Bethanie Evans and Professor David Kaiser, Exercise Science

A greater incidence of ACL injuries in women compared to men may stem from complex, interrelated factors, including hamstring-quadriceps strength imbalances, joint laxity, and neuromuscular deficits. While congenital joint laxity cannot be reversed, both hamstring/quadriceps imbalances and neuromuscular deficits have been shown to improve with functional neuromuscular training.1,2,3 Consequently, research needs to be conducted to quantitatively measure the changes to hamstring/quadriceps strength ratio as a result of neuromuscular functional training.

We hypothesized that Closed-Kinetic Chain (CKC) exercises would result in a greater reduction of a quadriceps to hamstring ratio, as well as an increase in quadriceps and hamstring strength as compared to Open-Kinetic Chain (OKC) exercises. To quantitatively measure the quadriceps and hamstring strengths and ratio, we tested each subject before and after a six week CKC, OKC, or a no-exercise training program, on the Biodex Isokinetic Dynamometer. We tested each subject’s peak quadriceps and hamstring torque at 60°s/second and at 180°s/second.

Using a random-control styled research model, each subject was assigned to the CKC, OKC, or control group. The CKC exercise program consisted of progressive functional exercises of lunges and multi-planar neuromuscular exercises. The OKC program consisted of a progressive uni-planar knee flexion and extension exercises on a leg flexion/extension machine. The control group did not start or change any exercise regimens.

Although ANOVA data analysis has not been completed, the post-treatment data does show promising concurrence with the hypothesis. The data thus far has shown that there is a greater increase in quadriceps and hamstring strength in the CKC exercise group as compared to the control and OKC groups. However, statistical significance is required to reinforce the hypothesis, which will be completed January 2006. In addition, a concern of skewed data resulting from non-compliance of subjects may have altered the individual outcomes.

While this was the most beneficial learning experiences I have had here at BYU, it has also been one of the most frustrating because of non-compliance from research subjects. My subject pool was female college students over eighteen, so I recruited subjects in classes, by advertising, and by word of mouth. I conducted an orientation meeting in which I informed each potential subject of their obligation and responsibility, then had them sign an informed consent. Each subject agreed to the parameters, but yet it was very difficult to get the subjects to come in for pre and post testing and for their exercises. Compliance was the most significant problem in this study. Consequently, the significance of the data may have been greater if the compliance would have increased. Despite this issue, not only me, but many other students, learned a lot about knee injuries, the use of the Biodex Isokinetic Dynamometer, and about the research process.

When I was first investigated the use of CKC exercises in ACL injury prevention, I never thought that I would conduct my own research. I have had the wonderful opportunity to learn about research proposals, performing research, and about academia in general. This project not only spurred my interest in further research, but also encouraged other undergraduate students to can do their own research. Several students that assisted me are considering writing their own proposals and carrying out projects.

Conducting this research has been the most beneficial learning experience of my college career, and has opened many doors academically and professionally. Upon completion of the ANOVA statistical analysis in January 2006, I will submit my research to the National Athletic Training Association for presentation at the National and Regional levels. I will also submit the research to The Journal of Athletic Training for publication.

References

• Chimelewski TL, Wilk KE, Snyder-Mackler L. “Changes in weight-bearing following injury or surgical reconstruction of the ACL: relationship to quadriceps strength and function.” Gait Posture. 16(1): 87-95 2002
• Moeller JL, Lamb MM. “Anterior cruciate ligament injuries in female athletes: Why are women more susceptible.” The Physician and Sports Medicine. 25 (4): 1997.
• Myer GD, Ford KR, Hewett TE. “Rationale and clinical techniques for anterior cruciate ligament injury prevention among female athletes.” Journal of Athletic Training 39(4):352–364 2004