scholarly journals The 400-m Front Crawl Test: Energetic and 3D Kinematical Analyses

2019 ◽  
Vol 41 (01) ◽  
pp. 21-26
Author(s):  
Ricardo de Assis Correia ◽  
Wellington Gomes Feitosa ◽  
Pedro Figueiredo ◽  
Marcelo Papoti ◽  
Flávio Antonio de Souza Castro
Keyword(s):  
Oxygen Consumption ◽  
Test Performance ◽  
Lactate Concentration ◽  
Three Dimensional ◽  
Velocity Variation ◽  
Centre Of Mass ◽  
Front Crawl ◽  
Competition Level ◽  
The Mean ◽  
Linear Regressions

AbstractThe aim of the study was to verify the relative contributions of energetic and kinematic parameters to the performance in 400-m front crawl test. Fourteen middle-distance swimmers participated in the study. Oxygen consumption was measured directly and blood samples were collected to assay lactate concentration. Both oxygen consumption and lactate concentration were used to calculate the: (i) overall energy expenditure, (ii) anaerobic (alactic and lactic) and (iii) aerobic contributions. The mean centre of mass speed and intracycle velocity variation were determined through three-dimensional kinematic analysis. Mean completion time was 315.64±26.91s. Energetic contributions were as follows: 6.1±0.28% from alactic anaerobic metabolism, 5.9±0.63% from anaerobic lactic and 87.8±0.88% from aerobic. Mean intracycle velocity variation was 0.14±0.03. The results indicated that performance of 400-m test relies predominantly on aerobic power. Parameters such as lactate, mean speed, anaerobic lactic and alactic (kW) correlated with performance of 400-m test (p <0.05). Multiple linear regressions indicated that mean centre of mass speed and anaerobic alactic (kW) determined the 400-m test performance (R2=0.92). Even though the T400 is characterized by aerobic metabolism, the anaerobic alactic component cannot be negligible at this competition level.

Assessment of Fatigue Thresholds in 50-m All-Out Swimming

2014 ◽  
Vol 9 (6) ◽  
pp. 959-965 ◽  
Author(s):  
Susana M. Soares ◽  
Ricardo J. Fernandes ◽  
J. Leandro Machado ◽  
José A. Maia ◽  
Daniel J. Daly ◽  
...  
Keyword(s):  
Fatigue Threshold ◽  
Velocity Variation ◽  
Time Interval ◽  
Stroke Index ◽  
Time Intervals ◽  
Front Crawl ◽  
Mean Velocity ◽  
Individual Level ◽  
Variation Patterns ◽  
The Mean

Context:It is essential to determine swimmers’ anaerobic potential and better plan training, understanding physiological effects of the fatigue.Purpose:To study changes in the characteristics of the intracyclic velocity variation during an all-out 50-m swim and to observe differences in speed and stroking parameters between these changes.Methods:28 competitive swimmers performed a 50-m front-crawl all-out test while attached to a speedometer. The velocity–time (v[t]) curve off all stroke cycles was analyzed per individual using a routine that included a wavelet procedure, allowing the determination of the fatigue thresholds that divide effort in time intervals.Results:One or 2 fatigue thresholds were observed at individual level on the v(t) curve. In males, when 1 fatigue threshold was identified, the mean velocity and the stroke index dropped (P < .05) in the second time interval (1.7 ± 0.0 vs 1.6 ± 0.0 m/s and 3.0 ± 0.2 vs 2.8 ± 0.3 m/s, respectively). When 2 fatigue thresholds were identified, the mean velocity of the first time interval was higher than that of the third time interval (P < .05), for both male (1.7 ± 0.0 vs 1.6 ± 0.1 m/s) and female (1.5 ± 0.1 vs 1.3 ± 0.1 m/s) swimmers.Conclusion:One or 2 fatigue thresholds were found in the intracyclic velocity-variation patterns. Concurrently, changes in velocity and stroke parameters were also observed between time intervals. This information could allow coaches to obtain new insights into delaying the degenerative effects of fatigue and maintain stable stroke-cycle characteristics over a 50-m event.

scholarly journals Changes in heart rate and blood lactate concentration during karate kata competition

2020 ◽  
Vol 24 (3) ◽  
pp. 137-142 ◽  
Author(s):  
R. Penov ◽  
P. Petrov ◽  
S. Kolimechkov
Keyword(s):  
Heart Rate ◽  
Blood Lactate ◽  
Muscle Tension ◽  
Lactate Concentration ◽  
Three Dimensional ◽  
Blood Lactate Concentration ◽  
Moderate Increase ◽  
National Team ◽  
The Third ◽  
The Mean

