Two-dimensional high-speed photography was used to compare the performances of six elite gymnasts on a Yurchenko vault and two associated teaching drills. Analysis of variance with repeated measures was used to test the significance of the differences between those variables common to both drills and the vault, while a one-way analysis of variance was used to test for differences between biomechanical variables common to only one drill and the vault. Results indicated that in general the variables common to each drill and the vault were similar in magnitude. However, a number of kinematic characteristics recorded in the drills differed from those recorded for the vault both in this study and from data reported in the literature for international level performers. These included horizontal velocity at takeoff from beat board; knee joint, lower trunk, midtrunk, and head/neck segments at takeoff from beat board; knee joint angle and vertical velocity of CG at impact with horse; vertical velocity, trunk angles, and ankle joint angle at takeoff from horse; horizontal displacement of CG while hands were in contact with horse; and the time the hands were in contact with horse. Variables identified as being important for success in the vault were also reported.
Bruce Elliott and Joanne Mitchell
Bruce Elliott, Kotaro Takahashi and Guillermo Noffal
In tennis groundstrokes, the speed of the racket head depends on the rotational velocities of the upper limb segments and the corresponding instantaneous position of the racket. The method of holding the racket may influence these factors. Six high-performance tennis players who preferred the eastern method of holding the racket and a further 6 who preferred the western method were filmed. The displacement histories of 16 selected landmarks were calculated using the direct linear transformation approach and were used to calculate the contribution that the three-dimensional individual segment rotations for the upper limb made to racket head velocity. Horizontal flexion/abduction and internal rotation of the upper arm, in addition to linear velocity of the shoulder, were the primary contributors to racket head speed at impact, regardless of grip. Significant variations, however, were recorded for the contribution of the hand segment to racket head speed for the different grip positions.
Bruce Elliott, J. Robert Grove and Barry Gibson
Eight international baseball pitchers were filmed in a laboratory while throwing from a pitching rubber attached to a Kistler force platform. Following a warm-up, all subjects threw fastballs (FB) until two strike pitches were assessed by an umpire positioned behind the catcher for both wind-up and set pitching techniques. Subjects then followed the same procedures for curveball pitches (CB). Both vertical (Z) and horizontal (Y) ground reaction force (GRF) data were recorded. A shutter correlation pulse was encoded so the temporal data from the film could be synchronized with the kinetic data from the force platform. Analysis of variance was used to analyze differences in force data at selected points in both pitching actions for both techniques. Vertical and horizontal GRFs increased from the first balance position to maximum levels at the cocked position for both techniques. Nonsignificant changes in GRF then occurred between the cocked position and front-foot landing. The Z GRFs were similar throughout the pitching action but higher in magnitude for the CB compared to the FB. Mean resultant forces were similar for the three fastest FB pitchers when compared to the three slowest pitchers. However, the slower group produced their peak resultant force earlier in the action, thus reducing the ability to drive over a stabilized front leg.
Bruce Elliott, Tony Marsh and Peter Overheu
Three-dimensional (3-D) high-speed photography was used to compare different forehand techniques of high performance players. Subjects, who hit a topspin forehand drive with the hitting limb moving almost as a single unit (Gs: single-unit group), were compared with players whose individual segments of the upper limb moved relative to each other (Gm: multisegment group) when playing the same stroke. The Direct Linear Transformation method was used for 3-D space reconstruction from 2-D images recorded from laterally placed phase-locked cameras operating at 200 fps. A third Photosonics camera operating at 100 fps filmed from overhead. Significant differences between the groups were recorded at the shoulder and elbow joints at the completion of the backswing. Maximal elbow joint angular velocities occurred 0.06 sec prior to impact, with the Gm group recording a significantly higher mean value for elbow extension than the Gs group. At impact, however, the Gm group recorded a significantly higher level of elbow flexion than the Gs group and achieved a higher mean angular velocity at the wrist joint than the Gs group. The Gm group recorded a higher racket tip linear velocity at impact and higher postimpact ball velocity when compared to the Gs group. The Gm technique of racket movement produced higher racket and ball velocities for this group of high performance players.
Duane Knudson, Bruce Elliott and Tim Ackland
Applied research in kinesiology that can truly inform professional practice places high demands on researchers. Clear citation of research evidence is required to design meaningful research and is particularly important in the interpretation of evidence in proposing how the new results may be applied in sport, exercise, or physical activity. This paper summarizes principles for accurate citation of research evidence in justifying and designing applied research in kinesiology; it also proposes an evidence-based practice approach for interpreting the strength of evidence for the application potential of research results. Improved application of kinesiology research is important to advance recognition of the field and support for kinesiology professions.
