The influence of tracking marker locations on three-dimensional wrist kinematics.

OBJECTIVES: To determine the influence of tracking marker locations on wrist kinematics during free movements and the golf swing, with the intention of recommending a solution that generates meaningful three-dimensional wrist kinematics. DESIGN: Repeated measures. METHODS: Six participants performed free movements of flexion/extension, radial/ulnar deviation and forearm supination/pronation, with a further sixteen participants performing golf drives. A passive motion capture system tracked four different marker sets located on participants' hand and forearm segments. Variables of peak angle and range of motion were used to compare marker sets during free movements and angles at the top of the backswing and impact were compared during the golf swing. RESULTS: Wrist marker set had a large (η2≥0.557) and often significant (p≤0.051) effect on the variables measured during free movements, and a mixed (η2≥0.108, p≤0.198) effect on wrist angles during the golf swing. Wrist axial rotation range of motion during free forearm supination/pronation revealed the greatest difference between marker sets (∼42°). The large values generated by two of the marker sets for this rotation appeared to influence the values of flexion/extension and radial/ulnar deviation during the golf swing. CONCLUSIONS: The location of markers used to measure wrist kinematics can have a large effect on the angles generated. A solution of two markers located at the distal end of the forearm and one at the proximal, appears to minimise values of wrist axial rotation during free forearm supination/pronation and, consequently, produce more meaningful three-dimensional wrist kinematics.

Elite Players' Perceptions of Football Playing Surfaces: A Qualitative Study.

Purpose: The decision by the International Football Association Board in 2004 to approve the use of artificial surfaces in elite football (soccer) competitions remains controversial amongst many players, managers and coaching staff. The aim of this study was to conduct a comprehensive assessment of players' opinions to better understand the influence of playing surfaces on the game of football and identify factors that may contribute to differences of opinion. Method: Qualitative data were collected from 103 elite footballers and 21 coaching staff during a series of interviews and focus groups. A thematic analysis was conducted to identify patterns in the data. Results: Players considered that the type and condition of a playing surface influenced ball-surface interactions, game play, tactics/strategy, footwear selection, movement, risk of injury and fatigue. Together these influence a player's perception of the suitability of a surface and also their mindset, which could ultimately affect their performance. Conclusion: The majority of participants in this study expressed a higher preference for natural grass over artificial turf pitches. A perceived increased risk of injury on artificial turf remains a primary concern despite a lack of supporting evidence in research studies. To address this discrepancy, the reporting of muscle soreness and the effect of constant surface switching merit further consideration. Not all participants shared the same views and player characteristics such as age, surface experience, injury history and playing style/position were found to be potential factors that could account for differences in elite players' opinions regarding the surfaces used in football.

Perceived Links Between Playing Surfaces and Injury: a Worldwide Study of Elite Association Football Players.

BACKGROUND: Injuries in association football (soccer) are debilitating for players and can also be detrimental to the success of a team or club. The type or condition of a playing surface has been empirically linked to injuries, yet results are inconclusive. The overall purpose of this study was to analyse elite football players' perceived links between playing surfaces and injury from a worldwide cohort of players. The results of this study can help to inform areas for future playing surface research aimed at trying to alleviate user concerns and meet user (i.e. the player) needs. METHODS: Quantitative data were collected from 1129 players across the globe to address the aim of this study. RESULTS: Ninety-one percent of players believed the type or condition of a surface could increase injury risk. Abrasive injuries, along with soreness and pain, were perceived to be greater on artificial turf. Surface type, surface properties and age were all potential risk factors identified by the players and linked to the playing surfaces. CONCLUSIONS: The results identified three areas where future research should be focussed to help develop surfaces that alleviate user concerns and meet user (i.e. player) needs: (i) current reporting of soreness, pain or fatigue as injuries, (ii) contribution of surface properties to injury; and (iii) surface experience of players from different countries differentiates their views of injury risk.

Comparison of centre of gravity and centre of pressure patterns in the golf swing.

