Validation of Body Volume Acquisition by Using Elliptical Zone Method.

The elliptical zone method (E-Zone) can be used to obtain reliable body volume data including total body volume and segmental volumes with inexpensive and portable equipment. The purpose of this research was to assess the accuracy of body volume data obtained from E-Zone by comparing them with those acquired from the 3D photonic scanning method (3DPS). 17 male participants with diverse somatotypes were recruited. Each participant was scanned twice on the same day by a 3D whole-body scanner and photographed twice for the E-Zone analysis. The body volume data acquired from 3DPS was regarded as the reference against which the accuracy of the E-Zone was assessed. The relative technical error of measurement (TEM) of total body volume estimations was around 3% for E-Zone. E-Zone can estimate the segmental volumes of upper torso, lower torso, thigh, shank, upper arm and lower arm accurately (relative TEM<10%) but the accuracy for small segments including the neck, hand and foot were poor. In summary, E-Zone provides a reliable, inexpensive, portable, and simple method to obtain reasonable estimates of total body volume and to indicate segmental volume distribution.

Three-dimensional analysis of intracycle velocity fluctuations in frontcrawl swimming.

The purpose of this study was to determine accurately the magnitude and changes of intra-cycle velocity fluctuation (Vfluc), maximum (Vmax) and minimum velocity (Vmin) of the center of mass during a maximum 200 m frontcrawl swim, and to examine whether they are associated with performance. Performance was indicated by the mean velocity (Vmean) of the stroke cycle (SC) in the swimming direction. The relative Vfluc, Vmax and Vmin were also calculated as a percentage of Vmean, while Vfluc was calculated for all three directions. Eleven male swimmers of national/international level participated in this study and their performance was recorded with four below- and two above-water-synchronized cameras. Four SCs were analyzed for the 200 m swim (one for each 50 m). Anthropometric data were calculated by the elliptical zone method. Vmean generally decreased throughout the test. Vmax and Vmin were positively correlated to performance and were significantly higher in SC1 than in the other SCs. However, the relative Vmax and Vmin values were remarkably consistent during the 200 m and not associated with performance. Despite the noteworthy magnitude of Vfluc in all directions, they were in general not correlated with performance and there were no significant changes during the test.

Effects of visual impairment on stroke parameters in Paralympic swimmers.

PURPOSE: To examine the relationship between degree of vision and stroking parameters in male and female Paralympic swimmers with visual impairment during the 50- and 100-m freestyle events. METHODS: A video analysis was conducted at the 1996 Paralympic Games in which swimmers competed in three groups based on degree of impairment (S11, S12, and S13; S11 least amount of vision). A video camera placed 25 m from the start, perpendicular to the swimming direction, recorded the performance of each swimmer during the clean swim phase. Variables measured included total race time, clean swimming speed (CSS), stroke rate (SR), stroke length (SL), and stroke index (SI = CSS x SL). Comparisons of performance were made between the classes and between men and women. RESULTS: The men showed no significant differences between S12 and S13 on any of the variables or between all three classes on SL and SI. The S11 swimmers demonstrated a significantly slower total race time and CSS in both events. In the women, an increase in class was associated with a decrease in total race time, faster CSS, and increase in SI. In comparing men and women, men demonstrated a significantly faster CSS and total race time during both events, whereas no differences were observed in SR. CONCLUSION: Stroke parameters during the clean swim phase were affected by visual impairment in both men and women. The male classes, however, were not clearly distinct from each other based on the swimming variables measured, as no significant differences were found between S12 and S13 in either event. With the exception of stroke rate and length, performance of the women tended to increase with an increase in class.

Wave characteristics of butterfly swimming.

In this study it was hypothesized that elite butterfly performance is characterized by wave motions with particular frequency, amplitude, and phase characteristics. Particular emphasis was accorded the question of whether 'waves' travel along the body during the butterfly stroke. Selected body landmarks and the center of mass (CM) of eight elite males and eight elite female swimmers were quantified. Fourier analysis was conducted to determine the frequency, amplitude, and phase characteristics of the vertical undulations of the vertex of the head, shoulders, hips, knees, and ankles. The differences in phase between these landmarks for the first (H1) and second (H2) Fourier frequencies were investigated to establish whether waves travelled along the body in a caudal direction. The absolute average velocity of H1 wave travel from vertex to ankle was found to be a mean of 0.34 ms-1 faster than the forward velocity of the CM for the male swimmers and 0.17 m s-1 faster for the female swimmers. There was a very strong relationship (p < 0.01) between velocity of H1 wave travel and CM velocity. There was no evidence to suggest that elite swimmers timed their actions to minimise vertical CM displacement to reduce mechanical work. In fact, the phase relationships among adjacent segments suggested that energy gained by raising the CM was transmitted caudally and contributed to a propulsive 'whip-like' action.

