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Longzhen Dai, Guo-Wei He, Xiang Zhang, Xing Zhang
The intermittent locomotion performance of a fish-like elastic swimmer is studied numerically in this paper. The actuation is imposed only at the head and the locomotion is indirectly driven by passive elastic mechanism. For intermittent swimming, certain time durations of passive coasting are interspersed between two half-periods of active bursting. To facilitate the comparison of energy efficiencies in continuous and intermittent swimming at the same cruising speed, we consider both intermittent swimming at various duty cycles and also continuous swimming at reduced actuation frequencies...
July 18, 2018: Bioinspiration & Biomimetics
Claudia Ferreiro-Córdova, John Toner, Hartmut Löwen, Henricus H Wensink
The dynamics of self-locomotion of active particles in aligned or liquid crystalline fluids strongly deviates from that in simple isotropic media. We explore the long-time dynamics of a swimmer moving in a three-dimensional smectic liquid crystal and find that the mean-square displacement transverse to the director exhibits a distinct logarithmic tail at long times. The scaling is distinctly different from that in an isotropic or nematic fluid and hints at the subtle but important role of the director fluctuation spectrum in governing the long-time motility of active particles...
June 2018: Physical Review. E
T A Fisher, S A Petrov, E L Dotsenko, Yu G Suhovei
The data presented in this article illustrate the dynamics of the affective sphere of the mental processes associated with the higher nervous activity and the characteristics of the neuroendocrine system (including the vegetative index of Kerdo, cortisol and serotonin levels) in the participants of the marathon swimming competition covering the distance of 101.4 km. We investigated the relationship between the levels of the above hormones and the functional activity of the vegetative nervous system. AIM: The objectives of the present study were (1) to determine the dynamics of the changes in the psychophysiological characteristics of the participants in the marathon swimming competition during which the world record for the covering of the 101,4 km distance in the ice water was set and (2) to follow up the development of the stress response at different levels of the life support system...
2018: Voprosy Kurortologii, Fizioterapii, i Lechebnoĭ Fizicheskoĭ Kultury
T Amorim, C Durães, J C Machado, G S Metsios, M Wyon, J Maia, A D Flouris, F Marques, L Nogueira, N Adubeiro, Y Koutedakis
The association of genetic polymorphisms with low bone mineral density in elite athletes have not been considered previously. The present study found that bone mass phenotypes in elite and pre-elite dancers are related to genetic variants at the Wnt/β-catenin and ER pathways. INTRODUCTION: Some athletes (e.g. gymnasts, dancers, swimmers) are at increased risk for low bone mineral density (BMD) which, if untreated, can lead to osteoporosis. To investigate the association of genetic polymorphisms in the oestrogen receptor (ER) and the Wnt/β-catenin signalling pathways with low BMD in elite and pre-elite dancers (impact sport athletes)...
July 5, 2018: Osteoporosis International
João Valente-Dos-Santos, Óscar M Tavares, João P Duarte, Paulo M Sousa-E-Silva, Luís M Rama, José M Casanova, Carlos A Fontes-Ribeiro, Elisa A Marques, Daniel Courteix, Enio R V Ronque, Edilson S Cyrino, Jorge Conde, Manuel J Coelho-E-Silva
BACKGROUND: Exploring the osteogenic effect of different bone-loading sports is particular relevant to understand the interaction between skeletal muscle and bone health during growth. This study aimed to compare total and regional bone and soft-tissue composition between female adolescent swimmers (n=20, 15.71±0.93 years) and volleyball players (n=26, 16.20±0.77 years). METHODS: Dietary intake was obtained using food frequency questionnaires. Body size was given by stature, sitting height, and body mass...
July 3, 2018: BMC Pediatrics
Anna Marszewska, Anna Cichy, Jana Bulantová, Petr Horák, Elżbieta Żbikowska
Swimmer's itch is a re-emerging human disease caused by bird schistosome cercariae, which can infect bathing or working people in water bodies. Even if cercariae fail after penetrating the human skin, they can cause dangerous symptoms in atypical mammal hosts. One of the natural methods to reduce the presence of cercariae in the environment could lie in the introduction of non-host snail species to the ecosystem, which is known as the "dilution" or "decoy" effect. The caenogastropod Potamopyrgus antipodarum -an alien in Europe-could be a good candidate against swimmer's itch because of its apparent resistance to invasion by European bird schistosome species and its high population density...
2018: PeerJ
Letícia Parada Moreira, Landulfo Silveira, Marcos Tadeu Tavares Pacheco, Alexandre Galvão da Silva, Debora Dias Ferraretto Moura Rocco
Raman spectroscopy (RS) is a vibrational technique that is suitable for performing biochemical analyses in human tissues and fluids. This work has investigated the identification of biochemical markers due to physical performance in the urine of swimming athletes. This was achieved by means of the Raman features that were found before and after the swimming training compared to the sedentary control subjects. These particular biochemical marker identifications refer to and infer the physiological status of individuals...
