Research Interests:
Research Interests:
Research Interests:
The primary purpose of this study was to determine the optimal release conditions and corresponding arm movement pattern for the free throw for players classified as 3 to 4.5 on the international player classification system in wheelchair... more
The primary purpose of this study was to determine the optimal release conditions and corresponding arm movement pattern for the free throw for players classified as 3 to 4.5 on the international player classification system in wheelchair basketball. A 2-D, three-segment simulation model was used to investigate this problem. The computational process involved a two-step optimization scheme in which an outer computational loop was used to optimize the magnitude and timing of the muscle torques that generate the arm's motion, and an inner computational loop was used to determine the optimal angle and speed of the ball at the moment of release. The inner optimization loop revealed that Brancazio's (1981) and Hay's (1993) approaches to determining the optimal release angle produced identical results. The lowered seated height of the wheelchair basketball player required that the ball be released at a steeper angle with greater vertical velocity, and hence the need for greate...
Research Interests:
Dual-Energy X-Ray Absorptiometry to Measure the Effects of a Thirteen-Week Moderate to Vigorous Aquatic Exercise and Nutritional Education Intervention on Percent Body Fat in Adults with Intellectual Disabilities from Group Home Settings... more
Dual-Energy X-Ray Absorptiometry to Measure the Effects of a Thirteen-Week Moderate to Vigorous Aquatic Exercise and Nutritional Education Intervention on Percent Body Fat in Adults with Intellectual Disabilities from Group Home Settings People with intellectual disability are more likely to be obese and extremely obese than people without intellectual disability with rates remaining elevated among adults, women and individuals living in community settings. Dual-energy X-ray absorptiometry measured the effects of a 13-week aquatic exercise and nutrition intervention on percent body fat in eight adults with intellectual disabilities (aged 41.0 ± 13.7 yrs) of varying fat levels (15%-39%) from two group homes. A moderate to vigorous aquatic exercise program lasted for the duration of 13 weeks with three, one-hour sessions held at a 25m pool each week. Nutritional assistants educated participants as to the importance of food choice and portion size. A two-tailed Wilcoxon matched-pairs s...
Research Interests:
Dual-Energy X-Ray Absorptiometry to Measure the Effects of a Thirteen-Week Moderate to Vigorous Aquatic Exercise and Nutritional Education Intervention on Percent Body Fat in Adults with Intellectual Disabilities from Group Home Settings... more
Dual-Energy X-Ray Absorptiometry to Measure the Effects of a Thirteen-Week Moderate to Vigorous Aquatic Exercise and Nutritional Education Intervention on Percent Body Fat in Adults with Intellectual Disabilities from Group Home Settings People with intellectual disability are more likely to be obese and extremely obese than people without intellectual disability with rates remaining elevated among adults, women and individuals living in community settings. Dual-energy X-ray absorptiometry measured the effects of a 13-week aquatic exercise and nutrition intervention on percent body fat in eight adults with intellectual disabilities (aged 41.0 ± 13.7 yrs) of varying fat levels (15%-39%) from two group homes. A moderate to vigorous aquatic exercise program lasted for the duration of 13 weeks with three, one-hour sessions held at a 25m pool each week. Nutritional assistants educated participants as to the importance of food choice and portion size. A two-tailed Wilcoxon matched-pairs s...
Research Interests:
Research Interests:
Research Interests:
A novel jump-focused (JF) technique of the jump float serve was compared with the conventionally used contact-focused (CF) method. Seven elite male (height: 195 ± 6 cm) and two elite female (height: 181 and 182 cm) volleyball players were... more
A novel jump-focused (JF) technique of the jump float serve was compared with the conventionally used contact-focused (CF) method. Seven elite male (height: 195 ± 6 cm) and two elite female (height: 181 and 182 cm) volleyball players were videoed at 60 Hz performing both techniques. Horizontal and vertical ball contact coordinates, pre- and postcontact ball velocities, and initial projection angles were determined. The JF technique resulted in a significantly higher mean contact height, t(8) = 4.12, p = .006, d = 0.72, initial serve speed, t(8) = 4.71, p = .006, d = 2.03, and significantly flatter initial projection angle, t(8) = 2.53, p = .036, d = 0.63, relative to the CF technique. The precontact vertical ball velocity was also significantly higher, t(8) = 8.04, p = .004, d = 2.86. The higher precontact vertical ball velocity suggests it is more difficult to make accurate contact with the ball during the JF technique. However, this method promotes a more favorable ball trajectory...
Research Interests:
Research Interests:
Research Interests:
INTRODUCTION In volleyball, in order for a serve to be effective it must be difficult for the opposition to receive, and therefore pass to a teammate. This can be achieved by optimizing the parameters that limit the amount of time a... more
INTRODUCTION In volleyball, in order for a serve to be effective it must be difficult for the opposition to receive, and therefore pass to a teammate. This can be achieved by optimizing the parameters that limit the amount of time a receiver has to react to the ball or by executing a serve that has an unpredictable trajectory. A serve that meets both these criteria is the jump float serve, and when executed properly the ball will float through the air with an irregular flight path [1]. Traditionally this knuckle ball effect has been attributed to a phenomenon known as the drag crisis, a region defined by a sharp drop in the drag coefficient [2]. In volleyball, this occurs at speeds of roughly 14.5 m/s [1]. However, it’s been shown that the forces exerted on nonspinning volleyballs, which produce the irregular flight, fluctuate randomly by large magnitudes at velocities outside of the drag crisis region [3]. Nevertheless, the movement of a high speed float serve has not been quantifi...
