Search

Augmented feedback (aF) positively influences motor performance by enhancing motivation and/or by providing information about task execution. It was speculated that aF-induced performance increments that rely on motivation should also occur when providing incorrect aF, while performance increments that rely on guidance towards "successful executions" (i.e. improved performances) should only occur when aF is correct. We further hypothesised that the informational content of aF is more important in more complex motor tasks. Thus, 32 participants received two forms of aF (correct, incorrect) during maximal voluntary contractions (MVC's; maximise force without time constraints; less complex) and maximal explosive contractions (MEC's; maximise force in the shortest possible way; more complex) of the knee extensors. Peak torque (MVC), peak rate of torque development (MEC) and EMG signals of rectus femoris (RF) and vastus lateralis were recorded. Correct and incorrect aF significantly enhanced MVC performance, indicating that performance improvements resulted mainly from the motivational property of aF. The observed trend towards increased RF muscle activity supports this conclusion. In contrast, while correct aF positively impacted MEC performance, incorrect aF had a negative influence. This indicates that the informational property of aF guided participants towards movement executions resulting in improved (correct aF) or decreased (incorrect aF) performances. The observed simultaneous decrease in muscle activity suggests that participants changed motor strategy, supporting the guiding role of aF. Our results demonstrate that the motivational aspect of aF dominates in maximal tasks with lower complexity (MVC), while the informational aspect is used during more complex maximal tasks (MEC). Augmented feedback (aF) can influence performance by enhancing the motivation and/or by providing information about the execution of a task. Our results demonstrate that over the short-term, the motivational aspect of aF dominates in maximal tasks with lower complexity (maximal voluntary contractions). In contrast, the informational aspect will predominantly be used during more complex maximal tasks (maximal explosive contractions). This is the first study distinguishing between the motivational and informational aspects of aF during maximal motor tasks. Future research should focus on the long-term effects of these two separate aspects of aF. [ABSTRACT FROM AUTHOR]

The aims of the present study were to assess the validity and reliability of a novel simple test [Five Seconds Power Test (W5″ Test)] for estimating the mean power output during the bench press exercise at different loads, and its sensitivity to detect training-induced changes. Thirty trained young men completed as many repetitions as possible in a time of ≈5 s at 25%, 45%, 65% and 85% of one-repetition maximum (1RM) in two test sessions separated by four days. The number of repetitions, linear displacement of the bar and time needed to complete the test were recorded by two independent testers, and a linear encoder was used as the criterion measure. For each load, the mean power output was calculated in the W5″ Test as mechanical work per time unit and compared with that obtained from the linear encoder. Subsequently, 20 additional subjects (10 training group vs. 10 control group) were assessed before and after completing a seven-week training programme designed to improve maximal power. Results showed that both assessment methods correlated highly in estimating mean power output at different loads (rrange: 0.86–0.94;p < .01) and detecting training-induced changes (R2: 0.78). Good to excellent intra-tester (intraclass correlation coefficient (ICC) range: 0.81–0.97) and excellent inter-tester (ICC range: 0.96–0.99; coefficient of variation range: 2.4–4.1%) reliability was found for all loads. The W5″ Test was shown to be a valid, reliable and sensitive method for measuring mean power output during the bench press exercise in subjects who have previous resistance training experience. [ABSTRACT FROM PUBLISHER]

Augmented feedback (AF) can play an important role when learning or improving a motor skill. As research dealing with AF is broad and diverse, the purpose of this review is to provide the reader with an overview of the use of AF in exercise, motor learning and injury prevention research with respect to how it can be presented, its informational content and the limitations. The term ‘augmented’ feedback is used because additional information provided by an external source is added to the task-intrinsic feedback that originates from a person's sensory system. In recent decades, numerous studies from various fields within sport science (exercise science, sports medicine, motor control and learning, psychology etc.) have investigated the potential influence of AF on performance improvements. The first part of the review gives a theoretical background on feedback in general but particularly AF. The second part tries to highlight the differences between feedback that is given as knowledge of result and knowledge of performance. The third part introduces studies which have applied AF in exercise and prevention settings. Finally, the limitations of feedback research and the possible reasons for the diverging findings are discussed. The focus of this review lies mainly on the positive influence of AF on motor performance. Underlying neuronal adaptations and theoretical assumptions from learning theories are addressed briefly. [ABSTRACT FROM PUBLISHER]

The knee is a common site of injury in netball players. In this study, 10 high-performance netball players underwent a biomechanical assessment of their single leg landing technique whilst receiving a pass. Three-dimensional video and ground reaction force data were recorded using a motion analysis system. Net internal knee joint moments were calculated using a rigid body analysis and inverse dynamics. The kinematics of the support leg and front-on video footage was used to investigate whether players adhered to guidelines on safe and effective landing strategies. Results indicated that for most players the internal valgus moment was the largest frontal plane knee moment during the landing phase. This may reflect a relatively greater need to resist varus knee excursion or may be related to the kinematics of the hip. For 6 of the 10 players the rapid change to an internal knee valgus moment coincided with hip adduction. Since an increase in the magnitude of the internal valgus moment may increase the compressive forces in the medial compartment of the knee, further work should be undertaken to determine if a neuromuscular training intervention to improve the strength of the hip musculature may be beneficial for these players. A large relative excursion of the knee compared to the hip may indicate that these players had a greater reliance on the more distal segments of the lower extremity for the attenuation of the ground reaction forces. This information may be used to better understand potential knee injury mechanisms in netball players. [ABSTRACT FROM AUTHOR]

The aim of the study was to assess frontal and sagittal plane kinetics (normalized ground reaction force and normalized knee moment) in male and female university volleyball players when performing opposed block jump landings. Females displayed a significantly lower normalized knee extension moment at the start of muscle latency than males. The greater normalized knee extension moment at the start of muscle latency in females suggests that, through practice, they may have developed a landing strategy that minimizes the moment acting about the knee in the sagittal plane to reduce the likely strain on the passive support structures. The time histories of the normalized knee moment in the frontal plane were different between males and females. The maximum normalized knee valgus moment was significantly greater in females than males. The significantly different maximum normalized knee valgus moment between males and females indicates a greater likelihood of overloading the muscles of the knee in females during landing, which, in turn, is likely to increase the strain on the passive support structures. The increased likely strain on the passive support structures of the knee in females could contribute to the higher incidence of non-contact anterior cruciate ligament injury in females compared with males. [ABSTRACT FROM AUTHOR]