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Papers by Clark Dickin

D. Clark Dickin for the degree of Doctor of Philosophy in Human Performance presented on February... more D. Clark Dickin for the degree of Doctor of Philosophy in Human Performance presented on February 15, 2002. Title: Sensory Integration during Balance in Individuals with Differing Degrees of Senile Dementia of the Alzheimer's Type. ... Individuals with Senile Dementia of the Alzheimer ...

This study was performed to examine the effects of movement velocity and eccentric contractions o... more This study was performed to examine the effects of movement velocity and eccentric contractions on the bilateral deficit. To accomplish this, 18 participants performed bilateral and unilateral contractions eccentrically and concentrically across 6 movement velocities (30, 60, 90, 120, 150, and 180{dollar}\sp\circ{dollar}/s). Repeated measures ANOVA's revealed that for both eccentric and concentric contractions, significant differences existed between bilateral and summed unilateral contractions; and at each of the six tested velocities. Further analyses revealed that the degree of the bilateral deficit increased as movement velocity increased. It is believed that the decreased tension developed during bilateral eccentric and concentric contractions, is attributed to incomplete activation of fast twitch muscle fibers recruited during unilateral contractions.

Journal of Science and Medicine in Sport, 2019

Objectives: To determine if a history of exercise involving multiaxial loading, through soccer pa... more Objectives: To determine if a history of exercise involving multiaxial loading, through soccer participation, influences tibial stains during incremented load carriage. Design: Cross-sectional study. Methods: 20 female soccer players (20 ± 1 yr) and 20 mass-and height-matched healthy women (21 ± 1 yr) participated in walking tasks with 0 kg, 10 kg, 20 kg, and 30 kg loads on a force instrumented treadmill at 1.67 m/s. Subject-specific tibial CT models were combined with subject-specific musculoskeletal models for forward-dynamic simulations and finite element analyses. Strains from the middle third of the tibial shaft were analyzed. A mixed model repeated measures analysis of variance (ANOVA) and one-way ANOVAs were run with a Bonferroni correction setting significance at 0.0009. Results: Significant differences in tibial characteristics were found among loading conditions and between groups (all p < 0.0001). Tensile strains were 19.6%, 22.2%, 44.1%, and 20.7% lower in soccer players at 0 kg, 10 kg, 20 kg, and 30 kg of load carriage, respectively. Strain rates were 20.4%, 29.9%, 43.4%, and 18.9% lower, respectively, in soccer players. Lower compressive and shear strain magnitudes and rates were also observed in soccer players, with the only exception at the 30 kg loading condition in which controls had 2.4% lower strain magnitudes in compression, on average, compared to soccer players. Conclusions: A history of activity involving multiaxial loading was associated with generally lower estimated tibial strains during load carriage. Lower strain levels during repetitive physical activity may be protective from stress fracture. These findings suggest that physical training, such as participating in soccer, may be effective for preconditioning prior to entering military or endurance training.

PubMed, Mar 1, 2013

Objectives: As adults with cerebral palsy (CP) are surviving longer, interventions are needed to ... more Objectives: As adults with cerebral palsy (CP) are surviving longer, interventions are needed to reduce spasticity and increase strength to improve mobility and life quality. Adults with CP are lacking a form of independent exercise that allows them to maintain or improve their ambulation skills. A new approach to increase muscle strength and flexibility called whole-body vibration (WBV) was assessed. Methods: Using an individualized frequency (I-Freq) approach to WBV therapy the acute effects on gait in adults with CP was measured. In this study, eight adults with CP (age 20-51 years, two female) participated in two testing sessions: session one determined each individual's I-Freq; and session two included a 3D gait analysis before and after a WBV treatment. The WBV was administered in five, one minute bouts of vibration followed by one minute of rest. Results: Following WBV exposure subjects experienced a significant increase in walking speed (P=0.047), stride length (P=0.017) and dynamic ankle range of motion (P=0.042). Conclusions: These data show that acute WBV treatments at I-Freq can improve measures of gait and mobility in adults with CP, however, future should assess potential long-term improvements.

