Rowing Motion Research Articles

実映像と筋活動の重畳表示によるローイング動作教育システム

In many sports, essential skills exist in terms of muscle activation in order to improve performance. However, it is difficult to identify the important muscle activation, and moreover novices cannot observe and imitate it since muscle activation is hardly visible. This study especially focuses on human rowing motion to extract an important skill in terms of muscle activation and we develop skill education system for novices to learn the skill. Firstly, strength and activation timing of lower leg muscle are evaluated to detect the expert skill based on their peak value and cross correlation during movement. Next, new skill education system is suggested by simultaneous presentation of real human movement and muscle activations of the targeted muscle. In the proposed system, muscle color is continuously changed based on its activation level for novices to perceive their muscle activation visually. Both experts and novices participated at our skill extraction experiment to compare their muscle activation. Results showed that experts had larger peak activation level and different profile in rectus femoris muscle. Therefore, our skill education system focused on rectus femoris muscle to present its activation level and movement simultaneously. In order to evaluate efficacy of the developed system, four different education instructions were conducted to novices; linguistic education, simultaneous presentation of motion and muscle activation of the expert, off-line presentation of novice's motion and muscle activation, and real time presentation of novice's motion and muscle activation. Performance of novices was evaluated after each instruction based on peak activation level, cross correlation, and exerted power on the rowing ergometer. These performance change after each education implied providing integrated view of novice's motion and muscle activation in real-time could improve performance of rowing motion.

Anthropometry and high-speed resistive exercise performance by male athletes

BACKGROUND: High-speed exercise is an essential training component to prepare athletes for competition. To date correlations between anthropometry and high-speed exercise performance are mixed. OBJECTIVE: To assess anthropometry as a correlate to performance from workouts comprised exclusively of tonic or phasic repetitions done on a high-speed resistive exercise device (Impulse Training Systems; Newnan, GA). METHODS: Male athletes (n = 31) did two workouts that involved performance of a standing unilateral rowing motion with their left arm for two 60-second sets. Each workout was comprised solely of tonic or phasic repetitions. Anthropometric measurements included: height, mass, body fat percentage, shoulder width, upper and lower arm lengths as well as torso length. Mean force and total work values from each type of workout served as criterion variables. RESULTS:Anthropometry predicted significant amounts of variance for both mean force and total work values (r 2 ∼ 0.21) from tonic workouts. However anthropometry failed to predict a significant amount of performance variance from phasic workouts. CONCLUSIONS: Anthropometry acts as a better correlate to high-speed resistive exercise performance for repetitions that do not terminate with impact forces and are inherently less ballistic, as the latter likely utilizes less momentum.

Analysis of Indoor Rowing Motion using Wearable Inertial Sensors

In this exploratory work the motion of rowers is analyzed while rowing on a rowing machine. This is performed using inertial sensors that measure the orientation at several positions on the body. Using these measurements, this work provides a preliminary analysis of the differences between experienced and novice rowers, or between a good and a bad technique. The analysis shows that the measured postural angles show no clear trend that would set apart experienced and novice rowers or a bad and a good technique. However, there are clear differences in absolute postural angle's consistency and timing consistency of strokes between novice and experienced rowers. We also applied a machine learning technique to the data to find the similarities between different rowers and an experienced reference rower. The results can be used to compare the quality of the rowing technique with respect to a reference. In this paper, we present our initial results as well as the challenges that need to be further explored.

3P1-I05 ロボコックス(筋骨格モデリング)

The difference between life expectancy and healthy-life years, around 10 years, is social problem in Japan. In the difference of years, people with the limitation of life activities have to require medical treatments and nursing cares for living. Physical exercise is one of the most effective methods for improving the potential of life activities. This study focused on a rowing motion for whole-body exercise and developed an intelligent supervisor system for physical exercise "RoboCox," named after robotic cox. The system consisted of rowing machine and Kinect and helped beginners rapidly learn the appropriate movement of rowing.

