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1.
Michaud-Paquette Y Magee P Pearsall D Turcotte R 《Sports biomechanics / International Society of Biomechanics in Sports》2011,10(1):12-21
The purpose of this study was to identify joint angular kinematics that corresponds to shooting accuracy in the stationary ice hockey wrist shot. Twenty-four subjects participated in this study, each performing 10 successful shots on four shooting targets. An eight-camera infra-red motion capture system (240 Hz), along with passive reflective markers, was used to record motion of the joints, hockey stick, and puck throughout the performance of the wrist shot. A multiple regression analysis was carried out to examine whole-body kinematic variables with accuracy scores as the dependent variable. Significant accuracy predictors were identified in the lower limbs, torso and upper limbs. Interpretation of the kinematics suggests that characteristics such as a better stability of the base of support, momentum cancellation, proper trunk orientation and a more dynamic control of the lead arm throughout the wrist shot movement are presented as predictors for the accuracy outcome. These findings are substantial as they not only provide a framework for further analysis of motor control strategies using tools for accurate projection of objects, but more tangibly they may provide a comprehensive evidence-based guide to coaches and athletes for planned training to improve performance. 相似文献
2.
Margaret H. Collins David J. Pearsall Gerald S. Zavorsky Hamid Bateni Rene A. Turcotte David L. Montgomery 《Journal of sports sciences》2013,31(2):83-90
The aims of this study were to determine if there are significant kinematic changes in running pattern after intense interval workouts, whether duration of recovery affects running kinematics, and whether changes in running economy are related to changes in running kinematics. Seven highly trained male endurance runners (VO 2max = 72.3 +/- 3.3 ml kg -1 min -1 ; mean +/- s) performed three interval running workouts of 10 X 400 m at a speed of 5.94 +/- 0.19 m s -1 (356 +/- 11.2 m min -1 ) with a minimum of 4 days recovery between runs. Recovery of 60, 120 or 180 s between each 400 m repetition was assigned at random. Before and after each workout, running economy and several kinematic variables were measured at speeds of 3.33 and 4.47 m s -1 (200 and 268 m min -1 ). Speed was found to have a significant effect on shank angle, knee velocity and stride length (P ? 0.05). Correlations between changes pre- and post-test for VO 2 (ml kg -1 min -1 ) and several kinematic variables were not significant (P > 0.05) at both speeds. In general, duration of recovery was not found to adversely affect running economy or the kinematic variables assessed, possibly because of intra-individual adaptations to fatigue. 相似文献
3.
Tyler J. Stidwill Rene Albert Turcotte Phil Dixon David J. Pearsall 《Sports Engineering》2009,12(2):63-68
The purpose of this study was to develop a portable force measurement system for ice hockey skating. The system consisted
of three strain gauge pairs affixed to an ice hockey skate’s blade holder with wire leads connected to a microprocessor controlled
data acquisition device carried in a backpack worn by the skater. The configuration of the strain gauges simultaneously determined
the vertical and medial–lateral force components experienced by the blade holder with a resolution accuracy of 1.9 N and a
coefficient of variation of 9.2%. On-ice testing of this system with subjects performing forward start, acceleration, and
constant velocity skating permitted unencumbered, natural movement and demonstrated clear, unambiguous signal responses, high
trial-to-trial repeatability, and easy data retrieval. The practicality and accuracy of this testing approach have many applications,
such as a quantitative tool for skating force assessment to aid athletes and coaches, as well as providing the means to examine
other skill-specific dynamics. 相似文献
4.
Background: computer software is widely used to support literacy learning. There are few randomised trials to support its effectiveness. Therefore, there is an urgent need to rigorously evaluate computer software that supports literacy learning.
Methods: we undertook a pragmatic randomised controlled trial among pupils aged 11–12 within a single state comprehensive school in the North of England. The pupils were randomised to receive 10 hours of literacy learning delivered via laptop computers or to act as controls. Both groups received normal literacy learning. A pre‐test and two post‐tests were given in spelling and literacy. The main pre‐defined outcome was improvements in spelling scores.
Results: 155 pupils were randomly allocated, 77 to the ICT group and 78 to control. Four pupils left the school before post‐testing and 25 pupils did not have both pre‐ and post‐test data. Therefore, 63 and 67 pupils were included in the main analysis for the ICT and control groups respectively. After adjusting for pre‐test scores there was a slight increase in spelling scores, associated with the ICT intervention, but this was not statistically significant (0.954, 95% confidence interval (CI) – 1.83 to 3.74, p = 0.50). For reading scores there was a statistically significant decrease associated with the ICT intervention (?2.33, 95% CI ?0.96 to ?3.71, p = 0.001).
Conclusions: we found no evidence of a statistically significant benefit on spelling outcomes using a computer program for literacy learning. For reading there seemed to be a reduction in reading scores associated with the use of the program. All new literacy software needs to be tested in a rigorous trial before it is used routinely in schools. 相似文献
5.
