Differences in the directions of torque produced by motor units might be used by the nervous system to coordinate posture and movement. Here we report plantar flexion and abduction isometric torques exerted at the ankle by 158 motor units in the cat medial gastrocnemius (MG) muscle. In five cats, motor unit torque direction differed by an average of 10°. Torque direction was weakly correlated with unit contraction time in 3 of 5 experiments, with tetanic force in 3 of 5 experiments, and with conduction velocity in 1 of 5 experiments. The direction of whole muscle torque, however, was constant at all levels of MG activation produced in sural and crossed extension reflexes. Thus, although there is a range in the direction of torque produced by motor units in the cat MG, we find no evidence for the ordering of motor units according to torque direction during MG activation.
Alan J. Sokoloff, Timothy C. Cope, T. Richard Nichols and Arthur W. English
Serge Brand, Markus Gerber, Flora Colledge, Edith Holsboer-Trachsler, Uwe Pühse and Sebastian Ludyga
) “Reading the Mind in the Eyes” test would have yielded a different pattern of results. Third, we acknowledge that further latent and unassessed psychological processes might have biased two or more dimensions in the same or opposite direction. Fourth, the latter observation holds particularly true as it
A. Mark Williams and Bradley Fawver
.01.006 Loffing , F. , Sölter , F. , Hagemann , N. , & Strauss , B. ( 2016 ). On-court position and handedness in visual anticipation of stroke direction in tennis . Psychology of Sport and Exercise, 27 , 195 – 204 . doi:10.1016/j.psychsport.2016.08.014 10.1016/j.psychsport.2016.08.014 Loffing , F
Hatice Mujde Ayık and Michael J. Griffin
magnitude, the frequency, the direction, and the duration of the oscillations combine to cause loss of balance. In trains, buses, aircraft, buildings, and so on, the motions causing instability are often transient, so it is desirable to understand whether instability can be predicted from a peak measure of
J. Greg Anson, Brian l. Hyland, Rolf Kötter and Jeffery R. Wickens
A movement task was used to investigate the effects of precued variables on reaction time. The task involved rapid rotation of a hand-held manipulandum to target locations and required either pronation or supination of the forearm through short or long extent. The effects on reaction time of precues signalling target direction, extent, or a combination of direction and extent, were measured. The longest reaction times occurred when no information about direction or extent was provided in the precue (all parameters uncertain). Complete prior specification of target position produced the shortest reaction times. Specification of direction when extent was uncertain produced a significantly larger reduction in reaction time than specification of extent when direction was uncertain. Prior specification of extent also produced a small but significant reduction in reaction time relative to the condition in which direction and extent were specified in a mutually conditional manner. The results are discussed in relation to parameter precuing and motor programming, in which the direction is programmed by the pre-selection of neurons representing the muscles to be used in the task while programming of extent is represented by their level of activity during task performance.
Atsushi Makimoto, Yoko Sano, Satoru Hashizume, Akihiko Murai, Yoshiyuki Kobayashi, Hiroshi Takemura and Hiroaki Hobara
75 Hz for GRFs 12 and 10 Hz for marker trajectories. 13 According to a previous study, 14 the timing of foot-ground contacts was determined using a threshold greater than 16 N of vertical GRF. The GRF variables analyzed were the peak vertical forces, peak braking (posterior direction
Javier Yanci, Daniel Castillo, Aitor Iturricastillo, Tomás Urbán and Raúl Reina
high international repercussion, footballers with CP deserve special attention. Most research has investigated the physical characteristics of footballers with CP, such as cardiovascular capacity, running economy, 4 changes of direction (CODs) ability, 5 jump capacity, muscle strength, and anaerobic
Antonio C.S. Guimaraes and James G. Hay
The purpose of this study was to identify the mechanical characteristics of the hands-between-the-feet grab starting technique which contribute to a faster start. Twenty-four high school swimmers performed four trials of a grab start followed by a glide to a distance of 9 m. The results suggested that to obtain a faster start, swimmers should (a) move the center of mass fast in the forward direction while the feet are in contact with the starting block, (b) maximize the force exerted through the feet in the backward direction, and (c) maximize the force exerted through the hands against the starting block in the forward and upward direction.
Nick Dobbin, Jamie Highton, Samantha L. Moss and Craig Twist
.3) 42.5 (5.2) 0.63 (0.12) Most likely ↑ 1.12 (0.12) Most likely ↑ 0.70 (0.14) Most likely ↑ Change of direction, s 20.31 (1.22) 20.44 (1.30) 19.68 (0.84) 0.10 (0.13) Likely trivial −0.46 (0.14) Most likely ↓ −0.60 (0.13) Most likely ↓ Medicine-ball throw, m 6.3 (0.9) 7.1 (0.8) 8.1 (0.8) 1.00 (0.14) Most
Cornelius John, Andreas Stotz, Julian Gmachowski, Anna Lina Rahlf, Daniel Hamacher, Karsten Hollander and Astrid Zech
their shoes on and jump off the box with both feet in the direction of the landing line. Immediately after landing, the participant had to rebound for a maximal vertical jump. To assure that the participants understood the task and to avoid any incorrect trials, participants were asked to conduct some