Hop Distance Symmetry Moderately Reflects Knee Biomechanics Symmetry During Landing But Not For Controlled Propulsions.
Stefano Di Paolo, Naoaki Ito, Kayla D Seymore and 5 others
PMID 39268226WHAT IT FOUND
Single and triple hop distance symmetry partly reflected knee landing symmetry, but crossover hop distance symmetry did not.
Timed hop symmetry reflected take-off more than landing. Poorer distance symmetry can indicate landing asymmetry.
Key findings
01Single and triple hop distance symmetry showed positive associations with landing knee symmetry, with rho=0.39 for the single hop and rho=0.48 to 0.66 for the triple hop.
02Crossover hop distance symmetry showed no association with sagittal knee symmetry during take-off or landing.
03Timed six-meter hop symmetry showed a moderate positive association with take-off knee symmetry (rho=0.51) and a negative association with landing initial contact knee symmetry.
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What it does not show
Only knee sagittal plane motion was measured, because markerless motion capture was considered less reliable for other planes, so frontal and transverse knee control were not assessed. The crossover hop requires changing direction and likely needs frontal and transverse plane knee control, but those planes were not measured, which may explain its null result. The group mixed healthy participants and people with previous lower limb surgery to widen the range of scores, so the results do not describe a single patient group such as people after ACL reconstruction. The study was cross-sectional and correlational, so it cannot establish that hop asymmetry causes knee asymmetry or a causal relationship. In some tests, hop symmetry values varied widely while knee symmetry values were centered around 100%, so the clinical hop score may reveal asymmetry that the knee angle measure did not capture.
Declared interests
The authors report no conflicts of interest. The work was supported by NIH grants R01AR072034-04S1 and R37HD037985.
The easy way to misread this
Do not conclude that all hop test symmetry reflects landing control. In this study, crossover hop distance symmetry showed no association with sagittal knee landing symmetry, and the timed hop showed a moderate association with take-off and a negative association with landing initial contact.