Darren J Stefanyshyn

• University of Calgary

Artificial turf is a widespread surface used for various field sports, offering unique advantages to natural grass such as all-weather availability and durability. This study aimed to determine the influence of infill depth and the exposed fibre height on shoe–surface traction for artificial turf surfaces. Particular focus was placed upon rotationa...

Increased midsole deformation can limit exposure to high impact and vibration magnitudes while running. The aim of this study was to evaluate the effect of shoes eliciting different midsole deformation on ground reaction forces, heel impact, soft tissue vibrations and bone vibrations. Forty-eight runners performed a 5-minutes running task on an ins...

INTRODUCTION Due to the repetitive movement of running, a large number of foot-ground impacts will be sustained over the course of a single run. From the repetitiveness of these impacts, the body is exposed to substantial impact-related mechanical stress [1]. Aside from the mechanical impact, runners will also experience mechanical vibrations in th...

INTRODUCTION: Running performance continues to increase thanks to better training programs and footwear. A key parameter of level and long-distance performance is running economy-the energy spent by a runner to move 1kg of their mass over 1km. With continuous improvements in footwear technology, the impact on average running economy is becoming sma...

The objective of this study was to compare head impact magnitudes and time between impacts among positions in Canadian high-school football. Thirty nine players from two high-school football teams were recruited and assigned a position profile: Profile 1 (quarterback, receiver, defensive back, kicker), Profile 2 (linebacker, running back), and Prof...

Kinematic and kinetic changes in the lower extremities occur as an athlete becomes fatigued during vertical jumping; however, the specifics of these changes are not well-understood. Therefore, the purpose of this study was to quantify the influence of a sport-specific, vertical jumping fatigue protocol on the biomechanics of the ankle, knee, and hi...

Machine learning methods such as a stepwise linear regression and a feedforward neural network were implemented and analyzed for their capability of estimating stride length using wearable sensors. Strides were segmented using acceleration data from a sacrum mounted inertial measurement unit. Stride length was then obtained by calculating the diffe...

Despite basketball being a popular sport among both genders, basketball footwear is designed primarily based on men. This may be problematic for women as the footwear they utilize may not be optimized for female performance and excessive traction may increase the risk of lower extremity non-contact injuries. While there are known sex-associated dif...

The purpose of this study was to investigate whether there are any age-related differences in impact characteristics during running between healthy older and younger men. Ten healthy older (age: 58.7 ± 2.5 years) male and ten healthy younger (age: 22.3 ± 1.6 years) male recreational runners ran on a treadmill at three different running speeds (i.e....

Matching a runner’s arch stiffness with appropriate midsole bending stiffness can help optimize the overall system stiffness of the foot-shoe interface and improve running economy.

Footwear midsole material can have a direct influence on running performance. However, the exact mechanism of improved performance remains unknown. The purpose of this study was to determine if Achilles tendon energetics could potentially play a role in the performance improvements, by testing if changes in footwear midsole stiffness elicit changes...

Background: Artificial turf (AT) has been related to increased injury rates when compared to natural grass (NG). One potential reason for the differences in injury rates is the difference in mechanical characteristics of the surfaces. Over the course of a season on artificial turf, due to heavy use and environmental factors, properties of the surfa...

The objectives of this study were to first determine whether a newly designed 3D-printed midsole, configured with a mechanism to increase anterior-posterior deformation, could increase anterior midsole shear during the stance phase of running. We then wanted to determine whether these shoes could affect running economy and smoothness. Two footwear...

Patellar tendinopathy is an overuse injury that occurs from repetitive loading of the patellar tendon in a scenario resembling that of mechanical fatigue. As such, fatigue-life estimates provide a quantifiable approach to assess tendinopathy risk and may be tabulated using nominal strain (NS) or finite element (FE) models with varied subject-specif...

The objective was to compare biomechanical data between different head impact locations using impact monitoring mouthguards in high school football players. Side and Top head impact magnitudes were significantly greater than Rear and Front head impacts for all biomechanical variables (linear/angular acceleration and velocity).

One possible modality to profile gait speed and stride length includes using wearable technologies. Wearable technology using global positioning system (GPS) receivers may not be a feasible means to measure gait speed. An alternative may include a local positioning system (LPS). Considering that LPS wearables are not good at determining gait events...

