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The objective of this study was to examine the influence of relative hamstring flexibility and lumbar extensor strength on lumbar flexion during a stoop lift. Lumbar flexion during stoop lifting has been associated with increased bending stress and load on the lumbar spine. The potential impairments that contribute to a flexed lumbar lifting posture during stoop lifting are unclear. Forty-nine healthy individuals (27 females and 22 males) between the ages of 18 and 40 participated. Strength of the lumbar extensors was measured with a motor-driven dynamometer, and relative hamstring flexibility was estimated with the passive knee extension test. Peak lumbar flexion and pelvis anterior rotation were quantified with 3D motion capture during a stoop lift. There was a positive correlation between relative hamstring flexibility and peak pelvis anterior rotation angle during the stoop lift (r = .544, P < .001). Meanwhile, there was a negative correlation between middle lumbar spine peak flexion and relative hamstring flexibility (r = −.538, P < .001) and a negative correlation between lumbar extensor strength and lower lumbar peak flexion (r = −.288, P = .045). Individuals with decreased strength and limited relative hamstring flexibility tended to exhibit increased lumbar flexion during stoop lifting.

A higher risk of knee osteoarthritis (OA) has been identified in patients with slower walking speeds following anterior cruciate ligament reconstruction (ACLR). Given that altered loading of the surgical knee has been the most proposed mechanism for early knee OA post-ACLR, understanding how modulating walking speed may modify knee joint loading is essential for developing strategies to reduce the risk of knee OA in ACLR patients. The purpose of this study was to determine how modulation of walking speed affects knee joint loading during overground walking post-ACLR. Lower extremity kinematics and kinetics were recorded during overground walking at a self-selected, slower, and faster speed from 16 patients with unilateral ACLR. The results showed that ACLR patients demonstrated lesser peak knee flexion and adduction moments of the surgical knees when walking at slower speeds. However, modulating walking speed did not alter between-limb knee loading asymmetry. The ACLR limbs had lower peak knee flexion moments than the uninjured limbs across all 3 walking speeds. Although interventions that increase walking speed may deter the onset of knee OA by elevating the mechanical stimulation at the surgical knee, additional gait training strategies may be needed to restore the between-limb loading symmetry in ACLR patients.

The effect of gait speed on minimum toe clearance (MTC) amount may vary across the lifespan due to changes in joint relationships, potentially affecting trip-related fall risk in older adults. We evaluated whether age influences the relationship between gait speed and MTC amount, as well as between joint movements and MTC amount. Optical motion capture data was collected on 62 participants between the ages of 20 and 83 years during 25 gait trials at self-selected normal, fast, and slow speeds. Multilevel models were used for data analysis. Gait speed was associated with a 0.13 cm increase in MTC amount for every meter per second increase in gait speed with other factors constant and was unaffected by age. Ankle dorsi–plantarflexion, knee and hip flexion–extension, and stance hip abduction–adduction changed the MTC amount by 0.05, 0.02, 0.04, and 0.04 cm, respectively, for each degree of joint movement, with other factors constant, and was unaffected by age. Age did not affect the relationship between gait speed and MTC amount, nor the relationship of joint moments with MTC, indicating that these factors may not be associated with trip-related fall risk with healthy aging.

The lack of normative data for single-leg vertical jump testing makes it challenging to determine when an injured athlete has achieved a level of interlimb symmetry that is within normal limits. The purpose of this study was to establish normative values for single-leg vertical jump height interlimb symmetry based on data from uninjured adolescent athletes. One hundred seventy three uninjured adolescent athletes completed single-leg vertical jump testing with both limbs. Descriptive statistics were generated to summarize the percent differences in jump heights between the limbs (interlimb symmetry) for the male and female athletes. Having normative data available will help clinicians assess injured athletes’ recovery.