June 22, 2018: Journal of Photochemistry and Photobiology. B, Biology
Daniel S Graciaa, Jennifer R Cope, Virginia A Roberts, Bryanna L Cikesh, Amy M Kahler, Marissa Vigar, Elizabeth D Hilborn, Timothy J Wade, Lorraine C Backer, Susan P Montgomery, W Evan Secor, Vincent R Hill, Michael J Beach, Kathleen E Fullerton, Jonathan S Yoder, Michele C Hlavsa
Outbreaks associated with untreated recreational water can be caused by pathogens, toxins, or chemicals in fresh water (e.g., lakes, rivers) or marine water (e.g., ocean). During 2000-2014, public health officials from 35 states and Guam voluntarily reported 140 untreated recreational water-associated outbreaks to CDC. These outbreaks resulted in at least 4,958 cases of disease and two deaths. Among the 95 outbreaks with a confirmed infectious etiology, enteric pathogens caused 80 (84%); 21 (22%) were caused by norovirus, 19 (20%) by Escherichia coli, 14 (15%) by Shigella, and 12 (13%) by Cryptosporidium...
June 29, 2018: MMWR. Morbidity and Mortality Weekly Report
Rob Davies-Colley, Amanda Valois, Juliet Milne
Swimming is a popular activity in Aotearoa-New Zealand (NZ). Two variables that strongly influence swimming suitability of waters are faecal contamination, as indicated by the bacterium Escherichia coli, and visual clarity as it affects aesthetics and safety with respect to submerged hazards. We show that E. coli and visual clarity are inversely related overall in NZ rivers (R = -0.54), and more strongly related in many individual rivers, while similar (but positive) correlations apply also to turbidity. This finding, apparently reflecting co-mobilisation of faecal contamination and fine sediment, suggests that visual clarity, measured or estimated from appearance of submerged features, should be a valuable indicator of faecal contamination status and (more generally) swimming suitability...
June 2018: Journal of Water and Health
Clover Su, Médea Padra, Maira Alves Constantino, Sinan Sharba, Anders Thorell, Sara K Lindén, Rama Bansil
We present particle tracking microrheology results on human mucins, isolated from normal surface and gland mucosa and one tumor sample, and examine the motility of Helicobacter pylori in these mucins. At 1.5% concentration human mucin solutions are purely viscous, with viscosity η (gland mucin) > η (surface mucin) > η (tumor mucin). In the presence of motile H. pylori bacteria, particle diffusion is enhanced, with diffusivity D+bac (tumor mucin) > D+bac (gland mucin) > D+bac (surface mucin). The surface and tumor mucin solutions exhibit an elastic response in the presence of bacteria...
June 26, 2018: Scientific Reports
Craig Robertson, Angelica Lodin-Sundström, John OʼHara, Roderick King, Barney Wainwright, Matthew Barlow
Robertson, C, Lodin-Sundström, A, O'Hara, J, King, R, Wainwright, B, and Barlow, M. Effects of pre-race apneas on 400-m freestyle swimming performance. J Strength Cond Res XX(X): 000-000, 2018-This study aimed to establish whether a series of 3 apneas before a 400-m freestyle time-trial affected swimming performance when compared with and combined with a warm-up. Nine (6 males and 3 females) regional to national standard swimmers completed four 400-m freestyle time-trials in 4 randomized conditions: without warm-up or apneas (CON), warm-up only (WU), apneas only (AP), and warm-up and apneas (WUAP)...
June 22, 2018: Journal of Strength and Conditioning Research
Ricardo Peterson Silveira, Pro Stergiou, Pedro Figueiredo, Flávio de S Castro, Larry Katz, Darren J Stefanyshyn
The aim of this study was to determine the biomechanical parameters that explain ventral start performance in swimming. For this purpose, 13 elite swimmers performed different variants of the ventral start technique. Two-dimensional video analyses of the aerial and underwater phases were used to assess 16 kinematic parameters from the starting signal to 5 m, and an instrumented starting block was used to assess kinetic data. A Lasso regression was used to reduce the number of parameters, providing the main determinants to starting performance, revealing different combinations of key determinants, depending on the variant (r² ≥ 0...
June 24, 2018: European Journal of Sport Science
Natsuhiko Yoshinaga, Tanniemola B Liverpool
We study how hydrodynamic interactions affect the collective behaviour of active particles suspended in a fluid at high concentrations, with particular attention to lubrication forces which appear when the particles are very close to one another. We compute exactly the limiting behaviour of the hydrodynamic interactions between two spherical (circular) active swimmers in very close proximity to one another in the general setting in both three and (two) dimensions. Combining this with far-field interactions, we develop a novel numerical scheme which allows us to study the collective behaviour of large numbers of active particles with accurate hydrodynamic interactions when close to one another...
