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Fernanda A P Habechian, Kim Van Malderen, Paula R Camargo, Ann M Cools
BACKGROUND: The shoulder complex is highly loaded during swimming. No studies were found analyzing the changes in shoulder girdle strength in young swimmers, through the years. OBJECTIVE: To analyze the changes in strength of internal rotators and external rotators of the arm, lower trapezius and supraspinatus and in the external rotators/internal rotators ratio in young elite swimmers through 3 years. METHODS: 31 adolescent elite swimmers (14-18 years, of both sexes) participated in the study...
February 6, 2018: Brazilian Journal of Physical Therapy
Andreas Härtel, David Richard, Thomas Speck
Self-propelled Brownian particles show rich out-of-equilibrium physics, for instance, the motility-induced phase separation (MIPS). While decades of studying the structure of liquids have established a deep understanding of passive systems, not much is known about correlations in active suspensions. In this work we derive an approximate analytic theory for three-body correlations and forces in systems of active Brownian disks starting from the many-body Smoluchowski equation. We use our theory to predict the conditional forces that act on a tagged particle and their dependence on the propulsion speed of self-propelled disks...
January 2018: Physical Review. E
Cato Sandford, Alexander Y Grosberg
The Ornstein-Uhlenbeck particle (OUP) model imagines a microscopic swimmer propelled by an active force which is correlated with itself on a finite time scale. Here we investigate the influence of external potentials on an ideal suspension of OUPs, in both one and two spatial dimensions, with particular attention paid to the pressure exerted on "confining walls." We employ a mathematical connection between the local density of OUPs and the statistics of their propulsion force to demonstrate the existence of an equation of state in one dimension...
January 2018: Physical Review. E
Kaley Ann Sheppard, David Emory Rival
A bio-inspired, slotted delta wing was abstracted from a multi-vane propulsor geometry ubiquitous in nature, and analysed to investigate aerodynamic performance during acceleratory and steady-state motions. Evolutionary convergence of slotted geometries in nature suggests an aerodynamic benefit in manoeuvrability, as exemplified in the fins and wings of a broad range of extant and extinct swimmers and flyers, respectively. Through direct force measurements and stereoscopic particle image velocimetry, it was found that the abstracted, slotted geometry exhibited a region of steady-state lift and drag enhancement at angles of attack greater than 25° when compared to a reference profile based on a delta-wing plate...
February 15, 2018: Bioinspiration & Biomimetics
Hongmiao Tian, Zhijian Wang, Yilong Chen, Jinyou Shao, Tong Gao, Shengqiang Cai
Optically-driven active materials have received much attention because their deformation and motion can be controlled remotely, instantly and precisely in a contactless way. In this article, we investigated an optically-actuated elastomer with rapid response: polydopamine (PDA)-coated liquid crystal elastomer (LCE). Due to the photothermal effect of PDA coating and thermal responsiveness of LCE, the elastomer film contracted significantly with near infrared (NIR) irradiation. With a fixed strain, light-induced actuating stress in the film could be as large as 1...
February 15, 2018: ACS Applied Materials & Interfaces
R Godoy-Diana, B Thiria
Questions of energy dissipation or friction appear immediately when addressing the problem of a body moving in a fluid. For the most simple problems, involving a constant steady propulsive force on the body, a straightforward relation can be established balancing this driving force with a skin friction or form drag, depending on the Reynolds number and body geometry. This elementary relation closes the full dynamical problem and sets, for instance, average cruising velocity or energy cost. In the case of finite-sized and time-deformable bodies though, such as flapping flyers or undulatory swimmers, the comprehension of driving/dissipation interactions is not straightforward...
February 2018: Journal of the Royal Society, Interface
Jordan T Andersen, Ross H Sanders
Propulsion, one of the most important factors in front crawl swimming performance, is generated from both the upper and lower limbs, yet little is known about the mechanisms of propulsion from the alternating movements of the lower limbs in the flutter kick (FK). The purpose of this systematic review was to review the literature relating to the mechanisms of propulsion from FK in front crawl. There was limited information about the mechanisms of propulsion in FK. Since movements of the lower limbs are similar between FK and the dolphin kick (DK), mechanisms of propulsion from DK were reviewed to better understand propulsion from FK...