Background and Study Aim : Karate is going to take part in the Olympic games, for the first time in Tokyo 2020. The aim of this study was to analyse the changes in heart rate (HR) and blood lactate concentration of karate practitioners performing different katas in competitive conditions. Material and Methods : This study consisted of five elite male athletes (26.80±5.97 years), members of the Bulgarian national team in Shotokan karate, competing in the kata discipline. The study was conducted in competitive conditions during national competitions, in which three katas were performed by each of the competitors. Capillary blood lactate concentration (La) was determined at rest and after each kata. Heart rate (HR) was registered and physical activity was monitored by using three-dimensional accelerometers. Results: The mean La increased progressively after each following kata: 1.4±0.32 mmol/L at rest, 4.7±1.91 mmol/L after the first, 6.8±2.59 mmol/L after the second, and 7.1±2.35 mmol/L after the third kata. This increase was significant after the second (р<0.05) and third (р<0.01) kata, in comparison with the registered La at rest. The mean HR values reached 179±11.55 bpm during the first, 180±11.63 bpm during the second, and 181.5±15.44 bpm during the third kata. Conclusions: The La appeared to be a more informative parameter than heart rate, and the moderate increase of the La values (4-6 mmol/L) indicated optimal muscle tension and amplitude of moves when performing katas in competitive conditions. Further research is needed to determine the optimal La levels for the performance of different katas.

scholarly journals Can a Science, Technology, Engineering, and Mathematics (STEM) Approach Enhance Students’ Mathematics Performance?

2021 ◽  
Vol 14 (1) ◽  
pp. 379
Author(s):  
Suik Fern Kong ◽  
Mohd Effendi Ewan Mohd Matore
Keyword(s):  
Conventional Method ◽  
Test Performance ◽  
Student Attitudes ◽  
Teaching And Learning ◽  
Three Dimensional ◽  
Mathematics Performance ◽  
Student Interactions ◽  
Post Test ◽  
Quasi Experimental ◽  
The Mean

The STEM approach is a student-centred teaching and learning process that involves an inquiry process in problem-solving questions. This study was conducted to examine the effectiveness of the STEM approach in enhancing students’ mathematics performance. The study used a quasi-experimental design of unbalanced groups through the pre-test and post-test for treatment and control groups. The instrument included a set of questionnaires on student attitudes towards STEM implementation and the three-dimensional geometric shapes achievement test. The research samples included 14-year-old students from one of the private secondary schools in Kuching, which involved 68 students who were selected using purposive sampling. The results showed that student attitudes towards the implementation of the STEM approach were at a moderate level. In addition, the results illustrated a significant and moderate difference in mathematics performance between students who participated in the STEM approach and the conventional method using pre-test and post-test. The mean score of the post-test performance for the STEM approach was higher compared to the mean score of post-test performance for the conventional method. The results of the study demonstrated that the implementation of the STEM approach that involved both inquiry-based learning and problem-based learning was effective and able to improve the students’ academic performance. This can help teachers to vary their teaching and learning methods by increasing student interactions and engagement. Improvements can be made in the future by adding more research samples to expand the context of the study and prolong the treatment duration. Researchers can also add research variables in future studies by examining student interests and motivations towards the STEM approach.

Intracycle Velocity Variation of the Body Centre of Mass in Front Crawl

2012 ◽  
Vol 33 (04) ◽  
pp. 285-290 ◽  
Author(s):  
P. Figueiredo ◽  
P.-L. Kjendlie ◽  
J. Vilas-Boas ◽  
R. Fernandes
Keyword(s):  
The Body ◽  
Velocity Variation ◽  
Centre Of Mass ◽  
Front Crawl

Electron Holographic Nano-Characterization of Gold Catalyst at Interface

2002 ◽  
Vol 727 ◽  
Author(s):  
S. Ichikawa ◽  
T. Akita ◽  
M. Okumura ◽  
M. Haruta ◽  
K. Tanaka
Keyword(s):  
Contact Angle ◽  
Titanium Oxide ◽  
Gold Catalyst ◽  
Three Dimensional ◽  
High Resolution Electron Microscopy ◽  
Electron Holography ◽  
Gold Particles ◽  
Oxide Support ◽  
The Mean ◽  
A Charge

