The Relationship Between Propulsive Force in Tethered Swimming and 200-m Front Crawl Performance

In this study the propelling efficiency (ep) of front-crawl swimming, by use of the arms only, was calculated in four subjects. This is the ratio of the power used to overcome drag (Pd) to the total mechanical power (Po) produced including power wasted in changing the kinetic energy of masses of water (Pk). By the use of an extended version of the system to measure active drag (MAD system), Pd was measured directly. Simultaneous measurement of O2 uptake (VO2) enabled the establishment of the relationship between the rate of the energy expenditure (PVO2) and Po (since when swimming on the MAD system Po = Pd). These individual relationships describing the mechanical efficiency (8-12%) were then used to estimate Po in free swimming from measurements of VO2. Because Pd was directly measured at each velocity studied by use of the MAD system, ep could be calculated according to the equation ep = Pd/(Pd + Pk) = Pd/Po. For the four top class swimmers studied, ep was found to range from 46 to 77%. Total efficiency, defined as the product of mechanical and propelling efficiency, ranged from 5 to 8%.

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Design, Implementation and Control of a Fish Robot with Undulating Fins

International Journal of Advanced Robotic Systems ◽

10.5772/50898 ◽

2011 ◽

Vol 8 (5) ◽

pp. 60 ◽

Cited By ~ 17

Author(s):

Mohsen Siahmansouri ◽

Ahmad Ghanbari ◽

Mir Masoud Seyyed Fakhrabadi

Keyword(s):

Field Trials ◽

Robotic Fish ◽

Propulsive Force ◽

Fish Robot ◽

Revolution Speed ◽

The Individual ◽

And Control ◽

Phase Angles ◽

The Relationship ◽

Undulating Fin

Biomimetic robots can potentially perform better than conventional robots in underwater vehicle designing. This paper describes the design of the propulsion system and depth control of a robotic fish. In this study, inspired by knife fish, we have designed and implemented an undulating fin to produce propulsive force. This undulating fin is a segmental anal fin that produces sinusoidal wave to propel the robot. The relationship between the individual fin segment and phase angles with the overall fin trajectory has also been discussed. This propulsive force can be adjusted and directed for fish robot manoeuvre by a mechanical system with two servomotors. These servomotors regulate the direction and depth of swimming. A wireless remote control system is designed to adjust the servomotors which enables us to control revolution, speed and phase differences of neighbor servomotors of fins. Finally, Field trials are conducted in an outdoor pool to demonstrate the relationship between robotic fish speed and fin parameters like phase difference, the number of phase and undulatory amplitude.

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Design, Propulsive Force Prediction and Test of a Electromagnetic Drive Mechanism of a New Concept of Micro Flapping Wing Rotor

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.490-495.2300 ◽

2012 ◽

Vol 490-495 ◽

pp. 2300-2304 ◽

Cited By ~ 1

Author(s):

Jing Lu ◽

Ning Jun Fan ◽

Yi Wei Wang

Keyword(s):

High Amplitude ◽

Flapping Wing ◽

Test Results ◽

Propulsive Force ◽

Force Prediction ◽

Drive Mechanism ◽

Electromagnetic Drive ◽

Relationship Of ◽

The Relationship

To further increase the lift and rotate speed of a micro flapping wing rotor, a electromagnetic mechanism is designed to achieved high amplitude and small friction. Then average propulsive force using Theodorsen’s theory is simulated to confirm the parameter affect. In the end, the relationship of average lift, average propulsive force, rotate speed are shown in the experiment and test results represent that this mechanism has much better performance than PZT one.

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Quantitative analysis of the front crawl in men and women

Journal of Applied Physiology ◽

10.1152/jappl.1977.43.3.475 ◽

1977 ◽

Vol 43 (3) ◽

pp. 475-479 ◽

Cited By ~ 94

Author(s):

D. R. Pendergast ◽

P. E. Di Prampero ◽

A. B. Craig ◽

D. R. Wilson ◽

D. W. Rennie

Keyword(s):

