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Purpose: Coordination in ice hockey skating has been minimally investigated, particularly in females. The objective was to compare lower-extremity inter-segment coordination of collegiate male and female ice hockey players during forward skating starts. Methods: 3D kinematic data were collected on collegiate male (n = 9) and female (n = 10) participants during accelerative steps. Continuous relative phase (CRP) was calculated for shank-sagittal/thigh-sagittal, shank-sagittal/thigh-frontal, and foot-sagittal/shank-sagittal segment pairs across 2.5 strides on each side. Principal component analysis (PCA) extracted features of greatest variability of the CRP and relationships between principal components and sex were investigated using hierarchical linear model. Results: Males demonstrated more out-of-phase coordination (higher CRP) for side one (p = .01) and side two (p < .01) shank-sagittal/thigh-sagittal as well as side one shank-sagittal/thigh-frontal (p < .01) segment pairs throughout each step. Females demonstrated a greater change in CRP from late stance/early swing to late swing/early stance on side two for shank-sagittal/thigh-frontal segments (p < .01). For side two shank-sagittal/thigh-frontal segments, faster males utilized more out-of-phase coordination throughout each step whereas faster females utilized more in-phase coordination (p < .01). Conclusion: Males and females may employ different coordinative strategies to achieve faster skating speeds. Males tend to utilize more out-of-phase coordination of the shank and thigh throughout strides, although coordinative differences of the shank and foot were not found between sexes. Further investigation is needed to examine the relationship between lower limb strength and coordination as well as the effect of targeted training protocols on lower extremity coordinative patterns.
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Deficits in movement patterns during cutting while running might place soccer players at risk of injury. The objective was to compare joint angles and intersegment coordination between sexes and ages during an unanticipated side-step cutting task in soccer players. This cross-sectional study recruited 11 male (four adolescents and seven adults) and 10 female (six adolescents and four adults) soccer players. Three-dimensional motion capture was used to measure lower-extremity joint and segment angles as participants performed an unanticipated cutting task. Hierarchical linear models examined relationships between joint angle characteristics with age and sex. Continuous relative phase was used to quantify intersegment coordination amplitude and variability. These values were compared between age and sex groups using analysis of covariance. Adult males had greater hip flexion angle excursions than adolescent males, while adult females had smaller excursions than adolescent females (p = .011). Females had smaller changes in hip flexion angles (p = .045), greater hip adduction angles (p = .043), and greater ankle eversion angles (p = .009) than males. Adolescents had greater hip internal rotation (p = .044) and knee flexion (p = .033) angles than adults, but smaller changes in knee flexion angles at precontact compared with stance/foot off (p < .001). For intersegment coordination, females were more out-of-phase than males in the foot/shank segment in the sagittal plane. There were no differences in intersegment coordination variability between groups. Differences in joint motion during an unanticipated cutting task were present between age groups and sexes. Injury prevention programs or training programs may be able target specific deficits to lower injury risk and improve performance.
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Futebol , Adulto , Adolescente , Humanos , Masculino , Feminino , Futebol/lesões , Articulação do Joelho , Estudos Transversais , Amplitude de Movimento Articular , Extremidade Inferior , Fenômenos BiomecânicosRESUMO
The objective was to compare lower extremity inter-segment coordination between high-calibre and low-calibre ice hockey players during forward full stride skating. A 10-camera Vicon motion capture system collected kinematic data on male high-calibre (n = 8) and low-calibre (n = 8) participants. Continuous relative phase (CRP) was calculated for shank-sagittal/thigh-sagittal, shank-sagittal/thigh-frontal and foot-sagittal/shank-sagittal segment pairs. Principal component analysis (PCA) was used to extract features of greatest variability of the CRP and hierarchical linear model investigated relationships between principal components and skill level. High-calibre players demonstrated more out-of-phase coordination (higher CRP) of shank-sagittal/thigh-sagittal throughout glide/push-off (p = 0.011) as well as a delay in the transition to more in-phase coordination during early recovery phase (p = 0.014). For shank-sagittal/thigh-frontal (p = 0.013), high-calibre players had more out-of-phase coordination throughout the entire stride. High-calibre players were also associated with an earlier transition to more out-of-phase coordination of the foot-sagittal/shank-sagittal during push-off (p = 0.007) and a smaller difference in CRP between mid-glide/early recovery (p = 0.016). Utilising more out-of-phase modes of coordination may allow players to more easily adjust to optimal modes of coordination throughout skating strides. Skating drills incorporating varying speed, directionality and external stimuli may encourage the development of more optimal coordination during skating.