AbstractThe catalytic properties of nanostructured gold catalyst are known to depend on the size of the gold particles and to be activated when the size decreases to a few nanometers. We investigated the size dependence of the three-dimensional nanostructure on the mean inner potential of gold catalysts supported on titanium oxide using electron holography and high-resolution electron microscopy (HREM). The contact angle of the gold particles on the titanium oxide tended to be over 90° for gold particles with a size of over 5 nm, and below 90° for a size of below 2 nm. This decreasing change in the contact angle (morphology) acts to increase the perimeter and hence the area of the interface between the gold and titanium oxide support, which is considered to be an active site for CO oxidation. The mean inner potential of the gold particles also changed as their size decreased. The value of the inner potential of gold, which is approximately 25 V in bulk state, rose to over 40 V when the size of the gold particles was less than 2 nm. This phenomenon indicates the existence of a charge transfer at the interface between gold and titanium oxide. The 3-D structure change and the inner potential change should be attributed to the specific electronic structure at the interface, owing to both the “nano size effect” and the “hetero-interface effect.”

The Influence of Blade Wakes on the Performance of Interturbine Diffusers

1996 ◽  
Vol 118 (2) ◽  
pp. 347-352 ◽  
Author(s):  
R. G. Dominy ◽  
D. A. Kirkham
Keyword(s):  
Performance Modeling ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Two Dimensional ◽  
Correct Performance ◽  
Analysis Methods ◽  
Flow Factor ◽  
The Mean ◽  
Lp Turbine

Interturbine diffusers provide continuity between HP and LP turbines while diffusing the flow upstream of the LP turbine. Increasing the mean turbine diameter offers the potential advantage of reducing the flow factor in the following stages, leading to increased efficiency. The flows associated with these interturbine diffusers differ from those in simple annular diffusers both as a consequence of their high-curvature S-shaped geometry and of the presence of wakes created by the upstream turbine. It is shown that even the simplest two-dimensional wakes result in significantly modified flows through such ducts. These introduce strong secondary flows demonstrating that fully three-dimensional, viscous analysis methods are essential for correct performance modeling.

scholarly journals Proximity of the middle meningeal artery and maxillary artery to the mandibular head and mandibular neck as revealed by three-dimensional time-of-flight magnetic resonance angiography

2021 ◽  
Author(s):  
Daphne Schönegg ◽  
Raphael Ferrari ◽  
Julian Ebner ◽  
Michael Blumer ◽  
Martin Lanzer ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Angiography ◽  
Three Dimensional ◽  
Time Of Flight ◽  
Middle Meningeal Artery ◽  
Individual Variability ◽  
Maxillary Artery ◽  
Condylar Process ◽  
The Mean ◽  
Meningeal Artery

Abstract Purpose The close topographic relationship between vascular and osseous structures in the condylar and subcondylar region and marked variability in the arterial course has been revealed by both imaging and cadaveric studies. This study aimed to verify the previously published information in a large sample and to determine a safe surgical region. Methods We analyzed the three-dimensional time-of-flight magnetic resonance angiography images of 300 individuals. Results The mean distance between the middle meningeal artery and the apex of the condyle or the most medial point of the condyle was 18.8 mm (range: 11.2–25.9 mm) or 14.5 mm (range: 8.8–22.9 mm) respectively. The course of the maxillary artery relative to the lateral pterygoid muscle was medial in 45.7% of cases and lateral in 54.3%. An asymmetric course was evident in 66 patients (22%). The mean distance between the maxillary artery and condylar process at the deepest point of the mandibular notch was 6.2 mm in sides exhibiting a medial course (range: 3.7–9.8 mm) and 6.6 mm in sides exhibiting a lateral course (range: 3.9–10.4 mm). The distances were significantly influenced by age, gender, and the course of the maxillary artery. Conclusion Our study emphasizes the marked inter- and intra-individual variability of the maxillary and middle meningeal arterial courses. We confirmed the proximity of the arteries to the condylar process. Extensive surgical experience and thorough preparation for each individual case are essential to prevent iatrogenic vascular injury.

scholarly journals Interactions between Tandem Cylinders in an Open Channel: Impact on Mean and Turbulent Flow Characteristics

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1718
Author(s):  
Hasan Zobeyer ◽  
Abul B. M. Baki ◽  
Saika Nowshin Nowrin
Keyword(s):  
Turbulent Flow ◽  
Open Channel ◽  
Recirculation Zone ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Recirculation ◽  
Tandem Cylinders ◽  
Flow Development ◽  
The Mean ◽  
Recirculation Length

