Effects of a lighter discus on shoulder muscle activity in elite throwers, implications for injury prevention

Background: Performance in discus throw requires high forces and torques generated from the shoulder of the throwing arm, making shoulder muscles at risk of overuse injury. Little is known on muscle activation patterns in elite discus throw. Hypothesis/Purpose: The purpose of this study was to examine the kinetics and shoulder muscle activation during discus throws by using two discs of different mass. It was hypothesized that the use of a lighter discus would modify the activation of the shoulder musculature compared to a standard discus. Study design: Case-control laboratory study Methods: Seven male elite discus throwers performed five throws using a standard discus (STD, 2.0 kg) and five throws using a lighter weight discus (LGT, 1.7 kg). Surface EMG was recorded for the biceps brachii (BB), deltoideus anterior (DA), deltoideus medialis (DM), clavicular head of the pectoralis major (PM), latissimus dorsi (LD), and trapezius medialis (TM). Three-dimensional high-speed video analysis was utilised to record discus speed and identify the different temporal phases of each throw from the preparation phase (P1) to the delivery phase (P5). Results: The EMG activation of LD lasted longer (p < 0.01) in P1 and was initiated later in P5 with the LGT discus compared to STD. In P5, the EMG intensity of BB decreased (p = 0.02) with LGT (%EMGmax = 50.4 ± 49.6%) compared to STD (64.8 ± 77.9%) and the activation of PM increased (p < 0.01) with LGT (86.2 ± 40.3%) compared to STD (66.2 ± 26.9%). The discus speed at release was increased (p = 0.04) by using the LGT discus (20.62 ± 0.75m.s-1) compared to STD (19.61 ± 0.57m.s-1). The throwing distance was also increased (P < 0.01) with the LGT (43.1 ± 4.3m) discus compared to STD (39.4 ± 3.4m). Conclusion: A lighter discus could be used by elite athletes in training t 50 o add variability in muscle solicitation and thus limit the overload on certain muscles of the shoulder region. These results may have implications to lower the risk of injury in discus throw. Clinical relevance: The increase in shoulder muscle activity combined with the accelerated forward swing of the throwing arm in P5 may help explain the incidence of muscle and tendon injuries clinically observed in discus throw. Using a lighter discus in training may add variability in muscle activity and motion kinetics to lower the mechanical load on the shoulder and tendons

The development of a track and field management manual for local organising committees in South Africa

Thesi

Effect of Attentional Focus on Learning and Performance in Youth Sports

Youth athletes are different from adult and elite athletes in several domains that include cognitive resources, working memory, automaticity of motor movements, conscious control for propensity, attentional focus, and acquisition of motor-skills. Due to significant differences between athletes, not all instructions and feedback provided by coaches are best suited for every player. Instructions and feedback may direct an athlete’s attentional focus and cognitive resources incorrectly leading to poor acquisition and performance of motor-skills. Clinical psychologists with knowledge of motor-skill acquisition, cognitive resources, learning theory, conscious control propensity, automaticity of motor movements, constrained action hypothesis, and attentional focus can follow the Youth Sports Consultation Model when working with youth sports programs, coaches, and youth athletes to improve the youth athlete’s experience by improving the language used by coaches and correctly directing the youth athlete’s attentional focus during the performance and acquisition of motor-skills

Learner-centred teaching methods in PE. Processing athletics teaching material in project method

We would like to present the methodological experience involves the participation of 11 teachers with their 20 classes of different grades each, within a period of 4-6 weeks. Processing the athletics teaching material was performed by adopting the project method and clustering around two project titles: ’Peasant Olympics’ (9 projects), and ‘Approaching Athletics’ (11 projects). Contents outside the PE class and school environment were in the limelight. Differentiating was main focal point, just like individual activity and volunteering. Pupils performed tasks on their own, in group and on class level. The students’ vitality increased in the field of motion and other activities. Because other subjects and fields of activity were involved in the framework of a PE lessons, students who had never been proactive, in this process have become so. In many fields of activity – of course in motion activities as well– differentiation became obvious. Therefore, the various activities in the project provided for many students chances of success, perhaps more than in a usual routine. The individual work, the cooperative solutions between students and external relationship-building was a characteristic of the process. Isolation of school classes was solved by project activity. Connecting different fields of science can raise understanding, the awareness, thus connecting sciences to real life. In this synthesis many teachers of other majors helpfully supported the PE teacher. It was hard for the teachers on the other hand, to get used to the helpful, supportive role demanded by the project-method, instead of the common ‘boss role’ which was usual

Utilization of Wearable Technology in Individual Sports

Wearable technology can be utilized in injury prevention and training analysis. Different user groups have to be taken into account when designing wearable devices

