Gender Differences in Metabolic Responses During Water Walking

The purpose of this study was to compare metabolic responses between men and women during water walking. Japanese men (27-73 yr, n = 26) and women (33-70 yr, n = 14) performed water walking at 25 m/min, 30 m/min and 35 m/min. Oxygen consumption (VO2), VO2 per weight (VO2/W), respiratory ventilation (VE), heart rate (HR), energy expenditure (EE), EE per weight (EE/W), and actual walking speed were analyzed at each velocity. VO2/W and EE/W were higher in women compared to men. However, VO2 and EE showed similar values between men and women. HRs were significantly higher for women than those of men at all speeds. The regression analysis with third-ordered polynomial equation by actual walking speed showed high correlation coefficients for VO2 and VO2/W. In relative terms exercise intensity was higher for women than men; however, absolute intensity were similar in both men and women during water walking. Moreover, analysis using third-ordered equations found that absolute intensity during water walking was dominated by walking spee

Optimization of the moment of inertia and the release conditions of a discus

AbstractThis paper describes the concurrent optimization of the design of a discus and the skill with which it is thrown. The objective function for optimization is the flight distance, where longer is better. Thirteen control variables are considered, twelve of which are concerned with the skill of the thrower. These determine the launch conditions, which are controlled by the thrower when he or she throws the discus. The final variable is concerned with the discus itself. This is the moment of inertia on its transverse axis. The optimization was carried out with the aid of a genetic algorithm, and the entire trend for each generation between the objective function and the control variables could be visualized with the aid of self organizing maps. It was found that the flight distance achieved with concurrent optimization was longer than that optimized for skill alone. In the case of the optimal flight, the angle of attack should always be less than the stalling angle

A KINEMATICAL AND KINETICAL ANALYSIS ON THE SWING PHASE OF AMPUTEE GAIT

The authors investigated the swing phase of the transfemoral and transtibial amputees by using optical motion capture system. The thigh, shank foot were modeled as a three-linked rigid segment model. Kinematical parameters, such as joint angle, angular velocity/acceleration and linear acceleration of the center of mass were also calculated by the obtained coordinates of the anatomical landmark markers. Using the inverse dynamics, the kinetical parameters, such as the joint force and torque acting at each joint were calculated. The authors focused on the initiation of the swing phase caused by the force at both the hip and knee joints. In addition, the relationships between the internal/external rotation and the abduction/adduction of the lower extremity during the swing phase was also discussed in this study

A COMPARISON OF LOWER LIMB JOINTS ANGULAR DISPLACEMENT BETWEEN LAND AND WATER-WALKING USING DYNAMIC TIME WARPING

The purpose of this study was firstly to compare lower limb joints angular displacement between land and water-walking by dynamic time warping. Six subjects (age 30.0±5.3 yr) performed 10 m land and water-walking at self-selected speed. Ankle, knee and hip joint angular displacements were calculated from video (25Hz) and compared to the two wave forms from the dynamic time warping procedure. Results showed the ankle and knee joints demonstrated warping periods in water-walking, when compared with land-walking. However, the warping periods around toe-off was seen at the hip joint in land-walking, compared with water-walking. Overall the ankle and knee joints motion in water walking were comparable to land-walking motion. However, the hip joint kinematics during water walking were not always comparable with land walking kinematics

Underwater Electromyogram for Human Health Exercise

The physical qualities of water are well established and include buoyancy, water drag force, hydrostatic pressure and thermal conductivity. The large difference in these physical qualities, compared to land-based activities, affect the human body in both physiologic and biomechanical aspects. An example of this is buoyancy, which acts vertically against gravity on the immersed object thus decreasing weight of the human body. The buoyancy level is equal to the mass of water displaced by the immersed object and is based on the accepted Archimedean principle. When a human is immersed in water up to the level of pubis around 40% of weight is accounted for, 50% at umbilical, 60% at xiphoid, and almost 80% at the level of axillary. When immersed to their lower limb joint and waist in a water environment, humans can easily move, without gravitational overload, due to the buoyancy effect

Features of Acceleration and Angular Velocity Using Thigh IMUs during Walking in Water

Ten participants were assessed while walking in water and on land with wearable inertial measurement units (IMUs) attached to the right thigh. Longitudinal acceleration, anterior-posterior acceleration, and frontal axis angular velocity were measured at 100 Hz, matched with video analysis sampled at 25 Hz during the walking trials. The longitudinal acceleration showed almost 1 g from initial heel contact to 70% of one cycle, and the anterior-posterior acceleration showed a sinusoidal pattern, synchronizing the approximate posture of the thigh in water. The frontal axis angular velocity fluctuated less while walking in water compared with on land, because thigh motion speed was slower in water than on land. The acceleration and angular velocity in water were stable and did not fluctuate. Walking exercises in water may be effective in individuals with knee- or thigh-related medical issues

Ski jumping flight skill analysis based on high-speed video image

AbstractMages of the initial 40 m part of a flight of 120-m ski jumping were recorded by a fixed high-speed video camera in Hakuba Ski Jumping Stadium. The time variations of the forward leaning angle and the ski angle of attack were measured from the video image and the aerodynamic forces were calculated from kinematic data. Some correlations were investigated between the reduced jumping distance Dr, which is an initial speed corrected flight distance, and some key angles and the initial transition time, as well as those between Dr and the aerodynamic force coefficients. Jumping performance is compared between advanced jumpers and beginner jumpers