No description available.

Context: Several recovery strategies have been used, with limited effectiveness, to reduce the muscle discomfort or pain and the diminished muscle performance following a bout of unaccustomed physical activity, a condition known as delayed onset of muscle soreness (DOMS). Muscle damage in this condition is associated with mechanical disruption of the muscle and connective tissue and inflammation and increased oxidative stress. Low frequency, low intensity, whole body periodic acceleration (WBPA) that increases nitric oxide (NO) release from vascular endothelium into the circulation through increased pulsatile shear stress offers a potential solution. This is because endothelial derived nitric oxide has anti-inflammatory, antioxidant and anti-nociceptive properties. Objective: The purpose of this study was to examine the effects of WBPA on the pain and diminished muscle performance associated with DOMS induced by unaccustomed eccentric arm exercise in young male subjects. Design: Longitudinal. Setting: University Exercise Physiology Laboratory. Participants: Seventeen active men, 23.4 +/- 4.6 yr of age. Intervention: Subjects made six visits to the research facility over a two-week period. On day one, the subject performed a 1RM elbow flexion test and was then randomly assigned to the WBPA or control group. Criterion measurements were taken on Day 2, prior to and immediately following performance of the eccentric exercise protocol (10 sets of 10 repetitions using 120% of 1RM) and after the recovery period. During all subsequent sessions (24, 48, 72, and 96 h) these data were collected before the WBPA or passive recovery was provided. Main Outcome Measures: Isometric strength (MVC), blood markers (CPK, MYO, IL-6, TNF-alpha and Uric Acid), soreness, pain, circumference, and range of motion (ROM). Results: Significantly higher MVC values were seen for the WBPA group across the entire 96 h recovery period. Additionally, within group differences were seen in CPK, MYO, IL-6, soreness, pain, circumference, and ROM showing a smaller impact and more rapid recovery by the WBPA group. Conclusion: Application of WBPA hastens recovery from DOMS after eccentric exercise. Given the lack of other potential mechanisms, these effects appear to be mediated by the increased NO release with WBPA.

Thesis (PhD (Sports Science))--Stellenbosch University, 2008. / There is general consensus that athletes, striving to compete and perform at the highest level, should optimally balance training and competition stress with adequate regeneration. Although a well-planned training programme is of utmost importance, the time between training sessions and competitions is critical for the modern-day athlete. It is suggested that athletes should apply a variety of recovery methods to enhance the regeneration process. Although team sport is a popular entity throughout the world, there is limited published research on the regeneration process in team athletes and recovery methods to enhance the regeneration process. The aim of this study was to develop a model that could serve as a guideline for the regeneration of team athletes within the South African context. Two phases were involved in the process of developing a model. Phase one involved a research of literature in order to assess which strategies can be implemented for athletic regeneration, and what information team athletes are given for regeneration. The second phase involved an investigation into the recovery strategies that are currently used for regeneration by elite South African team players during the competitive phase of the year. Research questions focused on the recovery methods used by players, the perceived importance of various recovery methods to the players, and the relationship between sport and level of participation in the use of recovery strategies. This study did not attempt to assess the knowledge of the players on recovery methods.