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Hóquei , Patinação , Humanos , Masculino , Fenômenos Biomecânicos , Extremidade Inferior , Perna (Membro)RESUMO
The aims of this study were to evaluate the feasibility of using IMU sensors and machine learning algorithms for the instantaneous fitting of ice hockey sticks. Ten experienced hockey players performed 80 shots using four sticks of differing constructions (i.e., each stick differed in stiffness, blade pattern, or kick point). Custom IMUs were embedded in a pair of hockey gloves to capture resultant linear acceleration and angular velocity of the hands during shooting while an 18-camera optical motion capture system and retroreflective markers were used to identify key shot events and measure puck speed, accuracy, and contact time with the stick blade. MATLAB R2020a's Machine Learning Toolbox was used to build and evaluate the performance of machine learning algorithms using principal components of the resultant hand kinematic signals using principal components accounting for 95% of the variability and a five-fold cross validation. Fine k-nearest neighbors algorithms were found to be highly accurate, correctly classifying players by optimal stick flex, blade pattern, and kick point with 90-98% accuracy for slap shots and 93-97% accuracy for wrist shots in fractions of a second. Based on these findings, it appears promising that wearable sensors and machine learning algorithms can be used for reliable, rapid, and portable hockey stick fitting.
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Hóquei , Aceleração , Fenômenos Biomecânicos , Aprendizado de Máquina , Projetos PilotoRESUMO
There is currently no efficient way to quantify overhead throwing volume in water polo. Therefore, this study aimed to test the feasibility of a method to detect passes and shots in water polo automatically using inertial measurement units (IMU) and machine-learning algorithms. Eight water polo players wore one IMU sensor on the wrist (dominant hand) and one on the sacrum during six practices each. Sessions were filmed with a video camera and manually tagged for individual shots or passes. Data were synchronised between video tagging and IMU sensors using a cross-correlation approach. Support vector machine (SVM) and artificial neural networks (ANN) were compared based on sensitivity and specificity for identifying shots and passes. A total of 7294 actions were identified during the training sessions, including 945 shots and 5361 passes. Using SVM, passes and shots together were identified with 94.4% (95%CI = 91.8-96.4) sensitivity and 93.6% (95%CI = 91.4-95.4) specificity. Using ANN yielded similar sensitivity (93.0% [95%CI = 90.1-95.1]) and specificity (93.4% [95%CI = 91.1 = 95.2]). The results suggest that this method of identifying overhead throwing motions with IMU has potential for future field applications. A set-up with one single sensor at the wrist can suffice to measure these activities in water polo.
