Document Title: Noyes-AJSM-Feb05.shtml
Article Title: The Drop-Jump Screening Test: Difference in Lower Limb Control By Gender and Effect of Neuromuscular Training in Female Athletes
Authors: Frank R. Noyes, MD, Sue D. Barber-Westin*, Cassie Fleckenstein, MS, Cathy Walsh, MS and John West, MS
Publication: American Journal of Sports Medicine, Baltimore, Maryland
Date: February 2005
Volume 33, pages 197-207
Keywords: video drop-jump test, lower limb alignment, neuromuscular training, proprioceptive training, ACL injury prevention.

(Reference-denoting numbers appear in the same font and point size as the document text. As with all Knee Library documents, this article is provided in full-text form, complete with all figures and tables.)

Comments: This highly insightful study looks at the biomechanics of landing jumps -- and, ultimately, the resulting influence on ACL-injury proclivity. Because valgus knee alignment (i.e. knees too close together) upon landing has been correlated with noncontact-type ACL injuries, using a video camera to record the knee alignment upon jump landing makes sense. This video capture would then make it easy to screen for and target valgus-knee-landing athletes (both male and female) with special remedial jump-training programs; the use of video recording also makes it easy to track the progress of the athletes. (The video camera used in this study was an ordinary one, which makes this kind of work easy to do in the field. No ultra-expensive high-specialized laboratory equipment is needed here. The authors note that a second camera could additionally be used, so as to enable the knee-flexion angles to be recorded directly [i.e. views from the side, not just from the front]. However, they elected to use only one camera because of the goal of making this a screening test which could easily be done by coaches and athletic trainers with equipment one would find at home.) The injury-prevention training used in this study was Cincinnati Sportsmetrics, a program whose injury-prevention benefits are very well-supported by peer-reviewed research.

ABSTRACT

Background: A valgus lower limb alignment has been noted during noncontact anterior cruciate ligament injuries. A video drop-jump test can indicate an athlete’s ability to control lower limb axial alignment in the coronal plane.

Hypotheses: Female athletes have decreased knee separation distances on landing and acceleration; male athletes have a neutrally aligned lower limb position. A neuromuscular training program will significantly increase knee separation distance in female athletes.

Study Design: Cohort study; Level of evidence, 2.

Methods: The authors tested 325 female and 130 male athletes aged 11 to 19 years. The distance between the hips, knees, and ankles was measured during a drop-jump test. The separation distance between the knees and ankles was normalized by the hip separation distance. A neuromuscular training program (Sportsmetrics) was completed by 62 female athletes, and their jump-landing characteristics were reexamined.

Results: A marked decrease in knee separation distance was found on takeoff in 80% of female athletes and in 72% of male athletes. There was no difference between male and female athletes in the normalized knee and ankle separation distance during the landing and takeoff phases. The knee separation distance on landing was 23 ± 9 cm in the female athletes and 22 ± 8 cm in the male athletes. The normalized knee separation distance was 51% ± 19% in the female athletes and 51% ± 15% in the male athletes. After training, statistically significant increases were found in the female athletes in the knee separation distance on landing (29 ± 8 cm, P < .0001) and in the normalized knee separation distance (68% ± 18%, P < .0001). The trained female athletes had significantly greater knee separation distance and normalized knee separation distance than did the males (P < .0001).

Conclusions: The majority of untrained female and male athletes demonstrated a valgus alignment appearance on the video test. After neuromuscular training, female athletes had improved knee separation distances and a more neutral lower limb alignment on landing and takeoff.

To access the full text of this article, please click here.
There is no charge for viewing articles. However, a password is required.
If you do not already have a password, please e-mail Michael Frind at frind@execulink.com for one.
Prior to requesting a password, please make certain you have read the Site Terms of Use pertaining to this site.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Copyright American Journal of Sports Medicine, American Orthopaedic Society for Sports Medicine, February 2005. For details regarding copyright as it applies to this page, please visit the page entitled Site Terms of Use and Aspects of Copyright on this site.

This website was created for the benefit of the world's largest knee-injury community, Bob's ACL WWWBoard (also known as the Kneeboard), accessible to everyone at http://factotem.org.

Documents posted on this site serve merely as a virtual library, and are intended solely for purposes of making access to high-quality peer-reviewed medical-journal articles convenient for all users of the Kneeboard. Knee-injury patients are hereby encouraged to discuss this material with their respective medical teams.

Site Terms of Use and Aspects of Copyright

Printing Hints and Tips