The design and selection of surface treatment binders in service is currently based on specifications that only account for the penetration and ductility of emulsion residues or the penetration and viscosity of hot-applied asphalt cements. These specifications consider neither the entire range of temperatures that the binders may be subjected to during production and in service, nor long-term aging behavior. A surface performance-graded (SPG) specification for the selection of surface treatment binders was developed as part of previous Texas Department of Transportation (TxDOT) and National Cooperative Highway Research Program (NCHRP) projects. The work performed under the TxDOT Project 0-6616 was the basis for this thesis. In this project, the SPG specification, which is performance-based and takes into account the physical properties of the binder at the temperature ranges in which the material will be used, was further validated. This was accomplished by standardizing the emulsion residue recovery method through the evaluation of two warm oven methods, exploring the exclusive use of the dynamic shear rheometer (DSR) for determining performance-based properties, and further field validating the thresholds for these properties. The laboratory and field results were used to revise the SPG specification for surface treatment binders in service. Binder samples collected from chip seal projects constructed on selected highway sections in Texas in summer 2011 were tested and graded according to the existing SPG specification developed in previous research projects. Two warm oven emulsion residue recovery methods were used and compared. New DSR tests, including the multiple stress creep recovery (MSCR) test and the frequency sweep test were evaluated for developing additional criteria in the SPG specification. The SPG grades of the surface binder samples evaluated from laboratory tests were compared with the actual field performance of the highway sections one year after construction. The SPG specification was found to be functional in terms of enabling the selection of binders to ensure adequate surface treatment performance. Moreover, the results obtained from the MSCR and DSR frequency sweep tests were compared with field performance to develop additional criteria in the specification. Further validation is recommended to investigate the effects of construction and quality control processes, as this study is limited to producing a revised SPG specification for properties that address stiffness and aggregate retention in service.

Heavy oil production depends on the understanding of mechanical and flow properties of unconsolidated or weakly consolidated sands under different loading paths and boundary conditions. Reconstituted bitumen-free Athabasca oil-sands samples were used to investigate the geomechanics of a steam injection process such as the Steam Assisted Gravity Drainage (SAGD). Four stress paths have been studied in this work: triaxial compression, radial extension, pore pressure increase and isotropic compression. Absolute permeability, end-point relative permeability to oil & water (kro and krw), initial water saturation and residual oil saturation were measured while the samples deformed. Triaxial compression is a stress path of increasing mean stress while radial extension and pore pressure increase lead to decreasing mean stress. Pore pressure increase experiments were carried out for three initial states: equal axial and confining stresses, axial stress greater than confining stress and confining stress greater than axial stress. Pore pressure was increased under four boundary conditions: 1) constant axial and confining stress; 2) constant axial stress and zero radial strain; 3) zero axial strain and constant confining stress; and 4) zero axial and radial strain. These experiments were designed to mimic geologic conditions where vertical stress was either S1 or S3, the lateral boundary conditions were either zero strain or constant stress, and the vertical boundary conditions were either zero strain or constant stress. Triaxial compression caused a decrease in permeability as the sample compacted, followed by appreciable permeability enhancement during sample dilation. Radial extension led to sample dilation, shear failure and permeability increase from the beginning. The krw and kro increased by 40% and 15% post-compaction respectively for the samples corresponding to lower depths during triaxial compression. For these samples, residual oil saturation decreased by as much as 40%. For radial extension, the permeability enhancement decreased with depth and ranged from 20% to 50% while the residual oil saturation decreased by up to 55%. For both stress paths, more shear-enhanced permeability was observed for samples tested at lower pressures, implying that permeability enhancement is higher for shallower sands. The pore pressure increase experiments showed an increase of only 0-10% in absolute permeability except when the effective stress became close to zero. This could possibly have occurred due to steady state flow not being reached during absolute permeability measurement. The krw curves generally increased as the pore pressure was increased from 0 psi. The increase ranged from 5% to 44% for the different boundary conditions and differential stresses. The kro curves also showed an increasing trend for most of the cases. The residual oil saturation decreased by 40-60% for samples corresponding to shallow depths while it increased by 0-10% for samples corresponding to greater depths. The reservoirs with high differential stress are more conducive to favorable changes in permeability and residual oil saturation. These results suggested that a decreasing mean stress path is more beneficial for production increase than an increasing mean stress path. The unconsolidated sands are over-consolidated because of previous ice loading which makes the sand matrix stiffer. In this work, it was found that over-consolidation, as expected, decreased the porosity and permeability (40-50%) and increased the Young’s and bulk moduli of the sand. The result is sand which failed at higher than expected stress during triaxial compression. Overall, results show that lab experiments support increased permeability due to steam injection operations in heavy oil, and more importantly, the observed reduction in residual oil saturation implies SAGD induced deformation should improve recovery factors. / text