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BACKGROUND: Very limited investigations have been conducted exploring risk factors for injury in water polo players. A gap remains in the literature regarding identification of variables that should be considered as part of player screening evaluations. PURPOSE: To estimate whether previous injury, changes in strength, range of motion (ROM) or upward scapular rotation (UR) are related to shoulder injuries in water polo players. STUDY DESIGN: Descriptive cohort study. METHODS: Thirty-nine international-level players participated (19 males). Shoulder internal (IR) and external rotation (ER) peak torque was measured using an isokinetic device (CONtrex MJ). Shoulder ROM was measured passively using standard goniometry. Scapular UR was measured using a laser digital inclinometer. At baseline players were divided into groups: those with and without previous shoulder injuries. Independent t-tests and Mann-Whitney U tests were used to compare the study variables between groups. After nine months, a second analysis compared the same athletes, who were then grouped by those who had or had not sustained new injuries. Effect sizes were calculated with a Hedge's g. Chi squared analysis compared proportion of injured players with and without previous injury. RESULTS: Eighteen participants (46%) had previous injuries at baseline. Players with a previous injury showed higher peak torques for IR (0.62±0.15 vs 0.54±0.13N/kg, p=0.04, g=0.60); larger loss of IR ROM (9.9±9.1 vs 4.1±7.5°, p=0.04, g=0.68), but no statistical difference in UR (p=0.70). After nine months, there were no statistical strength differences between groups. Loss of IR ROM was significantly higher in the injured group (9.8±9.8 vs 4.0±6.7°, p=0.04, g=0.68), as well as UR (13.0±3.0 vs 10.4±3.3°, p=0.01, g=0.81). History of previous injury was significantly related to developing a new injury (OR 6.5, p=0.02). Logistic regression found previous injury and UR most important contributors to injury risk. CONCLUSIONS: Previous injury, changes in IR ROM and UR are related to new shoulder injuries in water polo, but further variables such as rest, training load, or psychosocial factors may explain the incidence of new injuries. LEVEL OF EVIDENCE: Level 3.
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OBJECTIVE: To summarise the information available in the literature on the prevalence of injuries in water polo and injury risk factors. METHODS: Protocol was registered on Open Science Framework. MEDLINE, CINAHL, Embase and SPORTDiscus databases were searched for keywords relating to water polo and injuries on 3 February 2021. References were searched for additional studies. Only original research papers in English or French were included, and studies without an injured group were excluded. A data extraction file was made based on the Cochrane Collaboration recommendations. Study quality was evaluated with the Newcastle-Ottawa scales for cohorts and a modified version for cross-sectional studies. RESULTS: The initial search yielded 581 articles, with 5 more added from reference lists, but only 41 remained after removing duplicates and applying inclusion/exclusion criteria. Thirty-one articles identified the head, fingers and shoulders as the most common sites of injury. Ten articles on mechanism of injury focused mainly on the shoulder, with degenerative changes, posture, scapular alignment, strength, flexibility and overhead shooting kinematics as the main injury risk factors. Publication types included cohort studies, cross-sectional studies, and one case series. CONCLUSIONS: Most traumatic injuries affect the hands and the head from unexpected contact with the ball or opponents. Conversely, training injuries seem to affect mainly the shoulder area. Low level evidence suggests a correlation between shoulder injuries and lack of strength or flexibility as well as large volumes of overhead throwing. Further prospective research is needed to investigate risk factors for other body areas.
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CONTEXT: Previous authors suggest that lack of strength is an important risk factor for injuries in water polo. Hand-held dynamometers have potential as a clinical tool to measure strength, but they have not been validated in water polo players. OBJECTIVE: The purpose of this study was to estimate intertrial variability and concurrent validity of hand-held dynamometer shoulder strength measurements in elite water polo players. METHODS: A total of 19 male and 20 female elite water polo players performed isometric external (ER) and internal (IR) rotation strength tests against a hand-held dynamometer bilaterally in supine position with the shoulder in a 90-90 position. In addition, concentric IR and ER was captured at 90 deg/s with an isokinetic dynamometer, and torque values were determined near the 90-90 position. MAIN OUTCOME MEASURES: Spearman correlation coefficients were calculated for ER torque, IR torque, and ER/IR ratios between the devices. Two-way mixed-model intraclass correlations were used to assess intertrial variability. RESULTS: Correlations between the devices were strong to very strong (ρ = .65-.82, P < .01) for absolute IR and ER but low for ER/IR ratios (ρ = .29, P = .07). There was less agreement at higher torque values. Intertrial variability was low with intraclass correlation values .88 to .93, P < .05. CONCLUSIONS: These results show that hand-held dynamometers are adequate clinical alternatives to measure absolute shoulder strength in water polo players. Stronger players may require stronger evaluators to resist the player's push and obtain reliable results.
