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Arthur Alves Dos Santos, James Sorce, Alexandra Schonning, and Grant Bevill

This study evaluated the performance of 6 commercially available hard hat designs—differentiated by shell design, number of suspension points, and suspension tightening system—in regard to their ability to attenuate accelerations during vertical impacts to the head. Tests were conducted with impactor materials of steel, wood, and lead shot (resembling commonly seen materials in a construction site), weighing 1.8 and 3.6 kg and dropped from 1.83 m onto a Hybrid III head/neck assembly. All hard hats appreciably reduced head acceleration to the unprotected condition. However, neither the addition of extra suspension points nor variations in suspension tightening mechanism appreciably influenced performance. Therefore, these results indicate that additional features available in current hard hat designs do not improve protective capacity as related to head acceleration metrics.

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Andrea Biscarini, Roberto Panichi, Cristina V. Dieni, and Samuele Contemori

A biomechanical model has been developed to assess the effects of a voluntary effort of quadriceps–hamstring cocontraction on tibiofemoral force during isometric knee flexion and knee extension exercises with constant external resistance. The model establishes the analytic condition in the moment arms and traction angles of the quadriceps and hamstring muscles that determines the direction (anterior/posterior) of the tibiofemoral shear force developed by the cocontraction. This model also establishes the mechanical effect (loading/unloading) on the anterior cruciate ligament (ACL). At about 15° of knee flexion (where the ACL experiences its maximum quadriceps-induced strain) a voluntary quadriceps–hamstring cocontraction effort yields: (1) nearly the same enhancement in hamstring and quadriceps activation, (2) an increase in hamstring force about 1.5 times higher than that of the quadriceps, and (3) posterior (ACL unloading) tibial pull and compressive tibiofemoral force that increase linearly with the level of quadriceps and hamstring activation. The sensitivity of the results to intersubject variability in the posterior slope of the tibial plateau and muscle moment arms has been estimated with the use of anatomic data available in the literature. An anterior (ACL loading) tibial pull is actually developed at 15° of knee flexion by a voluntary effort of quadriceps–hamstring cocontraction as the posterior tibial slope exceeds 14°.

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Bruno G. Straiotto, David P. Cook, Darren C. James, and P. John Seeley

Patterns of interjoint coordination in the kicking legs of taekwondo players were investigated to understand movement pattern variability as a functional property of skill level. Elite and nonelite players performed roundhouse kicks against a custom-built moving target fitted with an accelerometer, and movements were recorded by motion capture. Average foot segment velocities of 13.6 and 11.4 m/s were recorded for elite and nonelite players, respectively (P < .05), corresponding to target accelerations of 87.5 and 70.8g (P < .05). Gradient values derived from piecewise linear regression of continuous relative phase curves established the comparative incoordination of nonelite taekwondo players in the form of an overshoot behavior during the crucial period leading to target impact (P < .05). This overshoot was apparent in both knee–hip and ankle–knee continuous relative phase curves. Elite players generated greater limb speed and impact force through more effective limb segment coordination. The combination of continuous relative phase and piecewise linear regression techniques allowed identification of alternate joint control approaches in the 2 groups.

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Joseph G. Wasser, Julian C. Acasio, Ross H. Miller, and Brad D. Hendershot

Individuals with lower limb loss often walk with altered/asymmetric movement mechanics, postulated as a catalyst for development of low back and knee pain. Here, the authors simultaneously investigated trunk-pelvic movement patterns and lower limb joint kinematics and kinetics among 38 males with traumatic, unilateral lower limb loss (23 transtibial and 15 transfemoral), and 15 males without limb loss, at a self-selected and 2 standardized (1.0 and 1.6 m/s) speeds. Individuals with versus without lower limb loss walked with greater trunk range of motion in the frontal and transverse planes at all speeds (despite ∼10% slower self-selected speeds). At all speeds, individuals with versus without limb loss exhibited +29% larger medial ground reaction forces, and at 1.6 m/s also exhibited +50% to 110% larger vertical hip power generation, +27% to 80% larger vertical hip power absorption, and +21% to 90% larger medial–lateral hip power absorption. Moreover, pervasive biomechanical differences between transtibial versus transfemoral limb loss identify amputation-level movement strategies. Overall, greater demands on the musculoskeletal system across walking speeds, particularly at the hip, knee, and low back, highlight potential risk factors for the development/recurrence of prevalent secondary musculoskeletal conditions (eg, joint degeneration and pain) following limb loss.

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Jana Fogaca, Illene Cupit, and Matthew Gonzalez

Although there is awareness of the impact of grief on survivors’ well-being, almost no research exists on the impact of death on sports team bereavement. The present study surveyed 40 members of athletic teams (coaches, staff, and athletes) from various levels to determine what happens in the aftermath of a team member’s death. Findings of the survey indicated that many of the respondents experienced acute grief responses affecting performance, which memorialization and community support was helpful whereas the news media was often not. In addition, a need for appropriate resources and a school bereavement policy specific to student athletes was seen. In line with the dual process model, the responses indicated use of both emotion focused and restoration focused coping. Implications of the findings suggested that addressing bereavement needs for athletes, and their coaches was tantamount to mitigating some of the complications associated with disenfranchised grief.

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Jacob J. Levy, Terrance L. Tarver, and Hannah R. Douglas

Changes in exercise behavior and negative emotional states (i.e., depression, anxiety, and stress) in combat sport (e.g., boxing, wrestling, martial arts) athletes were examined the month prior to gym closures related to the COVID-19 pandemic (February 2020), and approximately 1 month following gym closures (May 2020). A total of 312 combat sport athletes from 33 different countries responded to the study solicitation. Results indicated a significant decrease in combat sport training following gym closures; however, participation in other exercise activities did not significantly change. Significant mean increases in depression, anxiety, and stress were found following combat gym closures. Regression analyses revealed that number of hours of participants participated in combat sport training added significant incremental variance explained in depressive and stress symptoms above and beyond that accounted for by sex differences, preexisting conditions, and training level. Practical implications regarding losses to preferred exercise activities are discussed.

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Megan Drew, Trent A. Petrie, and Tess Palmateer

College student athletes face unique, sport-related stressors that may lead to, or exacerbate, mental health (MH) concerns and symptoms. Although the National Collegiate Athletic Association has identified MH screening as a best practice, minimal data exist regarding contemporary screening practices. We explored National Collegiate Athletic Association Division I (DI), Division II (DII), and Division III (DIII) athletic departments’ current MH screening practices (N = 264). Compared with DII/DIII (53%), a greater percentage of Division I (89%) conducted formal MH screening. At DII/DIII institutions, athletic trainers were more likely to both administer and review screeners than any other sports medicine professional; sport psychologists primarily oversaw these tasks at DI schools. DI, compared with DII/DIII, institutions were more likely to have had a student athlete attempt suicide (62% vs. 40%) and participate in inpatient treatment (69% vs. 43%). There is a clear need for the National Collegiate Athletic Association to continue to promote policies that support MH screening and to create mechanisms in which it can monitor institutional involvement.