Sports Biomechanics, Sep 10, 2014

Sports Biomechanics, Aug 17, 2018

Female volleyball athletes incorporate dynamic and static stretching into a warm-up, with evidenc... more Female volleyball athletes incorporate dynamic and static stretching into a warm-up, with evidence generally supporting dynamic stretching to improve performance. However, the effects of these stretching practices on injury risk during subsequent volleyball manoeuvres have yet to be fully elucidated in the warm-up literature. Threedimensional kinematic data associated with non-contact, lower extremity injury were recorded on 12 female collegiate club volleyball athletes during unilateral landing tasks on the dominant and non-dominant limb. Participants performed landings as part of a volleyball-simulated manoeuvre prior to and post-dynamic (DWU) and combined dynamic-static (CDS) warm-ups. A significant reduction in non-dominant hip adduction angle was found at 15 min post CDS warm-up (p = 0.016; d = 0.38), however, no other warm-up differences were detected. The non-dominant limb demonstrated greater knee abduction (p = 0.006; d = 0.69) and internal rotation angle (p = 0.004; d = 0.88), suggesting that this limb demonstrates more risky landing patterns that are potentially due to altered trunk positioning upon landing. The results show that the majority of selected landing kinematics are unaffected by additional static stretching to a dynamic warm-up and that the non-dominant limb may be at a higher injury risk in female volleyball athletes.

Gait & Posture, Apr 1, 2014

Walking is a popular form of exercise and is associated with many health benefits; however, front... more Walking is a popular form of exercise and is associated with many health benefits; however, frontal-plane knee joint loading brought about by a large internal knee-abduction moment and cyclic loading could lead to cartilage degeneration over time. Therefore, knee joint mechanics during an alternative walking exercise needs to be analyzed. The purpose of this study was to examine the lower-extremity joint mechanics in the frontal and sagittal planes during incline walking. Fifteen healthy males walked on a treadmill at five gradients (0%, 5%, 10%, 15%, and 20%) at 1.34m/s, and lower-extremity joint mechanics in the frontal and sagittal planes were quantified. The peak internal knee-abduction moment significantly decreased from the level walking condition at all gradients except 5%. Also, a negative relationship between the internal knee-abduction moment and the treadmill gradient was found to exist in 10% increments (0-10%, 5-15%, and 10-20%). The decrease in the internal knee-abduction moment during incline walking could have positive effects on knee joint health such as potentially reducing cartilage degeneration of the knee joint, reducing pain, and decreasing the rate of development of medial tibiofemoral osteoarthritis. This would be beneficial for a knee surgery patient, obese persons, and older adults who are using incline walking for rehabilitation and exercise protocols. Findings from the current study can provide guidance for the development of rehabilitation and exercise prescriptions incorporating incline walking.

Sports Biomechanics, Oct 1, 2018

Hill running is often used as a foundational training mechanism to build strength and speed. Dist... more Hill running is often used as a foundational training mechanism to build strength and speed. Distance runners in particular are at an increased likelihood of encountering steep hills during training runs. There is limited research regarding downhill running, and there is no research available on the biomechanics of females specifically during downhill running. The purpose of this study was to quantify the differences in loading when running downhill at different grades compared to a level surface in female distance runners to determine the potential risk for injury. Fifteen female distance runners (age: 23.5 ± 4.9 y), who ran 56.3 ± 20.9 km a week participated in this study. Participants ran on a force-instrumented treadmill at 4.0 m/s for 2 min at 0%, −5%, −10%, −15%, and −20% grades, with 5 min of rest between conditions. Study findings showed increased impact forces (p < 0.001), and increased loading rates (p < 0.001) with increasing downhill grades compared to level. These results indicate a significantly greater risk of overuse injury to the lower extremity with steeper downhill grades. Individuals need to be aware of these risks to plan and implement training programmes that will increase performance while minimising injury risk.