Quantifying the functional role of discrete movement variability: Links to adaptation and learning

Introduction: Movement variability can be defined as the variance in human movement from one trial or cycle to the next, often when attempting to maintain dynamic equilibrium (in the case of continuous skills) or achieve consistent movement outcome (for discrete skills). Some theoretical perspectives of motor control consider movement variability to be deleterious. However, the dynamical systems perspective proposes beneficial and functional roles for movement variability. Within this view variability has developed as an independent theme of research that has gained momentum over the past 25 years, attracting focus from various sub-disciplines within the field with a major contribution from sports biomechanics. The previous research within the field of movement variability has proposed that these functional roles include reducing the risk of injury, enabling coordination change and facilitating adaptation to varying task or environmental constraints. This thesis is primarily constituted of four sequential studies designed to further the method-related approach to, and theoretical understanding of, the interaction between variability in discrete movement and adaptation

Wenatchee School District Middle School Athletic Program: A New Concept in Middle Level Sports

The Wenatchee School District in Wenatchee, Washington instituted a new middle school athletic program in response to the construction of a new middle school. The new dynamics in the district provided the opportunity to reassess the goals, objectives, and philosophy of their middle school athletic program. Visitations to several of these programs and interviews with many of the administrators, coaches, teachers, and student athletes revealed many of the strengths and weaknesses of the various programs. This information was presented to Wenatchee School District middle level administrators, community leaders, and middle school staff in order to develop the criteria that met with Wenatchee\u27s philosophical needs. Four athletic model proposals were presented to the school board. An in-district model of intra-scholastic competition was adopted. Five sports seasons and two traditional sport placement switches were implemented. Increased participation, appropriate competition, and program continuity with the high school were a few of the program objectives

Attentional Focus and the Development of Skilled Performance

A central question in the development of skilled movement is: how a performer should focus their attention while preparing for the execution of a motor skill? Considerable evidence has shown that directing attention towards an intended movement effect (i.e., external focus) results in performance benefits relative to focusing on body movements (i.e., internal focus). While most of the previous research has emphasized the effects of internal versus external foci, evidence also suggests that external foci located at greater distances from the body (distal foci) are more effective than external foci located in greater proximity to the body (proximal foci) and that proximal external foci are still more effective than internal foci. However, in the context of the “distance effect”, the interaction between the performer’s level of expertise and focus distance has yet to be fully elucidated by the present literature. Three experiments were conducted to examine how the effectiveness of different types of attentional focus affect motor performance for novice and expert (skilled) performers. In addition, an investigation into the quality of movement coordination regarding the optimal external focus of attention was carried out.The first study (Chapter 2) utilized a within-participants design to address the question whether a focus on an image that represents a body part (platform) (external focus) would be more effective for motor performance than a focus on the body parts (arm) themselves (internal focus). Results indicated that novice volleyball players performing a whole-body, dynamic, and continuous aiming task (volleyball pass) produced higher total scores when focused on the platform rather than their arms. The second study (Chapter 3) investigated whether the distance of the external focus impacts the performance of relatively inexperienced and experienced performers differently. Using the same motor task as the first study, the results showed that the expert group’s accuracy scores were higher in the distal relative to proximal focus condition whereas the novice group’s accuracy scores was greater in the proximal relative to distal focus condition. Finally, an overhand volleyball serve was used in the third study with a within- participants design (Chapter 4). Alongside movement outcome measures (accuracy scores), biomechanical analysis was used to identify whether the distance of the attentional focus would alter the structure of movement variability in skilled performers as measured by upper extremity joint kinematics. The results demonstrated that a distal external focus relative to a proximal or internal focus enhances movement outcomes by increasing functional variability. Overall, data from three experimental studies in this dissertation suggest that the optimal external focus is a function of both the physical distance from the body as well as the performer’s level of expertise. That is, when performing complex motor skills, novices benefit from a proximal external focus while skilled individuals produce more effective performance with a distal external focus. Underlying these effects is fluid goal-action coupling due to changes in motor control associated with an external focus. Practitioners can take advantage of these findings when deciding the wording of instructions to optimize motor performance

Analysis of the backpack loading efects on the human gait

Gait is a simple activity of daily life and one of the main abilities of the human being. Often during leisure, labour and sports activities, loads are carried over (e.g. backpack) during gait. These circumstantial loads can generate instability and increase biomechanicalstress over the human tissues and systems, especially on the locomotor, balance and postural regulation systems. According to Wearing (2006), subjects that carry a transitory or intermittent load will be able to find relatively efficient solutions to compensate its effects.info:eu-repo/semantics/publishedVersio