The aerodynamics and energy cost assessment of an able-bodied cyclist and amputated models by computer fluid dynamics

Background andObjectives: The aim of this study was to assess and compare the drag and energy cost of three cyclists assessed by computational fluid dynamics (CFD) and analytical procedures. Materials andmethods: A transradial (Tr) and transtibial (Tt) were compared to a full-body cyclist at different speeds. An elite male cyclist with 65 kg of mass and 1.72 m of height volunteered for this research with his competition cloths, helmet and bicycle with 5 kg of mass. A 3D model of the bicycle and cyclist in the upright position was obtained for numerical simulations. Upon that, two more models were created, simulating elbow and knee-disarticulated athletes. Numerical simulations by computational fluid dynamics and analytical procedures were computed to assess drag and energy cost, respectively. Results: One-Way ANOVA presented no significant differences between cyclists for drag (F = 0.041; p = 0.960; η2 = 0.002) and energy cost (F = 0.42; p = 0.908; η2 = 0.002). Linear regression presented a very high adjustment for absolute drag values between able-bodied and Tr (R2 = 1.000; Ra2 = 1.000; SEE = 0.200) and Tt (R2 = 1.00; Ra2 = 1.000; SEE = 0.160). The linear regression for energy cost presented a very high adjustment for absolute values between able-bodied and Tr (R2 = 1.000; Ra2 = 1.000; SEE = 0.570) and Tt (R2 = 1.00; Ra2 = 1.00; SEE = 0.778). Conclusions: This study suggests that drag and energy cost was lower in the able-bodied, followed by the Tr and Tt cyclists.This research is supported by the Portuguese Foundation for Science and Technology, I.P. (project UIDB04045/2020) and The APC was funded by Research Center in Sports Health and Human Development, Covilhã, Portugal.info:eu-repo/semantics/publishedVersio

Maximal oxygen uptake, total metabolic energy expenditure, and energy cost in swimmers with physical disabilities

The purpose of this study was to assess the maximum oxygen uptake (V̇ O2max), the total metabolic energy expenditure (_Etot), and the energy cost (C) measured as the speed of V̇ O2max in swimmers with physical impairments. Eleven swimmers performed an Nx200- m front crawl test from a low to all-out speed and data were obtained at maximum aerobic power. The oxygen uptake was measured breath-by-breath by a telemetric gas exchange system. The _Etot was calculated from the aerobic and anaerobic pathways at maximal intensity. The C was obtained by the ratio of the _Etot and the mean swimming speed. The V̇ O2max was 38.2 ± 8.3 mL.kg. min−1, the _E tot was 191.9 ± 51.7 kJ, and the C was 0.8 ± 0.2 kJ.m−1. The energy contribution of the aerobic pathway was higher (p < 0.001) than that of both the anaerobic pathways, which were similar (p > 0.05). There was no gender effect on the results of the energy contributions (p > 0.05). The anaerobic lactic pathway contribution was higher in male than in female swimmers (p < 0.05). The V̇ O2max and C were higher in swimmers who were less affected by physical impairment. The energy contribution of the aerobic pathways was similar for males and females.info:eu-repo/semantics/publishedVersio

Performance of disabled swimmers in protocols or tests and competitions: a systematic review and meta-analysis

Biomechanical and coordination measurements are useful tools to assess swimming performance. Regarding Paralympic swimming, function and technique make these measurements complex. The aim of this study was to perform a systematic review of studies on biomechanics, coordination and performance in disabled swimmers following swimming protocols and in competitions. Data sources: PubMed, EMBASE, ISI Web of Knowledge, SPORTDiscus and Academic Search Premier. We selected complete studies, published until June 2018. Eighteen studies satisfied the inclusion criteria and were selected for qualitative analysis; nine of these were included in the meta-analysis. Swimming speed and stroke length increase with less impact of physical, visual and intellectual impairment on performing specific swimming tasks. Stroke rate is more stable all through the sport classes than both swimming speed and stroke length. Most physically disabled swimmers adopt the catch-up coordination model. Stroke rate is responsible for most of the intracycle velocity variation in swimmers with amputations or malformations of the upper limbs. No study was found on propulsive efficiency. Swimmers with disabilities should work more on stroke rate, with small decreases in stroke length to achieve higher swimming speeds, lower swim coordination index (more negative) and lower speed variations.info:eu-repo/semantics/publishedVersio