Journal of Sport and Health Science, Sep 1, 2019

Background: Military recruits are often afflicted with stress fractures. The military's strenuous... more Background: Military recruits are often afflicted with stress fractures. The military's strenuous training programs involving load carriage may contribute to the high incidence of tibia stress fractures in the army. The purpose of this study was to assess the influences of incremented load carriage and history of physical activity on tibia bone strain and strain rate during walking. Methods: Twenty recreational basketball players and 20 recreational runners performed 4 walking tasks while carrying 0 kg, 15 kg, 25 kg, and 35 kg loads, respectively. Tibia bone strain and strain rate were obtained through subject-specific multibody dynamic simulations and finite element analyses. Mixed model repeated-measures analyses of variance were conducted. Results: The mean ± SE of the runners' bone strain (μs) during load carriages (

Medicine and Science in Sports and Exercise, May 1, 2018

To investigate lower extremity torque components changes in preparation for gait transition with ... more To investigate lower extremity torque components changes in preparation for gait transition with increased walking speed. METHODS: 11 male and 3 female college students (age: 22.6 ± 1.9 years, body mass: 75.4 ± 12.8 kg, height: 1.73 ± 0.08 m) were recruited for this study. Participants walked on a force plates embedded treadmill (AMTI, MA, USA) with continuously changed walking speed approaching walk-to-run transition. Ground reaction forces and kinematic data (VICON, Oxford, UK) were obtained at sampling rate of 1000 Hz and 200 Hz, respectively. The results of inverse dynamics were further decomposed into net joint torque (NET), gravitational torque (GTT), motion-dependent torque (MDT), contact torque (EXT), and generalized muscle torque (MST) for the last five strides before gait transition. Owe-way MANOVA employed to exam the difference among the five strides. Post hoc polynomial trend analyses were also employed to examine the trend with the five strides whenever suitable. RESULTS: Significant difference of all three lower extremity joints was detected during stance phase. Positive / negative values represent extension / flexion torque. EXT and MST of ankle (0.

Medicine and Science in Sports and Exercise, May 1, 2017

Tibia stress fracture (TSF) is very common in military recruits. Female Soldiers experience a hig... more Tibia stress fracture (TSF) is very common in military recruits. Female Soldiers experience a higher rate than their male counterparts. TSF occurs frequently in basic training due to repetitive impact loading from tasks such as load carriage. Common TSF sites are at distal and middle thirds of the tibia. To date, it is unknown whether training involved multiaxial loading (e.g. soccer) could help improve tibia quality and potentially increase bone's resilience on TSF. PURPOSE: To examine the effect of soccer history on tibia mechanical properties. METHODS: 20 female soccer players (20±1 yr) and 20 mass and height matched sedentary women (21±1 yr) completed a pQCT scan on their tibias at seven locations along the bone shaft. Cortical bone density and mechanical strength of the bone at 14%, 38%, 66%, and centers of the proximal, middle, and distal thirds of the bone shaft were examined. One-way ANOVAs were performed. RESULTS: Significant differences in area moments of inertia and bone strength index were found (p<0.05). The area moments of inertia along the anteroposterior, mediolateral, and longitudinal axes of the soccer players' tibia were 33.5%, 24.7%, 18.4% greater than those of the sedentary women, respectively. In addition, the bone strength index of the soccer players was 19.6% higher than that of the sedentary women. Significant differences in cortical bone density were also found (p<0.01). Sedentary women possessed an average of 2.2% higher cortical bone density in all seven locations of the bone shaft than those of the soccer players. CONCLUSION: Participants with a soccer history had enhanced tibia mechanical properties, including greater bone strength, but reduced cortical bone density when compared to sedentary controls. These results suggest a co-adaptation of intracortical bone remodeling and bone formation modeling during training such that bone geometry is optimized without excessive increases in bone density, which would be metabolically expensive. Enhanced mechanical properties in soccer players could make the tibia more resilient to unaccustomed mechanical loading, such as load carriage during military training. Future studies should examine whether enhanced bone mechanical properties result in reduced bone strains and a lower risk of TSF. US ARMY #W81XWH-08-1-0587; #W81XWH-15-1-0006. Sclerostin (ng/mL) 0.442 ± 0.021 ** 0.353 ± 0.019 0.400 ± 0.015 ** p < 0.01 and *** p < 0.001 significant differences between men and women, respectively