(1) Background: The purpose of this study was to investigate the effects of a rounded heel shoe (RHS) and rounded lateral heel shoe (RLHS) on impact and lower extremity stability as well as their relationships with comfort during running. (2) Methods: Twenty healthy male adults participated in the study. The data were collected using eight infrared...

In recent years, increasing the midsole bending stiffness (MBS) of running shoes by embedding carbon fibre plates in the midsole resulted in many world records set during long-distance running competitions. Although several theories were introduced to unravel the mechanisms behind these performance benefits, no definitive explanation was provided s...

Properties of conventional playing surfaces have been investigated for many years and the stiffness of the surface has potential to influence athletic performance. However, despite the proliferation of different infilled artificial turfs with varying properties, the effect of surface stiffness of these types of surfaces on athlete performance remai...

Introduction Soccer players are at high risk of stress injuries in the foot. While most research addresses this issue in professional athletes, there is little information concerning young athletes. As soccer is practiced around the world since early infancy, we set out to determine whether young soccer athletes are susceptible to increased foot lo...

Changes in forefoot bending stiffness have been shown to affect metatarsophalangeal peak bending angles as well as athletic performance. Increasing bending stiffness tends to reduce peak bending angles, which could potentially reduce hyperextension injuries such as turf toe. Limited information is available, however, on the efficacy of increasing f...

Foot-ground contact upon landing from a jump results in an impulsive impact force. Parameters of impact including vertical ground reaction force (vGRF), loading rate, tibial acceleration, and impact attenuation have been associated with lower limb injury risk. Differences in shoe stiffness and surface construction may influence impact loading and a...

Background: Tendinopathies are painful overuse injuries observed in athletes participating in jumping sports. These injuries are heavily dependent on the resulting strain from the applied mechanical load. Therefore, mechanisms to reduce tendon strain may represent a primary prevention strategy to reduce the incidence of tendinopathy. Purpose: Th...

Artificial turf advances have enabled surfaces to behave like natural grass, however, debate remains as to whether artificial turf is as safe as natural grass. To reduce injury risk, sport surfaces should have low rotational traction with artificial surfaces having a potential advantage as components can be manipulated to change surface properties...

Background: Soccer players are at high risk of stress injuries in the foot. While most research addresses this issue in professional athletes, there is little information concerning young athletes. Objective: As soccer is practiced around the world since early infancy, we set out to determine whether young soccer athletes are susceptible to increas...

Background: The purpose of this study was to investigate how lower extremity kinematics and kinetics change when running downhill. Methods: Fifteen male recreational runners ran on an instrumented treadmill with three different slope conditions [level (0°), moderate (−6°), and steep (−9°)] at a controlled speed of 3.2 m/s. Ten consecutive steps wer...

Context: Footwear performance and injury mitigation may be compromised if the footwear is not properly sized for an athlete. Additionally, poor fit may result in discomfort and foot injury such as fifth metatarsal stress fracture, foot deformities, turf toe, and blisters. Current footwear fitting methods consist of foot length and width measuremen...

The aim of this study was to determine the biomechanical parameters that explain ventral start performance in swimming. For this purpose, 13 elite swimmers performed different variants of the ventral start technique. Two-dimensional video analyses of the aerial and underwater phases were used to assess 16 kinematic parameters from the starting sign...

The relationship between static foot structure characteristics and knee joint biomechanics during walking, or the biomechanical response to wedged insoles are currently unknown. In this study, 3D foot scanning, dual X-ray absorptiometry and gait analysis methods were used to determine structural parameters of the foot and assess their relation to k...

Background Treadmills are often used to assess running biomechanics, however the validity of applying results from treadmill graded running to overground graded running is currently unknown. Research question The purpose of this study was to investigate whether treadmill and overground graded running have comparable kinematics and ground reaction...

Objective: To determine whether Dr. Scholl's Active Series (DSAS) footwear insoles alter biomechanical variables associated with running injuries. Design: Randomized, controlled experiment. Setting: Sport medicine and biomechanics gait analysis laboratory. Participants: Fifteen healthy adults. Interventions: The control condition was the p...

The influence of nonlinear bending stiffness footwear, which alters the metatarsophalangeal (MTP) joint bending as a function of forefoot bending stiffness, has been postulated to improve athletic performance and reduce injury risk during many sports. As the shoe moves through greater amounts of bending, forefoot stiffness should increase nonlinear...

