Phillip Cheetham

The purpose of this study was to compare two-dimensional rearfoot motion during walking measured by a traditional video-based motion analysis system to that of an electromagnetic analysis system. Twenty-five individuals (15 men, 10 women) with a mean age of 29.8 years served as subjects for this study. The results of the study showed that there was a high correlation ( r = 0.945) between the mean motion paths produced by the two systems, indicating that they were very similar. The electromagnetic motion analysis system was able to produce these similar results in a fraction of the time required by the video-based system.

Men's Olympic gymnastics today is comprised of six events. Listed in order of Olympic competition they are: floor exercise, pommel horse, Roman rings, vaulting horse, parallel bars, and horizontal bar. In five of these events a routine is required by the Inter national Gymnastics Federation (FIG) to consist of 11 moves. The exception is vaulting. This event consists of only one jump over the vaulting horse for which a maximum score of 10 points can be awarded. This one skill is rated at the same value as 11 skills on any other apparatus. Ten points can be won or lost on this one skill. It is possible to see zero awarded for an unsuccessful vault. In this light, the importance of vaulting can be seen. One of the difficult vaults of the past, which has become a basic vault today, is the handspring vault. This vault is, however, rarely seen in modern high-level competition since it has a maximum score of 9.0. It does, however, form the basis of the most common of the more difficul...

The purpose of this study was to compare key magnitude and timing parameters of the kinematic sequence between amateur recreational players (amateurs) and PGA touring professionals (pros). It was hypothesized that the key magnitude parameters would be significantly higher in the pros than the amateurs, and that the key timing parameters would be significantly different between the two groups. A representative swing from each of 19 amateurs and 19 pros was captured using three-dimensional (3D) motion analysis techniques. Eighteen key kinematic sequence performance variables that occur during the downswing were computed from the data. Student t-test’s were used to compare the group means for each parameter with an experiment-wise level of significance set at p<0.2, and a corresponding test-wise significance of p<0.011. All the magnitude variables including rotational accelerations; rotational decelerations, (except pelvis); peak rotational speeds; rotational speed gains; and lin...

The purpose of this study was to compare key magnitude and timing parameters of the kinematic sequence between amateur recreational players (amateurs) and PGA touring professionals (pros). It was hypothesized that the key magnitude parameters would be significantly higher in the pros than the amateurs, and that the key timing parameters would be significantly different between the two groups. A representative swing from each of 19 amateurs and 19 pros was captured using three-dimensional (3D) motion analysis techniques. Eighteen key kinematic sequence performance variables that occur during the downswing were computed from the data. Student t-test’s were used to compare the group means for each parameter with an experiment-wise level of significance set at p<0.2, and a corresponding test-wise significance of p<0.011. All the magnitude variables including rotational accelerations; rotational decelerations, (except pelvis); peak rotational speeds; rotational speed gains; and lin...

At the 1992 Barcelona Olympic Games, 70 dismounts and release-regrasp movements on the high bar were selected from films gathered with three synchronized cameras during the compulsory and the optional men's high bar competition. The skills were classified into 10 groups depending on the direction of rotation, body configuration, and flight projection. Kinematic variables were used to profile the movement groups. Statistically significant differences between the groups were identified by ANOVA. Three groups with significant differences in terms of the maximum values and the locations of the maxima could be differentiated. These were (a) backward rotating swings with an increase of rotation (e.g., overgrip giant swing—triple backward tuck somersault dismount), (b) backward rotating swings with a change of the direction of rotation (e.g., overgrip giant—Tkatchov straddle), and (c) forward rotating swings with an increase or a decrease of rotation (e.g., undergrip giant swing—Jaeger...

The purpose of this project is to describe the procedures used in acquiring data on the Men's Olympic Long Horse Vaulting Competition. A descriptive biomechanical analysis is provided of the filmed performances of the eight male finalists in this event. All of the performed vaults are grouped into the following two vault families: Handspring Front Somersault and Tsukahara. Comprehensive kinematic descriptions are presented for these two vault families.

Summary A simple disk-spring model of the pelvis and thorax does a good job at explaining the reason for acceleration and deceleration in the kinematic sequence curves during the downswing in golf. The Model Cochran and Stobbs (1968) in their famous book "Search for The Perfect Swing" described the golf swing action using a disk spring model. Each disk represents a part of the body; disk a, the pelvis, disk b the thorax (upper body) and disk c the arms and club; the springs represent the muscles across the joints between the body segments. They stated in their article: "The question is now; in what order should the springs be released to impart the greatest possible rotation speed to the topmost cylinder? The answer is that they should operate in sequence from the bottom upwards with each successive spring releasing when all or most of the energy of the previous spring has been imparted to the system."

ABSTRACT It is known that proper proximal to distal sequencing of body rotations is important in the production of high club head velocities in the golf swing. Since these rotations originate at the pelvis, it is not clear how differences in pelvic kinematics are related to essential determinants of ball flight. One essential ball flight measure that has not been previously investigated is the ratio of club velocity before impact to ball velocity after impact, or smash factor. Therefore, this study investigated the differences in pelvic kinematics and ball flight determinants between golfers of different skill levels. It also determined the correlations between pelvic kinematic measures and these determinants of ball flight. Skilled golfers were found to have greater pelvic accelerations and a larger time between peak pelvic velocity and ball contact (peak to impact time). It was also discovered that pelvic acceleration correlated with the shot distance and with the smash factor. There was also a correlation between peak to impact time and smash factor. This is the first data to suggest that appropriate pelvic rotations is important in producing an efficient strike on ball so that the maximum amount of energy is transferred from the club to the ball.

The motions studied In biomechanics today are Increasingly more complex, requiring spatial, force and myographic measures. The Peak system employs off-the-shelf video equipment and an AT compatible microcomputer to perform spatial and analog data acquisition. Every video field can be analyzed in either NTSC (North American) or PAL (European) video formats. Video sampling rates can vary from 50 to 2000Hz, depending upon the video hardware used. The body locations of interest may be obtained using any of three methods. The manual acquisition method superimposes a colored cursor over the video image and its position is controlled by a handheld mouse. The semi-automatic option controls the initial position of the cursor by predicting the position based upon its location in previous frames. The value of these options is that they can be applied in difficult experimental settings or for digitizing points that are internal to the body (e.g., joint centers). The third method is automatic tracking, which determines the center of area of a marker that contrasts with its immediate background. An individual criterion may be set for each marker to discriminate it from noise, background and other markers. Hidden markers can be treated via manual digitization, interpolation or ignored if seen by other cameras. Once collected, spatial data can be translated and/or rotated with respect to external reference frames, or to internal reference frames within the moving subject. An analog to digital sampling module acquires data from sensors and synchronizes them with the video generated spatial data. Subsequently, complete motion information can be generated rapidly and accurately for countless applications. The performance of the video measurement system was assessed by measuring its precision and accuracy in two dimensional static tests. The precision for manual digitizing was found to be 1 in 2422 and for automatic digitizing, 1 in 5280. The accuracy for manual digitizing was found to be 1 in 3267 and for automatic digitizing, I in 4310.