
Thomas W KernozekUniversity of Wisconsin–La Crosse | UWLAX · Department of Health Professions
Thomas W Kernozek
PhD
About
206
Publications
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Introduction
Research interests include lower extremity biomechanics. We use musculoskeletal models to help understand joint and tissue loading. Recent work has examined patellofemoral joint load and estimated Achilles tendon loading during movement performance.
We also have used either real-time feedback or post-trial feedback to influence performance during running, squatting and landing.
Additional affiliations
August 1996 - present
Education
August 1994 - August 1996
August 1990 - August 1994
Publications
Publications (206)
Recent human performance studies have shown that various kinematic and kinetic parameters may be implicated in non-contact anterior cruciate ligament (ACL) injury during landing and cutting. In this paper, a phenomenological sagittal plane model was used to estimate the ACL tension during drop landing from the net knee moments and forces, obtained...
Purpose:
This study aimed to quantify differences in patellofemoral joint stress that may occur when healthy runners alter their foot strike pattern from their habitual rearfoot strike to a forefoot strike to gain insight on the potential etiology and treatment methods of patellofemoral pain.
Methods:
Sixteen healthy female runners completed 20...
Achilles tendon (AT) injuries are common in runners. The AT withstands high magnitudes of stress during running which may contribute to injury. Our purpose was to examine the effects of foot strike pattern and step frequency on AT stress and strain during running utilizing muscle forces based on a musculoskeletal model and subject specific ultrasou...
Patellofemoral pain (PFP) is common in females. Patellofemoral joint stress (PFJS) may be important in the development of PFP. Ground reaction force (GRF) during landing activities may impact PFJS. Our purpose was to determine how healthy females alter their landing mechanics using visual post-trial feedback on their GRF and assess how PFJS changes...
Background: Elevated patellofemoral joint forces appear to contribute to the development of patellofemoral pain. As a result, treatment of patellofemoral pain often includes movement retraining intended to reduce patellofemoral joint forces. Real-time visual feedback has been shown to be effective for retraining running kinematics; however, we are...
Background and Purpose
Anterior cruciate ligament (ACL) tears often occur due to non-contact mechanisms in landing within females. Impact loading and aberrant landings may be addressed with augmented feedback training. The purpose of this study was to identify which female athletes most readily respond to a single session of augmented feedback to a...
Knee osteoarthritis (OA) is a common condition affecting millions of people globally. Recent research suggests that prolonged loading (forces) on the knee can be a potential factor affecting articular cartilage and deform knee structures, ultimately leading to the development and progression of medial knee OA. Hence, reducing loading is a common th...
Knee osteoarthritis (OA) is a common condition affecting millions of people globally. Recent research suggests that prolonged loading (forces) on the knee can be a potential factor affecting articular cartilage and deform knee structures, ultimately leading to the development and progression of medial knee OA. Hence, reducing loading is a common th...
Background and Purpose
Load asymmetry can be present before and after total knee arthroplasty (TKA), which may affect progress during knee rehabilitation in an outpatient sports medicine setting. Current rehabilitation primarily focuses on strength, pain, and range of motion deficits; however, recent evidence suggests the use of movement retraining...
Achilles tendon (AT) tendinopathy is common in runners. Repetitive AT loading may play a role in etiology. Interventions such as body weight support (BWS) may reduce loading on the AT in running. Examine how ground reaction force, AT loading, foot strike and cadence variables change in running with BWS. Twenty-four healthy female runners free from...
Running has a high incidence of overuse injuries. Achilles tendon (AT) injuries may occur due to high forces and repetitive loading during running. Foot strike pattern and cadence have been linked to the magnitude of AT loading. The effect of running speed on AT stress and strain, muscle forces, gait parameters and running kinematics is not well ad...
Background:
Biomechanical factors have been associated with running-related injury, but associations are unclear. Dynamic postural stability may be a factor related to injury that has not been studied extensively.
Research question:
Does dynamic postural control differ in those with a history of running-related injury or those who go on to susta...
Background:
Comparing the performance of one leg to another is a common means of assessing running gait to help inform clinical management strategies. Various methods are employed to quantify asymmetries between limbs. However, limited data is available describing the amount of asymmetry that may be expected during running and no index has been id...