February 12, 2018: Journal of Sports Sciences
Jennifer L Murphy, Michele C Hlavsa, Brittany C Carter, Candace Miller, Narayanan Jothikumar, Taryn R Gerth, Michael J Beach, Vincent R Hill
During the 2012 summer swim season, aquatic venue data and filter backwash samples were collected from 127 metro-Atlanta pools. Last-recorded water chemistry measures indicated 98% (157/161) of samples were from pools with ≥1 mg/L residual chlorine without stabilized chlorine or ≥2 mg/L with stabilized chlorine and 89% (144/161) had pH readings 7.2-7.8. These water quality parameters are consistent with the 2016 Model Aquatic Health Code (2nd edition) recommendations. We used previously validated real-time polymerase chain reaction assays for detection of seven enteric microbes, including Escherichia coli, and Pseudomonas aeruginosa...
February 2018: Journal of Water and Health
Tathyane Krahenbühl, Roseane de Fátima Guimarães, Antonio de Azevedo Barros Filho, Ezequiel Moreira Gonçalves
OBJECTIVE: To perform a systematic review on the practice of physical activity and/or sports in health and its influence on bone geometry of healthy children and adolescents. DATA SOURCE: The method used as reference was the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Databases searched for articles published from 2006 to 2016, with "Bone geometry" AND (Sport* OR Exercise* OR "Physical Activity") as descriptors, were PubMed, BIREME/LILACS and SciELO...
January 15, 2018: Revista Paulista de Pediatria: Orgão Oficial da Sociedade de Pediatria de São Paulo
Alireza Mojahed, Majid Rajabi
The concept of ultrasound acoustic driven self-motile swimmers which is the source of autonomous propulsion is the acoustic field generated by the swimmer due to the partial oscillation of its surface is investigated. Limiting the subject to a body with simple spherical geometry, it is analytically shown that the generated acoustic radiation force due to induction by asymmetric acoustic field in host medium is non-zero, which propels the device. Assuming low Reynolds number condition, the frequency-dependent swimming velocity is calculated as a function of design parameters and optimum operating condition is obtained...
January 22, 2018: Ultrasonics
Rachel M Frank, Gift Ukwuani, Jorge Chahla, Brian Batko, Charles A Bush-Joseph, Shane J Nho
PURPOSE: To evaluate patients' ability to return to swimming after hip arthroscopy for femoroacetabular impingement syndrome (FAIS) with capsular closure. METHODS: Consecutive FAIS patients who had undergone hip arthroscopy for the treatment of FAIS by a single fellowship-trained surgeon were reviewed. The inclusion criteria included patients with a diagnosis of FAIS who self-reported being swimming athletes with a minimum clinical follow-up duration of 2 years...
February 2, 2018: Arthroscopy: the Journal of Arthroscopic & related Surgery
Stelios G Psycharakis, Toshimasa Yanai
We investigated the rotational effect of buoyant force around the body's transverse axis, termed buoyant torque, during a 200m front crawl maximal swim. Eleven male swimmers of national or international level participated. One stroke cycle (SC) for each 50m was recorded with two above and four below water cameras. The following variables were analysed: swimming velocity; absolute and normalised buoyant force; minimum, average and maximum buoyant torque; SC and arm recovery times. The average value of buoyant torque was higher in the first 50m (14...
February 4, 2018: Journal of Sports Sciences
Stephen Cobley, Shaun Abbott, Sera Dogramaci, Adam Kable, James Salter, Mirjam Hintermann, Michael Romann
OBJECTIVES: To determine the prevalence, magnitude and transient patterning of Relative Age Effects (RAEs) according to sex and stroke event across all age-groups at the Australian National age swimming Championships. DESIGN: Repeated years of cross-sectional participation data were examined. METHODS: Participants were 6014 unique male (3185) and female (2829) swimmers (aged 12-18 years) who participated in Freestyle (50, 400m) and/or Breaststroke (100, 200m) at the National age swimming Championships between 2000-2014 (inclusive)...
December 29, 2017: Journal of Science and Medicine in Sport
N Williams, M Russell, C J Cook, L P Kilduff
The effect of ischemic preconditioning (IPC) on swimming performance was examined. Using a randomized, crossover design, National-and International-level swimmers (n=20; 14 males, 6 females) participated in three trials (Con, IPC-2h, IPC-24h). Lower-body IPC (4 x 5 min bi-lateral blood-flow restriction at 160-228 mmHg, and 5 min reperfusion) was used 2- (IPC-2h) or 24-h (IPC-24h) before a self-selected (100 m, n=15; 200 m, n=5) swimming time-trial (TT). The Con trial used a sham intervention (15 mmHg) 2h prior to exercise...
