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Alejandro Pérez-Castilla, Daniel Jerez-Mayorga, Dario Martínez-García, Ángela Rodríguez-Perea, Luis J. Chirosa-Ríos and Amador García-Ramos

regression model (linear and polynomial) 15 may provide the L-V with a higher accuracy. However, although the grip width used during the BP is known to affect muscle activation, 16 , 17 no study has examined the effect of the BP grip width on the L-V relationship. The L-V relationship has been commonly

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Dustin J. Oranchuk, Eric J. Drinkwater, Riki S. Lindsay, Eric R. Helms, Eric T. Harbour and Adam G. Storey

common practice for athletes to utilize the hook grip (HG; Figure  1 ) during the pull. 20 The HG anecdotally prevents the barbell from rotating in the hands therefore facilitating a secure grip. 20 In addition, athletes and coaches report that a relatively minimal amount of muscular effort is required

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Rienk M.A. van der Slikke, Annemarie M.H. de Witte, Monique A.M. Berger, Daan J.J. Bregman and Dirk Jan H.E.J. Veeger

, albeit only in 1 direction (adding mass). Finally, additional grip is expected to enhance performance. 7 – 9 It is common practice to use high-friction gloves in wheelchair racing and rugby, but not in wheelchair basketball. Although the use of gloves will probably not find its way into basketball, but

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Jérémy Rossi, Benjamin Goislard De Monsabert, Eric Berton and Laurent Vigouroux

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.

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Andreas Schweizer and Robert Hudek

The aim was to investigate differences of the kinetics of the crimp and the slope grip used in rock climbing. Nine cadaver fingers were prepared and fixated with the proximal phalanx in a frame. The superficial (FDS) and deep (FDP) flexor tendons were loaded selectively and together with 40 N in the crimp grip (PIP joint flexed 90°/DIP joint hyperextended) and the slope grip position (<25° flexed/50° flexed respectively). Five different grip sizes were tested and the flexion force which was generated to the grip was measured. In the crimp grip the FDP generated more flexion force in small sized holds whereas the FDS generated more force in the larger holds. During the slope grip the FDP was more effective than the FDS. While both tendons were loaded, the flexion force was always greater during crimp grip compared with the slope grip. The FDP seems to be most important for very small holds using the crimp grip but also during slope grip holds whereas the FDS is more important for larger flat holds.

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Loree L. Wagner, Sharon A. Evans, Joseph P. Weir, Terry J. Housh and Glen O. Johnson

The purpose of this study was to determine the effects of grip width, chest depth, limb lengths, and bar path on the performance of a maximal bench press. Subjects were 24 experienced male weight trainers. Bench press performance was assessed at six different grip widths (G1–G6). Repeated-measures ANOVA with Tukey post hoc comparisons revealed that bench press strength values at the two moderate grip widths (G3 and G4) were significantly greater than either the narrow or wide grip widths. First-order partial correlations showed no significant relationship between strength values and anthropometric variables when adjusted for differences in body weight. Standard two-dimensional cinematographic procedures were used to film a subsample (n = 6) while bench pressing using G1, G3, and G6. The results of the statistical comparisons of bar path indicated that as grip width increased, the horizontal and vertical distance from the bar to the shoulder decreased.

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Rafael F. Escamilla, Glenn S. Fleisig, Coop DeRenne, Marcus K. Taylor, Claude T. Moorman III, Rodney Imamura, Edward Barakatt and James R. Andrews

A motion system collected 120-Hz data from 14 baseball adult hitters using normal and choke-up bat grips. Six swings were digitized for each hitter, and temporal and kinematic parameters were calculated. Compared with a normal grip, the choke-up grip resulted in 1) less time during stride phase and swing; 2) the upper torso more opened at lead foot contact; 3) the pelvis more closed and less bat linear velocity at bat-ball contact; 4) less range of motion of the upper torso and pelvis during swing; 5) greater elbow flexion at lead foot contact; and 6) greater peak right elbow extension angular velocity. The decreased time during the stride phase when using a choke-up grip implies that hitters quicken their stride when they choke up. Less swing time duration and less upper torso and pelvis rotation range of motion using the choke-up grip supports the belief of many coaches and players that using a choke-up grip results in a “quicker” swing. However, the belief that using a choke-up grip leads to a faster moving bat was not supported by the results of this study.

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Stella Maris Michaelsen, Eliane C. Magdalon and Mindy F. Levin

Decreased dexterity in chronic stroke survivors results in diminished hand use and impacts quality of life. We studied reach-and-grasp coordination and aperture scaling during reach to grasp using different grasp types and object sizes (33–55mm). Chronic stroke survivors with hand paresis and controls grasped cylinders with the whole hand or fingertips. Three stroke subjects with more severe hand paresis had disrupted reach/grasp coordination and used compensatory strategies for arm transport and/or grasping. Nine stroke subjects with less severe paresis scaled aperture to cylinder diameter (p < .001) but had slower movements, used excessive trunk movement, and had prolonged deceleration times. Relative time to maximal grip aperture (TMA) occurred earlier in stroke subjects and in both groups when grasping the small cylinder (p < .002). Despite deficits in reach and grasp, chronic stroke survivors with mild to moderate hand paresis may retain grip aperture scaling to object size for different grasp types.

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Philip E. Martin and Gary D. Heise

Archery instructors believe that force distribution (FD) between the hand and bow grip can have a considerable effect on arrow flight, but there is no empirical support for this speculation. This study examined FD on the bow grip in experienced archers and explored the possible relationships between FD, performance, and fatigue. FD was quantified for 15 experienced archers (8 highly skilled [HS] and 7 less skilled [LS]) using 15 unobtrusive force sensors as each archer completed 72 shots. Arrow position relative to the target center, estimated net moments and moment arms about vertical and horizontal axes through the grip, and shot-to-shot variability in the estimated moments and moment arms were computed for three blocks of six shots. Results demonstrated that (a) estimated moments and moment arms were not consistently related to observed vertical or horizontal deviations in arrow position, (b) there were no systematic differences in FD between HS and LS archers, (c) fatigue had no quantifiable effect on FD, and (d) HS archers displayed less shot-to-shot variability in vertical FD than LS archers, but similar variability horizontally. Results did not support the above-noted common belief of archery instructors.

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Leanna Ferrand and Slobodan Jaric

The purpose of this study was to explore the effects of handedness on coordination of grip (G) and load (L) forces in static bimanual manipulation tasks. Participants (N = 10) exerted various L profiles against an externally fixed hand-held device based on presumably open-loop and closed-loop neural control mechanisms, (i.e., mediated and not mediated, respectively, by sensory feedback). Average G/L ratio and the coupling of G and L (i.e., stability of the G/L ratio and correlation between G and L) were separately assessed in each hand. The results revealed a lower average G/L ratio in the non-dominant hand suggesting a more economical grip, while the indices of G and L coupling were similar in two hands. The dominant and non-dominant hand failed to reveal relative advantages in the tasks predominantly based on open- and closed-loop control mechanisms, respectively. We conclude that, due to the static nature of the tested tasks, the particular advantage of the non-dominant hand in G and L coordination could be in line with the recently proposed specialization of the non-dominant limb for control of position. However, the overall results are not in line with classic views of the prevailing open- closed-loop neural mechanisms in the control of the dominant and nondominant limb, respectively.