Journal of orthopedics and orthopedic surgery, Apr 30, 2021

Soccer is becoming an increasingly popular sport amongst women. Common movements during play, suc... more Soccer is becoming an increasingly popular sport amongst women. Common movements during play, such as jumping and cutting, require rapid acceleration and deceleration of multiple lower-limb joints. The anterior cruciate ligament (ACL), which contributes to stabilization of the knee, is often injured during these events. ACL injury typically requires costly surgery, extended time away from sports, and jeopardizes long-term joint health. Due to sex-specific factors such as menstruation and anatomical disadvantages, women are more susceptible to tearing their ACL. Injury often occurs in non-contact scenarios during rapid acceleration or deceleration movements. Research has examined these movements and established several kinematic and kinetic mechanisms as well as muscle activation patterns that frequently occur at the time of injury, however results tend to vary based on population. This article summarizes recent and relevant literature of ACL injury mechanisms and highlights the lack of specific research in the high-risk female soccer athlete population. Due to inconclusive risk factors, injury prevention programs within this population have been inconsistent. ACL injury risk for female soccer athletes should be closer examined so that more specific injury risks can be established, and effective protective measures can be taken. Raised awareness of this need may capture attention in the research and medical communities and potentially stimulate the development of strategies that limit future ACL injury and thus the challenges it brings to the high-risk female soccer athlete.

International Journal of Sports Science & Coaching, Feb 3, 2021

Conclusions from biomechanical data can make a significant difference in the performance of athle... more Conclusions from biomechanical data can make a significant difference in the performance of athletes in the hammer throw if properly understood by coaches. By utilizing this scientific approach to the hammer throw event, the throws coach will be able to determine more accurate adjustments and devise training stimuli to better accommodate the athlete. In this case study, we have attempted to bridge the gap between the researcher and the coach in our approach to teaching the hammer throw, by integrating biomechanical analysis. We have employed the use of video analysis as an essential part of our coaching/teaching system. This USATF Women's development hammer project is an example in which the cooperation between sport science and coaching helped to produce an American record of 73.87m by Erin Gilreath in the women's hammer in 2005.

Journal of Strength and Conditioning Research, Jul 1, 2014

for his guidance throughout the entire thesis process, well, make that the whole Masters process.... more for his guidance throughout the entire thesis process, well, make that the whole Masters process. Dr. Paul Nagelkirk for not only serving on my committee but for allowing me to use the shiny new Monark. Dr. Henry Wang for being willing to serve on my committee and giving me guidance throughout my time at Ball State. Jeffrey Frame for giving me an insight into the cycling world and sharing some contacts with me. Barb Schornstein for collecting with me on those late nights in the lab. Kate Faust for enduring a summer of individualized frequency, lit reviews, and ultimately the pool. Lisa Kaufman for all of her help and support and life guidance. The Smith family for all of their laughs and encouraging words. My loving family for listening during times of stress and providing words of encouragement. And finally Dakota Smith for all the loving support, the much needed diversions and laughter Nomenclature I-Freq-Individualized Frequency

Journal of orthopedics and orthopedic surgery, Apr 9, 2020

Load carriage is a common activity used in daily tasks for many occupations, so understanding its... more Load carriage is a common activity used in daily tasks for many occupations, so understanding its injury mechanisms, as well as the biomechanical modifications made to gait and posture during load carriage, could reduce injury risk during this activity. The purpose of this review was to compile the most recent literature regarding biomechanical adaptations to load carriage, including its effects on musculoskeletal injury, kinematic, spatiotemporal, and kinetic adaptations, and insights about the future of load carriage research. Researchers found a high degree of injury in personnel who participate in heavy load carriage activities as a part of their job, with lower back and lower extremity injuries being the most common. An observation of several studies that measured kinematic, spatiotemporal, and kinetic adaptations suggest that there may be a threshold in which typical gait kinematics must change to account for the additional load. Not adapting proper mechanisms to deal with increased load carriage forces may lead to lower extremity injury. Future studies should observe how persons untrained in load carriage respond to these loads, and how controlling for variables like speed and cadence affect gait adaptations.