ABSTRACT This study investigated how the combination of workload and fatigue affected the frequency components of muscle activation and possible recruitment priority of motor units during skating to exhaustion. Ten male competitive speed skaters performed an incremental maximal test on a slide board. Activation of six muscles from the right leg was...

Torsion, the relative in-/eversion between forefoot and rearfoot, is a concept that has been incorporated into running shoes for almost 30 years. Studies have shown an influence of footwear torsional stiffness on lower extremity biomechanics during running but results are inconclusive. However, the influence of the torsion axis of the shoe on kinem...

Patent#: US 20160367199 A1 The present invention provides a method for predicting changes to the knee adduction moment during walking resulting from a wedged insole intervention using mediolateral position data of the lower extremity during a single step movement. This method may allow for simple biomechanical data collection and analysis in clinic...

Lacrosse requires the coordinated performance of many complex skills. One of these skills is shooting on the opponents’ net using one of three techniques: overhand, sidearm or underhand. The purpose of this study was to (i) determine which technique generated the highest ball velocity and greatest shot accuracy and (ii) identify kinematic and kinet...

The mountain goat (Oreamnos americanus) is one of the most extraordinary mountaineers in the animal kingdom. While observational descriptions exist to indicate factors that may influence their climbing ability, these have never been assessed biomechanically. Here, we describe whole-body motion of a mountain goat during ascent of a 45° incline based...

Background Clinical effectiveness of lateral wedges for knee osteoarthritis is inconsistent across studies. One explanation is that knee loading is not fully described by the peak frontal-plane knee moment. The purpose of this study was to propose a 3D resultant approach to describing moments at the knee and evaluate how this moment changes in resp...

The aim of this study was to investigate the effect of stage duration (Long-stage-LS: 3-min, Short-stage-SS: 1-min) on maximal and submaximal aerobic physiological variables during a simulated skating test performed on a slide board. Ten well-trained male speed skaters performed two maximal incremental tests on slide board until voluntary exhaustio...

The study of gait biomechanics in individuals with knee osteoarthritis has become widespread, especially in regards to the knee adduction moment-a variable commonly believed to be associated with knee osteoarthritis progression. Unfortunately, this variable is often studied clinically without considering how it is derived, or what it means in a mec...

Background: Wedged insoles have been used to treat knee pathologies and to prevent injuries. Although they have received much attention for the study of knee injury, the effects of wedges on ankle joint biomechanics are not well understood. This study sought to evaluate the immediate effects of lateral and medial wedges on knee and ankle internal...

Wedged insoles are believed to be of clinical benefit to individuals with knee osteoarthritis by reducing the knee adduction moment (KAM) during gait. However, previous clinical trials have not specifically controlled for KAM reduction at baseline, thus it is unknown if reduced KAMs actually confer a clinical benefit. Forty-eight participants with...

The aim of this study was to determine the precision and accuracy of the vertical and anterior–posterior force components of the portable PASCO PS-2142 force plate. Impulse, peak force, and time to peak force were assessed and compared to a gold standard force plate in three different tasks: vertical jump, forward jump, and sprint start. Two health...

During jump-landing tasks, knee kinematics such as excessive valgus have been linked to knee injury in females. Here we determine the influence of a compressive garment on knee valgus during landing. Physically active women (n=27, mean age 23 years) performed four different jump-landing tasks with two apparel conditions (compressive garment and reg...

Footwear insoles/orthotics alter variables associated with musculoskeletal injury; however, their clinical effectiveness is inconclusive. One explanation for this is the possibility that control conditions may actually produce biomechanical changes that induce clinical responses. The purpose of this study was to compare insole/orthotic control cond...

Forefoot bending stiffness is a footwear property that has recently been gaining interest despite previously receiving limited attention compared to other footwear characteristics. This review focuses on relevant research studies examining the influence of forefoot bending stiffness on reducing injury and optimizing performance. Discussion of the c...

Previous research has shown that altering forefoot (FF) bending stiffness can enhance running economy; however, the mechanism behind the changes in running economy remains unknown. Therefore, the purpose of this study was to investigate the relationship between forefoot bending stiffness, running economy, and lower limb kinematics during overground...

Wedged insoles are prescribed for medial knee osteoarthritis to reduce the knee adduction moment; however, it is currently not possible to predict which patients will in fact experience reduced moments. The purpose of this study was to identify a simple method using two-dimensional data for predicting the expected change in knee adduction moments w...

