Jumper’s Knee paradox – jumping ability is a risk factor for developing jumper’s knee: a 5-year prospective study
Visnes H, Aandahl HA, and Bahr R. Br J Sports Med. 2012; [Eup Ahead of Print].
Jumping is essential to volleyball as it is a key component of spiking, blocking, and serving. Unfortunately, this activity will often results in the development of jumper’s knee (patellar tendonitis). The jumper’s knee paradox, where symptomatic athletes perform substantially better in counter movement jumps (CMJ;ballistic movement with rapid eccentric action followed by maximal concentric contraction) compared to asymptomatic controls, has never been adequately explained in the literature. Therefore, Visnes and colleagues performed a 5-year prospective study to determine if jumping ability and change in jumping ability affects risk of developing jumper’s knee. The authors recruited students (n=189) at an elite volleyball training program/high-school boarding school in Norway who were free of jumper’s knee at the time of baseline testing. Baseline testing included recording of height, weight, and previous training. A portable force plate was used to assess jumping ability by estimating vertical jump heights for both counter movement jumps and squat jumps (jumping from a standing flexed position with no counter movement). These two tests were performed twice a year. Once at the start of school (approximately, August/September) and the end of volleyball season (approximately March/April) and training volume was recorded on a weekly basis. A diagnosis of jumper’s knee was made if the subject had a history of quadriceps or patellar tendon pain and tenderness to palpation in the area of complaint for at least 12 weeks. If these symptoms were reported, the subject would then undergo a standard knee examination to exclude any other diagnoses and complete a VISA-P questionnaire to assess the severity of the symptoms. At the conclusion of the study, 28 of the final 150 student sample (19%) developed jumper’s knee during their time at the school (on average 1.6 years). The authors found no differences in height, weight, and previous strength training between those that developed jumper’s knee and those who did not. Males who developed jumper’s knee reported more volleyball training and less other training, as well as better baseline CMJ results compared to asymptomatic males. No difference in squat jump ability was observed.
The authors present an interesting look at how higher CMJ heights is associated with developing jumper’s knee. This data could become useful to clinicians as a method for preemptively identifying those at a high risk of developing jumper’s knee. Preventative treatment could then be applied to attenuate pain caused by jumper’s knee. Caution should be exercised interpreting these results for clinical applicability. First, this study was conducted in high-level volleyball players. These athletes have been trained in proper jumping and landing techniques. It is possible that lesser trained athletes may lack the ability to land properly and may develop jumper’s knee at a different rate than trained athletes. Therefore, this study should be repeated with athletes of various training levels. Also, a limitation of this study was the high level of subjectivity in the diagnosis of jumper’s knee. To be diagnosed with jumper’s knee subjects had to “consider that the symptoms were sufficient to represent a substantial problem.” This subjectivity raises the possibility that some athletes may have experienced symptoms of jumper’s knee but self-treated and therefore did not report this as a case of jumper’s knee. Therefore, future research should focus on using more objective measurements to diagnose jumper’s knee. Tell us what you think. Is jumper’s knee a condition that you see often in your athletes? If so, do you think this information could be applicable to you in identifying athletes at risk of developing jumper’s knee?
Written by: Kyle Harris
Reviewed by: Laura McDonald
Related Posts:Visnes H, Aandahl HA, & Bahr R (2012). Jumper's knee paradox--jumping ability is a risk factor for developing jumper's knee: a 5-year prospective study. British Journal of Sports Medicine PMID: 23060653