In our previous work, we found that vertical jump performance (height) is a more representative metric for knee function than horizontal hop performance (distance) in healthy individuals.
What is going on with athletes after #ACLR at the time they are cleared to #RTS? So, we studied their biomechanical status during a single leg vertical jump and the reactive phase of a single leg drop jump
During the propulsion of a single leg vertical jump, in terms of biomechanics the knee work symmetry was 75%. In terms of performance the symmetry was 83%
During the single leg drop jump, the symmetry in knee work generation was 70%. In terms of performance, symmetry of jump height was 77% and for reactive strength index symmetry was 70%
Remember, our athletes passed all the discharge criteria and they had 97% symmetry for hop distance.
It seems that vertical performance metrics can better identify interlimb asymmetries than hop distance and should be included in the testing battery for the #RTS
Someone might say that measuring distance is easy but measuring height is not.
This argument might be valid 20 years ago, but now with the advances in technology, measuring jump height is also very easy.
We used #EMGmodeling to estimate the individual muscle forces.
Lateral hamstrings muscle contribution was greater in the involved compared to the uninvolved limb and controls. #Soleus contribution was bilaterally lower in the ACLR group compared to controls.
Why triple hop?
During many sports, it is unusual for an athlete to be required to make a single movement such as an isolated jump or hop.
Triple hop provides additional information about the patient’s ability to absorb and release energy during consecutive plyometric loading.
We measured athletes after #ACLR during propulsion & landing of a single leg hop for distance after they have been cleared to #RTS
During propulsion symmetry in work done by the knee is only 69% & during landing it’s 81%, despite achieving 97% of hop distance
The relatively large between-leg knee work difference is easy to miss as the knee joint contributes little (12%) to propulsion in a single hop for distance.
Hop testing after #ACLR – horizontal (distance) is easier to measure than vertical (height) but are they the same?
(Spoiler: not even close)
Thread 👇
During a vertical hop, the hip, knee, and ankle contribute almost equally, during push-off (height achieved) and landing (force absorption).
Horizontal hop is very different.
Work during propulsion (=distance achieved): knee contributes only 13% but the landing phase (absorption) is done 2/3 by the knee.