While it is probably true that it is easier to comprehend the cause-and-effect dynamics of impact, I would argue that the dynamics of the rest of the golf swing (e.g., the downswing) should not be regarded as a matter of opinion. The same... more
While it is probably true that it is easier to comprehend the cause-and-effect dynamics of impact, I would argue that the dynamics of the rest of the golf swing (e.g., the downswing) should not be regarded as a matter of opinion. The same set of dynamical laws that allow the prediction of ball flight following the ~0.00045 s of impact time with the club head, can be used to explain how the club head is able to arrive at impact with a specific set of kinematics based on the forces the golfer applies to the club over the ~0.25 s of downswing time. Perhaps Foley was simply trying to highlight the challenges with developing a deterministiclike model for the downswing. However, if one of the most renowned golf instructors in the world believes that our scientific understanding of impact is far beyond that of the downswing, then a Master of Science degree in golf teaching/coaching has an important role to play in the development of professionalism in the discipline.
Research Interests:
Introduction This paper summarizes my collection of research findings on the role of shaft flexibility in the golf swing. The research was initiated during my PhD thesis under the supervision of Dr. Eric Sprigings. The goal was to gain a... more
Introduction This paper summarizes my collection of research findings on the role of shaft flexibility in the golf swing. The research was initiated during my PhD thesis under the supervision of Dr. Eric Sprigings. The goal was to gain a comprehensive understanding of the role that shaft stiffness plays in the golf swing. This paper will provide a rationale for the methodologies I’ve used, a summary of the important findings, and suggestions for future research on shaft flexibility.
3-Dimensional Organization and Dynamics of the ... 3-Dimensional organization and dynamics of the microsporidian polar tube invasion machinery. Microsporidia, a divergent group of single-celled eukaryotic parasites, harness a specialized... more
3-Dimensional Organization and Dynamics of the ... 3-Dimensional organization and dynamics of the microsporidian polar tube invasion machinery. Microsporidia, a divergent group of single-celled eukaryotic parasites, harness a specialized harpoon-like invasion apparatus called the polar tube (PT) to gain entry into host cells. The PT is tightly coiled within the transmissible extracellular spore, ...
Research Interests:
The purpose of this study is to examine the effects of the number of data points on modeling the MRE using a sphere. The fitting routine was performed on data sets containing 1800, 600, 300, 100, 50, 20, and just 10 data points for each... more
The purpose of this study is to examine the effects of the number of data points on modeling the MRE using a sphere. The fitting routine was performed on data sets containing 1800, 600, 300, 100, 50, 20, and just 10 data points for each subject. It was demonstrated that the model generated using as few as 10 points was not significantly different from a model generated when using all 1800 points. The model accurately represented the reach envelopes, with an average overall error of 2%. All the models closely fit the MRE near the central region (+ 5 mm) of the reach envelope but at the extremes of the envelope the error in the predicted MRE increased to 40 mm. These findings have implications for the reach surface modeling techniques and the types of reach measurement systems used in the future.
The work the golfer does on the club is the primary determinant of clubhead speed and is a function of four factors: hand path length, average force along the hand path, club angular distance, and the average couple applied over this... more
The work the golfer does on the club is the primary determinant of clubhead speed and is a function of four factors: hand path length, average force along the hand path, club angular distance, and the average couple applied over this distance. The primary purpose was to evaluate the relative importance of these factors in generating clubhead speed. The drives of 76 golfers were captured using a launch monitor and an optical system. Regression was used to determine the relative importance of each of the four factors. Average force accounted for the greatest proportion of variability in clubhead speed (r = .96). Hand path length (r = .45) and the average golfer applied couple (r = .45) were also found to be meaningful predictors of clubhead speed, while angular distance was not (r = .14). These findings will be applicable to instructors and golfers attempting to increase clubhead speed.
Research Interests:
Research Interests:
The purpose of the study was to determine the influence of grip mass on driver clubhead kinematics at impact as well as the resulting kinematics of the golf ball. Three club mass conditions (275, 325, and 375 g) were tested by 40... more
The purpose of the study was to determine the influence of grip mass on driver clubhead kinematics at impact as well as the resulting kinematics of the golf ball. Three club mass conditions (275, 325, and 375 g) were tested by 40 experienced golfers (handicap = 7.5 ± 5.3) representing a range of clubhead speeds (36 to 54 m/s). Each participant executed 12 drives per condition using matched grips and shafts and a single clubhead. Club mass was modified by inserting 50 g and 100 g into the grips of the two heavier conditions. The heaviest condition was associated with the slowest clubhead speed (p = 0.018) and highest vertical launch (p = 0.002), which resulted in no net influence on driving distance (p = 0.91). Lateral dispersion was greatest with the 325 g condition (p = 0.017), as was horizontal impact spot variability on the driver face (p = 0.031). Findings at the individual golfer level were not reliable enough to suggest that grip mass could be effectively used in a fitting env...
