.
    Journal of Applied Biomechanics, 2015
    Co-Authors: Jeremy Rossi, Benjamin Goislard De Monsabert, Eric Berton, Laurent Vigouroux
    Abstract:

    The objectives of this study were to investigate the effect of handle shape on the Grip force distribution in the hand and on the muscle forces during maximal Power Grip tasks. Eleven subjects maximally grasped 3 handles with different external shapes (circular, elliptic, and double-frustum). A handle dynamometer, equipped with both a force sensor and a pressure map, was used to record the forces exerted at the hand/handle interface. The finger and wrist joint postures were also computed from synchronized kinematic measurement. These processed data were then used as input of a biomechanical hand model to estimate muscle forces. The results showed that handle shape influences the maximal Grip force, the Grip force distribution, and the finger joint postures. Particularly, we observed that the elliptical shape resulted in a 6.6% lower maximal Grip force compared with the circular and double-frustum handle. Concomitantly, the estimated muscle forces also varied significantly according to the handle shape, with up to 48% differences for the flexor digitorum superficialis muscle for example. Interestingly, different muscle coordination strategies were observed depending on the handle shape, therefore suggesting a potential influence of these geometrical characteristics on pathological risks such as tendonitis.

  • Quantification of Hand and Forearm Muscle Forces during a Maximal Power Grip Task
    Medicine and Science in Sports and Exercise, 2012
    Co-Authors: Benjamin Goislard De Monsabert, Jeremy Rossi, Eric Berton, Laurent Vigouroux
    Abstract:

    GOISLARD DE MONSABERT, B., J. ROSSI, E. BERTON, and L. VIGOUROUX. Quantification of Hand and Forearm Muscle Forces during a Maximal Power Grip Task. Med. Sci. Sports Exerc., Vol. 44, No. 10, pp. 1906-1916, 2012. Purpose: The aim of this study was to estimate muscle and joint forces during a Power Grip task. Considering the actual lack of quantification of such internal variables, this information would be essential for sports sciences, medicine, and ergonomics. This study also contributed to the advancement of scientific knowledge concerning hand control during Power Grip. Methods: A specially designed apparatus combining both an instrumented handle and a pressure map was used to record the forces at the hand/handle interface during maximal exertions. Data were processed such that the forces exerted on 25 hand anatomical areas were determined. Joint angles of the five fingers and the wrist were also computed from synchronized kinematic measurements. These processed data were used as input of a hand/wrist biomechanical model, which includes 23 degrees of freedom and 42 muscles to estimate muscle and joint forces. Results: Greater forces were applied on the distal phalanges of the long fingers compared with the middle and the proximal ones. Concomitantly, high solicitations were observed for FDP muscles. A large cocontraction level of extensor muscles was also estimated by the model and confirmed previously reported activities and injuries of extensor muscles related to the Power Grip. Quantifying hand internal loadings also resulted in new insights into the thumb and the wrist biomechanics. Output muscle tension ratios were all in smaller ranges than the ones reported in the literature. Conclusions: Including wrist and finger interactions in this hand model provided new quantification of muscle load sharing, cocontraction level, and biomechanics of the hand. Such information could complete future investigations concerning handle ergonomics or pathomechanisms of hand musculoskeletal disorders.

  • Quantification of Hand and Forearm Muscle Forces during a Maximal Power Grip Task
    Medicine and Science in Sports and Exercise, 2012
    Co-Authors: Benjamin Goislard De Monsabert, Jeremy Rossi, Eric Berton, Laurent Vigouroux
    Abstract:

    AB Purpose: The aim of this study was to estimate muscle and joint forces during a Power Grip task. Considering the actual lack of quantification of such internal variables, this information would be essential for sports sciences, medicine, and ergonomics. This study also contributed to the advancement of scientific knowledge concerning hand control during Power Grip. Methods: A specially designed apparatus combining both an instrumented handle and a pressure map was used to record the forces at the hand/handle interface during maximal exertions. Data were processed such that the forces exerted on 25 hand anatomical areas were determined. Joint angles of the five fingers and the wrist were also computed from synchronized kinematic measurements. These processed data were used as input of a hand/wrist biomechanical model, which includes 23 degrees of freedom and 42 muscles to estimate muscle and joint forces. Results: Greater forces were applied on the distal phalanges of the long fingers compared with the middle and the proximal ones. Concomitantly, high solicitations were observed for FDP muscles. A large cocontraction level of extensor muscles was also estimated by the model and confirmed previously reported activities and injuries of extensor muscles related to the Power Grip. Quantifying hand internal loadings also resulted in new insights into the thumb and the wrist biomechanics. Output muscle tension ratios were all in smaller ranges than the ones reported in the literature. Conclusions: Including wrist and finger interactions in this hand model provided new quantification of muscle load sharing, cocontraction level, and biomechanics of the hand. Such information could complete future investigations concerning handle ergonomics or pathomechanisms of hand musculoskeletal disorders. (C)2012The American College of Sports Medicine

  • Characterisation of forces exerted by the entire hand during the Power Grip: effect of the handle diameter
    Ergonomics, 2012
    Co-Authors: Jeremy Rossi, Eric Berton, Laurent Grélot, Charlie Barla, Laurent Vigouroux
    Abstract:

    The objective of this study was to analyse the effect of the handle diameter on the Grip forces exerted by the hand during a maximal Power Grip task. A handle ergometer, combining six instrumented beams and a pressure map, was used to determine the forces exerted by the palm side of the hand regrouping data from 10 anatomical sites (fingertips, phalanges, thumb, palm…). This methodology provided results giving new insight into the effect of the handle diameter on the forces exerted by the hand. First, it appeared that the relationship between the hand length/handle diameter ratio and the maximal Grip force fit a U-inverted curve with maximal values observed for a handle diameter measuring 17.9% of the hand length. Second, it was showed that the handle diameter influenced the forces exerted on the anatomical sites of the hand. Finally, it was showed that the handle diameter influenced the finger force sharing particularly for the index and the little fingers. Practitioner Summary: This study analysed the e...

  • Characterisation of forces exerted by the entire hand during the Power Grip: effect of the handle diameter
    Ergonomics, 2012
    Co-Authors: Jeremy Rossi, Eric Berton, Laurent Grélot, Charlie Barla, Laurent Vigouroux
    Abstract:

    The objective of this study was to analyse the effect of the handle diameter on the Grip forces exerted by the hand during a maximal Power Grip task. A handle ergometer, combining six instrumented beams and a pressure map, was used to determine the forces exerted by the palm side of the hand regrouping data from 10 anatomical sites (fingertips, phalanges, thumb, palm...). This methodology provided results giving new insight into the effect of the handle diameter on the forces exerted by the hand. First, it appeared that the relationship between the hand length/handle diameter ratio and the maximal Grip force fit a U-inverted curve with maximal values observed for a handle diameter measuring 17.9% of the hand length. Second, it was showed that the handle diameter influenced the forces exerted on the anatomical sites of the hand. Finally, it was showed that the handle diameter influenced the finger force sharing particularly for the index and the little fingers. Practitioner Summary: This study analysed the effect of the handle diameter on the Grip forces exerted by the hand during a maximal Power Grip force. This study showed that measurement of the totality of the forces exerted at the hand/handle interface is needed to better understand the ergonomics of handle tools. Our results could be re-used by designers and clinicians in order to develop handle tools which prevent hand pathologies.