The Effects of Unsteadiness and Compressibility on the Interaction Between Hub Leakage and Mainstream Flows in High-Pressure Turbines

This paper investigates the effects of compressibility and unsteadiness due to the relative blade row motion and their importance in the interaction between hub leakage (purge) and mainstream flows. First, the challenges associated with the blade redesign for low-speed testing are described. The effects of Mach number are then addressed by analyzing the experiments in the low-speed linear cascade equipped with the secondary airflow system and computations performed on the low- and high-speed blade profiles. These results indicate that the compressibility does not significantly affect the interaction between the leakage and mainstream flows despite a number of compromises made during the design of the low-speed blade. This was due to the fact that the leakage–mainstream interaction takes place upstream of the blade throat where the local Mach numbers are still relatively low. The analysis is then extended to the equivalent full-stage unsteady computations. The periodic unsteadiness resulting from the relative motion of the upstream vanes appreciably affected the way in which the leakage flow is injected and the rotor flow field in general. However, the time-average flow field was still found to be dominated by the rotor blade's potential field. For the present test arrangement, the unsteady effects were not very detrimental and caused less than a 10% increase in the losses due to the leakage injection relative to the steady calculations.

Rowing, Expertise and Biological Motion

Rowing, Expertise and Biological Motion

Forelimb kinematics and motor patterns of swimming loggerhead sea turtles (Caretta caretta): are motor patterns conserved in the evolution of new locomotor strategies?

Novel functions in animals may evolve through changes in morphology, muscle activity or a combination of both. The idea that new functions or behavior can arise solely through changes in structure, without concurrent changes in the patterns of muscle activity that control movement of those structures, has been formalized as the neuromotor conservation hypothesis. In vertebrate locomotor systems, evidence for neuromotor conservation is found across evolutionary transitions in the behavior of terrestrial species, and in evolutionary transitions from terrestrial species to flying species. However, evolutionary transitions in the locomotion of aquatic species have received little comparable study to determine whether changes in morphology and muscle function were coordinated through the evolution of new locomotor behavior. To evaluate the potential for neuromotor conservation in an ancient aquatic system, we quantified forelimb kinematics and muscle activity during swimming in the loggerhead sea turtle, Caretta caretta. Loggerhead forelimbs are hypertrophied into wing-like flippers that produce thrust via dorsoventral forelimb flapping. We compared kinematic and motor patterns from loggerheads with previous data from the red-eared slider, Trachemys scripta, a generalized freshwater species exhibiting unspecialized forelimb morphology and anteroposterior rowing motions during swimming. For some forelimb muscles, comparisons between C. caretta and T. scripta support neuromotor conservation; for example, the coracobrachialis and the latissimus dorsi show similar activation patterns. However, other muscles (deltoideus, pectoralis and triceps) do not show neuromotor conservation; for example, the deltoideus changes dramatically from a limb protractor/elevator in sliders to a joint stabilizer in loggerheads. Thus, during the evolution of flapping in sea turtles, drastic restructuring of the forelimb was accompanied by both conservation and evolutionary novelty in limb motor patterns.

Numerical simulation of a pectoral fin during labriform swimming

We numerically examine the fluid-structure interaction and force generation of a skeleton-reinforced fin that geometrically, structurally and kinematically resembles the pectoral fin of a fish during labriform swimming. This fin contains a soft membrane with negligible bending stiffness and 12 embedded rays (modeled as beams). A potential flow-based boundary element model is applied to solve the fluid flow around the fin, in which the vorticity field is modeled as thin vorticity sheets shed from prescribed locations (the sharp trailing edge). The fin motion is actuated by dorsoventral and anteroposterior rotations of the rays (the motion of each ray is controlled individually), as well as pitching motion of the baseline. Consequently, the fin undergoes a combination of flapping (lift-based) and rowing (drag-based) motions typical in labriform swimming. The fin motion contains two strokes: a recovery stroke and a power stroke. The performance of the fin depends upon kinematic parameters such as the Strouhal number, the phase lag between rays, the pitching motion of the baseline and the passive deformations of the rays. The most interesting finding is that the strengthening of the ray at the leading edge plays a pivotal role in performance enhancement by reducing the effective angle of attack and decreasing the power expenditure during the recovery stroke.

