Browsing by Author "Stefanyshyn, Darren"
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- ItemOpen AccessDevelopment of a forward simulation model of the speed skating push-off for the optimization of subject specific klapskate design(2009) Hettinga, Blayne A.; Stefanyshyn, Darren
- ItemOpen AccessEffect of Relative Marker Movement on the Calculation of the Foot Torsion Axis Using a Combined Cardan Angle and Helical Axis Approach(Hindawi Publishing Corporation, 2012-02-27) Graf, Eveline; Wright, Ian; Stefanyshyn, Darren
- ItemOpen AccessExperimental Measurement and Applied Modelling of Patellar Tendon Strain(2021-05-27) Firminger, Colin Robert; Edwards, William Brent; Stefanyshyn, Darren; Hart, DavidPatellar tendinopathy is an overuse injury that occurs from repetitive loading of the patellar tendon in a scenario resembling mechanical fatigue. Tendon strain is correlated with the number of repetitive loading cycles that can be withstood prior to fatigue failure, and therefore represents a potential metric to infer patellar tendinopathy risk. To this end, I first quantified the mechanical fatigue behaviour of the patellar tendon in a cyclic loading scenario. I discovered that initial peak nominal strain, initial peak median strain, creep rate, and damage rate all displayed significant power law relationships with fatigue life. Based on the non-linear relationship between strain and fatigue life, I examined the effect of shoe outsole stiffness and surface construction on in vivo estimates of patellar tendon strain with the aim of exponentially increasing the number of jumps that could be performed prior to fatigue failure. Unfortunately, I discovered that neither intervention altered patellar tendon strain during jumping, potentially because the differences in shoe stiffness and surface construction were not large enough to require kinetic and/or kinematic changes at the knee. Finally, I assessed the effect of two strain estimation methodologies with varied levels of subject-specificity on fatigue-life estimates. I discovered that nominal strain models overestimated patellar tendon fatigue life compared to finite element models as they do not account for strain concentrations both within the tendon midsubstance and near the entheses, while fatigue-life estimates from both finite element and nominal strain models were sensitive to the use of generic material properties but not generic geometry. The results of these studies form a principled basis for the estimation of patellar tendon strain and additional time-dependent metrics to characterize patellar tendinopathy risk from a mechanical fatigue perspective, and further illustrate appropriate methodological approaches to do so.
- ItemOpen AccessFootwear traction and lower extremity non-contact injury(2012-08-21) Wannop, John; Stefanyshyn, DarrenFor the past forty years footwear traction has been thought to be one of the causes of non-contact lower extremity injury in sport. Previous studies have shown that rotational traction was associated with ACL injury, however, no studies have determined the relationship between footwear traction, both translational and rotational, and all lower extremity non-contact injuries. Therefore, the purposes of this thesis were to 1) determine if a relationship exists between an athlete’s specific footwear traction (both translational and rotational) and lower extremity non-contact injury and 2) determine how independently altering translational and rotational traction affects ankle and knee joint loading. Over the course of three years, 555 athletes had their footwear traction tested on the actual playing surface; either an artificial or natural grass field. The athletes were followed over each season and any injury that they sustained during a game was recorded by certified athletic therapists on site at the field. No differences in injury rate were seen between the artificial and natural grass surfaces. A relationship was found between rotational traction and lower extremity non-contact injury, with increases in rotational traction leading to an increase in injury rate. A relationship was also seen between translational traction and injury with the mid-range of translational traction leading to a higher injury rate. To determine how translational and rotational traction affect injury mechanism, three shoes were constructed that had independent alterations in translational and rotational traction. The footwear conditions consisted of a control shoe, a low rotational traction shoe and a high translational traction shoe. Joint loading was calculated with inverse dynamics on 10 athletes performing a v-cut and an s-cut movement in the three footwear conditions. The results indicate that both rotational traction as well as translational traction can affect the ankle and knee joint loading during football related movements. Coupled with the results of the injury study, although less clear for translational traction, it is believed that these increases in joint loading (joint moments and angular impulses) in the transverse and frontal plane are one of the possible mechanisms in terms of lower extremity non-contact injury.