January 30, 2018: Journal of Strength and Conditioning Research
Jaideep Katuri, William E Uspal, Juliane Simmchen, Albert Miguel-López, Samuel Sánchez
For natural microswimmers, the interplay of swimming activity and external flow can promote robust directed motion, for example, propulsion against (upstream rheotaxis) or perpendicular to the direction of flow. These effects are generally attributed to their complex body shapes and flagellar beat patterns. Using catalytic Janus particles as a model experimental system, we report on a strong directional response that occurs for spherical active particles in a channel flow. The particles align their propulsion axes to be nearly perpendicular to both the direction of flow and the normal vector of a nearby bounding surface...
January 2018: Science Advances
Cheng-Shin Jang, Ching-Ping Liang
Taiwan is surrounded by oceans, and therefore numerous pleasure beaches attract millions of tourists annually to participate in recreational swimming activities. However, impaired water quality because of fecal pollution poses a potential threat to the tourists' health. This study probabilistically characterized the health risks associated with recreational swimming engendered by waterborne enterococci at 13 Taiwanese beaches by using quantitative microbial risk assessment. First, data on enterococci concentrations at coastal beaches monitored by the Taiwan Environmental Protection Administration were reproduced using nonparametric Monte Carlo simulation (MCS)...
January 2018: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Vicente Javier Clemente-Suárez, Juan Jaime Arroyo-Toledo
The aim of the present research was to analyze the autonomic response in a group of trained swimmers before and after conducting a 4-week period of high-intensity interval training (HIT). Heart rate variability was analyzed in 14 swimmers (16.2 ± 2.6 years, 169.1 ± 10.2 cm and 61.3 ± 9.9 kg) in basal condition and during a HIT session before and after completing a training period. The HIT session that was evaluated consisted of: 16 × 25 m maximum speed, resting 30 s between sets. Participants combined aerobic training with tethered swimming and HIT sessions three times per week in a period of 4 weeks...
January 25, 2018: Journal of Medical Systems
Fernanda A P Habechian, Ana Letícia Lozana, Paula R Camargo
OBJECTIVES: To compare the humeral retrotorsion (HRT) among non-athletes, amateur swimmers and competitive swimmers and to analyze the relationship between HRT and swim volume in competitive swimmers. DESIGN: Cross-sectional. SETTING: Laboratory. PARTICIPANTS: Ninety children and adolescents, both genders (30 non-athletes: 11.50 ± 1.94 years; 30 amateur swimmers: 11.56 ± 1.81 years; and 30 competitive swimmers: 12...
November 8, 2017: Physical Therapy in Sport
Diana Vilela, Unai Cossío, Jemish Parmar, Vanessa Gómez-Vallejo, Angel Manu Martínez, Jordi Llop, Samuel Sanchez
Micro/nanomotors are useful tools for several biomedical applications, including targeted drug delivery and minimally invasive microsurgeries. However, major challenges such as in vivo imaging need to be addressed before they can be safely applied on a living body. Here, we show that positron emission tomography (PET), a molecular imaging technique widely used in medical imaging, can also be used to track a large population of tubular Au/PEDOT/Pt micromotors. Chemisorption of an Iodine isotope onto the micromotor's Au surface rendered them detectable by PET and we could track their movements in tubular phantom over time frames of up to 15 minutes...
January 23, 2018: ACS Nano
Behnam Liaghat, Birgit Juul-Kristensen, Thomas Frydendal, Camilla Marie Larsen, Karen Søgaard, Aki Ilkka Tapio Salo
Generalised Joint Hypermobility including shoulder hypermobility (GJHS) in swimmers is considered an intrinsic risk factor for shoulder injuries. The aim was to investigate the association of GJHS with shoulder strength, fatigue development and muscle activity during swimming-related shoulder rotations. Totally, 38 competitive swimmers (aged 13-17 years) participated, 19 were competitive swimmers with GJHS and 19 were age, sex and club matched swimmers without GJHS. Concentric isokinetic force in medial and lateral rotations were measured at 60°/s (5 repetitions) and 180°/s (10 repetitions)...
January 10, 2018: Journal of Electromyography and Kinesiology
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