Well-posedness of a 2D swimming model governed in the nonstationary Stokes fluid by multiplicative controls

We introduce and discuss the well-posedness of a schematic simplified mathematical model of an abstract object ‘swimming’ in the 2D nonstationary Stokes fluid. The object consists of finitely many subsequently connected small sets, each of which can act upon a pair of the adjacent sets in a rotation fashion with the purpose to generate its fish-like or rowing motion. The structural integrity of the object is maintained by respective elastic Hooke's forces. Such models are of interest in biological and engineering applications dealing with propulsion systems in fluids. Mathematics-wise, the model equations are described by a complex highly nonlinear hybrid system of partial differential equations and ordinary differential equations, which include a fluid equation and an equation describing the motion of the object in it. Our study is linked to viewing the swimming process as the one governed by multiplicative (bilinear) controls.

Construction and Central Pattern Generator-Based Control of a Flipper-Actuated Turtle-Like Underwater Robot

This paper deals with the construction and control of a turtle-like underwater robot with four mechanical flippers. Each flipper consists of two joints generating a rowing motion by a combination of lead-lag and feathering motions. With cooperative movements of four flippers, the robot can propel and maneuver in any direction without rotation of its main body and execute complicated three-dimensional movements, including ascending, submerging, rolling and hovering. The control architecture is constructed based on a central pattern generator (CPG). A model for a system of coupled nonlinear oscillators is established to construct a CPG and has been successfully applied to the eight-joint turtle-like robot. The CPGs are modeled as nonlinear oscillators for joints and inter-joint coordination is achieved by altering the connection weights between joints. Rowing action can be produced by modulating the control parameters in the CPG model. The CPG-based method performs elegant and smooth transitions between swimming gaits, and enhanced adaptation to the transient perturbations due to nonlinear characteristics. The effectiveness of the proposed method is confirmed via simulations and experimental results.

Muscle cross-sectional areas and performance power of limbs and trunk in the rowing motion

Although it is clear that rowers have a large muscle mass, their distribution of muscle mass and which of the main motions in rowing mediates muscle hypertrophy in each body part are unclear. We examine the relationships between partial motion power in rowing and muscle cross-sectional area of the thigh, lower back, and upper arms. Sixty young rowers (39 males and 21 females) participated in the study. Joint positions and forces were measured by video cameras and rowing ergometer software, respectively. One-dimensional motion analysis was performed to calculate the power of leg drive, trunk swing, and arm pull motions. Muscle cross-sectional areas were measured using magnetic resonance imaging. Multiple regression analyses were carried out to determine the association of different muscle cross-sectional areas with partial motion power. The anterior thigh best explained the power demonstrated by leg drive (r 2 = 0.508), the posterior thigh and lower back combined best explained the power demonstrated by the trunk swing (r 2 = 0.493), and the elbow extensors best explained the power demonstrated by the arm pull (r 2 = 0.195). Other correlations, such as arm muscles with leg drive power (r 2 = 0.424) and anterior thigh with trunk swing power (r 2 = 0.335), were also significant. All muscle cross-sectional areas were associated with rowing performance either through the production of power or by transmitting work. The results imply that rowing motion requires a well-balanced distribution of muscle mass throughout the body.

Computation of unsteady flow past a biomimetic fin

The unsteady hydrodynamics of a biomimetic fin attached to a cylindrical body has been studied numerically using a computational fluid dynamic (CFD) simulator based on an in-house solver of the Navier-Stokes equations, combined with a recently developed multi-block, overset grid method. The fin-body CFD model is based on a mechanical pectoral fin device, which consists of a cylindrical body and an asymmetric fin and can mimic flapping, rowing and feathering motions of the pectoral fins in fishes. First the multi-block, overset grid method incorporated into the NS solver was verified through an extensive study of unsteady flows past a single fin undergoing rowing and feathering motion. Then unsteady flows past the biomimetic fin-body model undergoing the same motions were computed and compared with the measurements of forces of the mechanical pectoral fin, which shows good agreement in both time-varying and time-averaged hydrodynamic forces. The relationship between force generation and vortex dynamics points to the importance of the match in fin kinematics between power and recovery strokes and implies that an optimal selection of parameters of phase lags between and amplitudes of rowing and feathering motions can improve the performance of labriform propulsion in terms of either maximum force generation or minimum mechanical power.

