Effect of Increasing Levels of Fatigue on Knee Proprioception

Ligament injuries of the knee, particularly the anterior cruciate ligament (ACL), represent a significant percentage of lower extremity injuries during athletic participation. One possible factor associate with the high percentage of knee ligament injuries is a decrease in proprioception associated with fatigue. Previous research has found a decrease in proprioception following maximal fatigue of the knee musculature and following low intensity work to maximum fatigue. To date no investigation has examined if incremental increases in fatigue have an effect on proprioception. Therefore, the purpose of this study was to examine the effect of increasing levels of fatigue on active joint reposition sense (AJRS) of the knee

THE EFFECT OF INCREASING LEVELS OF EXERTION ON KNEE JOINT PROPRIOCEPTION

THE EFFECT OF INCREASING LEVELS OF EXERTION ON KNEE JOINT PROPRIOCEPTIONWilliam S. Gear, PhDUNIVERSITY OF PITTSBURGH, 2004The purpose of this study was to examine the effect of incremental levels of isokinetic concentric muscle exertion on passive reproduction of passive positioning (PRPP) and active reproduction of passive positioning (ARPP) at the knee joint in male and female collegiate soccer and basketball players.Subjects for this study included 20 (10 males and 10 females) volunteers. Subjects performed knee extension and flexion concentric isokinetic exercise until torque output fell below the 10%, 30%, or 50% of maximum hamstring torque for three consecutive repetitions. Subjects were then tested on either PRPP or ARPP following the isokinetic exercise session. Following testing of the first independent measure, subjects were given a 20 minute rest period. Following the rest period, the procedure was repeated for two more exercise sessions. Testing of PRPP and ARRP was counterbalanced between trials and sessions in order to decrease the chance of a learning effect on the results of each testing session.The major findings of this study indicate that increasing levels of exertion do not have a significant effect on either active reproduction ability [ARPP-45 degrees (F2,38 = 0.88, p = 0.42), ARPP-30 degrees (F2,38 = 0.69, p = .51), and ARPP-15 (F2,38 = .23, p = 0.80) or passive reproduction ability [PRPP-60 degrees*s-1 (F2,38 = 0.25, p = .78) , PRPP-90 degrees*s-1 (F2,38 = 0.31, p = 0.73), and PRPP120 degress*s-1 (F2,38 = 1.58, p = 0.22)]. However, the reliability of all PRPP and ARPP measures at 15 degrees demonstrated poor reliability.Fatigue has long been theorized to be a contributing factor in decreased proprioceptive acuity, and therefore a contributing factor to joint injury. The lack of significant findings may be explained by the idea that as the level of muscle fatigue increases muscle spindle discharge increases. Poor reliability for all PRPP and ARPP at 15 degrees draws into question the meaningfulness of the results for these measures

The development of Shetland's pelagic fishing industry : 1945-2000

This thesis is a case study in the transformation of a fishing industry on the North Atlantic fringe between 1945 and 2000. Fishing industries worldwide underwent fundamental and wide-ranging changes during this post-war period. For the fishing industries of the North Atlantic, the 1970s were a time of particularly profound crisis and change. Three interlinked revolutions were at their height: the second industrialisation of fisheries, the territorialisation of the seas and the imposition of multifarious fisheries management measures. These combined to mean that access to marine resources were seriously curtailed. Many fishing industries on the North Atlantic rim suffered and some never recovered. In contrast the Shetland pelagic fishing industry emerged from the crisis period having experienced a particularly dramatic and positive transformation. Part 1 (chapters 2 and 3) detail these changes in the catching and processing sectors. Part 2 analyses the forces which drove this development. It is demonstrated that these changes in the pelagic industry in Shetland were driven by three primary factors. In chapter 4, environmental and sociological drivers are examined together under a holistic framework known as the ‘maritime cultural landscape.’ It is shown that Shetland’s environmental context - as an isolated relatively barren island in the North Atlantic surrounded by fecund seas - has made the exploitation of marine resources both practical and necessary. Further, it describes how the historic socio-culture of the archipelago has been shaped by fishing, and in the post-war period how this was especially manifest in some of the outlying islands. Chapter 5 analyses the impact that market forces (demand) and technological drivers (supply) had on the development of the industry. It shows that consistent demand from Continental Europe has been the industry’s backbone but that increasing globalisation opened up new markets to the local processors. The chapter also argues that new catching methods increased productivity and profit and impelled development in other spheres such as vessel design and processing techniques. Finally chapter 6 discusses the political factors which have underpinned the industry’s development and argues that various forms of subvention and management measures impacted the industry’s development in a particularly positive way. Part 3 puts these developments in Shetland’s pelagic sector in the context of other North Atlantic maritime communities. The peculiarities of the Shetland case are especially highlighted. In summation, the work posits that the Shetland pelagic industry developed dramatically during the 1945-2000 period due to the positive confluence of three primary drivers, and the particular interaction of these drivers can explain the peculiarities of the Shetland example

Systematic exploration of energy landscapes in stochastic simulators

In this work, we present an approach for the exploration of low-dimensional effective potential landscapes. Making use of extrapolation in a low dimensional space of automatically learned variables (i.e. Diffusion Maps - DMAPs - variables) and machine learning schemes (e.g. Geometric Harmonics - GH) for lifting the new points into the ambient space, the described method enables to escape from local potential wells towards new minima. A simple three-dimensional stochastic differential equation system with a non-linear two-dimensional attractive manifold is considered for illustration purposes

Effect of Ankle Taping and Bracing on Dynamic Balance and Perception of Stability

Ankle injuries are the most common injury associated with sports participation. A recent study examining NCAA injury data found that 14.9% of all injuries sustained in 15 intercollegiate sports were injuries to the ankle. Taping and bracing are commonly used measures to prevent and/or protect the ankle from injury. Patients often report a feeling of increased stability due to tape and/or brace, however previous studies examining the effect of ankle appliances on stability have produced conflicting results. The purpose of this study was to examine the effect of taping and bracing on dynamic stability, and the perception of stability with and without ankle taping and bracing during dynamic stability testing