- ItemOpen AccessIce friction in the sport of bobsleigh(2011) Poirier, Louis; Thompson, Robert Ian; Stefanyshyn, DarrenThe primary objective of this work is to examine the effect of the bobsleigh runner profile on ice / runner friction. The work is centered on a computational model (F.A.S.T. 3.2b) which calculates the coefficient of friction between a steel blade and ice. The first step was to analyze runners used in the sport of bobsleigh. This analysis was performed using a handheld rocker gauge, a device used in speed skating. The size of the device was optimized for hockey, short and long track speed skating, and bobsleigh. A number of runners were measured using the gauge and it was found that the portion of the runner contacting the ice generally has a rocker value of (20 - 50) m. Next, the hardness of athletic ice surfaces was analyzed. The ice hardness was determined by dropping steel balls varying in mass from (8 - 540) g onto the ice surface, from a height of (0.3 - 1.2) m, and measuring the diameter of the indentation craters. The ice hardness was found to be P(T) = ((-0.6 ± 0.4)T + 14.7 ± 2.1) MPa and the elastic recovery of the ice surface was found to be negligible. The F.A.S .T. model was adapted from a speed skate model to calculate the coefficient of friction between a bobsleigh runner and a flat ice surface. The model predicts that maximum velocities are obtained for temperatures between -10 and -20°C, in agreement with observations on the Calgary bobsleigh track. The model for flat ice suggests that the flattest runners produce the lowest coefficient of friction and that the rocker affects friction more than the cross-sectional radius. The coefficient of friction between runners and ice and the drag performance of 2- men bobsleighs were determined from radar speed measurements taken at the Calgary Olympic Oval and at Canada Olympic P ark: at the Ice House and on the bobsleigh track during a World Cup competition. The mean coefficient of friction was found to be ? = (5.3 ± 2.0) x 10- 3 and the mean drag performance was CdA = (0.18 ± 0.02) m2 .
- ItemOpen AccessThe Influence of Midsole Thickness on Running, Does Size Matter?(2023-03-09) Barrons, Zach; Stefanyshyn, Darren; MacInnis, Martin; Edwards, Brent; Goldsmith, Peter; Hoogkamer, WouterIn 2020, World Athletics amended their footwear regulations to include a maximum midsole thickness of 40-mm to “protect the integrity of sport”. However, there was no evidence to support the restriction therefore, the purposes of this dissertation were to determine; i) the influence of midsole thickness on the energetic cost of running, ii) the influence of midsole thickness on frontal plane ankle angle and performance when running curves, and iii) the influence of midsole thickness on muscle damage associated with a training-style run. Twenty-one runners participated in the first study, performing five-minute treadmill running trials in four footwear conditions. The footwear conditions were nearly identical except for their midsole which ranged from 35- to 50-mm in increments of 5-mm. Midsole thickness did not influence the energetic cost of running however, it did increase ankle eversion. In conclusion, running on a midsole thicker than 35-mm is inadvisable given that it will not provide a performance advantage but will impact frontal plane ankle angle. Thirteen recreational athletes participated in the second study testing the impact of two footwear conditions on curved running. Participants performed ten running trials around each of three curves of radii. Midsole thickness did not impact frontal plane ankle angle of the outside leg or performance across any of the three curves. Sixteen recreational runners with personal best 5-, or 10-km race times shorter than 24-, and 50-minutes, respectively, were recruited to participate in the third study. Participants performed a 60-minute training-style run in two nearly identical footwear conditions that differed only in midsole thickness, before and after which blood draws were performed for markers of muscle damage. Pre-to-post, there was not a statistically significant difference in magnitude of change in concentration of markers of muscle damage between shoes, although the concentration of lactate dehydrogenase did increase more so when running in the 35-mm footwear condition. In conclusion, midsole thickness did not impact the change in concentration of markers of muscle damage during a simulated training-style run. The results of this dissertation would suggest the World Athletic restriction on midsole thickness is not required and should be reconsidered.
