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

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
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