June 14, 2018: European Physical Journal. E, Soft Matter
Ana Catarina Sousa, Ricardo J Fernandes, Joao Paulo Vilas Boas, Pedro Figueiredo
To provide information for high-intensity interval training (HIIT) load, we compared the temporal variables of VO2 response at, and after, a time sustained at the exercise intensity corresponding to VO2max (Tlim) in different exercise modes. Forty-five trained male swimmers (11), rowers (13), runners (10) and cyclists (11) completed an incremental protocol to determine the velocity (vVO2max ) or power (wVO2max ) at VO2max and a square wave exercise from rest to 100% of vVO2max /wVO2max . The temporal variables of VO2 response were examined using a breath-by-breath gas analyzer...
June 20, 2018: International Journal of Sports Medicine
Nuno Batalha, Sónia Dias, Daniel A Marinho, José A Parraca
The continuous execution of swimming techniques, supported mainly by the upper limbs, may cause shoulder rotator muscle imbalances, which leads to injuries. The aim of this study was to evaluate and compare the effects of two training programs on strength, balance and endurance of shoulder rotator cuff muscles in youth swimmers. Twenty-five male swimmers were evaluated and randomly divided into two groups - the land group (n = 13), which conducted a conventional dry-land training program with elastic bands, and the water group (n = 12), which conducted a water resistance program...
June 2018: Journal of Human Kinetics
Shinya Abe, Nathaniel Narra, Riku Nikander, Jari Hyttinen, Reijo Kouhia, Harri Sievänen
Sideways falls impose high stress on the thin superolateral cortical bone of the femoral neck, the region regarded as a fracture-prone region of the hip. Exercise training is a natural mode of mechanical loading to make bone more robust. Exercise-induced adaptation of cortical bone along the femoral neck has been previously demonstrated. However, it is unknown whether this adaption modulates hip fracture behavior. The purpose of this study was to investigate the influence of specific exercise loading history on fall-induced hip fracture behavior by estimating fracture load and location with proximal femur finite element (FE) models created from magnetic resonance images (MRI) of 111 women with distinct exercise histories: 91 athletes (aged 24...
June 8, 2018: Journal of Biomechanics
Kenzo Narita, Motomu Nakashima, Hideki Takagi
The purpose of this study was to examine the effect of leg kick on the resistance force in front-crawl swimming. The active drag in front-crawl swimming with and without leg motion was evaluated using measured values of residual thrust (MRT method) and compared with the passive drag of the streamlined position (SP) for the same swimmers. Seven male competitive swimmers participated in this study, and the testing was conducted in a swimming flume. Each swimmer performed front-crawl under two conditions: using arms and legs (whole stroke: WS) and using arms only (arms-only stroke: AS)...
June 15, 2018: Journal of Biomechanics
George H Crocker, Joseph F Moon, Jeff A Nessler, Sean C Newcomer
Crocker, GH, Moon, JF, Nessler, JA, and Newcomer, SC. Energetics of swimming with hand paddles of different surface areas. J Strength Cond Res XX(X): 000-000, 2018-Hand paddles are one of the most common training aids used by the competitive swimmer, yet little is known regarding how hand paddle surface area affects the metabolic cost of transport (COT) while swimming. The purpose of this study was to determine how altering hand paddle size affects energy use during submaximal, front-crawl (i.e., freestyle) swimming...
June 15, 2018: Journal of Strength and Conditioning Research
Francisco Cuenca-Fernández, Ana Ruiz-Teba, Gracia López-Contreras, Raúl Arellano
Cuenca-Fernández, F, Ruiz-Teba, A, López-Contreras, G, and Arellano, R. Effects of 2 types of activation protocols based on postactivation potentiation on 50-m freestyle performance. J Strength Cond Res XX(X): 000-000, 2018-Postactivation potentiation (PAP) is a phenomenon which improves muscle contractility, strength, and speed in sporting performances through previously applied maximal or submaximal loads on the muscle system. This study aimed to assess the effects of 2 types of activation protocols based on PAP, on sprint swimming performance...
June 14, 2018: Journal of Strength and Conditioning Research
Amy Tanner, Shannon Day
Given the limited research into the physiological and psychological demands of elite synchronised swimming, the aim of this study was to examine 10 elite female synchronised swimmers and analyse the relationship between training load, stress, illness episodes, and salivary biomarkers during a period of training and competition. Saliva samples were collected before (BASE), during an intensified training camp (CAMP), during an international competition period (COMP), and post competition recovery (REC) for analysis of cortisol, testosterone, and secretory immunoglobulin A (SIgA)...
September 1, 2017: Sports
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