Brian Beatty & Rob Schneider
It is difficult to perform and enjoy endurance exercise when any part of the lower extremity is not functioning at its best. The following quick and easy test can help determine if you are at risk for a lower extremity injury.
This simple single leg standing reach test is derived from a functional exercise known as the Star Excursion Balance Test. This test requires level ground and a tape measure. The test yields more definitive results if performed after exercise when the legs are post exertion ‘tired’ but not fully fatigued. It is performed by:
1. Standing on one leg while reaching with the opposite foot as far as you can along the taped line.
2. For a valid test repetition, the standing foot should not wobble or move. The foot that is reaching must touch the ground lightly, but cannot have any weight shifted to it or be used to support the body in any way when it touches the ground.
3. Three different directions of reaching should be measured. A: Medial (opposite leg reaches out to the opposite side, i.e. for left standing foot, reach the right leg as far directly right as possible); B: Anteromedial, at a 45 degree angle opposite and forward from the stance side; C: Posteromedial, at a 45 degree angle opposite and back from the stance side.
4. Measure the distance of 3 valid reaches in each direction allowing a 10 second rest between attempts, for each leg.
5. Average the distances for each direction and compare the results left to right.
If the difference in average reach left to right leg is greater than 5-to10% in any direction, then there is an increased risk for problems on that side. Most relevant to runners, this test has been shown to be predictive of chronic ankle problems. Turning one’s ankle while running is a familiar event for most of us. Often we get lucky and can walk or run after the incident and show no lasting effect. Unluckily, this is not always the case and a significant ankle sprain injury will result. Research suggests that 40% of the people who suffer a sprain will develop some level of long-term ankle difficulty.
Recurrent ankle sprains / pain is the most common problem, and is known clinically as Chronic Ankle Instability (CAI). The greatest impacts of ankle sprains are a loose ankle joint and a loss of sensorimotor control. Sensorimotor control is a fancy way of saying that the body can no longer accurately know how to react to the position of the foot relative to the forces traveling through it. It is a multi-dimensional problem of neurologically knowing where the foot is in space, forming the appropriate response to maneuver the body, and having the skill and strength to maintain optimal joint position.
The great news is that the above test also functions as an excellent exercise for training the lower extremity for strength and sensorimotor control. Research has shown that improved performance using this and similar sensorimotor control exercises result in less lower extremity injuries and improved performance in sport activities and daily life. This month’s ‘Core Corner’ illustrates a protocol for using the Star Excursion Balance Test as a training exercise.