Spraining an ankle is one of the most common injuries suffered by athletes. And if you've twisted once, you're likely to twist again - apparently a sprain leads to a chronically symptomatic or unstable ankle in approximately 40 per cent of cases. But apart from an increased risk of another sprain, is your balance per se compromised? This is a particularly relevant question for sports where balance is a key component of the activity, such as gymnastics.

There have been two theories proposed to explain recurrent ankle sprains. The more immediately obvious one is the 'mechanical instability' theory, which assumes that instability is caused by damage to the integrity of supporting ligaments. The other theory proposes that problems arise because of 'functional instability' - damage to the nerves in the ankle area which would normally feed back information to the brain about the position of the ankle, interacting with balance mechanisms. If the latter explanation is true, ankle sprain would be expected to affect standing balance on one leg.

To investigate this possibility, a team of Israeli researchers studied a group of young gymnasts who had previously suffered ankle sprains to only one ankle. Eight female gymnasts were brought into the lab and asked to stand on a craftily designed floor plate. The plate is able to detect and quantify postural sway in forward-back and side-to-side directions. Measurements of sway were made while the gymnasts stood balanced on each leg in turn. Comparisons of impact on balance could then be made between injured and uninjured ankle.

When all the results were analysed, there was no significant difference in balance when standing on the injured or uninjured ankle. From this the researchers concluded that the normal activities of muscles and nerves involved in maintaining balance are not compromised by spraining an ankle ('Is balance impaired by recurrent sprained ankle?' Isakov and Mizrahi, British Journal of Sports Medicine 1997, vol 31, pp 65-67)
Janet Stansfeld