Context:
Achilles tendon (AT) injuries are common in female runners and military personnel where increased AT loading may be a contributing factor. Few studies have examined AT stress during running with added mass. The purpose was to examine the stress, strain, and force placed on the AT, kinematics and temporospatial variable in running with dif...
Background
Structure-specific loading may have implications in understanding the mechanisms of running related injury. As females demonstrate a prevalence of patellofemoral pain twice that of males, this may indicate differences in patellofemoral loads between males and females. Previous works investigating differences in patellofemoral joint stres...
Increased vertical ground reaction force (vGRF) and dynamic knee valgus contribute to non-contact anterior cruciate ligament (ACL) injuries. We examined feedback’s influence during landing and transfer to a game-specific drill, measured by deceleration. Thirty-one female athletes performed 30 drop landings with augmented feedback and dual-task cond...
Background
Structure-specific loading is being increasingly recognized as playing a role in running related injuries. The use of interventions targeted at reducing patellofemoral joint loads have shown effectiveness in reducing symptoms of patellofemoral pain. Use of bodyweight support (BWS) has the potential to reduce loading on the patellofemoral...
# Background and Purpose
Load asymmetry can be present before and after total knee arthroplasty (TKA), which may affect progress during knee rehabilitation in an outpatient sports medicine setting. Current rehabilitation primarily focuses on strength, pain, and range of motion deficits; however, recent evidence suggests the use of movement retrain...
Context : Targeted training using augmented feedback to influence landing mechanics may be beneficial to athletes. Purpose : Examine how augmented feedback may influence vertical ground reaction force (VGRF) and improve knee valgus in females that display greater VGRF during drop landings. Main Results : Two hundred and forty female athletes partic...
Osteoporosis currently afflicts 8 million postmenopausal women in the US, increasing the risk of bone fractures and morbidity, and reducing overall quality of life. We sought to define moderate exercise protocols that can prevent postmenopausal osteoporosis. Our previous findings singled out higher walking speed and pre-exercise meals as necessary...
Objectives:
To determine the relationship between knee flexion excursion symmetry and lower extremity kinematics, kinetics, and muscle, joint, and ligament forces in females 1-3 years after ACL reconstruction.
Design:
Cross-sectional.
Setting:
Laboratory.
Participants:
Twenty-one, college-aged females.
Main outcome measures:
Lower extremit...
Context
Non-contact ACL injuries are common in female athletes during landing tasks. Post-trial performance-based feedback may be an effective method to reduce landing forces and knee valgus during landing. Information regarding the retention of these changes based on such training is generally lacking for weekly and monthly retention.
Objective
T...
Background
An estimated 56% of recreational runners sustain a running-related injury related to the high impact forces in running. Increasing step frequency (cadence) while maintaining a consistent speed has been shown to be an effective way to lower impact forces which may reduce injury risk.
Purpose
To examine effects of increased cadence on pea...
Injuries are often attributed to ruck marching. Therefore, it is important to examine how load carriage influences gait mechanics. The purpose of this study was to examine how subtle changes in rucksack load influence joint torque patterns during marching. Fourteen Army ROTC cadets marched with light, moderate, and heavy rucksack loads. Kinetic and...
Context: Running related injury occurs frequently in collegiate cross-country runners. Hip strength is one factor that may be important in the rehabilitation and training of cross-country runners. However, no normative values exist to inform these strategies.
Objective: Establish normative values for hip abduction and external rotation isometric st...
Background:
Post-performance verbal and visual feedback based on data collected via lab-based instruments have been shown to improve landing patterns related to non-contact ACL injury. Biomechanical methods are often complex, difficult to transport and utilize in field settings, and costly, which limits their use for injury prevention. Developing...
Objective
To examine patellofemoral joint (PFJ) loading in two lunge movements: Forward Lunge (FL) and Backward Lunge (BL).
Design
Repeated Measures.
Setting
University Biomechanics Laboratory.
Participants
20 asymptomatic females.
Main outcome measures
Six trials of two lunge movements (FL and BL) to a depth of 75% of leg length were performed...
