Peak Forces and Force Generating Capacities of Lower Extremity Muscles During Dynamic Tasks in People With and Without Chronic Ankle Instability

People with chronic ankle instability (CAI) exhibit neuromuscular deficits. However, no study has investigated deficits in forces or force-generating capacities of individual muscles in people with CAI during dynamic tasks. Therefore, the purpose of this study was to estimate and compare peak forces and force-generating capacities of individual muscles during dynamic tasks in people with CAI and healthy controls (CON). Eleven people with CAI and eleven CON performed landing, anticipated cutting, and unanticipated cutting as motion capture, force plate, and electromyography data were recorded. A musculoskeletal model was used to estimate the force and force-generating capacity of lower extremity muscles. People with CAI exhibited greater gluteus maximus force and force-generating capacity than CON during all tasks. In addition, people with CAI exhibited greater force-generating capacity of the vastii muscles than CON during the unanticipated cutting task. These findings suggest that, during dynamic tasks, people with CAI exhibit a neuromuscular control strategy that is characterised by differences in peak forces and force-generating capacities of proximal muscles, which may allow them to compensate for previously described deficits in distal muscles

Isolated hip and ankle fatigue are unlikely risk factors for anterior cruciate ligament injury

Lower extremity neuromuscular fatigue purportedly increases anterior cruciate ligament (ACL) injury risk through promotion of extreme landing mechanics. However, the impact of fatigue on muscle groups critical to the landing strategy remains unclear. This study examined the effects of isolated hip rotator and triceps surae fatigue on lower extremity landing biomechanics. Sixteen healthy females (18–22 years) reported for testing on two occasions, with one muscle group fatigued per session. Subjects performed three single-leg landings onto a force platform pre- and post-fatigue, defined as an 80% decrease in peak torque in the targeted muscle group. Hip rotator fatigue was induced via alternating concentric contractions and triceps surae fatigue through concentric plantar flexion contractions on an isokinetic dynamometer. Initial contact (IC) kinematics and peak stance (PS) kinetics and kinematics were analyzed pre- and post-fatigue. Hip rotator fatigue increased IC ( P =0.05) and PS ( P =0.04) hip internal rotation angles. Triceps surae fatigue decreased IC knee flexion ( P =0.01) angle. Isolated hip rotator and triceps surae fatigue each produced modifications in lower limb kinematic parameters viewed as risk factors for ACL injury. These modifications, however, do not appear of sufficient magnitude to compromise ligament integrity, suggesting injury via an integrative lower extremity fatigue mechanism is more likely.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78722/1/j.1600-0838.2009.01076.x.pd

A unique anisotropic R2 of collagen degeneration (ARCADE) mapping as an efficient alternative to composite relaxation metric (R2â R1Ï ) in human knee cartilage study

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/148373/1/mrm27621.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/148373/2/mrm27621_am.pd

Knee osteoarthritis in obese women with cardiometabolic clustering

Objective To assess the role of obesity and metabolic dysfunctionality with knee osteoarthritis (OA), knee joint pain, and physical functioning performance, adjusted for joint space width (JSW) asymmetry. Methods Knee OA was defined as a Kellgren/Lawrence score ≥2 on weight-bearing radiographs. Obesity was defined as a body mass index ≥30 kg/m 2 . Cardiometabolic clustering classification was based on having ≥2 of the following factors: low levels of high-density lipoprotein cholesterol; elevated levels of low-density lipoprotein cholesterol, triglycerides, blood pressure, C-reactive protein, waist:hip ratio, or glucose; or diabetes mellitus. The difference between lateral and medial knee JSW was used to determine joint space asymmetry. Results In a sample of women (n = 482, mean age 47 years), prevalences of knee OA and persistent knee pain were 11% and 30%, respectively. The knee OA prevalence in nonobese women without cardiometabolic clustering was 4.7%, compared with 12.8% in obese women without cardiometabolic clustering and 23.2% in obese women with cardiometabolic clustering. Nonobese women without cardiometabolic clustering were less likely to perceive themselves as limited compared with women in all other obesity/cardiometabolic groups ( P < 0.05). Similar associations were seen with knee pain and physical functioning measures. The inclusion of a joint space asymmetry measure was associated with knee OA but not with knee pain or physical functioning. Conclusion Knee OA was twice as frequent in obese women with cardiometabolic clustering compared with those without, even when considering age and joint asymmetry. Obesity/cardiometabolic clustering was also associated with persistent knee pain and impaired physical functioning.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/64312/1/24739_ftp.pd

An efficient R1Ï dispersion imaging method for human knee cartilage using constant magnetization prepared turbo- FLASH

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/167754/1/nbm4500.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167754/2/nbm4500_am.pd

Descriptive Epidemiology of Collegiate Women's Volleyball Injuries: National Collegiate Athletic Association Injury Surveillance System, 1988–1989 Through 2003–2004

Objective: To review 16 years of NCAA injury surveillance data for women's volleyball and to identify potential areas for injury prevention initiatives