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Running shoes and surfaces have been developed to help enhance running efficiency and to reduce ground impacts by altering the total surface stiffness. However, to maintain running mechanics, an individual will increase leg joint stiffness while running across a more compliant ground surface and show an inverse effect when running across harder surfaces. Increasing leg stiffness causes landing impact forces to increase and may counteract the softer surface in terms of knee joint contact forces. Since the knee is an essential determinant for reducing impact forces and a primary site for changing leg stiffness, knowing more about knee joint forces while running on surfaces with different stiffnesses can be beneficial in developing injury prevention programs. It is our objective to determine the effect of surface stiffness on knee joint contact forces during running. We recruited 17 healthy recreational heel strike runners and ran across a 15m track at a consistent pace (3.46m/s + 5%) on 3 ground conditions (hard floor with embedded force plate and 1 and 2 layers of shock absorbing mat). The study protocol took place over 2 days. On day 1, participants were able to practice running over the various ground conditions at the test speed, on day 2, data were collected. Five successful trials per surface condition were gathered and analyzed with focus being on the knee joint and knee joint forces through musculoskeletal modeling. Data were statistically compared among surface conditions with a one way ANOVA, using three levels and alpha
Every year workers' low-back, hand, and arm problems lead to time away from jobs and reduce the nation's economic productivity. The connection of these problems to workplace activities-from carrying boxes to lifting patients to pounding computer keyboards-is the subject of major disagreements among workers, employers, advocacy groups, and researchers. Musculoskeletal Disorders and the Workplace examines the scientific basis for connecting musculoskeletal disorders with the workplace, considering people, job tasks, and work environments. A multidisciplinary panel draws conclusions about the likelihood of causal links and the effectiveness of various intervention strategies. The panel also offers recommendations for what actions can be considered on the basis of current information and for closing information gaps. This book presents the latest information on the prevalence, incidence, and costs of musculoskeletal disorders and identifies factors that influence injury reporting. It reviews the broad scope of evidence: epidemiological studies of physical and psychosocial variables, basic biology, biomechanics, and physical and behavioral responses to stress. Given the magnitude of the problem-approximately 1 million people miss some work each year-and the current trends in workplace practices, this volume will be a must for advocates for workplace health, policy makers, employers, employees, medical professionals, engineers, lawyers, and labor officials.
ACL injuries are common, costly, and can lead to long term dysfunction. Studies have shown that non-contact ACL injuries are a function of shallow knee flexion, valgus and rotational collapse, and high impact forces. Quadriceps and hamstrings have been shown to play roles in neuromuscular control of knee movements in jump-landing tasks, and kinesiotape may help alleviate the fatigue effect on muscles to facilitate neuromuscular control and improve performance. This study examined the effects of kinesiotaping fatigued quadriceps and hamstrings on knee joint position sense and jump-landing biomechanics associated with ACL injury risk. 51 participants were randomly assigned to 3 groups (NT-no tape, H-hamstrings, or Q-quadriceps) to perform both jump-landings (JL) and joint position sense (JPS) tasks before and after receiving a fatigue protocol that involved repetitive maximum effort jumps until the pre-determined fatigue level was met. The results showed that fatigue reduced JL performance for all, however, H group did not decrease impact force during landing compared to NT and Q groups, and both H and Q groups decreased initial knee flexion compared to NT group. As for JPS, fatigue increased variability but not accuracy, and no effect was seen for kinesiotaping. In conclusion, kinesiotaping fatigued quadriceps and hamstrings did not help improve JL and JPS performance, and instead may increase ACL loading – thus, risk of ACL injury – due to the associated psychological effect.