Running kinematics have been related to injury and therefore may provide a therapeutic avenue for injury prevention and rehabilitation. The effect of strengthening exercise on running kinematics has not been systematically reviewed. The objective of this study was to determine the effect of strengthening exercise programs on 3D running kinematics i...
ACL injuries in the athletic population are a common occurrence with over 70% associated with non-contact mechanisms. The hamstring to quadriceps ratio is a widely used clinical measure to assess an athlete's readiness to return to sport; however, its relationship to knee forces and ACL tension during landing is unknown. Baseline isokinetic testing...
Objectives
To assess the influence of center line width on crossover hop for distance test (XHOP) performance.
Design
Repeated measures.
Setting
University laboratory
Participants
33 physically active females without history of a ligamentous knee injury (age: 22.5 ± 2.3 years).
Main Outcome Measures
Hop distance was measured during four XHOP co...
Background:
It has been recognized that anterior cruciate ligament (ACL) injuries typically occur when athletes are attending to a secondary task or object, including teammates, opponents, and/or a goal. Commonly applied tests after ACL injury include a series of hop tests to determine functional status, yet do not control for visual fixation.
Pu...
Introduction
Upright infant active cervical motion (ACM) is difficult to measure accurately by a single examiner. Clinically, physical therapists use visual estimation, which has limited reliability and concurrent validity with gold standards. Consistent, reliable, and valid active motion measurements are needed to document infant status and respon...
Objective
To determine if there is a relationship among isometric hip strength, hip kinematics, and peak gluteal muscle forces in cross-country runners during running.
Design
Cross Sectional
Setting
University Biomechanics Laboratory
Participants
Forty-six NCAA Division III collegiate cross-country runners (18 males, 28 females).
Main Outcome M...
Background:
Hop tests are commonly used within a testing battery to assess readiness for return to sport after anterior cruciate ligament (ACL) injury, yet athletes still experience a high rate of re-injury. Simultaneous performance of a secondary task requiring cognitive processing or decision-making may test the athlete under more realistic cont...
Background:
The role of biomechanical variables of running gait in the development of running related injury has not been clearly elucidated. Several systematic reviews have examined running biomechanics and its association with particular running related injuries. However, due to retrospective designs, inferences into the cause of these injuries...
Patellofemoral joint (PFJ) pain syndrome is a commonly reported form of pain in female runners and military personnel. Increased PFJ stress may be a contributing factor. Few studies have examined PFJ stress running with added load. Our purpose was to analyze PFJ stress, PFJ reaction force, quadriceps force, knee flexion angle, and other kinematic a...
Males and females demonstrate unique running mechanics that may contribute to sex-related differences in common running related injuries. Understanding differences in muscle forces during running may inform intervention approaches, such as gait retraining addressing muscle force distribution. The purpose of this study was to compare muscle force ch...
Context:
Single-leg hopping is used to assess a dynamic knee stability. Patellofemoral pain is often experienced during these exercises, and different cadences of jumping are often used in rehabilitation for those with patellofemoral pain. No studies to date have examined patellofemoral joint loading during single-leg hopping exercise with differe...
Background:
Athletes in jumping and running sports have a high incidence of Achilles tendon (AT) injuries. We compared AT loading during jumping and landing phases in anteroposterior (AP) and mediolateral (ML) directions.
Methods:
Sixteen males (age: 21.6±1.8 years, height: 178.4±6.4 cm, weight: 76.4±11.2 kg) performed single leg AP and ML jump-...
Previous cross-sectional studies have reported that higher drop heights do not always result in improved performance, and may increase injury risk during drop jumps (DJ). The purpose of this study was to analyze the kinematics and kinetics during the DJ in order to determine the relative drop height that maximize performance without exposing the lo...
Type 2 diabetes increases bone fracture risk in postmenopausal women. Usual treatment with anti-resorptive bisphosphonate drugs has some undesirable side effects, which justified our interest in the osteogenic potential of nutrition and exercise. Since meal eating reduces bone resorption, downhill locomotion increases mechanical stress, and brief o...