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Ombro , Esportes Aquáticos , Feminino , Força da Mão , Humanos , Masculino , Força Muscular , Dinamômetro de Força Muscular , Rotação , TorqueRESUMO
The objective was to compare joint angles during full stride skating on ice between high- and low-calibre hockey players. High (n = 8) and low (n = 8) calibre male participants completed full stride skating on ice for two to five trials. A 10-camera motion capture system collected kinematic data. Ankle, knee, and hip angles were calculated. Principal component analysis (PCA) identified important angle characteristics and each trial was scored against principal components (PC-scores). Hierarchical linear models examined relationships between PC-scores and skill level with and without controlling for speed. High-calibre participants were associated with greater ankle inversion during push-off and recovery (p < 0.001), greater knee extension (p = 0.051) and external rotation at push-off (p = 0.038), and greater hip flexion throughout stride (p = 0.027) after controlling for speed. Interactions existed between speed and skill level including faster skating speeds were associated with increased plantarflexion at push-off in low-calibre participants while there was no relationship in high-calibre participants. Skating pattern differences between skill levels provide an indication of ideal joint motion during skating. Players should be encouraged to plantarflex the ankle during push-off, extend and externally rotate the knee during push-off, and increase hip flexion throughout stride.
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Hóquei/fisiologia , Destreza Motora/fisiologia , Adulto , Tornozelo/fisiologia , Fenômenos Biomecânicos , Quadril/fisiologia , Humanos , Joelho/fisiologia , Masculino , Análise de Componente Principal , Estudos de Tempo e Movimento , Adulto JovemRESUMO
There has been minimal work examining kinematics of ice hockey wrist shots. The objective was to determine if puck and blade speed were related to trunk rotation during wrist shots in elite and recreational players. Elite (n = 10) and recreational (n = 10) ice hockey players completed wrist shots while skating and from a stationary position on real ice. A 14 camera motion capture system collected kinematic data for the trunk, pelvis, stick, and puck. Dependent variables included peak puck and blade speeds. Independent variables included peak trunk rotation angles, trunk rotation range of motion (ROM), and group (elite vs. recreational). Hierarchical linear models compared relationships between dependent and independent variables for both skating and stationary wrist shots. Greater peak trunk rotation away from the net was related (p < 0.05) to faster puck and blade speeds for skating and stationary wrist shots. This relationship was stronger in the recreational group for skating wrist shots (p < 0.01). Greater trunk rotation ROM was related (p = 0.01) to faster puck and blade speeds for the skating wrist shots only. Coaches should encourage players to increase trunk rotation away from the net during wrist shots, especially in recreational players.
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Fenômenos Biomecânicos/fisiologia , Hóquei/fisiologia , Movimento/fisiologia , Amplitude de Movimento Articular/fisiologia , Tronco/fisiologia , Articulação do Punho/fisiologia , Aceleração , Adulto , Análise de Variância , Desempenho Atlético/fisiologia , Estudos Transversais , Humanos , Modelos Lineares , Masculino , Movimento (Física) , Rotação , Patinação/fisiologia , Equipamentos Esportivos/normasRESUMO
The skating acceleration to maximal speed transition (sprint) is an essential skill that involves substantial lower body strength and effective propulsion technique. Coaches and athletes strive to understand this optimal combination to improve performance and reduce injury risk. Hence, the purpose of this study was to compare body centre of mass and lower body kinematic profiles from static start to maximal speed of high calibre male and female ice hockey players on the ice surface. Overall, male and female skaters showed similar centre of mass trajectories, though magnitudes differed. The key performance difference was the male's greater peak forward skating speed (8.96 ± 0.44 m/s vs the females' 8.02 ± 0.36 m/s, p < 0.001), which was strongly correlated to peak leg strength (R 2 = 0.81). Males generated greater forward acceleration during the initial accelerative steps, but thereafter, both sexes had similar stride-by-stride accelerations up to maximal speed. In terms of technique, males demonstrated greater hip abduction (p = 0.006) and knee flexion (p = 0.026) from ice contact to push off throughout the trials. For coaches and athletes, these findings underscore the importance of leg strength and widely planted running steps during the initial skating technique to achieve maximal skating speed over a 30 m distance.