- ItemOpen AccessLimiting factors for curved sprinting performance(2012-10-03) Luo, Geng; Stefanyshyn, DarrenSprinting along a curved path is regularly performed in athletics. Yet, the locomotion mechanisms behind curved sprinting performance are relatively unexplored. The current dissertation aimed to explore the limiting factors for curved sprinting performance from a biomechanical perspective. It was discovered that the available traction between footwear and ground can limit the maximum-effort curved sprinting performance, but only to a certain extent. As available traction was systematically increased from a traction coefficient of 0.26 to 0.82, the athletes leaned more into the ground, generated a greater impulse against the ground and achieved a higher performance. Further increases in the available traction could not be utilized by the athletes for additional performance benefits. With an experimental perturbation of additional body mass, the idea that non-sagittal plane joint stabilizing moments may limit performance was examined. It was revealed that for the ankle and knee joints, non-sagittal plane moments higher than that experienced in maximum-effort curved sprints can indeed be endured. This observation challenged the stabilizing moment limit theory. When sprinting with and without the additional mass, the total ankle moment generation remained constant, despite significant differences in the ground reaction force. It is possible that the ankle moment generation is at the limit. Through an induced acceleration analysis, it was identified that moment generated at the ankle contributed to the majority of the ground force generation. It is possible that the ankle moment generation was maximized for its importance in the ground force generation. To examine the idea that ankle moment generation may limit curved sprinting performance, an experimental intervention of wedged footwear was implemented aiming to increase the ankle moment. By aligning the ankle joint closer to its neutral configuration in the frontal plane, ankle moment generation increased. That increase was associated with significant improvements in ground impulse generation, and overall curved sprinting performance.
- ItemOpen AccessMechanical and performance effects of a modified point of foot rotation during the speed skating push(2003) Van Horne, Scott; Stefanyshyn, Darren
- ItemOpen AccessMechanics of Amphibian Skeletal Muscle at Long Lengths(2017) Hisey, Brandon; Herzog, Walter; Biewener, Andrew; Syme, Douglas; Stefanyshyn, Darren; MacIntosh, Brian; MacDonald, JustinLittle is known about the mechanical behavior of skeletal muscle at long lengths, or how these behaviors scale to different hierarchical levels. The purpose of this thesis is to examine the mechanical behavior of skeletal muscle leading up to, and at the point of failure. Failure was defined as a compromise in the muscles’ ability to produce force, as indicated by a decrease in force, during a steady stretch. Stretches were performed in active (i.e. contracting) and passive muscles in three different preparations from the semitendinosus muscle of the frog Rana pipiens – myofibrils, permeabilized fibres, and whole muscles. Stress in active myofibrils was significantly greater than in passive ones with the progression of stretch to failure, and was persistent despite being stretched to lengths beyond overlap of actin and myosin filaments (who’s interactions are responsible for the production of contractile force). This divergence in stress was reduced at the cellular level, and was abolished in whole muscles. It is suggested that higher active compared to passive stress is a result of an increased contribution by the large molecular spring, titin. As higher hierarchical levels are examined, the introduction of other passive elements and connections may break during stretch and mask the divergent behavior observed in myofibrils. Histology and electron microscopy showed complete loss of regular striation patterns in both active and passive fibres stretched to sarcomere lengths of approximately 5 um. Whole muscles showed indicators of damage as well, but to a much lesser extent, and with active muscles showing more evidence of damage. Mechanical data and histology suggest that failure in whole muscles occurs outside of the cell, perhaps in the extracellular matrix or at the myotendinous junction. Finally, it was demonstrated that whole muscles possessing a low passive compliance (in this case, the tibialis anterior from R. pipiens) were more prone to failure at short lengths than muscles having a higher compliance (i.e. semitendinosus). It is suggested that differing muscle compliances represent adaptive strategies to prevent damage according to functional demands of the specific muscle.
