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.
Arthur Alves Dos Santos, James Sorce, Alexandra Schonning, and Grant Bevill
Nathan J. Robey, Kurt O. Buchholz, Shane P. Murphy, Jeremy D. Smith, and Gary D. Heise
Individuals returning to sport after anterior cruciate ligament reconstruction (ACLR) are at an increased risk of sustaining a subsequent ACL injury. It is suspected that increased reliance on visual information to maintain stability may factor into this increased risk. The connection between visual reliance and ACLR is not well understood during dynamic tasks. Examination of the proposed visual reliance may help improve returning to sport standards and reduce subsequent ACL injury risk. A total of 12 ACLR individuals and 12 age- and sex-matched controls completed several trials of a normalized dynamic hop task on both limbs under 3 different visual conditions (eyes open, low visual disruption, and high visual disruption). Stroboscopic eyewear were worn by each participant to disrupt vision during testing. Ground reaction force data were collected during landing. Dynamic postural stability was assessed using 2 separate calculations: dynamic postural stability index and time to stability. No significant statistical interactions or group differences were observed. The stroboscopic eyewear did increase the medial–lateral stability index from the eyes open to the low visual disruption condition (P < .05). These findings suggest that ACLR individuals do not rely on visual information more than controls during a dynamic hop task.
Benno M. Nigg
Dr. Richard Nelson contributed to the development of sport biomechanics by being an international facilitator. Together with Dr. Jürg Wartenweiler, he contributed the necessary support and input that allowed the field of Movement and Sports Biomechanics to develop and flourish.
The author recalls his initial introduction to the field of biomechanics in the Penn State Biomechanics Laboratory, known as the Water Tower, and its positive and profound effect on his lifetime career. Under the directorship of Dr. Richard Nelson, Penn State’s biomechanics program provided the author with a variety of both professional and personal learning opportunities. The author credits these experiences as having a direct relationship to his successful development as teacher, mentor, and researcher.
Robert W. Norman, Stuart M. McGill, and James R. Potvin
Dr. Richard Nelson is internationally acknowledged in many countries as an extremely important leader in the emergence of biomechanics of human movement as a respected scientific discipline. As his PhD graduates, and, subsequently, their graduates, have become faculty members at many universities, Dr. Nelson’s influence has grown for more than 50 years via several generations of his biomechanics “children.” It was probably never known to him that he also had significant influence on all laboratory-based subdisciplines of the undergraduate and graduate education and faculty research programs of the then new (1967) Department of Kinesiology at the University of Waterloo, Canada. The teaching and research programs included not only biomechanics but also exercise and work physiology, anatomy, biochemistry, and neurophysiology of human movement.
Doris I. Miller
As the first PhD graduate of the Biomechanics Laboratory at the Pennsylvania State University under the leadership of Dr. Richard C. Nelson, I reflect on my early experience in sport biomechanics there and its influence on some of my subsequent, and typically unpublished, research challenges.
Robert J. Gregor
Richard C. Nelson started the Biomechanics Laboratory, one of the first of its kind in the world, on the campus of the Pennsylvania State University in 1967. His vision focused on connecting the physiological and mechanical elements of human performance analysis, specifically sport performance. The lab’s engaging, interdisciplinary environment supported self-designed programs of study, benefiting each individual student. Furthermore, the Biomechanics Lab became the nexus for the development of biomechanics as a field of study internationally. Richard Nelson’s diplomatic skills spread the word initially through the formation of the International Society of Biomechanics. This international effort resulted in the development of national societies of biomechanics around the world, for example, the American Society of Biomechanics. Second, these efforts stimulated the concept of sport performance analysis on the international stage. Richard Nelson’s passion was to analyze individual performances at the Olympic Games. This goal was finally realized, with the development of the Subcommission within the International Olympic Committee Medical Commission and biomechanical analysis projects completed at the 1984 Olympic Games in Los Angeles. Richard Nelson’s vision, mentoring style, and dedication planted and nurtured the seed of biomechanics as a discipline of study around the world.
The reasons for the renaming of the Japanese Society of Kinesiology to the Japanese Society of Biomechanics are explained, and the importance of the International Congress of Biomechanics, the International Society of Biomechanics, and Richard Nelson are outlined.
Kathryn Dainty Davis
As one of the early graduate students of the Penn State Biomechanics Laboratory (1970–1974), I had the pleasure of being involved in the lab developed under the direction of Dr. Richard Nelson. His vision of applying engineering principles to human movement, particularly through the vehicle of sport analysis, inspired many to commit to a career of biomechanical exploration of the many aspects of human movement. By bringing many international scholars to the lab, he exposed his students to innovative and unique approaches to research. By developing technical applications, he made biomechanical inquiry more scientific and applicable. By caring for and mentoring a new generation of scientists and providing them the direction and tools they would need to establish their own labs and careers, he helped us become teachers, researchers, consultants, and mentors for a new generation of students. His love of life inspired us all to further the groundbreaking work he had begun and continued throughout his amazing career. His contributions to the field of biomechanics through his visionary establishment of societies, journals, collegial relationships, and consulting skills have served our community well. It was an honor and a privilege to know and learn from him.
Recollections on meetings with Dick Nelson in the 1970s, his interactions with Soviet authorities, his impact on data collection at Olympic Games, and his work as the President of the International Society of Biomechanics.