Shinji Sakurai, Bruce Elliott and J. Robert Grove
Three-dimensional (3-D) high speed photography was used to record the overarm throwing actions of five open-age, four 18-year-old, six 16-year- old, and six 14-year-old high-performance baseball catchers. The direct linear transformation method was used for 3-D space reconstruction from 2-D images of the catchers throwing from home plate to second base recorded using two phase-locked cameras operating at a nominal rate of 200 Hz. Selected physical capacity measures were also recorded and correlated with ball release speed. In general, anthropometric and strength measures significantly increased through the 14-year-old to open-age classifications, while a range of correlation coefficients from .50 to .84 was recorded between these physical capacities and ball speed at release. While many aspects of the kinematic data at release were similar, the key factors of release angle and release speed varied for the different age groups.
Bruce Elliott, Tony Marsh and Brian Blanksby
Three dimensional (3-D) high-speed photography was used to record the tennis service actions of eight elite tennis players. The direct linear transformation (DLT) method was used for 3-D space reconstruction from 2-D images recorded from laterally placed cameras operating at 200fps. Seven of the eight subjects initially positioned their center of gravity toward the front foot during the stance phase. When the elbow reached 90° in the backswing, the knees of the eight subjects were at or near their maximum attained flexion, and the upper arm was an extension of a line joining both shoulder joints. A mean maximum vertical shoulder velocity of 1.7ms−1 during the leg drive produced a force at the shoulder that was eccentric to the racket-limb, thus causing a downward rotation of this limb as measured by a mean velocity of the racket of −5.8ms−1 down the back. This leg drive increased the angular displacement of the loop and therefore provided a greater distance over which the racket could be accelerated for impact. All subjects swung the racket up to the ball, and all but one hit the ball with the racket angled slightly backward (M = 93.9°). An effective summation of body segments was apparent because resultant linear velocities showed an increase as the more distal segment endpoint approached impact, although all subjects decelerated the racket immediately prior to impact. Mean resultant ball velocities of 34.4ms−1 for the female subjects and 42.4ms−1 for the male subjects were achieved.
Bruce C. Elliott, Robert N. Marshall and Guillermo J. Noffal
In the high-velocity tennis serve, the contributions that the upper limb segments' anatomical rotations make to racket head speed at impact depend on both their angular velocity and the instantaneous position of the racket with respect to the segments' axes of rotation. Eleven high-performance tennis players were filmed at a nominal rate of 200 Hz by three Photosonics cameras while hitting a high-velocity serve. The three-dimensional (3-D) displacement histories of 11 selected landmarks were then calculated using the direct linear transformation approach, and 3-D individual segment rotations for the upper limb were calculated using vector equations (Sprigings, Marshall, Elliott, & Jennings, 1994). The major contributors to the mean linear velocity of the center of the racket head of 31.0 m · s-1 at impact were internal rotation of the upper arm (54.2%), flexion of the hand (31.0%), horizontal flexion and abduction of the upper arm (12.9%), and racket shoulder linear velocity (9.7%). Forearm extension at the elbow joint played a negative role (-14.4%) and reduced the forward velocity of the center of the racket at impact.
Gregory J. Wilson, Bruce C. Elliott and Graham K. Kerr
The bar movement characteristics of 10 elite powerlifters were analyzed while bench pressing a maximum load and a submaximal load in a simulated competition using high-speed cinematography. Significant differences in bar path and alterations to the general force profile of movement were evident as the load was increased. These movement discrepancies resulted in the following conclusions being drawn with reference to the bench press movement: (a) The movement pattern adopted during the performance of an 81 % maximum load was not specific to that which was utilized during the maximal load. (b) Based upon the concepts of specificity of training and testing, the use of the popular one-repetition maximum test to quantify strength changes derived from submaximal training appeared invalid. This occurrence is further accentuated when the testing protocol is conducted on a bench press machine. (c) The design of “isotonic” bench press machines appeared to be load specific. Further, the development of bench press machines that would allow a number of bar paths to be pursued appear to represent a significant improvement over existing models.
Bruce Elliott, J. Robert Grove, Barry Gibson and B. Thurston
Three-dimensional (3-D) high speed photography was used to record the fastball (FB) and curveball (CB) actions of six members of the Australian National pitching squad. The direct linear transformation (DLT) method of motion analysis for 3-D space reconstruction from 2-D images was used to record the movement of selected anatomical features. Laterally positioned phase-locked cameras operating at 200 fps and a front-on camera operating at 300 fps were used to record the pitching action. Mean pitching velocities for the FB and the CB were recorded. A kinematic analysis of the two pitching motions from the first balance point following the completion of the pump and pivot to follow through are presented. The actions are very similar for the two pitches, as would be expected if disguised to confuse the batter. Minor differences were noted, however, for stride length, forearm action prior to release, and wrist action at release.