Journal of Sport and Health Science, Jun 1, 2017

To test the effectiveness of sitting surfaces with varied amounts of stability on muscle activity... more To test the effectiveness of sitting surfaces with varied amounts of stability on muscle activity and energy expenditure. Methods: Using a within-participants repeated measures design, 11 healthy young-adult females (age = 20.0 ± 1.8 years) were measured using indirect calorimetry to assess energy expenditure, and electromyography to assess muscular activation in trunk and leg musculature under three different sitting surfaces: flat-firm surface, air-filled cushion, and a stability ball. Data were analyzed using repeated measures analysis variance with follow-up pairwise contrasts used to determine the specific effects of sitting surface on muscle activation and energy expenditure. Results: Significantly greater energy expenditure was recorded for the stability ball (p = 0.01) and the cushion (p = 0.03) over the flat surface (10.4% and 9.6% greater, respectively), with no differences between the ball and the cushion. Both the ball and the cushion produced higher tibialis anterior activation over the flat surface (1.09 and 0.63 root-mean-square millivolts (RMSmv), respectively), while the stability ball produced higher soleus activity over both cushion and flat surfaces (3.97 and 4.24 RMSmv, respectively). Additionally, the cushion elicited higher adductor longus activity over the ball and flat surfaces (0.47 and 0.52 RMSmv, respectively), but no trunk musculature differences were revealed. Conclusion: Compliant surfaces resulted in higher levels of muscular activation in the lower extremities facilitating increased caloric expenditure. Given the increasing trends in sedentary careers and the increases in obesity, this is an important finding to validate the merits of active sitting facilitating increased caloric expenditure and muscle activation.

Gait & Posture, Mar 1, 2016

I would like to thank my thesis chair, Dr. Dickin, for helping me through the entire thesis proce... more I would like to thank my thesis chair, Dr. Dickin, for helping me through the entire thesis process. I appreciate all of the time and effort you expended on my behalf to overcome the many obstacles this project presented. On a side note, thank you for being an Oregon State fan, so I could truly feel like a winner during football season. I would also like to thank my committee members, Dr. Henry Wang and Dr. Jennifer Popp, for your input and guidance that aided me in producing a successful research project. It is also important to note that this study would not have happened without the generous donation of the BackTpacks from Mrs. Marilyn Miller von Forester. Thank you to my participants, without whom this project would not have been possible. Many thanks to my colleagues who became friends and were always there when I needed a second opinion, a laugh, or a distraction. And a special shout out to my little protégé for all your assistance during data collection. Last, but certainly not least, thank you to my family and friends back home who were always an encouraging phone call or text away even with 2,331 miles between us.

Medicine and Science in Sports and Exercise, Sep 1, 2022

Medicine and Science in Sports and Exercise, Jul 1, 2020

Journal of Sports Medicine and Physical Fitness, Jul 1, 2019

BACKGROUND Anticipation has been previously shown to affect lower extremity mechanics during both... more BACKGROUND Anticipation has been previously shown to affect lower extremity mechanics during both landing and cutting maneuvers. However, little research has been conducted looking at the effects of anticipation on lower body kinetics and kinematics during a land and cross step maneuver, which due to similar kinematics, may elicit injury. The purpose of this study was to investigate competitive female volleyball players and the effect of anticipation on lower extremity mechanics during a landing and subsequent cross stepping maneuver. METHODS Twelve female, college-level volleyball players performed right and left cross step maneuvers following a landing under anticipated and unanticipated conditions. Kinetics were measured for the ankle, knee and hip of the dominant limb during the landing phase of the land and cross step anticipatory conditions. RESULTS An interaction effect (anticipation x direction; P=0.001) was observed for vertical ground reaction force (VGRF), in which greater VGRF was found during unanticipated pivoting maneuvers. Additional interaction effects were determined for ankle (P=0.004) and hip (P=0.037) power absorption, in which greater absorption was found during anticipated, push off conditions. Frontal plant knee kinetics revealed a higher-order interaction, as a larger knee adduction moment was shown during anticipated, push off trials (P=0.001). CONCLUSIONS High risk cross step maneuvers were found during unanticipated and anticipated conditions, as athletes demonstrated movement mechanics that may increase the risk of knee injury when performing movements away from the dominant limb. Consideration should be given to drills familiarizing volleyball players with unanticipated and anticipated changes of direction, as well as improving strength of the lower extremity muscles required to effectively decelerate the body, as both training modalities may minimize injury risk during cross step maneuvers.