ASSESSMENT OF NORMALIZED DISTANCE PER STROKE AND SWIMMING EFFICIENCY IN THE 2000 OLYMPIC GAMES

Stroke length has been viewed as an important determinant in swimming speed and performance. However, recent studies of elite level athletes have shown that stroke length (SL) typically does not correlate with swimming speed in elite athletes. These studies have focused on absolute stroke length and have not taken into consideration the size of the athletes. The noted lack of correlation may be due to the variability introduced by differences in athlete size. This study looks at athlete SL normalized to body height and introduces the concept of using normalized SL (NSL) as a measure of efficiency. Pearson correlation coefficients were computed to relate NSL to swimming speed and analyses of variance were conducted to examine differences between finalists and semifinalists at the 2000 Olympic Games. Significant findings and their relationship to performance are discussed

ANALYSIS OF A SWIMMERS HAND AND ARM IN STEADY FLOW CONDITIONS USING COMPUTATIONAL FLUID DYNAMICS

As an alternative to the experimental determination of the hand and arm propulsive forces generated by swimmers, the numerical technique of computational fluid dynamics (CFD) has been used to calculate the steady flow around a swimmer's hand and arm at various angles of attack. Significant boundary layer separation was seen, ruling out the use of Bernoulli's equation to mathematically describe the lift generated by a swimmer. Computation of 3D lift is necessary to describe the propulsion generated by the arm at all angles of attack and the hand near angles of attack of 90 degrees. Force coefficients computed for the hand and arm compared well with steady-state coefficients determined experimentally. Such comparisons validate the chosen CFD techniques, and are an important first step toward the use of CFD for determining swimming hydrodynamic forces in more realistic unsteady flow conditions

CFD ANALYSIS OF A SWIMMER'S ARM AND HAND, ACCELERATION AND DECELERATION

The numerical technique of computational fluid dynamics (CFD) has been used to determine the effect of arm and hand acceleration and deceleration on the propulsive forces generated by swimmers. Relationships developed to predict hand and arm forces as a function of both velocity and acceleration show these forces can be significantly different from those calculated using the quasi-steady approach. Simple equations that provide a correction factor to forces calculated using the quasi-steady approach are provided. The analyses showed that drag and axial forces (along length of the arm) were affected more by unsteady flow than were the lift forces. Also, arm forces were affected more than were hand forces. And finally, maximum propulsion was obtained from the hand when it faced directly backwards towards the feet, even though the stroke itself may be moving diagonally

EFFECTS OF HANDLE AND BLOCK CONFIGURATION ON SWIM START PERFORMANCE

The purpose of this study was to quantify differences in swimming track start performances using side handle and front handle grip techniques and using an inclined platform at the rear of the starting platform. An instrumented starting block system was designed to allow front grip and side grip starting techniques and inclusion of a rear incline. Thirty male and 20 female junior elite swimmers completed three starts in each of four start block configurations: (1) Flat (traditional) block, front handle grip; (2) Flat (traditional) block, side handle grip; (3) Incline (new) block, front handle grip; (4) Incline (new) block, side handle grip. Force and video data were used to quantify parameters related to starting performance. Results indicated that use of side handles had a substantial impact on start performance while the effects of the rear incline were less pronounced. Compared to using a front grip technique, use of the side handles increased horizontal velocity at takeoff up to 18%, resulted in a more horizontal takeoff angle by up to 2°, increased contribution to horizontal impulse from arms up to 12%, increased peak horizontal power up to 28%, decreased time to 6 m by 4% and increased velocity at 6 m by 2.5%. These advantages were achieved at a cost of an 8% increase in propulsion time. Based on this study, we recommend swimmers develop familiarity with the use of side handles when performing a track start and to use this technique if handles are available on a starting block

MODELLING COMPETITIVE SWIMMING IN DIFFERENT STROKES AND DISTANCES UPON REGRESSION ANALYSIS: A STUDY OF THE FEMALE PARTICIPANTS OF SYDNEY 2000 OLYMPIC GAMES

The purpose of the study was to obtain the slope and y-intercept of the regression between race component times and race time for a group of top level female swimmers (the best 16 times) in the 2000 Sydney Olympic Games. All the 50, 100 and 200 rn events were analyzed in this study. A multi-camera video recording system (7 cameras) was located on the catwalk 18m above the center lanes of the pool. The regression and correlation coefficients were significant in 78% of the races analyzed, excluded stroke frequency, stroke length and stroke index. The quality of the swimmers analyzed enabled the calculation of the recommended times in each phase in relation to race time. This information may allow top level swimmers to train specifically in their weakest race component

RELATIONSHIPS BETWEEN STROKE EFFICIENCY MEASURES AND FREESTYLE SWIMMING PERFORMANCE: AN ANALYSIS OF FREESTYLE SWIMMING EVENTS AT THE SYDNEY 2000 OLYMPICS

The purpose of this study was to investigate the relationships between measures of stroke efficiency and performance in the freestyle swimming events of the Sydney 2000 Olympics. Measures of variables describing swimming performance were determined from overhead video of the races according to the Australian Institute of Sport protocol. All performances by swimmers in the finals and semifinals were included in the analysis for the 50, 100 and 200 m events and performances for finalists only were analyzed for longer events. A within subjects, repeated measures linear-regression analysis was used to determine relationships. The lack of relationships determined for SI with either swim velocity or performance time in the longer events indicated that the SI was not a good indicator of swimming efficiency for women's freestyle events. In contrast, a predominance of these relationships in the longer events indicated that the SI was possibly an indicator of swimming efficiency for men's freestyle events. SL was not found to be a good predictor of swimming speed or an indicator of swimming efficiency for the freestyle events

