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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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Stephen P. Hebard, James E. Bissett, Emily Kroshus, Emily R. Beamon, and Aviry Reich

Sport coaches can play an influential role in athletes’ mental health help seeking through purposeful communication, destigmatization of mental health concerns, and supportive relationships. To positively engage in these behaviors, coaches require mental health knowledge (or literacy), positive attitudes about that knowledge, and self-efficacy to use that knowledge. Guided by a multidimensional health literacy framework, we conducted a content analysis of web content and scholarly literature to identify health education programming for coaches that addressed athlete mental health. A purposive sample of Olympic National Governing Bodies, collegiate athletic associations, high school sport associations, youth sport governing bodies, and the scholarly literature were analyzed. We found inconsistent programming regarding a range of mental health disorders, behaviors critical to mental health promotion, and critical components of mental health literacy. Implications and next steps for mental health literacy support for coaches are discussed.

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Paige E. Rice, Kiisa Nishikawa, Kevin A. Zwetsloot, Amelia S. Bruce, Caroline D. Guthrie, and Sophia Nimphius

The purpose of this investigation was to elucidate whether ankle joint stretch-shortening cycle performance, isometric and isokinetic plantarflexion strength, and maximal Achilles tendon force and elongation differ between dancers, endurance runners, and untrained controls. To differentiate between dancers, endurance runners, and controls, the authors measured maximal Achilles tendon force and elongation during isometric ramp contractions with ultrasonic imaging, maximal isometric and isokinetic plantarflexion strength with dynamometry, and stretch-shortening cycle function during countermovement hopping and 30-cm drop hopping with a custom-designed sled. The Achilles tendon of dancers elongated significantly (P ≤ .05) more than runners and controls. Dancers were significantly stronger than controls during isometric contractions at different ankle angles. Concentric and eccentric strength during isokinetic contractions at 60°·s−1 and 120°·s−1 was significantly higher in dancers and runners than controls. Dancers hopped significantly higher than runners and controls during hopping tasks. Dancers also possessed significantly greater countermovement hop relative peak power, drop hop relative impulse, and drop hop relative peak power than controls. Finally, dancers reached significantly greater velocities during countermovement hops than runners and controls. Our findings suggest dancing and running require or likely enhance plantarflexion strength. Furthermore, dancing appears to require and enhance ankle joint stretch-shortening cycle performance and tendon elongation.

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Declan A. Patton, Colin M. Huber, Susan S. Margulies, Christina L. Master, and Kristy B. Arbogast

Field studies have evaluated the accuracy of sensors to measure head impact exposure using video analysis, but few have studied false negatives. Therefore, the aim of the current study was to investigate the proportion of potential false negatives in high school soccer head impact data. High school athletes (23 females and 31 males) wore headband-mounted Smart Impact Monitor-G impact sensors during competitive soccer games. Video footage from 41 varsity games was analyzed by 2 independent reviewers to identify head contact events, which were defined as visually observed contact to the head. Of the 1991 video-identified head contact events for which sensors were functioning and worn by the players, 1094 (55%) were recorded by the sensors. For female players, 45% of video-identified head contact events were recorded by the sensor compared with 59% for male players. For both females and males, sensitivity varied by impact mechanism. By quantifying the proportion of potential false negatives, the sensitivity of a sensor can be characterized, which can inform the interpretation of previous studies and the design of future studies using head impact sensors. Owing to the difficulty in obtaining ground truth labels of head impacts, video review should be considered a complementary tool to head impact sensors.

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Benoit R. Lafleur, Alyssa M. Tondat, Steven P. Pretty, Marina Mourtzakis, and Andrew C. Laing