Research Interests:
The influence of the location of the center of mass (cm) of the putter head, relative to the shaft, on golfer applied kinetics at the grip was investigated. Participants made 12 attempts at a straight up-hill (2.2° slope) 8 ft putt with... more
The influence of the location of the center of mass (cm) of the putter head, relative to the shaft, on golfer applied kinetics at the grip was investigated. Participants made 12 attempts at a straight up-hill (2.2° slope) 8 ft putt with half of the attempts executed using a PING Anser 4 toe-hang putter (TH) and half with an Anser 5 face-balanced putter (FB). The net torque applied by the golfer, acting about the long axis of the shaft, was significantly greater in magnitude with the TH putter in comparison to the FB putter. The TH putter was also associated with a higher angular velocity about the shaft and a more open face at impact. These findings may have important implications for fitting the style of putter to a particular stroke or individual golfer as golfer applied kinetics would be strongly associated with the ‘feel’ of a putter.
Research Interests:
The increased awareness of concussion in sport has led to an examination of head impacts and the associated biomechanics that occur during these sporting events. The high rate of concussions in football makes it particularly relevant.1... more
The increased awareness of concussion in sport has led to an examination of head impacts and the associated biomechanics that occur during these sporting events. The high rate of concussions in football makes it particularly relevant.1 The purpose of this study was to examine how frequently, and to what magnitude, Canadian University football players get hit in training camp and how this compares to practices and games in regular season. An ANOVA with repeated measures indicated that, on average, players were hit significantly more in games (45.2 hits) than training camp sessions (17.7 hits) and practices (8.0 hits), while training camp was associated with significantly more hits than practices (p < .001, η2 = .392). Multiple positional differences were found. In particular, significantly more hits were experienced by offensive linemen (36.7 hits) and defensive linemen (31.6 hits) compared with all other positions (p < .001, η2 = .247). Study outcomes determined players/positi...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
A novel jump-focused (JF) technique of the jump float serve was compared with the conventionally used contact-focused (CF) method. Seven elite male (height: 195 ± 6 cm) and two elite female (height: 181 and 182 cm) volleyball players were... more
A novel jump-focused (JF) technique of the jump float serve was compared with the conventionally used contact-focused (CF) method. Seven elite male (height: 195 ± 6 cm) and two elite female (height: 181 and 182 cm) volleyball players were videoed at 60 Hz performing both techniques. Horizontal and vertical ball contact coordinates, pre- and postcontact ball velocities, and initial projection angles were determined. The JF technique resulted in a significantly higher mean contact height, t(8) = 4.12, p = .006, d = 0.72, initial serve speed, t(8) = 4.71, p = .006, d = 2.03, and significantly flatter initial projection angle, t(8) = 2.53, p = .036, d = 0.63, relative to the CF technique. The precontact vertical ball velocity was also significantly higher, t(8) = 8.04, p = .004, d = 2.86. The higher precontact vertical ball velocity suggests it is more difficult to make accurate contact with the ball during the JF technique. However, this method promotes a more favorable ball trajectory...
Research Interests:
Research Interests:
Research Interests: Computer Science, Medicine, Instrumentation, Sport, Movement, and 15 moreKinematics, Reliability, Data Collection, Golf, Measurement Error, High Speed, Sports Sciences, Three Dimensional, Curriculum and Pedagogy, Reproducibility of Results, Data Processing, Task Performance and Analysis, Biomechanical Phenomena, Measurement System, and Limits of Agreement
Research Interests:
Research Interests: Sports Medicine, Obesity, Adolescent, Intellectual Disability, Exercise therapy, and 14 moreMedicine, Swimming, Adipose tissue, X Rays, Humans, Child, Female, Male, Body Mass Index, Clinical Sciences, Children and Adolescents, Public health systems and services research, Body Fat, and Training Program
Previous research indicates that the motion of the golf club is not planar and that the plane traced out by the club is different than that of the golfer's hands. The aim of the present study was to investigate how the position of... more
Previous research indicates that the motion of the golf club is not planar and that the plane traced out by the club is different than that of the golfer's hands. The aim of the present study was to investigate how the position of the club, relative to the golfer's swing plane, influences the motion of the club by using a
Research Interests:
An understanding of shaft dynamics during the golf swing was gained through a series of theoretical simulations, using a 3D forward dynamics model. By resolving the resultant force applied at the grip end of the club into a tangential and... more
An understanding of shaft dynamics during the golf swing was gained through a series of theoretical simulations, using a 3D forward dynamics model. By resolving the resultant force applied at the grip end of the club into a tangential and a radial (centripetal) component, the mechanisms of shaft deflection were quantified. It was determined that radial force plays an important