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Hóquei/fisiologia , Perna (Membro)/fisiologia , Destreza Motora/fisiologia , Corrida/fisiologia , Aceleração , Fenômenos Biomecânicos , Feminino , Quadril/fisiologia , Humanos , Joelho/fisiologia , Masculino , Força Muscular/fisiologia , Fatores Sexuais , Estudos de Tempo e Movimento , Adulto JovemRESUMO
The forward skating start is a fundamental skill for male and female ice hockey players. However, performance differences by athlete's sex cannot be fully explained by physiological variables; hence, other factors such as skating technique warrant examination. Therefore, the purpose of this study was to evaluate the body movement kinematics of ice hockey skating starts between elite male and female ice hockey participants. Male (n = 9) and female (n = 10) elite ice hockey players performed five forward skating start accelerations. An 18-camera motion capture system placed on the arena ice surface captured full-body kinematics during the first seven skating start steps within 15 meters. Males' maximum skating speeds were greater than females. Skating technique sex differences were noted: in particular, females presented ~10° lower hip abduction throughout skating stance as well as ~10° greater knee extension at initial ice stance contact, conspicuously followed by a brief cessation in knee extension at the moment of ice contact, not evident in male skaters. Further study is warranted to explain why these skating technique differences exist in relation to factors such as differences in training, equipment, performance level, and anthropometrics.
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Hóquei/fisiologia , Destreza Motora/fisiologia , Patinação/fisiologia , Aceleração , Fenômenos Biomecânicos , Feminino , Quadril/fisiologia , Humanos , Joelho/fisiologia , Masculino , Movimento , Fatores Sexuais , Estudos de Tempo e Movimento , Adulto JovemRESUMO
It is common for biomechanics data sets to contain numerous dependent variables recorded over time, for many subjects, groups, and/or conditions. These data often require standard sorting, processing, and analysis operations to be performed in order to answer research questions. Visualization of these data is also crucial. This manuscript presents biomechZoo, an open-source toolbox that provides tools and graphical user interfaces to help users achieve these goals. The aims of this manuscript are to (1) introduce the main features of the toolbox, including a virtual three-dimensional environment to animate motion data (Director), a data plotting suite (Ensembler), and functions for the computation of three-dimensional lower-limb joint angles, moments, and power and (2) compare these computations to those of an existing validated system. To these ends, the steps required to process and analyze a sample data set via the toolbox are outlined. The data set comprises three-dimensional marker, ground reaction force (GRF), joint kinematic, and joint kinetic data of subjects performing straight walking and 90° turning manoeuvres. Joint kinematics and kinetics processed within the toolbox were found to be similar to outputs from a commercial system. The biomechZoo toolbox represents the work of several years and multiple contributors to provide a flexible platform to examine time-series data sets typical in the movement sciences. The toolbox has previously been used to process and analyse walking, running, and ice hockey data sets, and can integrate existing routines, such as the KineMat toolbox, for additional analyses. The toolbox can help researchers and clinicians new to programming or biomechanics to process and analyze their data through a customizable workflow, while advanced users are encouraged to contribute additional functionality to the project. Students may benefit from using biomechZoo as a learning and research tool. It is hoped that the toolbox can play a role in advancing research in the movement sciences. The biomechZoo m-files, sample data, and help repositories are available online (http://www.biomechzoo.com) under the Apache 2.0 License. The toolbox is supported for Matlab (r2014b or newer, The Mathworks Inc., Natick, USA) for Windows (Microsoft Corp., Redmond, USA) and Mac OS (Apple Inc., Cupertino, USA).