Timing in the forward one and one half somersault with one twist 3m springboard dive.

The timing of actions to initiate and stop twist is critical to successful performance of the twisting and somersault rotations in 3m springboard dives. An important indicator of timing differences among subjects is the timing of hip flexion and extension. The purpose of this study was to quantify the timing and magnitude of hip flexions and extensions in the forward one and one half twisting dive with one twist. The timing and magnitude of hip flexion and extension of ten divers ranging in ability from New Zealand National to elite International standard were quantified using three-dimensional videography and analysis techniques. A Spearman (rho) correlation with p<.05 required for significance was conducted to determine the relationship between each of the variables and ability. The results indicated that skilled divers had more flight time than less skilled divers (rho=-.79), less hip flexion at takeoff (rho=.66), less pre-twist flexion (rho=.86), greater post-twist hip flexion, and had more time from the time of maximum post-twist flexion to entry than less skilled divers (rho=-.81). It was concluded that divers who currently initiate twist from a 'kick out' should learn to initiate twist without a 'kick out' and reduce hip flexion at takeoff to increase height and flight time.

Technique and timing in the womens forward two and one half somersault pike and mens three and one half somersault pike 3m springboard dives.

The purpose of this study was to compare the forward two and one half somersault dive in a pike position (105B) performed by females (n=25) and the forward three and one half somersault dive in a pike position (107B) performed by males (n=25) to determine changes required by females to successfully perform 107B. Video data of the dives performed at the 1999 FINA World Diving Cup were captured and digitised to obtain times and postures of the divers at specific events including hurdle landing, takeoff, and entry. Estimates of hurdle flight height and mass-normalised work done on the springboard were obtained from hurdle and flight times. Females performing 105B had significantly less hip and knee flexion at landing from the hurdle than males performing 107B. It is known from simulations that the ability to land in a very flexed position without absorbing energy depends on the ability to generate large extension torques at landing. Therefore, it is likely that females need to increase strength to successfully complete 107B.

Health care reform: the Clinton proposal and congressional counterproposals--Part II.

Note: Part I of this Article appears in the January 1994 issue of the JOURNAL OF HEALTH AND HOSPITAL LAW (V. 27, No. 1). Part II continues discussion of the potential effects of reform for the structure and financial security of various types of health care providers; identifies some possible effects of reform on health care facility operations; and describes proposed amendments to existing law appearing in various reform proposals.

Static and dynamic assessment of the Biodex dynamometer.

The validity and accuracy of the Biodex dynamometer was investigated under static and dynamic conditions. Static torque and angular position output correlated well with externally derived data (r = 0.998 and r greater than 0.999, respectively). Three subjects performed maximal voluntary knee extensions and flexions at angular velocities from 60 to 450 degrees.s-1. Using linear accelerometry, high speed filming and Biodex software, data were collected for lever arm angular velocity and linear accelerations, and subject generated torque. Analysis of synchronized angular position and velocity changes revealed the dynamometer controlled angular velocity of the lever arm to within 3.5% of the preset value. Small transient velocity overshoots were apparent on reaching the set velocity. High frequency torque artefacts were observed at all test velocities, but most noticeably at the faster speeds, and were associated with lever arm accelerations accompanying directional changes, application of resistive torques by the dynamometer, and limb instability. Isokinematic torques collected from ten subjects (240, 300 and 400 degrees.s-1) identified possible errors associated with reporting knee extension torques at 30 degrees of flexion. As a result of tissue and padding compliance, leg extension angular velocity exceeded lever arm angular velocity over most of the range of motion, while during flexion this compliance meant that knee and lever arm angles were not always identical, particularly at the start of motion. Nevertheless, the Biodex dynamometer was found to be both a valid and an accurate research tool; however, caution must be exercised when interpreting and ascribing torques and angular velocities to the limb producing motion.