Golf is a game that can be played by people of all ages, skill levels, and physical ability while only putting the participant at a moderate risk for sports injury. There are almost 26 million golfers in the United States alone, and its popularity continues to rise. Part of golfs popularity comes from the health benefits associated with walking the golf course. However, golf is not without risk. Even though there is only a moderate risk of injury, especially when compared to contact sports, injuries still do occur. The most common golf injuries are to the elbow, wrist, shoulder, and dorso-lumbar sites. However, overuse injuries or degenerative conditions in the knee are also common. These injuries may be a result of the excessive knee joint motion and loading during the golf swing. The purpose of this thesis was to analyze if there was any difference in target side knee kinematics and kinetics during the golf swing if both feet were perpendicular to the target line at address (straight stance) or if the target side foot was externally rotated at address (open stance). To do this sixteen golfers with handicaps ranging from 0-7 (3.8 ± 2.3) were recruited and tested using a 3D motion capture system and two force plates. Sixty-eight reflective markers were attached to each subject and motion data and ground reaction forces were recorded at 240 Hz and 1200 Hz, respectively, as the subject swung a 9-iron and driver using the two stance conditions. The lead knee joint kinematics were then calculated using Spoor's method, and the kinetics were calculated using inverse dynamics. The analysis revealed that externally rotating the target side foot did cause significantly different lead knee kinematics and kinetics. Specifically, the open stance caused significantly more rotation of the tibia relative to the femur in the internal/external direction and the varus/valgus direction. The open stance also significantly lowered the anterior/posterior force and varus/valgus torque. However, the open stance also significantly raised the medial/lateral forces on the knee. These findings could have an impact on golfers with knee osteoarthritis. Varus torque and lateral-medial shear forces have been shown to correlate with medial compartment osteoarthritis. The findings of this study show a reduction of the varus moment with the open stance but an increase in the forces in the medial/lateral direction. Therefore, while the external rotation of the target side foot may be a promising strategy to prevent or manage medial compartment osteoarthritis, further research should be done to fully understand the role that the torque and force play in knee osteoarthritis initiation and progression and the effectiveness this swing modification has.
Running is known for providing numerous health benefits that untimely leads to decreased cardiac mortality. Despite these health benefits, running can cause overuse injuries in up to 79% of runners with a high incidence rate occurring in the knee1,2. Decline running in particular is associated with increased GRFs, resulting in increased knee contact forces. While decreased surface stiffness can result in increased leg stiffness in level running, it is difficult to determine how a softer surface would affect the knee joint in a decline setting. We predict a softer running surface would cause a reduction in knee joint loads during decline running because the runner's momentum would be directed more along the surface in decline running than level running. Therefore, we hypothesized that decreasing surface stiffness in decline running would result in a reduction in knee joint loads. The purpose of this study was to test the effect surface stiffness has on the knee joint loads in decline and level running in order to help prevent injury in runners. 14 healthy recreational runners provided written informed consent to university approved procedures. Knee joint patello-femoral compression and tibio-femoral compression and shear forces were modelled from GRFs and kinematics during 10[degree] decline and level running at a mean speed of 3.2 ms?. Participants ran with and without a 3 cm thick polyvinyl chloride (PVC) sponge shock absorbing mat (closed cell, Shore 00 65) places along the entire runway. Maximum forces were analyzed with 2-way ANOVA followed by Schefe post hoc tests, all p[less-than]0.05. Decline running on the softer surface lower the A/P GRF 56%, the patello-femoral compression, tibio-femoral compression, and shear forces 15%, 6%, 15% compared to the stiffer decline condition (p[less-than]0.05). Surface stiffness had no effect on these forces in level running (p>0.18). Inclination angle and surface stiffness had no effect on maximum GRF. We predict the mat reduced knee forces in decline because the initial impact between the runner and the surface was more in line with the surface in decline, producing a larger displacement of the mat material in decline when compared to level. We demonstrated that reducing surface stiffness can reduce knee loads during decline running at a 10[degree] decline. Further, we found that the same decrease in surface stiffness had no effect on knee joint loads in level running. This interaction shows how there is a need for further analysis when investigating running biomechanics by investigating more than one setting and surface.
The Multiple Ligament Injured Knee: A Practical Guide to Management includes the most developed knowledge needed to successfully diagnose and treat knee ligament injuries. This thorough work presents anterior and posterior cruciate and collateral ligament anatomy and biomechanics along with non-invasive methods for diagnosing the extent of injury, such as radiographic and arthroscopic evaluation. Various injuries are discussed in addition to useful treatment techniques, including arthroscopic reconstruction, posterolateral and posteromedial corner injury and treatment, assessment and treatment of vascular injuries, assessment and treatment of nerve injuries, rehabilitation, and post-operative results. Each of these clearly written chapters is accompanied by a wealth of line drawings and photographs that demonstrate both the surgical and non-surgical approaches to examination and treatment.