- ItemOpen AccessPrescription of Specialized Footwear for Individuals with Knee Osteoarthritis(2016-02-02) Lewinson, Ryan; Stefanyshyn, Darren; Worobets, Jay; Herzog, Walter; Wiley, Preston; Schmidt, Tannin; Hildebrand, Kevin; Messier, StephenWedged footwear insoles can reduce peak knee adduction moments during gait, which are associated with knee osteoarthritis development and progression; however, randomized trials have been mixed in terms of wedged insole clinical efficacy. To address methodological and technical limitations of past studies, the purposes of this thesis were to (1) identify the most suitable footwear control condition, from a biomechanical perspective, (2) identify a method that can predict the effect of wedged insoles on resultant knee adduction moments, and (3) evaluate the effects of a reduced knee adduction moment intervention on clinical outcomes for individuals with knee osteoarthritis. In fifteen healthy individuals, three sham footwear conditions were compared against participant’s own footwear to determine if sham footwear were biomechanically inert. It was found that all three sham footwear conditions significantly altered biomechanical variables during gait, including the knee adduction moment, and thus participant’s own footwear was recommended as the best control condition, from a biomechanical perspective, for future clinical studies. In fifteen healthy and nineteen knee osteoarthritis participants, a method was discovered that utilizes two dimensional video data from a single stepping motion to predict the change in knee adduction moment induced by wedged insoles during walking. When compared to actual walking data, the method successfully identified the correct insole intervention for 12/15 healthy and 17/19 knee osteoarthritis individuals. It is hoped this method may be implemented into clinical settings for improved footwear prescription capability for individuals with knee osteoarthritis. Finally, a three month randomized trial was conducted. Biomechanical and clinical data were collected from 48 individuals with knee osteoarthritis at baseline, and participants were randomized to either an insole (knee adduction moment reduction) group, or a waitlist control group. At follow-up, no significant differences were noted between groups in terms of change in pain. Knee adduction moment reduction was not associated with reduced pain for the insole group. These data suggest that reduction of knee adduction moments do not confer a clinical benefit in the short term, but do not rule out the possibility that reduced moments are beneficial from a prevention standpoint, or for long term management.
- ItemOpen AccessSpeed generation in the golf swing: an analysis of angular kinematics, kinetic energy and angular momentum in player body segments(2007) Anderson, Brady C.; Stefanyshyn, Darren
- ItemOpen AccessThe effects of ramp angle in alpine ski boots on on-hill turning kinetics and postural control(2010) Edgecombe, Tiffany Lee; Stefanyshyn, Darren
- ItemOpen AccessThe Effects of Resistance Strength Training and Functional Strength Training on Risk Factors for Running Injury(2016) Baltich, Jennifer; Nigg, Benno; Emery, Carolyn; Stefanyshyn, Darren; Edwards, Brent; Hamill, Joseph; Matyas, JohnReduced muscular strength and relatively larger magnitudes of movements and moments at the lower extremity joints during running have been proposed as risk factors for sustaining an injury. Some have suggested that increased movements at the joints are partially due to reduced muscular strength. However, the influence of strength training on running mechanics has yet to be evaluated in a group of novice runners, which have been shown to be particularly prone to injury. Therefore, the purposes of this thesis were to 1) compare changes in strength, running mechanics, and balance and 2) to explore injury risk for novice runners enrolled in a resistance strength training program, a functional movement strength training program or a stretching control program. One hundred and twenty nine novice runners (18-60 years old, less than two years running experience) were randomly assigned to one of three groups: a “resistance” strength training group (n=43), a “functional” strength training group (n=43) or a stretching “control” group (n=43). Participants were asked to complete a home-based training program three to five times a week for the eight week training period. Following this training period, participants were asked to complete their respective training at least twice a week for a sixteen week maintenance period. Changes in strength, running mechanics, and balance pre- to post-training were compared between groups. Running injuries were self-reported and defined as any complaint sustained in relation to running that caused a restriction in running for at least one week. Eighty-six participants completed the follow up assessment (functional=34, resistance=28, control=24). Changes in lower extremity strength were similar between the training groups with all groups demonstrating strength gains at multiple lower extremity joints. Changes in running mechanics were small in magnitude and within the measurement error of the testing protocol. The functional training group demonstrated improved balance using force plate and field based measures of balance. Though exploratory in nature, injury rates were not different between the three training groups. The results of this thesis indicate that running and completing a home-based strength training program did not increase strength or reduce joint movements more than running and stretching for a group of novice runners.
