The purpose of this study was to analyse within subject differences in a number of static balance tests, performed during monopodal stance.

The tests were carried out comparing the ankle with a previous lateral ligament injury (with permanent ligament loosening) and the one without ligament loosening. Fourteen volunteer subjects were recruited for the study (6 women and 8 men), all of them physically active, with a mean age of 19.9±3.8 years. The measurements included the ankle range of motion (static and passive), and the path of the centre of pressures during a monopodal balance test on a force platform (60s last), in three different conditions: on the platform, on a foam pad and during the application of electrical stimulation on the tibialis anterior muscle. All the measurements and tests were applied on both legs, injured and uninjured.

The anterio-posterior path of the centre of pressures was greater in the previously injured limb in the test on the foam pad (injured=60.9±14.3mm; uninjured=51.8±9.5mm) (p <0 05 the mean position of centre pressures in injured limb was more medial during three tests p <0 05 and more posterior in the test on foam pad p <0 01 in the test with electrical stimulation total path of centre pressures injured="51.6±15.1mm/s;" uninjured and its average velocity were significantly greater limb p <0 05

When the tests became more challenging, the differences between injured and uninjured limbs were greater. The position of the injured extremity was more medial and posterior during the static tests.