The flow hydrodynamics around a single cylinder differ significantly from the flow fields around two cylinders in a tandem or side-by-side arrangement. In this study, the experimental results on the mean and turbulence characteristics of flow generated by a pair of cylinders placed in tandem in an open-channel flume are presented. An acoustic Doppler velocimeter (ADV) was used to measure the instantaneous three-dimensional velocity components. This study investigated the effect of cylinder spacing at 3D, 6D, and 9D (center to center) distances on the mean and turbulent flow profiles and the distribution of near-bed shear stress behind the tandem cylinders in the plane of symmetry, where D is the cylinder diameter. The results revealed that the downstream cylinder influenced the flow development between cylinders (i.e., midstream) with 3D, 6D, and 9D spacing. However, the downstream cylinder controlled the flow recirculation length midstream for the 3D distance and showed zero interruption in the 6D and 9D distances. The peak of the turbulent metrics generally occurred near the end of the recirculation zone in all scenarios.

scholarly journals Brain capillary structures of schizophrenia cases and controls show a correlation with their neuron structures

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rino Saiga ◽  
Masayuki Uesugi ◽  
Akihisa Takeuchi ◽  
Kentaro Uesugi ◽  
Yoshio Suzuki ◽  
...  
Keyword(s):  
Blood Vessels ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Superior Temporal Gyrus ◽  
Anterior Cingulate ◽  
Dimensional Structure ◽  
Constant Diameter ◽  
The Mean ◽  
Cartesian Coordinate ◽  
Micrometer Scale

AbstractBrain blood vessels constitute a micrometer-scale vascular network responsible for supply of oxygen and nutrition. In this study, we analyzed cerebral tissues of the anterior cingulate cortex and superior temporal gyrus of schizophrenia cases and age/gender-matched controls by using synchrotron radiation microtomography or micro-CT in order to examine the three-dimensional structure of cerebral vessels. Over 1 m of cerebral blood vessels was traced to build Cartesian-coordinate models, which were then used for calculating structural parameters including the diameter and curvature of the vessels. The distribution of vessel outer diameters showed a peak at 7–9 μm, corresponding to the diameter of the capillaries. Mean curvatures of the capillary vessels showed a significant correlation to the mean curvatures of neurites, while the mean capillary diameter was almost constant, independent of the cases. Our previous studies indicated that the neurites of schizophrenia cases are thin and tortuous compared to controls. The curved capillaries with a constant diameter should occupy a nearly constant volume, while neurons suffering from neurite thinning should have reduced volumes, resulting in a volumetric imbalance between the neurons and the vessels. We suggest that the observed structural correlation between neurons and blood vessels is related to neurovascular abnormalities in schizophrenia.

scholarly journals The follow-up of the robotic-assisted Soave procedure for Hirschsprung’s disease in children

2021 ◽  
Author(s):  
Tran Anh Quynh ◽  
Pham Duy Hien ◽  
Le Quang Du ◽  
Le Hoang Long ◽  
Nguyen Thi Ngoc Tran ◽  
...  
Keyword(s):  
Hirschsprung's Disease ◽  
Hirschsprung’S Disease ◽  
Pediatric Patients ◽  
Three Dimensional ◽  
Dentate Line ◽  
Robotic Arms ◽  
Robotic Assisted ◽  
The Mean ◽  
Pull Through

AbstractRobotic surgery offers three-dimensional visualization and precision of movement that could be of great value to gastrointestinal surgeons. There were many previous reports on robotic technology in performing Soave colonic resection and pull-through for Hirschsprung’s disease in children. This study described the follow-up of the Robotic-assisted Soave procedure for Hirschsprung’s disease in children. Robotic-assisted endorectal pull-through was performed using three robotic arms and an additional 5-mm trocar. The ganglionic and aganglionic segments were initially identified by seromuscular biopsies. The rest of the procedure was carried out according to the Soave procedure. We left a short rectal seromuscular sleeve of 1.5–2 cm above the dentate line. From December 2014 to December 2017, 55 pediatric patients were operated on. Age ranged from 6 months to 10 years old (median = 24.5 months). The aganglionic segment was located in the rectum (n = 38), the sigmoid colon (n = 13), and the left colon (n = 4). The mean total operative time was 93.2 ± 35 min (ranging from 80 to 180 min). Minimal blood was lost during the surgery. During the follow-up period, 41 patients (74.6%) had 1–2 defecations per day, 12 patients (21.8%) had 3–4 defecations per day, and 2 patients (3.6%) had more than 4 defecations per day. Fecal incontinence, enterocolitis, and mild soiling occurred in three (5.4%), four (7.3%), and two pediatric patients, respectively. Robotic-assisted Soave procedure for Hirschsprung’s disease in children is a safe and effective technique. However, a skilled robotic surgical team and procedural modifications are needed.

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