Optimization of Motion of a Mechanical Pectoral Fin

This paper describes the use of a mechanical pectoral fin as a new device for maneuvering and stabilizing an underwater vehicle. The mechanical pectoral fin consists of three servo-motors, which respectively generate a rowing motion, a feathering motion, and a flapping motion. We focused on the comparison of load characteristics of the mechanical pectoral fin between the drag-based swimming mode and the lift-based swimming mode, undertaken under the conditions of uniform flow and still water, respectively. Optimization of the parameters of fin motion so as to generate maximum propulsive force in terms of flow condition and motion pattern revealed that the lift-based rather than the drag-based swimming mode is suitable for generation of propulsive force in uniform flow, whereas the drag-based rather than the lift-based swimming mode is suitable for generation of propulsive force in still water within the range of motion of the mechanical pectoral fin.

Unsteady hydrodynamic load acting on an oar blade

The oar blade acts as hydrofoil in stroke phase. Its angle of attack and velocity of incoming flow is not constant but transient so that the load which acts on the oar blade should be unsteady. It is absolutely necessary to estimate the load to analyze the rowing motion. But it is not appropriate to estimate with assuming steady state.We carried a tank test using a circulating water channel. A flat plate attached to a load cell rotated in uniform flow and angle of attack varied according to the rotation of the plate. The result of this experiment indicates that the unsteady load is much larger than the steady one. And the load was properly arranged by reduced frequency. A method to estimate the unsteady load from the angle of attack and the velocity of incoming flow was established.

Biomechanics of Rowing. II. A Control Model for the Simulation Study of Rowing and Other Human Movement.

A new control model for the study of biomechanical simulation of human movement was investigated using rowing as an example. The objectives were to explore biological and mechanical alternatives to optimal control methods. The simulation methods included simple control mechanisms based on proportional and derivative (PD) control, consideration of a simple neural model, introduction of an inverse dynamics system for feedback, and computational adjustment of control parameters by using an evaluative criterion and optimization method. By using simulation, appropriate rowing motions were synthesized. The generated rowing motion was periodic, continuous, and adaptable so that the pattern was stable against the mechanical force and independent of the initial condition. We believe that the simulation model is not only practical as a computational research tool from a biomechanical-engineering viewpoint but also significant from the point of view of fundamental biological theories of movement.

Hydrodynamic Characteristics of a Mechanical Pectoral Fin

This paper describes the use of a mechanical pectoral fin as a new device for maneuvering and stabilizing an underwater vehicle. The mechanical pectoral fin consists of two servo-motors generating a feathering motion and a rowing motion. The hydrodynamic characteristics of the device were analyzed experimentally and theoretically. The mechanical pectoral fin generates a thrust force in a range of phase differences between both motions. The unsteady vortex-lattice method, which takes into account the effects of viscosity, reasonably expresses the unsteady forces acting on the mechanical pectoral fin.

Possible propulsion modes in Graptoloidea: a new model for graptoloid locomotion

The mode of locomotion of any swimming animal is constrained by its size, architecture, and phylogenetic history. Considering these factors and the range of locomotory systems used by extant zooplankton, the range of possible modes of locomotion for graptoloids can be effectively limited. Three assumptions have been made: (1) graptoloids did not use a mode of locomotion unknown among modern organisms; (2) all graptoloids employed essentially the same mode of locomotion except, possibly, in their early growth stages; and (3) graptoloids did not rely entirely on passive buoyancy—no extant zooplankton groups in the size range of the graptoloids do. Structures that increase buoyancy or drag are often found in actively swimming zooplankton. They enhance feeding efficiency and reduce sinking rates during nonswimming periods.The modes of locomotion utilized by extant zooplankton groups are ciliary propulsion, elongate body undulation, jet propulsion, rowing with skeletonized appendages, and rowing or undulation with muscular appendages. Of these, all but the last can be rejected for the graptoloids on the basis of scale or architecture. It is concluded that graptoloids probably used a rowing or undulatory motion with muscular appendages for swimming. Using a pterobranch model for the graptoloid zooids, the lophophore is considered an unlikely propulsive structure because the design requirements would conflict with those of a ciliarly suspension-feeding organ. Winglike, lateral extensions of the muscular cephalic shield, the same structure used for creeping locomotion in the benthic pterobranchs, is regarded as the most likely propulsive organ, analogous to the pteropod swimming wings.