Energy Cost ◽

Mechanical Efficiency ◽

Front Crawl ◽

Unit Distance ◽

Men And Women ◽

Proportionality Constant ◽

Body Drag ◽

The Relationship ◽

Competitive Swimmers ◽

Energy Cost Of Swimming

Body drag, D, and the overall mechanical efficiency of swimming, e, were measured from the relationship between extra oxygen consumption and extra drag loads in 42 male and 22 female competitive swimmers using the front crawl at speeds ranging from 0.4 to 1.2 m/s. D increased from 3.4 (1.9) kg at 0.5 m/s to 8.2 (7.0) kg at 1.2 m/s, with D of women (in brackets) being significantly less (P less than 0.05) than that of men. Mechanical efficiency increased from 2.9% at 0.5 m/s to 7.4% at 1.2 m/s for men, the values for women being somewhat greater than those for men. The ratio, D/e was shown to be identical to the directly measured energy cost of swimming one unit distance, V02/d, and was independent of the velocity up to 1.2 m/s. It averaged 52 and 37 l/km for men and women respectively (P less than 0.05). When corrected for body surface area the values were 27 and 22 l/km-m2 for men and women, respectively (P less than 0.05). The underwater torque, T, a measure of the tendency of the feet to sink, was 1.44 kg-m for men and 0.70 kg-m for women (P less than 0.05). VO2/d increased linearly with T for both men and women of similar competitive experience. However, the proportionality constant delta VO2/d-delta T was significantly less for competitive than noncompetitive swimmers. The analysis of the relationship VO2/d vs. T provides a valuable approach to the understanding of the energetics of swimming.

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Specific and Holistic Predictors of Sprint Front Crawl Swimming Performance

Journal of Human Kinetics ◽

10.2478/hukin-2021-0058 ◽

2021 ◽

Vol 78 (1) ◽

pp. 197-207

Author(s):

Marek Strzała ◽

Arkadiusz Stanula ◽

Piotr Krężałek ◽

Wojciech Rejdych ◽

Jakub Karpiński ◽

...

Keyword(s):

Swimming Performance ◽

Strongly Correlated ◽

Arm Cranking ◽

Front Crawl ◽

Dry Land ◽

Fitness Assessment ◽

Relationship Of ◽

The Impact ◽

The Relationship ◽

Sprint Swimming

Abstract The aim of the study was to examine the impact of selected water- and dry-land predictors of 50-m front crawl performance among 27 male swimmers aged 19.3 ± 2.67 years. The following water tests were performed: front crawl tethered arm stroking in a water flume (flow velocity: 0.9 m·s–1) and leg tethered flutter kicking in a swimming pool. Anaerobic tests on dry land included arm cranking and a set of 10 countermovement jumps. The maximal and average forces generated by legs in tethered swimming (Fl max and Fl ave) turned out to be the strongest predictors of sprint swimming aptitude. These values were strongly correlated with total speed (Vtotal50) (r = 0.49, p < 0.05 and r = 0.54, p < 0.01, respectively), start, turn, and finishing speed (VSTF) (r = 0.60, p < 0.01 and r = 0.67, p < 0.01, respectively). The relationship of Fl max and Fl ave with surface speed (Vsurface) was moderate (r = 0.33, non-significant and r = 0.41, p < 0.05, respectively). The maximal force generated by arms (Fa max) during flume tethered swimming significantly influenced Vsurface and Vtotal50 (0.51, p < 0.01 and 0.47, p < 0.05, respectively). Its relationship with VSTF was close to significant (0.36, p = 0.07). Upper and lower limb dry-land tests showed lower and more holistic relationships with the 50-m front crawl race, however, being a good complement to overall fitness assessment. Specific in-water evaluation, especially the newly prepared flutter kicking test, as well as dry-land tests, can be applied to regularly monitor progress in swimming training, and to identify talented swimmers.

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Relationship Between Fatigue and Changes in Swim Technique During an Exhaustive Swim Exercise

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2014-0310 ◽

2016 ◽

Vol 11 (1) ◽

pp. 33-39 ◽

Cited By ~ 3

Author(s):

Natália M. Bassan ◽

Tadeu E.A.S. César ◽

Benedito S. Denadai ◽

Camila C. Greco

Keyword(s):

