A series of hop tests are routinely used in the assessment for return to sports post-injury, be it an ankle sprain, stress fracture or anterior cruciate ligament reconstruction. They are both functional and quantitative, allowing a measurement of power and strength of the affected to unaffected leg.
- Single hop test
- Triple hop test
- Crossover hop test
- 6 meter timed hop test
Carrying out the hop tests
Single hop test
In this test, the aim is to jump as far as possible on a single leg, without losing balance and landing firmly. The distance is measured from the start line to the heel of the landing leg. The goal is to have a less than 10% difference in hop distance between the injured limb and uninjured limb.
Triple hop test
In the triple hop test, the aim is to jump as far as possible on a single leg three consecutive times, without losing balance and landing firmly. The distance is measured from the start line to the heel of the landing leg. The goal is to have a less than 10% difference in hop distance between the injured limb and uninjured limb.
Crossover hop test
In the crossover hop test, the aim is to jump as far as possible on a single leg three consecutive times, without losing balance and landing firmly. Between each hop, the athlete has to jump across a midline, hence including side-to-side movement in this test. The distance is measured from the start line to the heel of the landing leg. The goal is to have a less than 10% difference in hop distance between the injured limb and uninjured limb.
6 meter timed hop test
In the 6 meter timed hop test, the aim is to jump as fast as possible on a single leg over a distance of 6 meters, without losing balance and landing firmly. The goal is to have a less than 10% time difference in the time taken to hop through between the injured limb and uninjured limb.
It is recommended that an athlete has to score >90% on the tests to have a reduced risk of reinjury or injury. Quality of take-off and landing mechanics should also be assessed, on top of quantitive scores. Even with meeting the criteria for the hop tests, there is still a chance of an injury again. However, the risk of reinjury is much lower should these criteria be met.
The hop tests are also not used as standalone assessment in return to sports, Recent research has shown that RTS should be based on meeting a series of key performance criteria, rather than just timeline after an injury.
Other functional tests commonly included in return to sports include the T-test for agility, shuttle runs, beep tests. These look at a combination of power, endurance and functional movement patterns, providing a qualitative look at the specialized movements required in different sports.
On top of functional testing, other clinical tests include muscular strength, flexibility as well as range of motion of affected joint. Subjective assessments include the International Knee Documentation Committee Subjective Knee Form (IKDC 2000), which has been shown to be a valid outcome measure for knee function in patients with ACL injuries.
Single leg hop tests have shown to have a strong intra-rater reliability, with the ICC (Intraclass Correlations Coefficient) to be 0.85 for dominant and non-dominant legs). 
It is also a reliable and reproducible outcome measure, with ICC ranging from 0.92-0.97 for test-retest reliability for the single leg hop tests. The standard error of measurement (SEM) for the single-leg hop tests ranges from 4.61-17.74 cm, while the SEM for the 6-m hop for time test was 0.06 seconds. 
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