After 42 years with the University of Michigan Department of Mechanical Engineering, James Ashton-Miller, Albert B. Schultz Collegiate Research Professor and Distinguished Research Scientist, will retire from active faculty status on June 30.
Ashton-Miller joined the University of Michigan in 1983 as an assistant research scientist in ME. He has served as the director of the Biomechanics Research Laboratory since 1999 and currently serves as research professor in the Departments of Mechanical and Biomedical Engineering, Institute of Gerontology, Department of Internal Medicine, and School of Kinesiology.
To celebrate his outstanding contributions during his time at U-M, we asked Ashton-Miller to share some of his greatest accomplishments, biggest challenges, outlook for the future of engineering, and advice for aspiring engineers.
Q: What has been your greatest passion in your career? Your greatest challenge?
My greatest passion has been in finding solutions to problems that, if they can be solved, will help millions of people. It is thrilling to find the root cause(s) of unintentional injuries because one can help head off the pain and avoid the waste of time, money, and lifestyle changes those injuries can cause. The issues are sufficiently complex that no single individual can solve these problems on their own. U-M supports outstanding colleagues and a wonderful environment where colleagues can bring interesting unsolved problems and talented students can engage to help solve them. One is always learning—new disciplines, new techniques, new clinical approaches—there isn’t a day without learning something new.
My greatest challenge? I was offered a tenure-track position here, but I deliberately chose to become a research professor in order to have the time and freedom to pursue my goals. But the downside is that it means reliably bringing in grants and contracts to support the family and the research team. We succeeded, mainly because of the efforts of my colleagues and students from schools and colleges across U-M. I quickly learned that proposals slapped together at the last moment seldom get funded. Instead, our proposals started a year early to ensure the aims were really novel, they were supported by strong pilot data, and the significance was clear. Having reviewed more than 1,000 NIH proposals, I learned to embrace clear and uncomplicated writing to make reviewers’ jobs easier. The excitement, attention to detail, and productivity required forged lifelong friendships and partnerships.
Q: How have your research interests evolved from the start of your career to now?
Being a multisport athlete in school and occasionally sustaining non-contact injuries led to a natural interest in biomechanics. I started out as an MIT graduate student exploring ways of recruiting paralyzed muscles in patients’ spinal cord injuries at the West Roxbury VA Hospital. I moved to Oslo, Norway, for my doctorate, where I also raced cross-country skiing and practiced enough to finish ahead of two U.S. national team members in Norway’s most famous marathon race, the Birkebeiner. At the same time, I secured a fellowship to study the effects of rapid growth rates on the biomechanics of spine curve progression in children with adolescent idiopathic scoliosis, a torsional buckling of their thoracolumbar spine.
As a post-doc in 1980, I moved to Chicago to work with Professor Albert B. Schultz, a thought leader on idiopathic scoliosis, who was also applying biomechanics to the problem of low back pain. After three years, we were both recruited to U-M, where we continued to work on back pain. In 1990, a geriatrician at the U-M Institute of Aging invited us to apply biomechanics to mitigate the problems of mobility and falls in the elderly, a line of research involving physical and cognitive factors that continues to this day.
Around the same time, I began collaborating on the study of structure-function relationships in the female pelvic floor. We started the Pelvic Floor Research Group, the first in the world, applying biomechanics to investigate why as many as 20% of women are injured during their first vaginal deliveries, and later develop urinary incontinence and pelvic organ prolapse. Since then, we have made great progress. We published the first papers that pointed out the mechanism of levator (pelvic) muscle stretch injury during vaginal birth and identified forceps as the proximate cause of those injuries. Our insights have helped reduce the use of forceps and improved our understanding of how and why such injuries lead to pelvic organ prolapse in older women. We invented an inexpensive two-minute test to tell whether a mother-to-be is likely to have difficulty with her first delivery and thereby risk levator muscle injury.
Along the way I have consulted on injury prevention to the NBA (safety of wearable sensors), MLB (design of safety nets installed in baseball stadia across the country), NCAA (performance metrics for baseball bats), and ASTM (specifications for skylights to prevent fall-through injuries), and to Fortune 500 and startup companies in the medical device and consumer products areas.
Q: How has your discipline changed, broadly, from when you entered it?
Since the 1970s, biomechanics has evolved from whole body analyses, such as those used to study human gait by engineers and orthopedists, and those used in industrial medicine, dentistry, and dermatology. Today, every medical discipline has biomechanics problems that need solving. There are many opportunities for new people entering the field to make a real difference. Powerful new forms of imaging, discoveries in molecular biology, tools for manipulating and measuring tiny structures, methods for computer simulation, techniques for analyzing dynamic and control systems, and data science are allowing us to study the biomechanics of organisms in ways that were simply unfathomable when I started out: whether from the molecular level, the cellular level, the organ level, to the whole body level, or vice versa.
Q: What trajectory is your discipline taking on your exit? How have your contributions affected this trajectory?
Currently, biomechanists are learning to understand how tissue behaves across the length scales from the whole body to the single molecule, and back to the whole body. Theory and experiment can lead to a better understanding of vital processes like growth, inflammation, repair, remodeling, hypertrophy, atrophy, and aging. These affect the tissues of our internal organs as well as our muscles, cartilage, bones, ligaments, and tendons
Our contributions to this trajectory have come in different forms. In one example, my long-term interest in sports injuries led me to take a fresh look at why ACL injuries occur. They are important because 50% of all ACL injury patients risk having osteoarthritis start in the knee joint within 10 years. In the case of an ACL tear in a 12-year-old, this means that by 22 years of age, they may begin to develop osteoarthritis in the knee joint.
More than 10 years ago, we questioned the dogma that ACL tears during jump and cut landings are caused by excessive valgus loading of the knee. We used whole cadaver knees to demonstrate that ACL injuries can be caused by low-cycle fatigue of the ACL under repetitive sub-maximal jump landings in fewer than 100 loading cycles that significantly strain the ACL. This could be during certain cuts and turns, for example, but not during running, because the ACL strains are not intense enough.
More recently, we observed the same fatigue-damage signature in injured ACLs removed at the time of replacement surgery. Very recently, we showed that this weakening and subsequent failure of the ligament is likely due to unravelling of the ACL collagen fibrils in the region(s) of highest strain, where the ligament originates from the femur at an angle. At the whole-body level, we can intuit that better management of the amount and intensity of athlete training is required, which will become possible in the future with new wearable sensors. Such insights are likely applicable to many overuse injuries occurring in connective tissue that is placed under significant repetitive loading, like the shoulder, lateral elbow ligaments, intervertebral discs of the spine, and plantar fascia.
Q: What advice do you have for future engineers?
Go into the engineering discipline that really interests you and where you have a hunch that you can make a difference. When I decided to study biomechanics in 1972 as a graduate student, it wasn’t a field. The American Society of Biomechanics was not formed until 1977, so there were no companies visiting campuses to interview students for “biomechanics” jobs, because there were no such jobs. But I figured that the human body is so interesting that I would always be able to find something worthwhile to work on.
Today, 50 years later, there isn’t a field of medicine or dentistry that can’t benefit from biomechanics. Employers of biomechanics students include sports, automobile, hospital, and surgical equipment manufacturers; military equipment manufacturers; automotive manufacturers; professional sports teams; large, medium, and some small universities; orthotics and prosthetics manufacturers; consumer product manufacturers; and many start-ups. New fields emerge all the time, so follow your dream!