Peak Torque ◽

Stroke Rate ◽

Elbow Flexors ◽

Front Crawl ◽

Stroke Length ◽

Swim Test ◽

Strength Tests ◽

Before And After ◽

Arm Muscles ◽

The Relationship

Purpose:To analyze the relationship between the responses of isometric peak torque (IPT) and maximal rate of force development (RFDmax) with the changes in stroking parameters in an exhaustive exercise performed in front crawl.Methods:Fifteen male swimmers performed, on different days, the following protocols: maximal 400-m trial, strength tests before and after an exhaustive test at 100% of the mean speed obtained during the 400-m test, and the same procedures on day 2.Results:The IPT of elbow flexors (79.9 ± 19.4 and 66.7 ± 20.0 N·m) and elbow extensors (95.1 ± 28.0 N·m and 85.8 ± 30.5 N·m) was decreased after the swim test, as was RFDmax (521.8 ± 198.6 and 426.0 ± 229.9 N·m/s; 420.6 ± 168.2 and 384.0 ± 143.5 N·m/s, respectively). Stroke length decreased during the swim test (1.96 ± 0.22 and 1.68 ± 0.29 m/stroke), while stroke rate increased (37.2 ± 3.14 and 41.3 ± 4.32 strokes/min). The propulsive phases increased while the nonpropulsive phases decreased during the test. Significant correlation was found between the changes in IPT and stroke length, stroke rate and recovery (elbow flexors), and entry and catch phase (elbow extensors). In addition, significant correlation was found between the changes in RFDmax of elbow flexors with the changes in pull and recovery phases.Conclusion:Changes in swim technique during an exhaustive test can be, at least in part, associated with fatigue of the arm muscles.

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Understanding the Relationship Between Pitch Agility and Propulsive Aerodynamic Forces in Bio-Inspired Flapping Wing Vehicles

Volume 2: Integrated System Design and Implementation; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting ◽

10.1115/smasis2015-8835 ◽

2015 ◽

Cited By ~ 1

Author(s):

Zohaib Hasnain ◽

James E. Hubbard ◽

Joseph Calogero ◽

Mary I. Frecker ◽

Aimy A. Wissa

Keyword(s):

Motion Tracking ◽

Compliant Mechanisms ◽

Shape Change ◽

Tracking System ◽

Fold Increase ◽

Flapping Wing ◽

Small Scale ◽

Propulsive Force ◽

Aerodynamic Forces ◽

The Relationship

Ornithopters, or flapping wing mechanical birds, represent a unique category of aerial vehicles that fill a need for small-scale, agile, long range, and payload-capable flight vehicles. This study focuses on understanding the relationship between the propulsive aerodynamic forces and pitch agility in these flapping wing vehicles. Using analytical methods, the aerodynamic moment acting upon a wing undergoing elastic flapping was calculated. A method to determine the pitch stiffness of the vehicle was then derived using a preexisting stability analysis. This method was used to demonstrate that pitch agility in flapping wing birds is intricately tied to the flapping cycle with different parts of the cycle creating stabilizing and destabilizing effects. The results indicated that pitch agility, and propulsive force generation, have a dependency on the shape of the wing, and that deformations such as bend and sweep are capable of making the vehicle more agile. Contact-aided compliant mechanisms with nonlinear stiffness were designed and inserted into the wing of an ornithopter to induce controlled morphing. These elements have varying stiffness during the upstroke and downstroke parts of the cycle which introduces an asymmetry between the two halves of the flapping cycle. The resulting flapping motion exhibited a two fold increase in horizontal propulsive force over the baseline case. A motion tracking system was used to capture the free flight response of the ornithopter in steady level flight. This information was then used to calculate the pitch stiffness of the ornithopter with a rigid spar, and, one with a nonlinear compliant element inserted into the spar to induce a desired shape change. The results revealed that an upstroke in which the aerodynamic forces are similar in magnitude to that of the downstroke, may be necessary to make the vehicle more agile, and, that there is a compromise between vehicle agility and flight propulsive forces.

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Coordination changes in front-crawl swimming

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2020.0071 ◽

2020 ◽

Vol 476 (2237) ◽

pp. 20200071

Author(s):

R. Carmigniani ◽

L. Seifert ◽

D. Chollet ◽

C. Clanet

Keyword(s):

Physical Model ◽

Critical Velocity ◽

Recovery Time ◽

Large Range ◽

Open Water ◽

Propulsive Force ◽

Relative Duration ◽

Front Crawl ◽

Stroke Cycle

We report the evolution of the coordination with velocity in front-crawl swimming which is used in competitions over a large range of distances (from 50 m up to 25 km in open-water races). Inside this single stroke, top-level swimmers show different patterns of arm organization. At low velocities, swimmers select an alternated stroke with gliding pauses during their propulsion. The relative duration of the gliding pauses on a stroke cycle is independent of the velocity in this first regime. Above a critical velocity, the relative duration of the gliding pauses starts to decrease as speed increases. Above a second critical velocity, the gliding pauses disappear and the swimmers start to superpose their propulsion phases. These three regimes are first revealed experimentally and then studied theoretically. It appears that below the first critical velocity, swimmers use a constant coordination index and vary their speed by varying their propulsive force to minimize their cost of propulsion. For larger velocities, swimmers use their maximum propulsive force and vary their recovery time to increase further their speed. The physical model developed is general and could be applied to understand other modes of locomotion.

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