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Fenômenos Biomecânicos , Humanos , SoftwareRESUMO
Running on side-sloped surfaces is a common obstacle in the environment; however, how and to what extent the lower extremity kinematics adapt is not well known. The purpose of this study was to determine the effects of side-sloped surfaces on three-dimensional kinematics of hip, knee, and ankle during stance phase of running. Ten healthy adult males ran barefoot along an inclinable runway in level (0°) and side-sloped (10° up-slope and down-slope inclinations, respectively) configurations. Right hip, knee, and ankle angles along with their time of occurrence were analysed using repeated measures MANOVA. Up-slope hip was more adducted (p = 0.015) and internally rotated (p = 0.030). Knee had greater external rotations during side-sloped running at heel-strike (p = 0.005), while at toe-off, it rotated externally and internally during up-slope and down-slope running, respectively (p = 0.001). Down-slope ankle had greatest plantar flexion (p = 0.001). Up-slope ankle had greatest eversion compared with down-slope (p = 0.043), while it was more externally rotated (p = 0.030). These motion patterns are necessary to adjust the lower extremity length during side-sloped running. Timing differences in the kinematic events of hip adduction and external rotation, and ankle eversion were observed (p = 0.006). Knowledge on these alterations is a valuable tool in adopting strategies to enhance performance while preventing injury.
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Articulação do Tornozelo/fisiologia , Articulação do Quadril/fisiologia , Articulação do Joelho/fisiologia , Corrida/fisiologia , Adolescente , Adulto , Traumatismos em Atletas/prevenção & controle , Desempenho Atlético/fisiologia , Fenômenos Biomecânicos , Humanos , Extremidade Inferior/fisiologia , Masculino , Rotação , Fatores de Tempo , Adulto JovemRESUMO
The purpose of this study was to compare lower extremity joint angular position and muscle activity during elliptical exercise using different foot positions and also during exercise on a lateral elliptical trainer. Sixteen men exercised on a lateral elliptical and on a standard elliptical trainer using straight foot position, increased toe-out angle, and a wide step. Motion capture and electromyography systems were used to obtain 3D lower extremity joint kinematics and muscle activity, respectively. The lateral trainer produced greater sagittal and frontal plane knee range of motion (ROM), greater peak knee flexion and extension, and higher vastus medialis activation compared with other conditions (P < .05). Toe-out and wide step produced the greatest and smallest peak knee adduction angles, respectively (P < .05). The lateral trainer produced greater sagittal and frontal plane hip ROM and greater peak hip extension and flexion compared with all other conditions (P < .05). Toe-out angle produced the largest peak hip external rotation angle and lowest gluteus muscle activation (P < .05). Findings from this study indicate that standard elliptical exercise with wide step may place the knee joint in a desirable frontal plane angular position to reduce medial knee loads, and that lateral elliptical exercise could help improve quadriceps strength but could also lead to larger knee contact forces.
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Articulação do Tornozelo/fisiologia , Exercício Físico/fisiologia , Articulação do Quadril/fisiologia , Articulação do Joelho/fisiologia , Adulto , Fenômenos Biomecânicos , Eletromiografia , Humanos , Extremidade Inferior/fisiologia , Masculino , Músculo Esquelético/fisiologia , Amplitude de Movimento Articular , Adulto JovemRESUMO
Ice hockey requires rapid transitions between skating trajectories to effectively navigate about the ice surface. Player performance relates in large part to effective change-of-direction manoeuvres, but little is known about how those skills are performed mechanically and the effect of equipment design on them. The purpose of this study was to observe the kinetics involved in those manoeuvres as well as to compare whether kinetic differences may result between two skate models of varying ankle mobility. Eight subjects with competitive ice hockey playing experience performed rapid lateral (90°) left and right change-of-direction manoeuvres. Kinetic data were collected using force strain gauge transducers on the blade holders of the skates. Significantly greater forces were applied by the outside skate (50-70% body weight, %BW) in comparison to the inside skate (12-24%BW, p < 0.05). Skate model and turn direction had no main effect, though significant mixed interactions between leg side (inside/outside) with skate model or turn direction (p < 0.05) were observed, with a trend for left-turn dominance. This study demonstrates the asymmetric dynamic behaviour inherent in skating change-of-direction tasks.