A phase I study evaluating the pharmacokinetics, safety and tolerability of an antibody-based tissue factor antagonist in subjects with acute lung injury or acute respiratory distress syndrome

<p>Abstract</p> <p>Background</p> <p>The tissue factor (TF)-dependent extrinsic pathway has been suggested to be a central mechanism by which the coagulation cascade is locally activated in the lungs of patients with acute lung injury and acute respiratory distress syndrome (ALI/ARDS) and thus represents an attractive target for therapeutic intervention. This study was designed to determine the pharmacokinetic and safety profiles of ALT-836, an anti-TF antibody, in patients with ALI/ARDS.</p> <p>Methods</p> <p>This was a prospective, randomized, placebo-controlled, dose-escalation Phase I clinical trial in adult patients who had suspected or proven infection, were receiving mechanical ventilation and had ALI/ARDS (PaO₂/FiO₂≤ 300 mm). Eighteen patients (6 per cohort) were randomized in a 5:1 ratio to receive ALT-836 or placebo, and were treated within 48 hours after meeting screening criteria. Cohorts of patients were administered a single intravenously dose of 0.06, 0.08 or 0.1 mg/kg ALT-836 or placebo. Blood samples were taken for pharmacokinetic and immunogenicity measurements. Safety was assessed by adverse events, vital signs, ECGs, laboratory, coagulation and pulmonary function parameters.</p> <p>Results</p> <p>Pharmacokinetic analysis showed a dose dependent exposure to ALT-836 across the infusion range of 0.06 to 0.1 mg/kg. No anti-ALT-836 antibody response was observed in the study population during the trial. No major bleeding episodes were reported in the ALT-836 treated patients. The most frequent adverse events were anemia, observed in both placebo and ALT-836 treated patients, and ALT-836 dose dependent, self-resolved hematuria, which suggested 0.08 mg/kg as an acceptable dose level of ALT-836 in this patient population.</p> <p>Conclusions</p> <p>Overall, this study showed that ALT-836 could be safely administered to patients with sepsis-induced ALI/ARDS.</p> <p>Trial registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01438853">NCT01438853</a></p

Protein C anticoagulant system—anti-inflammatory effects

Activated protein C (APC) plays active roles in preventing progression of a number of disease processes. These include thrombosis due to its direct anticoagulant activity which is likely augmented by its cytoprotective activity, thereby limiting exposure of procoagulant cellular membrane surfaces on cells. Beyond that, the pathway signals the cells to prevent apoptosis, to dampen inflammation, to increase endothelial barrier function, and to selectively downregulate some genes implicated in disease progression. Most of these functions are manifested to APC binding to endothelial protein C receptor (EPCR) allowing PAR1 activation, but activation of other PARS is also implicated in some cases. In addition to EPCR orchestrating these changes, CD11b is also capable of supporting APC signaling. Selective control of these pathways offers potential in new therapeutic approaches to disease

Extramuscular myofascial force transmission alters substantially the acute effects of surgical aponeurotomy: assessment by finite element modeling

Effects of extramuscular myofascial force transmission on the acute effects of aponeurotomy were studied using finite element modeling and implications of such effects on surgery were discussed. Aponeurotomized EDL muscle of the rat was modeled in two conditions: (1) fully isolated (2) with intact extramuscular connections. The specific goal was to assess the alterations in muscle length-force characteristics in relation to sarcomere length distributions and to investigate how the mechanical mechanism of the intervention is affected if the muscle is not isolated. Major effects of extramuscular myofascial force transmission were shown on muscle length-force characteristics. In contrast to the identical proximal and distal forces of the aponeurotomized isolated muscle, substantial proximo-distal force differences were shown for aponeurotomized muscle with extramuscular connections (for all muscle lengths F dist > F prox after distal muscle lengthening). Proximal optimal length did not change whereas distal optimal length was lower (by 0.5 mm). The optimal forces of the aponeurotomized muscle with extramuscular connections exerted at both proximal and distal tendons were lower than that of isolated muscle (by 15 and 7%, respectively). The length of the gap separating the two cut ends of the intervened aponeurosis decreases substantially due to extramuscular myofascial force transmission. The amplitude of the difference in gap length was muscle length dependent (maximally 11.6% of the gap length of the extramuscularly connected muscle). Extramuscular myofascial force transmission has substantial effects on distributions of lengths of sarcomeres within the muscle fiber populations distal and proximal to the location of intervention: (a) Within the distal population, the substantial sarcomere shortening at the proximal ends of muscle fibers due to the intervention remained unaffected however, extramuscular myofascial force transmission caused a more pronounced serial distribution towards the distal ends of muscle fibers. (b) In contrast, extramuscular myofascial force transmission limits the serial distribution of sarcomere lengths shown for the aponeurotomized isolated muscle in the proximal population. Fiber stress distributions showed that extramuscular myofascial force transmission causes most sarcomeres within the aponeurotomized muscle to attain lengths favorable for higher force exertion. It is concluded that acute effects of aponeurotomy on muscular mechanics are affected greatly by extramuscular myofascial force transmission. Such effects have important implications for the outcome of surgery performed to improve impeded function since muscle in vivo is not isolated both anatomically and mechanically