Context: Triathlons are a popular endurance sport with an elevated injury risk. Prevalence for injuries in triathletes varies greatly and is thought to be related to racing distance. The most common injuries in triathletes occur in the lower-extremities and are considered overuse in nature. The primary purpose of this study was to examine injury patterns and prevalence among triathletes during the 2022 season. Design: This study adopts an epidemiological approach using a retrospective survey to better understand the prevalence, nature, and patterns of injuries among triathletes. Methods: A live online questionnaire was developed that collected information about demographics, triathlon racing, and injury epidemiology. The survey was posted to social media and emailed to large triathlon clubs and international federations at the beginning of 2023 and was left open for 75 days. Results: Two hundred nineteen triathletes reported at least 1 injury, with 58.5% classified as overuse. Eighty-one percent were reported as triathlon related. The most frequent area of injury was to the lower-extremity (73.8%). Triathletes sought advice from a health care provider 64.6% of the time. Eighty-seven percent of triathletes had to miss or modify training because of their injury. Those triathletes not reporting injury indicated that strength training (72.2%) and stretching/foam rolling (64.9%) were believed to help prevent injury. Conclusion: The risk of injury while training for a triathlon is significant and can be severe enough to require modifications to the training program. The most vulnerable area for injury is the lower-extremities, and such injuries are usually caused by overuse. To reduce the risk of injury, there is a need to examine preventive strategies further and determine their effectiveness.

Clinical Scenario: Anterior cruciate ligament (ACL) injury risk may increase when certain movements are noted during landings. Initial ACL injury produces poor long-term outcomes for patients. Movement assessments may help predict risk of initial ACL injuries. Clinical Question: Are movement assessments predictive of initial ACL injuries in college/high school athletes? Summary of Key Findings: Six articles met the inclusion criteria. Some movement assessments did not predict ACL injury. However, the functional movement screen composite score of 14 or less and landing error scoring system scores of 5 or greater were found to be associated with an increased risk of an ACL injury. Knee valgus angles of ≥6.5 cm were associated with future knee injury but only had fair predictive validity. Clinical Bottom Line: There are conflicting results on whether movement assessments can accurately predict primary ACL injuries. However, clinicians can consider the use of the functional movement screen composite score (14 or less) and the landing error scoring system score (5 or greater) as both may predict a future ACL injury. More research is needed to uncover movement assessments that better predict ACL injury. Strength of Recommendation: A grade B recommendation can be given that movement assessments may be used for screening for initial ACL injury.

Artificial neural networks (ANNs) are becoming a regular tool to support biomechanical methods, while physics-based models are widespread to understand the mechanics of body in motion. Thus, this study aimed to demonstrate the accuracy of recurrent ANN models compared with a physics-based approach in the task of predicting ground reaction forces and net lower limb joint moments during running. An inertial motion capture system and a force plate were used to collect running biomechanics data for training the ANN. Kinematic data from optical motion capture systems, sourced from publicly available databases, were used to evaluate the prediction performance and accuracy of the ANN. The linear and angular momentum theorems were applied to compute ground reaction forces and joint moments in the physics-based approach. The main finding indicates that the recurrent ANN tends to outperform the physics-based approach significantly (P < .05) at similar and higher running velocities for which the ANN was trained, specifically in the anteroposterior, vertical, and mediolateral ground reaction forces, as well as for the knee and ankle flexion moments, and hip abduction and rotation moments. Furthermore, this study demonstrates that the trained recurrent ANN can be used to predict running kinetic data from kinematics obtained with different experimental techniques and sources.

The aim of this study was to explore the association between pelvic floor dysfunction and running kinetics and pelvic acceleration in a cohort of postpartum women. The Australian Pelvic Floor Questionnaire was used to quantify symptom severity (mean [SD]: 6  [ 4] out of 40; range: 1–14) in 25 postpartum women. Participants completed a pelvic floor muscle assessment to measure pelvic muscle strength and endurance, then completed a 7-minute treadmill running protocol at a speed of 10 km·h⁻¹ to evaluate their running kinetics and pelvic acceleration. After the run, participants responded to a modified version of the symptom’s component of the PFD-SENTINEL screening tool. Mean pelvic muscle strength and endurance were 3 (1) and 9 (2), respectively. We found no significant association between PFD symptom severity and running kinetic (P = .209–.410) or pelvic acceleration (P = .081–.947) outcome measures. Fifteen participants experienced at least one symptom during the treadmill protocol. Running kinetics and pelvic acceleration may not affect or be affected by symptoms of PFD. Given the relatively low symptom expression among study participants, further research in a cohort of women with higher levels of PFD is recommended.