Structural integrity of bones is supported by mechanical loading, energy intake, and sex hormones. It is unclear why postmenopausal (PM) diabetics experience more bone breaks despite higher body weight and positive energy balance than non-diabetics. We hypothesized that greater bone fragility in PM diabetics may result from peripheral insulin resis...
Sex differences in common sports injuries to the lower extremity have been reported. Biomechanical factors of the hip have been investigated between sexes with regard to running-related injury. This study investigates gluteal muscle forces between sexes to aid in our understanding of sex-related biomechanical factors in running. Twenty-one healthy...
Background:
Female runners that habitually use a forefoot/midfoot strike pattern (non-rearfoot runners) may be at greater risk for Achilles tendinopathy compared to runners that habitually use a rearfoot strike pattern. Differences in Achilles tendon loading between non-rearfoot and rearfoot strike runners may be a contributing factor.
Research q...
Background:
Athletes that have had anterior cruciate ligament (ACL) reconstruction are at a greater risk for reinjury. The relationship between ACL reconstruction and the dynamic postural sway index (DPSI) has not yet been examined.
Hypothesis/purpose:
The purpose of this study was to examine the DPSI in a surgically reconstructed ACL limb compa...
This study evaluated the effect of running shoes with differing midsole cushioning on ankle, knee and hip contact forces during running. Joint contact forces were estimated in 40 recreational runners (28 female, 12 male) while running over ground in three shoe conditions. Shoes differed only in midsole cushioning (45, 57 and 70 Asker C). Three-dime...
Objective:
Compare the estimated Achilles tendon (AT) loading using a musculoskeletal model during commonly performed weight bearing therapeutic exercises.
Design:
Controlled laboratory study.
Setting:
University biomechanics laboratory.
Participants:
Eighteen healthy males (Age:22.1 ± 1.8 years, height:177.7 ± 8.4 cm, weight = 74.29 ± 11.3...
Background:
This study quantified the peak vertical ground reaction force (VGRF), impulse, and average and instantaneous loading rates developed during bilateral plyometric exercises.
Methods:
Fourteen collegiate male athletes performed four different bilateral plyometric exercises within a single testing session. Depth jumps from thirty, sixty...
Study Design
Cross-sectional study.
Background
The drop vertical jump task is commonly used to screen for anterior cruciate ligament injury risk; however, its predictive validity is limited. The limited predictive validity of the drop vertical jump task may be due to not imposing the cognitive demands that reflect sports participation.
Objectives...
The function and inherent stability of the hip are dependent upon the passive osseous and ligamentous structures of the joint and the activity of its musculotendinous structures. The purpose of this chapter is to review these general osseous and ligamentous support structures as well as the neuromuscular control strategies associated with normal hi...
Anterior cruciate ligament (ACL) injuries in basketball appear to be more common when players are in possession of the ball. The greater risk of ACL injury when in possession of the ball may result from the athlete’s inability to fully attend to their movement. However, it is also possible that having to carry/manipulate the ball restricts the athl...
Background:
Patellofemoral pain is a debilitating injury for many recreational runners. Excessive patellofemoral joint stress may be the underlying source of pain and interventions often focus on ways to reduce patellofemoral joint stress.
Purpose:
Heel lifts have been used as an intervention within Achilles tendon rehabilitation programs and to...
Our purpose was to evaluate the vertical ground reaction force, impulse, moments and powers of hip, knee and ankle joints, contact time, and jump height when performing a drop jump from different drop heights based on the percentage of a performer’s maximum vertical jump height (MVJH). Fifteen male Division III athletes participated voluntarily. El...
Sports involving frequent jumping (JUMP) and landing (LAND) and changes in direction may increase risk of Achilles tendon (AT) injury. Mechanisms of AT rupture are thought to be related to weight bearing activities such as JUMP and LAND that involve knee extension and vigorous dorsiflexion on a plantar flexed foot. Studies report less postural stab...
Undergraduates are usually required to complete one or more biomechanics courses in a movement science curriculum. Students often avoid taking this course, perhaps because they have a reduced perception of success due to low self-efficacy with the perceived content, particularly related to mathematics. Student learning may be increased through the...