- ItemOpen AccessThe influence of golf club shaft flex on clubhead speed(2008) Worobets, Jay Tofin; Stefanyshyn, Darren
- ItemOpen AccessThe influence of knee joint laxity and hormones on dynamic joint function in healthy females(2008) Park, Sang Kyoon; Stefanyshyn, Darren
- ItemEmbargoThe Influence of Lateral Wedged Insoles on the Performance of Basketball-Specific Movements(2023-09-21) Crawford, Reyna Cyan; Stefanyshyn, Darren; Edwards, William Brent; Ferber, Reed; Pasanen, Kati; Jordan, MatthewBasketball is a dynamic sport known for its fast-paced and multidirectional nature. The implementation of banking mechanisms has demonstrated performance enhancements and the potential to mitigate ankle and knee injury risks during non-linear movements. However, existing banking mechanisms used in a sport setting are often impractical for basketball. Lateral wedged insoles may be a promising alternative to address this challenge. The aims of this study were to assess the influence of lateral wedged insoles on the performance of basketball-specific movements and to observe any changes at the ankle or knee related to injury risk. Twenty-four collegiate basketball players (twelve females and twelve males) performed a shuffle, forward cutting, backward cutting, and sprinting drills, both with and without a 5° lateral wedged insole in their footwear. Performance times, subjective assessments, medial-lateral sway of the centre of mass, ground reaction forces (GRFs), as well as angles and moments of the left ankle and knee were compared using two tailed paired t-tests. Across all movements, completion time, ankle inversion angles, and knee frontal plane kinetics and kinematics remained unchanged. In the shuffle drill, the lateral wedge condition led to increased ankle plantarflexion moments, higher medial and vertical GRFs, and improved GRF vector alignment, resulting in reduced stance time. An increase in the average ankle eversion moment was observed, with no change in the peak value. While minor kinetic changes were observed in the forward and backward cutting drills with the lateral wedge condition, stance time remained unchanged. The lateral wedged insole had no impact on medial-lateral sway of the centre of mass, or the sagittal plane kinematics and kinetics during the sprint, suggesting that 5° lateral wedged insoles do not influence the performance of linear movements. In subjective assessments, participants expressed greater confidence in non- linear movements and improved stability with the lateral wedge condition, however, they rated the comfort of this condition significantly lower. The results indicate that lateral wedged insoles may induce modifications that could potentially enhance performance without changing the risk of ankle or knee joint injuries during lateral movements.
- ItemOpen AccessThe influence of shoe midsole bending stiffness on running economy, joint energetics and muscular activation(2004) Roy, Jean-Pierre; Stefanyshyn, Darren
- ItemOpen AccessThe influence of the metatarsophalangeal joint in determining sprint running(2002) Krell, Jason; Stefanyshyn, Darren
- ItemOpen AccessTorsion of the foot(2012) Graf, Eveline Silvia; Stefanyshyn, DarrenTorsion of the foot reduces the coupling between forefoot and rearfoot motion in the frontal plane. While the amount of torsion occurring in running and cutting has previously been described, the exact location of the rotation axis has not been detennined. It is known that footwear restricts torsional movement; it is unknown what effect footwear torsional stiffoess has on lower extremity joint biomechanics. Therefore, the purposes of this thesis were to 1) develop and assess the repeatability of a method to calculate the location of the torsion axis, 2) describe the torsion axis location during cutting movements, 3) determine the influence of footwear torsional stiffness on torsion angles and lower extremity joint biomechanics during running and cutting movements, and 4) quantify the effect of footwear torsional stiffness on perfom1ance during cutting movements. The torsion axis location was calculated usmg a modified finite helical axis approach, which allowed the calculation of the rotation axis between the forefoot and the rearfoot without the influence of forefoot flexion. The repeatability assessment of the modified finite helical axis approach revealed that the torsion axis location can be calculated repeatable for movements with large torsion angles. For movements with small torsion, however, it cannot be quantified due to the susceptibility of the method for error with small rotations. During the stance phase of cutting movements the torsion axis shifted from an initially medial location within the foot to a lateral location during mid-stance when the torsion angle was large. Towards the end of stance, the axis moved back to the medial side of the foot. The average axis calculated over the entire stance phase was located on the lateral aspect of the midfoot. When wearing torsional stiff shoes, the peak torsion angle was reduced for running, a lateral jab and a shuffle cut when compared to a flexible shoe. Even with a flexible shoe, the peak torsion was reduced compared to barefoot. Stiff shoes led to increased peak ankle inversion angles and peak eversion moments for the shuffle cut. No differences in performance during lateral cutting movements were found between footwear with different torsional stiffness.
- ItemOpen AccessUpper extremity proprioception in the golf swing(2010) Osis, Sean Thomas; Stefanyshyn, Darren