The influence of midsole horizontal and vertical deformation on soft tissue vibrations and bone acceleration during running.

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-min running task on an instrumented treadmill at a self-selected pace with four different shoes.

Differences in head impact biomechanics between playing positions in Canadian high school football players.

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 Profile 3 (linemen). Players wore instrumented mouthguards to measure peak magnitudes of linear and angular acceleration and velocity for each head impact throughout the season.

Effects of midsole cushioning stiffness on Achilles tendon stretch during running.

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 in Achilles tendon stretch.

The influence of midsole shear on running economy and smoothness with a 3D-printed midsole.

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 conditions, differing in midsole technology, were used in this study.

Are subject-specific models necessary to predict patellar tendon fatigue life? A finite element modelling study.

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-specificity. We compared patellar tendon fatigue-life estimates from NS and FE models of twenty-nine athletes performing countermovement jumps with subject-specific versus generic geometry and material properties.

Measuring Gait Velocity and Stride Length with an Ultrawide Bandwidth Local Positioning System and an Inertial Measurement Unit.

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).

Increasing the midsole bending stiffness of shoes alters gastrocnemius medialis muscle function during running.

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 so far. This study aimed to investigate how the function of the gastrocnemius medialis (GM) muscle and Achilles tendon is altered when running in shoes with increased MBS.

Influence of Artificial Turf Surface Stiffness on Athlete Performance.

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 remains unknown. Therefore, the purpose of this project was to determine the influence of surface stiffness of artificial turf systems on athlete performance.

Plantar loading in the youth soccer player during common soccer movements and risk for foot injury.

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 loading that increase risk factors for foot injuries in a similar manner as reported by the literature to the adult athlete.

Influence of forefoot bending stiffness on American football performance and metatarsophalangeal joint bending angle.

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 forefoot bending stiffness on large-sized athletes such as those that participate in American Football, with prior studies being conducted on smaller athlete populations.

Effect of a Commercially Available Footwear Insole on Biomechanical Variables Associated With Common Running Injuries.

Objective: To determine whether Dr. Scholl's Active Series (DSAS) footwear insoles alter biomechanical variables associated with running injuries.

Design: Randomized, controlled experiment.

Effect of Shoe and Surface Stiffness on Lower Limb Tendon Strain in Jumping.

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.

Influence of the composition of artificial turf on rotational traction and athlete biomechanics.

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 and traction. The purpose of this study was to investigate the influence that different components of artificial turf have on rotational traction and athlete lower extremity joint loading.

The effects of downhill slope on kinematics and kinetics of the lower extremity joints during running.

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.

Development of a Footwear Sizing System in the National Football League.

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 measurements, which may not properly describe the shape of the individual foot, correlated with shoe size descriptors that are not standardized.

Key determinants of time to 5 m in different ventral swimming start techniques.

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 signal to 5 m, and an instrumented starting block was used to assess kinetic data.

Joint kinematics and ground reaction forces in overground versus treadmill graded running.

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 force parameters.

Methods: Eleven healthy male adults ran overground and on an instrumented treadmill as motion capture and force platform data were collected for the following conditions: downhill running at a slope of -8° at 10, 13 and 16 km⋅h; level running at 10 and 13 km⋅h; uphill running at a slope of +8° at 8, 10 and 13 km⋅h.

Foot structure and knee joint kinetics during walking with and without wedged footwear insoles.

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 knee joint loading and biomechanical response to wedged insoles in 30 patients with knee osteoarthritis. In multiple linear regression models, foot fat content, height of the medial longitudinal arch and static hind foot angle were not associated with the magnitude of the knee adduction moment (R = 0.

Motor unit firing frequency of lower limb muscles during an incremental slide board skating test.

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 recorded throughout the test.

Effects of Lateral and Medial Wedged Insoles on Knee and Ankle Internal Joint Moments During Walking in Healthy Men.

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 joint loading and center of pressure (CoP) in men during walking.

Kinematic and kinetic analysis of overhand, sidearm and underhand lacrosse shot techniques.

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 kinetic variables that contribute to a high velocity and high accuracy shot.

A three dimensional approach for quantifying resultant loading at the knee.

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 response to lateral wedges.

Wedged Insoles and Gait in Patients with Knee Osteoarthritis: A Biomechanical Review.

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 mechanical context. The use of footwear for knee osteoarthritis management has received much attention as well.

Reduced knee adduction moments for management of knee osteoarthritis:: A three month phase I/II randomized controlled trial.

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 medial knee osteoarthritis were randomly assigned to either a control group where no footwear intervention was given, or a wedged insole group where KAM reduction was confirmed at baseline.