Analysing the centre of pressure (COP) and centre of gravity (COG) could reveal stabilising strategies used by golfers throughout the golf swing. This study identified and compared golfers' COP and COG patterns throughout the golf swing in medial-lateral (ML) and anterior-posterior (AP) directions using principal component analysis (PCA) and examined their relationship to clubhead velocity. Three-dimensional marker trajectories were collected using Vicon motion analysis and force plate data from two Kistler force plates for 22 low-handicap golfers during drives. Golfers' COG and COP were expressed as a percentage distance between their feet. PCA was performed on COG and COP in ML and AP directions. Relationships between principal component (PC) scores were examined using Pearson correlation and regression analysis used to examine the relationship with clubhead velocity. ML COP movements varied in magnitude (PC1), rate of change and timing (PC2 and PC3). The COP and COG PC1 scores were strongly correlated in both directions (ML: r = 0.90, P < .05; AP: r = 0.81, P < .05). Clubhead velocity, explained by three PCs (74%), related to timing and rate of change in COPML near downswing (PC2 and PC3) and timing of COGML late backswing (PC2). The relationship between COPML and COGML PC1 scores identified extremes of COP and COG patterns in golfers and could indicate a golfer's dynamic balance. Golfers with earlier movement of COP to the front foot (PC2) and rate of change (PC3) patterns in ML COP, prior to the downswing, may be more likely to generate higher clubhead velocity.

Comparison of Two- and Three-Dimensional Methods for Analysis of Trunk Kinematic Variables in the Golf Swing.

Two-dimensional methods have been used to compute trunk kinematic variables (flexion/extension, lateral bend, axial rotation) and X-factor (difference in axial rotation between trunk and pelvis) during the golf swing. Recent X-factor studies advocated three-dimensional (3D) analysis due to the errors associated with two-dimensional (2D) methods, but this has not been investigated for all trunk kinematic variables. The purpose of this study was to compare trunk kinematic variables and X-factor calculated by 2D and 3D methods to examine how different approaches influenced their profiles during the swing. Trunk kinematic variables and X-factor were calculated for golfers from vectors projected onto the global laboratory planes and from 3D segment angles. Trunk kinematic variable profiles were similar in shape; however, there were statistically significant differences in trunk flexion (-6.5 ± 3.6°) at top of backswing and trunk right-side lateral bend (8.7 ± 2.9°) at impact. Differences between 2D and 3D X-factor (approximately 16°) could largely be explained by projection errors introduced to the 2D analysis through flexion and lateral bend of the trunk and pelvis segments. The results support the need to use a 3D method for kinematic data calculation to accurately analyze the golf swing.

Dancer perceptions of the force reduction of dance floors used by a professional touring ballet company.

The mechanical properties of dance floors have the potential to influence dancers' performance and injury risk. Little information is available that describes dancers' preferences for dance floor mechanical properties. Investigation of dancers' perceptions of varied dance floors can serve to enlighten governing bodies, floor manufacturers, and the dance community. The aim of this study was to assess the perceptions of dancers from a touring professional ballet company regarding four floors with varied force reduction (FR) that were created to replicate those used by the company in normal dance training and performance. A specialized questionnaire was developed that incorporated a series of qualitative and quantitative measures that could be used by participants to express their perceptions of the custom built dance floors. Floor FR was quantified with reference to the protocols specified by European standards. Dancer perceptions were in general agreement with floor FR values; however, some discrepancies were observed. Dancers expressed a preference for floor FR within the mid to upper limits (57% to 72%) of the European standards, although a minority preferred low FR (approximately 36%) floors. A limited ability to perceive inconsistencies in FR across test floors was observed, which may have implications for injury risk. Investigation of the perceptions of dancers from more diverse backgrounds, on floors that provide a closer representation of typical dance studio and stage sizes, over longer periods of time, would provide further insight into the perceptual and adaptive responses of dancers to varied floor mechanical properties.

The transmission of tuberculosis in schools involving children 3 to 11 years of age.

Little is known about the risk of tuberculosis transmission from children. We reviewed the published literature on the transmission of tuberculosis during outbreaks involving children 3 to 11 years of age and report that transmission rates among close contacts in school outbreaks are on average higher (weighted average 69.8% vs. 39.3%) if the index case is a child than an adult.

Vascular endothelial growth factor promotes physical wound repair and is anti-apoptotic in primary distal lung epithelial and A549 cells.