Trochanteric soft tissue thickness (TSTT) is a protective factor against fall-related hip fractures. This study’s objectives were to determine: (1) the influence of body posture on TSTT and (2) the downstream effects of TSTT on biomechanical model predictions of fall-related impact force (F femur) and hip fracture factor of risk. Ultrasound was used to measure TSTT in 45 community-dwelling older adults in standing, supine, and side-lying positions with hip rotation angles of −25°, 0°, and 25°. Supine TSTT (mean [SD] = 5.57 [2.8] cm) was 29% and 69% greater than in standing and side-lying positions, respectively. The F femur based on supine TSTT (3380 [2017] N) was 19% lower than the standing position (4173 [1764] N) and 31% lower than the side-lying position (4908 [1524] N). As factor of risk was directly influenced by F femur, the relative effects on fracture risk were similar. While less pronounced (<10%), the effects of hip rotation angle were consistent across TSTT, F femur, and factor of risk. Based on the sensitivity of impact models to TSTT, these results highlight the need for a standardized TSTT measurement approach. In addition, the consistent influence of hip rotation on TSTT (and downstream model predictions) support its importance as a factor that may influence fall-related hip fracture risk.

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Linh Q. Vu, Rahul Agrawal, Mahdi Hassan, and Nils A. Hakansson

Human rolling, as turning in bed, is a fundamental activity of daily living. A quantitative analysis of rolling could help identify the neuromusculoskeletal disorders that prohibit rolling and develop interventions for individuals who cannot roll. This study sought to determine whether crossing the arms over the chest would alter fundamental coordination patterns when rolling. Kinematic data were collected from 24 subjects as they rolled with and without their arms crossed over their chest. Crossing the arms decreased the mean peak angular velocities of the shoulders (p = .001) and pelvis (p = .013) and influenced the mean duration of the roll (p = .057). There were no fundamental differences in shoulder and pelvis coordination when rolling with the arms crossed over the chest, implying that the arms may not have a major role in rolling.

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Sally Taunton Miedema, Ali Brian, Adam Pennell, Lauren Lieberman, Larissa True, Collin Webster, and David Stodden

Many interventions feature a singular component approach to targeting children’s motor competency and proficiency. Yet, little is known about the use of integrative interventions to meet the complex developmental needs of children aged 3–6 years. The purpose of this study was to examine the effects of an integrative universally designed intervention on children with and without disabilities’ motor competency and proficiency. We selected children (N = 111; disability = 24; no disability = 87) to participate in either a school-based integrative motor intervention (n = 53) or a control condition (n = 58). Children in the integrative motor intervention both with and without disabilities showed significant improvement in motor competency and proficiency (p < .001) as compared with peers with and without disabilities in a control condition. Early childhood center directors (e.g., preschool and kindergarten) should consider implementing integrative universally designed interventions targeting multiple aspects of motor development to remediate delays in children with and without disabilities.

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Matteo Briguglio, Roberta Galentino, Sara De Michele, Bernardo Dell’Osso, Leonardo Fogassi, and Mauro Porta

The learning process in humans requires continuous contacts with environmental stimuli, especially during neurodevelopmental growth. These functions are assisted by the coding potential of mirror neurons to serve social interactions. This ability to learn imitating the observed behavior is no longer necessary during adulthood, and control mechanisms prevent automatic mirroring. However, children with Gilles de la Tourette syndrome could encounter coding errors at the level of the mirror neurons system as these cortical regions are themselves the ones affected in the syndrome. Combined with impulsivity, the resulting sign would be a manifest echopraxia that persists throughout adulthood, averting these individuals from the appraisal of a spot-on motor control.

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Werner A.F. van de Ven, Jurjen Bosga, Wim Hullegie, Wiebe C. Verra, and Ruud G.J. Meulenbroek

The present study explores variations in the degree of automaticity and predictability of cyclical arm and leg movements. Twenty healthy adults were asked to walk on a treadmill at a lower-than-preferred speed, their preferred speed, and at a higher-than-preferred speed. In a separate, repetitive punching task, the three walking frequencies were used to cue the target pace of the cyclical arm movements. Movements of the arms, legs, and trunk were digitized with inertial sensors. Whereas absolute slope values (|β|) of the linear fit to the power spectrum of the digitized movements (p < .001, η2 = .676) were systematically smaller in treadmill walking than in repetitive punching, sample entropy measures (p < .001, η2 = .570) were larger reflecting the former task being more automated but also less predictable than the latter task. In both tasks, increased speeds enhanced automatized control (p < .001, η2 = .475) but reduced movement predictability (p = .008, η2 = .225). The latter findings are potentially relevant when evaluating effects of task demand changes in clinical contexts.