Copulatory behaviour of the tsetse flies Glossina morsitans and G.austeni

ABSTRACT. The copulatory behaviour of Glossina morsitans morsitans West. and G.austeni Newst. was analysed by filming. After a male and female engaged genitalia, the male performed a repertoire of five actions for 3–4 min: (1) ‘rubbing’ his metathoracic, tibiotarsal joint against the region of genital contact; (2) ‘stroking’ or hitting the female's head and thorax with his meso‐ and metathoracic legs; (3) ‘wing flick’ by moving his mesothoracic legs in a rowing motion whilst at the same time vibrating the wings as in normal flight; (4) ‘wing vibration’ with the wings vibrated in the closed position; (5) ‘wings out’ in which the wings are moved out to the flying position without any observable vibration. Each action was repeated many times, to give variable individual sequences, but declined in frequency exponentially over the first 3–4 min in copulo. The two species differed in the frequency of acts. Shortly before separation, a few hours later, actions 1 and 2 reappeared. Receptive females exhibited little overt behaviour except in the maintenance of a passive stance. Refractory females rejected a mating attempt by flexing the abdomen ventrally, vibrating their wings in the closed position, and pushing the male with meso‐ and metathoracic legs. The significance and possible functions of male behaviour are discussed in relation to mating in Glossina and other Diptera.

エネルギー示性式からみたローイングの運動学的研究

The purpose of this investigation was to examine force, velocity, and power of rowing motion and to calculate the energy equation applicable to such movement. Higher performance and better technique in rowing may be interpreted in terms of how to generate larger energy and minimize the energy expenditure during the rowing motion. Force, velocity, and power of rowing motion were recorded by the inertia wheel and power meter devised by the present author, as the subject pulled wire connected to an inertia wheel in simulated rowing motion. The equivalent masses of inertia wheel were graded into six load levels varying from 8.0kg to 986.3kg. The rowing motion was filmed by 16mm cine camera and the corresponding measures of force, velocity, and power were synchronized to the film. Experimental subjects were eight members of varsity crew and same number of juniorvarsity crew of Tokyo Institute of Technology and were termed as "Boat Man." In addition, eight trained athletes in track and field and basketball who had no experience in rowing formed a control group and were termed as "Non Boat Man." No appreciable difference was observed between the "Boat Man" and "Non Boat Man" in the measures of their physique and static maximum strength. Following results were obtained: 1. Rowing force and power reached maximum when the arm pull is simultaneously combined with the leg kick and the backward swing of the body. 2. The following equation was proposed to express the rowing motion: 1/2 (M+A) V^2 = Ed where: Ed = total generated energy A = coefficient of expended energy 1/2MV^2 = effective energy trasmitted to the boat 3. From the study of various rowing styles, i. e., using only legs or only arms, it was estimated that the total energy (100%) is contributed 37% by the leg kick, 36% by the backward swing of the body, and 27% by the arm pull. 4. There were remarkable differences between "Boat Man" and "Non boat Man" in their energy equations, although their muscular strength were comparable. These equations were: Varsity crew 1/2 (M+75.74)V^2 = 952.91 Junior Varsity crew 1/2 (M+74.76)V^2 = 879.10 "Non Boat Man" 1/2 (M+51.99)V^2 = 614.51 5. In selection of the crew members and determination of their positions, a consideration of the energy equation, especially of the high level and the balance in ED and A values may be recommendable.

Maximizing Human Power Output by Suitable Selection of Motion Cycle and Load

In this paper various factors affecting human power output are discussed, including the mechanical properties of muscle, the geometry of the input motion and the kinematics of the input motion. A mulitpurpose ergometer, designed and built to take account of these factors is described. Two basic motions are possible on the ergometer: cycling and rowing. The rowing motions may be made with any combination of seat and feet either sliding or fixed. In the rowing motions, during a single to and fro cycle, prescribed variations in velocity of the input links can be forced on a subject. Experimental work, which is described, showed that there are considerable differences in the effectiveness of the various ways of working, and that one in particular, a modified rowing motion, allowed the production of greater average amounts of power for periods up to two minutes than have so far been recorded and published (to the author's knowledge).