OBJECTIVE: There is evidence to suggest a beneficial role for growth factors, including vascular endothelial growth factor (VEGF), in tissue repair and proliferation after injury within the lung. Whether this effect is mediated predominantly by actions on endothelial cells or epithelial cells is unknown. This study tested the hypothesis that VEGF acts as an autocrine trophic factor for human adult alveolar epithelial cells and that under situations of pro-apoptotic stress, VEGF reduces cell death. DESIGN: In vitro cell culture study looking at the effects of 0.03% H2O2 on both A549 and primary distal lung epithelial cells. MEASUREMENT AND MAIN RESULTS: Primary adult human distal lung epithelial cells express both the soluble and membrane-associated VEGF isoforms and VEGF receptors 1 and 2. At physiologically relevant doses, soluble VEGF isoforms stimulate wound repair and have a proliferative action. Specific receptor ligands confirmed that this effect was mediated by VEGF receptor 1. In addition to proliferation, we demonstrate that VEGF reduces A549 and distal lung epithelial cell apoptosis when administered after 0.03% H2O2 injury. This effect occurs due to reduced caspase-3 activation and is phosphatidylinositol 3'-kinase dependent. CONCLUSION: In addition to its known effects on endothelial cells, VEGF acts as a growth and anti-apoptotic factor on alveolar epithelial cells. VEGF treatment may have potential as a rescue therapy for diseases associated with alveolar epithelial damage such as acute respiratory distress syndrome.

Heat shock factor-1 and nuclear factor-kappaB are systemically activated in human acute pancreatitis.

CONTEXT: Nuclear factor-kappa B (NF-kappaB) is a transcription factor for a wide range of proinflammatory mediators while heat shock factor-1 (HSF-1) transcribes stress proteins that protect against cellular damage. Both are attractive therapeutic targets, undergoing investigation in other acute inflammatory conditions, such as sepsis. OBJECTIVE: To evaluate the role of the transcription factors NF-kappaB and HSF-1 in human acute pancreatitis and their relationship to cytokine/chemokine production, disease severity and outcome. PATIENTS: Twenty-four patients with acute pancreatitis and 12 healthy controls. MAIN OUTCOME MEASURES: Peripheral blood mononuclear cells were isolated. NF-kappaB and HSF-1 were measured by electrophoretic mobility shift assay. Soluble tumor necrosis factor (TNF) receptor II and interleukin-8 were measured by ELISA. Acute physiology scores (APS), APACHE II scores and final Atlanta designations of severity were also determined. RESULTS: Systemic NF-kappaB activation occurs in acute pancreatitis compared to healthy controls (P=0.004). However, there was no significant difference between those with mild and severe disease (P=0.685). Systemic activation of HSF-1 was observed in acute pancreatitis compared to healthy controls although this did not reach statistical significance (P=0.053). Activation, however, was greatest in those who had a final Atlanta designation of mild pancreatitis compared to those who had a severe attack of acute pancreatitis (P=0.036). Furthermore, HSF-1 was inversely correlated with acute physiology score (APS; r=-0.49, P=0.019) and APACHE II score (r=-0.47, P=0.026). CONCLUSIONS: Both NF-kappaB and HSF-1 are systemically activated in human acute pancreatitis. HSF-1 activation may protect against severity of pancreatitis.

Activation of NF-kappaB and MAP kinase cascades by hypothermic stress in endothelial cells.

Signal transduction pathways and transcription factors are likely to be important mediators of stress responses to ischaemia and reperfusion injury following renal transplantation. We have investigated the activation of the transcription factor nuclear factor kappaB (NF-kappaB) and the mitogen activated protein kinases (MAPK), p44/42 (ERK 1/2), p38 and c-Jun N-terminal kinase (JNK) during cold stress at 4 degrees C. Human umbilical vein endothelial cells (HUVECs) were subjected to 72 h of hypothermia in a renal preservation solution. NF-kappaB activation was assessed by electromobility shift assays and MAPK activation by immunoblotting. Cell viability and apoptosis was assessed. Hypothermia activated the NF-kappaB complex, ERK 1/2 and p38 MAPK pathway. There was a 6-fold increase in NF-kappaB in the nucleus within minutes of hypothermia, correlating with p38 (p = 0.01) and ERK 1/2 activation (p = 0.03). A significant relationship was found between ERK 1/2, p38 and NF-kappaB throughout the 72 h time course (p = 0.01). In contrast, hypothermia had no effect on JNK phosphorylation. Inhibition of MAPK with an MEK inhibitor (PD098059) blocked the activation of NF-kappaB but a specific p38 inhibitor (SB203580) had no effect on NF-kappaB. Increased lactate production after 48 h indicated a switch towards anaerobic metabolism during prolonged hypothermia. Endothelial cells had a high viability and no DNA fragmentation throughout the experiment. Activation of stress pathways during organ procurement may be important in the quality of stored grafts.