Life cycle assessment tool of electricity generation in Portugal

ABSTRACT: This article presents and describes the LCA4Power tool, developed in this work to assess the potential environmental impacts, as, for example, the contribution to global warming, of electricity generation in continental Portugal, not considering the Madeira and Azores archipelagos. Based on a life cycle perspective, the tool considers the life cycles of various available technologies for producing electricity, on a cradle-to-gate perspective, excluding distribution and final use. It was implemented in MS Excel™ using emission factors obtained from the literature and other sources, instead of raw life cycle inventory data. The current version of the tool includes wind and hydroelectric power as renewable energy sources, and thermal and combined heat and power generation from fossil fuels as non-renewable energy sources. The combination of the aforementioned electricity generation technologies is responsible for more than 90% of the electricity generated in continental Portugal. Results were validated comparing the tool’s predictions with data from other LCA studies of electricity production, showing a good agreement, in particular for the greenhouse gas emissions. As added value, this tool provides a user-friendly way of simulating the potential environmental impacts of different endogenous energy mixes in Portugal, thus support decision making and communication. Future developments of the tool will include other technologies for electricity generation and its application to support decision making through the analysis of future scenarios for electricity generation in Portugal.info:eu-repo/semantics/publishedVersio

Synthesis of diarylamines in the benzo[b]thiophene series by palladium-catalyzed amination and structure-activity relationship as antibacterial agents

The palladium-catalyzed amination of arylhalides has become an important method for the synthesis of arylamines found in pharmaceuticals. Using this methodology we were able to synthesize several diarylamines in the benzo[b]thiophene series.Here we report the synthesis 01 differently substituted diarylamines derivatives 01 6-bromo or 6-amino- 2,3,5-trimethylbenzo[b]thiophene in good to high yields (50-90%) (Scheme), The amino precursor was prepared from the bromo compound using also a C-N palladium-catalyzed cross-coupling with benzophenone imine, followed by acidic hydrolysis in a 60% overall yield

Kinematic, coordinative and efficiency parameters of physically impaired swimmers at maximum aerobic power speed

In paralympic swimming, the biomechanical parameters related to performance are effectively determined according to the potentialities and peculiarities of each athlete. However, a clear integrated approach to these parameters for swimmers with physical disabilities at the speed of maximum oxygen uptake (vV̇O2max) is still practically non-existent. Objective: The purpose of this study was twofold: (i) to assess kinematic, coordinative and efficiency parameters measured at vV̇O2max in swimmers with physical impairments; and (ii) to correlate these biomechanical parameters with the time for a 200 m maximum test. Methods: Eleven swimmers with physical disabilities (seven males and four females) were assessed at vV̇O2max with support from a three-dimensional kinematic method. The performance parameters analysed were: (i) kinematic - stroke rate (SR), stroke length (SL), average swimming speed (SS) and intra-cyclic velocity variation (IVV); (ii) coordinative - index of coordination (IdC) and adapted index of coordination (IdCadapt); and (iii) swimming efficiency - propelling efficiency (çp). Results: The overall results showed high dispersion and wide confidence intervals for the kinematic and coordinative variables. The mean and standard deviation of vV̇O2max and V̇O2 at the same intensity were 0.90 ± 0.13 m/s and 38.2 ± 8.3 ml/kg/min, respectively. Conclusion: Swimmers with less significant impact of physical disability on specific swimming tasks presented higher SL, SS and çp. The IVV was higher in swimmers with a greater impact of disability on conducting specific competitive swimming tasks. In general, the catch-up inter-arm coordination model is adopted

Does Warm-Up Have a Beneficial Effect on 100-m Freestyle?

To investigate the effect of warm-up on 100-m swimming performance. Twenty competitive swimmers (with a training frequency of 8.0 ± 1.0 sessions/wk) performed 2 maximal 100-m freestyle trials on separate days, with and without prior warm-up, in a counterbalanced and randomized design. The warm-up distance totaled 1000 m and replicated the swimmers' usual precompetition warm-up strategy. Performance (time), physiological (capillary blood lactate concentrations), psychophysiological (perceived exertion), and biomechanical variables (distance per stroke, stroke frequency, and stroke index) were assessed on both trials. Performance in the 100-m was fastest in the warm-up condition (67.15 ± 5.60 vs 68.10 ± 5.14 s; P = .01), although 3 swimmers swam faster without warm-up. Critical to this was the 1st 50-m lap (32.10 ± 2.59 vs 32.78 ± 2.33 s; P < .01), where the swimmers presented higher distance per stroke (2.06 ± 0.19 vs. 1.98 ± 0.16 m; P = .04) and swimming efficiency compared with the no-warm-up condition (stroke index 3.46 ± 0.53 vs 3.14 ± 0.44 m2 · c1 · s1; P < .01). Notwithstanding this better stroke-kinematic pattern, blood lactate concentrations and perceived exertion were similar between trials. These results suggest that swimmers' usual warm-up routines lead to faster 100-m freestyle swimming performance, a factor that appears to be related to better swimming efficiency in the 1st lap of the race. This study highlights the importance of performing swimming drills (for higher distance per stroke) before a maximal 100-m freestyle effort in similar groups of swimmers.UBI/FCSH/Santander/2010info:eu-repo/semantics/publishedVersio