The goal of this research was to develop a method to quantify the dynamic strain profile (DSP) of an ice hockey stick shaft and assess the potential influence of player skill and stick shaft stiffness on DSP during slap (SS) and wrist shots (WS). Seventeen adult males performed shots with two different stick stiffness’ on synthetic ice. Subjects were subdivided as high (HC) and low calibre (LC). Dependent measures included strain measures from five strain gauge pairs along the shaft length recorded at 10 kHz. In general, this approach was sufficiently sensitive to clearly distinguish between shot types (strains SS > WS), player calibre (strains HC > LC) and stick models (strain flex77 > flex102) as well as to identify within stick deflection differences along the shaft. This strain based analysis has a time and spatial resolution undetected by common motion capture based systems. 相似文献
6.
Upjohn T Turcotte R Pearsall DJ Loh J 《Sports biomechanics / International Society of Biomechanics in Sports》2008,7(2):206-221
The objectives of the study were to describe lower limb kinematics in three dimensions during the forward skating stride in hockey players and to contrast skating techniques between low- and high-calibre skaters. Participant motions were recorded with four synchronized digital video cameras while wearing reflective marker triads on the thighs, shanks, and skates. Participants skated on a specialized treadmill with a polyethylene slat bed at a self-selected speed for 1 min. Each participant completed three 1-min skating trials separated by 5 min of rest. Joint and limb segment angles were calculated within the local (anatomical) and global reference planes. Similar gross movement patterns and stride rates were observed; however, high-calibre participants showed a greater range and rate of joint motion in both the sagittal and frontal planes, contributing to greater stride length for high-calibre players. Furthermore, consequent postural differences led to greater lateral excursion during the power stroke in high-calibre skaters. In conclusion, specific kinematic differences in both joint and limb segment angle movement patterns were observed between low- and high-calibre skaters. 相似文献
7.
Predictors of scoring accuracy: ice hockey wrist shot mechanics 总被引：1，自引：0，他引：1
The purpose of this study was to identify the stationary “wrist shot” technique (movement patterns) of the ice hockey stick
that corresponds to the accuracy of puck trajectory. A total of 25 subjects participated in this study, ranging from high
to low caliber players. Each performed ten successful wrist shots at four targets (two top corners, two bottom corners). Performances
were evaluated by recording the movements of the stick’s shaft and blade and of the puck with a 3D motion capture system at
240 Hz. Kinematics of the shaft and blade of the hockey stick were examined using a multiple regression analysis to predict
accuracy scores. In general, the results indicated that accuracy corresponded to release parameters (both puck release orientation
and velocity), shaft bending and change in blade orientations; though, parameter weighting differed substantially for top
versus bottom targets. Future studies are warranted to identify the whole body kinematic patterns associated with the hockey
stick kinematics. 相似文献
8.
The purpose of this study was to investigate the extent to which ice hockey facial protectors can decrease overall head acceleration
during blunt impacts, as well as to identify whether attenuation differences exist between visors and cages. Commercial models
of three cages and three visors were assessed. Blunt impacts were simulated, permitting the measurement of peak accelerations
(PA) within the surrogate headform. Results indicated that face protectors, in combination with helmets, substantially reduced
PA during blunt impacts within threshold safety limits (below 300g). In general, cages showed lower PA than visors. Differences
between models were also observed during repeated impacts and impact site. In conclusion, this study demonstrates that facial
protectors function beyond their role in solely preventing facial injuries, complementing the role of the helmet in attenuating
head deceleration during impact. Consequently, the utilisation of facial protectors may reduce the severity and incidence
of head injuries. 相似文献
9.
Collins MH Pearsall DJ Zavorsky GS Bateni H Turcotte RA Montgomery DL 《Journal of sports sciences》2000,18(2):83-90
The aims of this study were to determine if there are significant kinematic changes in running pattern after intense interval workouts, whether duration of recovery affects running kinematics, and whether changes in running economy are related to changes in running kinematics. Seven highly trained male endurance runners (VO2max = 72.3+/-3.3 ml x kg(-1) x min(-1); mean +/- s) performed three interval running workouts of 10 x 400 m at a speed of 5.94+/-0.19 m x s(-1) (356+/-11.2 m x min(-1)) with a minimum of 4 days recovery between runs. Recovery of 60, 120 or 180 s between each 400 m repetition was assigned at random. Before and after each workout, running economy and several kinematic variables were measured at speeds of 3.33 and 4.47 m x s(-1) (200 and 268 m x min(-1)). Speed was found to have a significant effect on shank angle, knee velocity and stride length (P < 0.05). Correlations between changes pre- and post-test for VO2 (ml x kg(-1) x min(-1)) and several kinematic variables were not significant (P > 0.05) at both speeds. In general, duration of recovery was not found to adversely affect running economy or the kinematic variables assessed, possibly because of intra-individual adaptations to fatigue. 相似文献
10.
Sarah M.S. Pearsall 《Cultural and Social History》2013,10(3):289-293
AbstractThis article examines the strategies and tactics of surveillance that were used by Manchester City Police in relation to anxieties about gender, sexuality, juvenile delinquency and drugs misuse in post-war England. In the early 1960s the members-only ‘coffee beat club’ became a target of police activity, resulting in a series of raids, minor prosecutions and the intensification of the licensing laws. Commenting on the relationship between police culture and youth culture, including the leisure practices of adolescent girls, this article argues that the targeting of the ‘coffee beat club’ became a motif for the defence of an older imagined social order. 相似文献