Student Research Impact – Trunk Biomechanics Influence ACL Loading Mechanisms During Cutting

Mentoring students is one of the most important and valued roles of our faculty in Exercise and Sport Science.  We are fortunate that we have the opportunity to work with the very best and brightest undergraduate and graduate students.  Many of our undergraduate students are engaged in various scholarly activities, such as serving as research assistants, initiating independent research projects with faculty, and undertaking senior honors thesis research projects.  All of our graduate students undertake a masters thesis research project, where they work with a primary faculty mentor in their area of interest, and have other faculty members involved as committee members.  The scholarly impact of these student projects is large, as many of these projects are presented at leading scientific meetings and published in top tier scientific journals.

Between our undergraduate and masters students, there are approximately 40 different student research projects ongoing each academic year.  When considering the PhD students from the Human Movement Science Curriculum (HMSC), there are likely another 10-15 ongoing student research projects.  It is a reasonable estimate, that there are over 50 different student research projects being conducted annually in EXSS research facilities.  We have a devoted group of faculty and staff who value providing student research experiences, and recognize the impact of these opportunities.  An added bonus is when these student’s efforts lead to a scientific publication.  One of the most rewarding things as a faculty member is to hear the excitement in a student’s voice when they receive the news of their first manuscript being accepted for publication.

This week we highlight the recent work of Barnett Frank, who is currently a PhD student in the HMSC Program and is also an alumni (2010) from our masters degree program.  This work was recently published in the American Journal of Sports Medicine and a copy of the article can be accessed here.   All of the co-authors are also alumni from EXSS programs: David Bell (2001 undergraduate in EXSS, 2010 PhD in HMSC), Marc Norcross (2003 masters in EXSS, 2011 PhD in HMSC), Ben Goerger (2005 undegraduate in EXSS, 2012 PhD in HMSC), Troy Blackburn (1998 undergraduate in EXSS, 2004 PhD in HMSC), Darin Padua (1998 masters in EXSS).  All of these co-authors began their scholarly endeavors while a student in EXSS, and now are faculty members at  outstanding academic institutions.  It will be exciting to see the next generation of EXSS Impact Scholars emerge from our current student body.

Trunk and Hip Biomechanics Influence Anterior Cruciate Loading Mechanisms in  Physically Active Participants.  Barnett Frank, Marc F. Norcross, J. Troy Blackburn, Benjamin M. Goerger, Darin A. Padua.  American Journal of Sports Medicine 41(11):1676-2683, 2014.

Why did you do this study?

Anterior cruciate ligament (ACL) injury is one of the most commonly injured ligaments in the knee joint during sport participation. Injury causes severe disability and requires expensive surgery and rehabilitation commonly lasting up to a year for return to high-level athletic participation. Many individuals who suffer from ACL injury return to sport but commonly return to participation with reduced function and athletic performance compared to their pre-injury status. Additionally, individuals who suffer an initial ACL injury are reported to be over 9-16 times greater risk of suffering a second ACL injury compared to those who do not injure their ACL. Thus there is a significant need to understand how to prevent this injury.

Cutting_Poor_Technique Approximately 70% of ACL injuries are a result of a non-contact mechanism, meaning the individual suffering the injury did not collide with another player or surface when they sustained the injury. A non-contact ACL injury is the result of an individual’s own body motions during a jumping or landing motion, side-step cutting, or changing direction. Commonly during an ACL injury, an individual’s trunk or upper body is observed to be out of alignment with their lower limb (Figure 1a). Previous research suggests that training programs can reduce an individual’s risk of ACL injury through strengthening, flexibility, agility, balance and teaching “good technique” during athletic motions such as body control during side-step cutting. While there is a significant amount of research on the effectiveness of these ACL injury prevention programs, the mechanism by which these programs help to reduce knee loading is not well understood. Specifically, research has not thoroughly explored “ideal” technique for athletic motions in which ACL injury has been observed to occur. Thus the purpose of this study was to determine if there is a relationship between trunk motion and lower extremity loading associated with ACL injury.

What did you do and what did you find in this study?

data_collectionWe measured trunk motion and lower extremity loads associated with ACL injury during a side-step cutting task in 30 physically active males and females using a 3D motion analysis system and a force platform. Participants ran toward the platform and then performed a side-step cut away from their stance limb; participants ran and jumped toward the force platform and changed direction after landing on the platform.

cuttingWe observed that when individuals side-step cut with their trunk flexed too far forward they tend to put more rotational loading on their knees. We also observed that when individuals side-step cut with their trunk less rotated (or rotated away) from the direction they are trying to move toward they put more valgus loading on their knee, a load associated with inward collapse of the knee (click for video link).

How do these findings impact the public?

Coaches, athletic trainers, strength and conditioning coaches, and other individuals working with athletes that perform side-step cutting maneuvers can teach these individuals to side-step cut with their trunk moving toward the new direction of travel, and to limit excessive forward flexion trunk motion during the cutting task to help reduce loading associated with ACL injury. Future research should investigate the long-term effectiveness of training programs that teach individuals a side-step cutting technique with rotation toward the direction of travel and that limit excessive trunk forward flexion to reduce knee injury risk in athletes.

EXSS Impact

Jan 19 blog - Movement Screening ArticleGiven the long term consequences of ACL injuries, such as a greater risk for developing osteoarthritis and decreased physical activity levels, these findings provide important insight into both risk factors and prevention strategies for ACL injury.  Individuals who display increased forward trunk flexion and lateral trunk flexion (away from the direction of cutting) place greater mechanical load on their, which may increase one’s risk for ACL injury.  Current students in EXSS are continuing this line of research by investigating factors associated with trunk motion during functional tasks and what strategies can be used to improve these movement patterns.  I look forward to providing future updates on these and other impactful works being done by our outstanding students in EXSS.