Context:
Squatting is a common rehabilitation training exercise for Patellofemoral pain syndrome (PFPS). Patellofemoral joint stress (PFJS) during squatting with more anterior knee displacement has not been systematically investigated.
Objective:
The aim was to compare PFJS during squatting using two techniques: Squat while keeping the knees bef...
Context:
Achilles tendinopathies are common injuries during sport participation, although men are more prone to Achilles tendon injuries than women. Heel-raising and -lowering exercises are typically suggested for Achilles tendon rehabilitation.
Objective:
To compare the estimated Achilles tendon loading variables and the ankle range of motion (...
Background
Patellar tendinopathy (PT) or “jumper's knee” is generally found in active populations that perform jumping activities. Graded exposure of patellar tendon stress through functional exercise has been demonstrated to be effective for the treatment of PT. However, no studies have compared how anterior knee displacement variations during the...
Tendon stress may be one of the important risk factors for running-related tendon injury. Several methods have been used to estimate Achilles tendon (AT) loading during a human performance such as inverse dynamics (ID) and inverse dynamics-based static optimisation (IDSO). Our purpose was to examine differences between ID and IDSO estimates of AT l...
Background:
While studies that have examined the prevalence of musculoskeletal injuries in alpine skiing and snowboarding exist, there has been no discussion of how neurocognitive deficits may influence such injuries. Recent authors have identified a possible link between Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) testing...
Persons unable to exercise due to old age, immobility or medical condition may develop low bone density, decline in muscle contraction, blood pooling or clot. Due to musculoskeletal fragility caution is required in bone and muscle strengthening. Similarly, caution is required to use anticoagulant drug to prevent blood clot due to side effect, and c...
Background:
Injury has been linked with altered postural control in active populations. The association between running injury and dynamic postural control has not been examined.
Hypothesis/purpose:
The purpose of this study was to examine dynamic postural control in injured and uninjured runners using the Star Excursion Balance Test (SEBT), Tim...
Combinations of smaller bone geometry and greater applied loads may contribute to tibial stress fracture. We examined tibial bone stress, accounting for geometry and applied loads, in runners with stress fracture.
23 runners with a history of tibial stress fracture & 23 matched controls ran over a force platform while 3-D kinematic and kinetic data...
Objectives:
Characterize plantar loading parameters when habitually rear foot strike (RFS) runners change their pattern to a non-rear foot strike (NRFS).
Design:
Experimental.
Setting:
University biomechanics laboratory.
Participants:
Twenty three healthy female runners (Age: 22.17 ± 1.64 yrs; Height: 168.91 ± 5.46 cm; Mass: 64.29 ± 7.11 kg)...
Joint specific models rely on muscle force estimates to quantify tissue specific stresses. Traditionally, muscle forces have been estimated using inverse dynamics alone. Inverse dynamics coupled with static optimization techniques allow for an alternative method in estimating muscle forces. Differences between these two techniques have not been com...
This study aimed to investigate biomechanical parameters during a change of direction task in collegiate soccer players. Fourteen male and twelve female players performed a 10-m sprint with a 60° change of direction at 5 m. Vertical and mediolateral ground reaction force (GRF) and contact time were measured by having the subjects run in both direct...
This study investigated the influence of patellofemoral pain (PFP) and fatigue on lower-extremity joint biomechanics in female dancers during consecutive simple ground échappé. 3-dimensional joint mechanics were analyzed from the no-fatigue to fatigue conditions. 2-way mixed ANOVAs were used to compare the differences of the kinematic and kinetic v...
Background:
Patellofemoral pain (PFP) is a common injury, particularly in females. Foot pronation may promote knee and hip transverse plane joint kinematics during gait thought to contribute to PFP. Greater knowledge of plantar loading characteristics in females with PFP may be valuable to provide a basis for clinical decisions regarding footwear...
Hip and knee joint kinematics during drop landings are relevant to lower extremity injury mechanisms. In clinical research the "gold standard" for joint kinematic assessment is 3D motion analysis. However, 2D kinematic analysis is an objective and feasible alternative.
To quantify the relationship between 2D and 3D hip and knee kinematics in single...