In the rehabilitation of most lower limb injuries, jump testing is important in tracking the progression of the legs ability to produce and absorb force. The results of this testing can be quite important in return to sport decision making. Particularly in knee injuries, jump testing is often overlooked, and patients are told to return to sport with a significant risk of re-injury. Imbalances in the injured and non-injured leg’s ability to perform in jump testing can highlight deficits that need to be addressed to keep patients as safe as possible. Jump height and jump distance are the most used outcomes with limb symmetry index thresholds normally set at 90% prior to discharge. 

Horizontal Jumps

Implementing horizontal jumps in rehab and testing is very important for those aiming to run at high speeds in their sport, particularly those in field sports. Horizontal jumps can be broadly defined as ‘jumping for distances, either in a straight line or in different directions to replicate a sporting environment. In those rehabbing a knee injury, horizontal hop distance symmetry commonly resolves before symmetry of vertical jump height does. This is achieved by athletes frequently using a “hip strategy” to maximise jump performance in the presence of ongoing deficits at the knee/quadriceps.

How far you hop horizontally is determined almost 90% by the work done at the hip and ankle! However, when it comes to the subsequent landing, knee work contributes over 65% to the landing strategy and therefore landing is much more demanding on any residual knee deficits than the propulsion phase but this information is lost when looking at hop distance alone. Single leg hop for distance is one of the best tests to challenge knee function during landing, highlighted by deficits in knee work with compensations at both hip and ankle. 

Vertical Jumps

The most commonly used vertical tests are countermovement jumps and drop jumps which express explosiveness and plyometric ability, respectively. In a clinical setting, jump height is a more sensitive metric than hop distance to evaluate an athlete’s status during rehabilitation and at the time to return to sport after a knee injury/surgery. Vertical performance metrics like jump height can better identify interlimb asymmetries than horizontal jumps. These findings are explained in part by the different demands on knee function between horizontal and vertical jumps. The greater knee work contribution during vertical hops likely explains why performance deficits are more readily apparent than during horizontal hops in those with knee impairments.

Summary

If you have injured any area of your leg, and you aim to return to a sport or running, then you need to do some jump testing. Having compensations and cutting corners in your rehab can leave you at risk of worsening your injury, or injury another body part in the kinetic chain.

If you have any questions on whether physio is the best option for you, or you have any questions about MVMNT in general, feel free to contact via email.

- Jay Towolawi, Specialist Sports Physiotherapist and MVMNT Founder.