The aim of this study was to investigate the effects of strengthening and stretching exercises on running kinematics and kinetics in older runners. One hundred and five runners (55-75 years) were randomly assigned to either a strengthening (n = 36), flexibility (n = 34) or control (n = 35) group. Running kinematics and kinetics were obtained using...

Advances in sport equipment have revolutionized athletic competition with engineers developing equipment that can enhance performance. However, not all athletes are able to benefit from the new, ideal equipment, with some athletes performing worse. Although the engineering may be sound, the interaction between the piece of equipment, the athlete, a...

Compression apparel alters both compression of the soft tissues and the hip joint stiffness of athletes. It is not known whether it is the compression elements, the stiffness elements, or some combination that increases performance. Therefore, the purpose of this study was to determine how systematically increasing upper leg compression and hip joi...

Far infrared radiation (FIR) has been shown to have physiological effects when used as a treatment modality for certain medical conditions. Athletic apparel are currently commercially available that are constructed with fabrics that purportedly emit FIR. If apparel with this technology are capable of inducing positive physiological effects, then th...

Objective: Determine if a change in internal knee abduction angular impulse (KAAI) is related to pain reduction for runners with patellofemoral pain (PFP) by comparing lateral and medial wedge insole interventions, and increased KAAI and decreased KAAI groups. Design: Randomized controlled clinical trial (ClinicalTrials.gov ID# NCT01332110). Se...

Previous studies have linked footwear traction to lower extremity non-contact injury; however, these studies mainly focussed on rotational traction exclusively. While studies have shown that increases in traction lead to increases in joint loading, represented by joint moments, these studies failed to determine how the individual components of rota...

Object : The goals of this research were to make Performance Enhanced Model(PE) taken the largest performance index (PI) through artificial variation of principle components calculated by principle component analysis for trial data, and to verify the effect through comparing kinematic factors between trial data (Raw) and PE. Method : Ten subjects (...

Joint moments can be used as an indicator of joint loading and have potential application for sports performance and injury prevention. The effects of walking and running speeds on joint moments for the different planes of motion still are debatable. Here we compared knee and ankle moments during walking and running at different speeds. Data were c...

Discussion and conclusion Preliminary results (to be augmented with 26 additional subjects) suggest that maximal shoes do not require as large of gait modification as minimal shoes. Minimal and maximal adoptions appear individual specific. We are currently examining the results of the dynamic foot stiffness as predictor of these strategies.

The external knee adduction moment (EKAM) is often studied in knee osteoarthritis research. This study compared EKAMs between two methods of calculation: a method that only requires ground reaction force and knee position data (i.e. lever-arm), and an inverse dynamics link-segment method. Sixteen participants walked while wearing a control shoe wit...

Sprint acceleration is important in various sports. The current study examined whether acceleration performance is limited by strength, more specifically the peak limb force generation. We tested this idea by altering the mechanical demand for the supporting limb, and then determining if the peak limb force is constantly operating at its maximum le...

Inability to control lower extremity segments in the frontal and transverse planes resulting in large knee abduction angle and increased internal knee abduction impulse has been associated with patellofemoral pain (PFP). However, the influence of hip rotation angles on frontal plane knee joint kinematics and kinetics remains unclear. The purpose of...

The peak external knee adduction moment (KAM) is implicated in progression of knee osteoarthritis (OA). Recently, hip abductor weakness has also been found in patients with knee OA; however, it remains unknown as to how or if this weakness is a consequence of OA, or a predisposing factor. If it is the latter, a direct relationship between hip stren...

Background: Risk factors have been proposed for running injuries including (a) reduced muscular strength, (b) excessive joint movements and (c) excessive joint moments in the frontal and transverse planes. To date, many running injury prevention programs have focused on a "top down" approach to strengthen the hip musculature in the attempt to reduc...

Knee osteoarthritis (OA) progression has been linked to increased peak external knee adduction moments (KAMs). Although some trials have attempted to reduce pain and improve function in OA by reducing KAMs with a wedged footwear insole intervention, KAM reduction has not been specifically controlled for in trial designs, potentially explaining the...

The influence of New Trekking Shoes on Muscle Activity during Uphill, Downhill and Level Walking

Abstract The purpose of this study was to identify the influence of cryotherapy on lower extremity running biomechanics. Twenty-six healthy male volunteers were randomised into two intervention groups: cold water (cold water at ~11°C) or tepid water (tepid water at ~26°C). They were required to run at 4.0 ± 0.2 m · s(-1) before and after they under...