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Hóquei/fisiologia , Patinação/fisiologia , Adulto , Articulação do Tornozelo/fisiologia , Fenômenos Biomecânicos/fisiologia , Pé/fisiologia , Humanos , Cinética , Masculino , Movimento/fisiologia , Equipamentos Esportivos , Análise e Desempenho de Tarefas , Transdutores , Adulto JovemRESUMO
Though transversely inclined (cross-sloped) surfaces are prevalent, our understanding of the biomechanical adaptations required for cross-slope locomotion is limited. The purpose of this study was to examine ground reaction forces (GRF) in cross-sloped and level walking and running. Nine young adult males walked and ran barefoot along an inclinable walkway in both level (0°) and cross-slope (10°) configurations. The magnitude and time of occurrence of selected features of the GRF were extracted from the force plate data. GRF data were collected in level walking and running (LW and LR), inclined walking and running up-slope (IWU and IRU), and down-slope (IWD and IRD), respectively. The GRF data were then analyzed using repeated measures MANOVA. In the anteroposterior direction, the timing of the peak force values differed across conditions during walking (p=.041), while the magnitude of forces were modified across conditions for running (p=.047). Most significant differences were observed in the mediolateral direction, where generally force values were up to 390% and 530% (p<.001) larger during the cross-slope conditions compared to level for walking and running, respectively. The maximum force peak during running occurred earlier at IRU compared to the other conditions (p≤.031). For the normal axis a significant difference was observed in the first maximum force peak during walking (p=.049). The findings of this study showed that compared to level surfaces, functional adaptations are required to maintain forward progression and dynamic stability in stance during cross-slope walking and running.
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Fenômenos Biomecânicos , Lateralidade Funcional , Orientação , Corrida , Caminhada , Suporte de Carga , Adolescente , Adulto , Marcha , Humanos , Masculino , Adulto JovemRESUMO
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.
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Desempenho Atlético/fisiologia , Hóquei/fisiologia , Articulação do Punho/fisiologia , Aceleração , Análise de Variância , Braço/fisiologia , Fenômenos Biomecânicos , Humanos , Imageamento Tridimensional , Masculino , Análise de Regressão , Equipamentos Esportivos , Adulto JovemRESUMO
Cross-slopes are a common terrain characteristic, however there is no biomechanical knowledge of the intra-foot adaptations required for running on these surface inclinations. The purpose of this study was to evaluate the kinematic changes induced within the foot while running on a transversely inclined surface. A three-segment foot model distinguishing between the hindfoot, forefoot, and hallux was used for this purpose. Nine healthy experienced male runners volunteered to perform level (0°) and cross-slope (10°) running trials barefoot at a moderate speed. Multivariate analysis of variance (MANOVA) for repeated measures was used to analyze the kinematics of the hindfoot with respect to tibia (HF/TB), forefoot with respect to hindfoot (FF/HF), and hallux with respect to forefoot (HX/FF) during level running (LR), incline running up-slope (IRU), and incline running down-slope (IRD) conditions. In the sagittal plane, the FF/HF angle showed greater dorsiflexion at peak vertical force production (MaxFz) in IRD compared to LR (p=0.042). The HX/FF was significantly more extended during IRU than LR at foot strike (p=0.027). More importantly, frontal plane asymmetries were also found. HF/TB angles revealed greater inversion at foot strike followed by greater eversion at MaxFz for IRU compared to IRD (p=0.042 and p=0.018, respectively). For the FF/HF angle, maximum eversion was greater during IRD than LR (p=0.035). Data suggests that running on cross-slopes can induce substantial intra-foot kinematic adaptations, whether this represents a risk of injury to both recreational and professional runners remains to be determined.