AUSTRALIAN Rules footballers may be banned from taking caffeine pills to enhance their performance - but they might want to stop now.

Research from the world's leading anti-doping authority has revealed caffeine pills could actually hinder performance, not boost it.

The pre-match practice of popping caffeine pills – exposed in the wake of the bungled use of caffeine and sleeping tablets by Richmond AFL player Ben Cousins – is purported to increase awareness and fight fatigue.

But World Anti-Doping Agency research warns excessive amounts of caffeine can actually be counterproductive on the field.

Leading AFL doctor Peter Larkins explained the threshold identified by WADA could be equal to as few as four No-Doz tablets or several cups of coffee, depending on the size and metabolism of the player.

Some AFL players have admitted taking up to six No-Doz during a game.

Until 2005, elevated caffeine readings constituted a breach of the WADA anti-doping code, which the AFL follows.

WADA changed its mind after discovering that "caffeine is performance-decreasing above the 12 microgram/ml threshold that was historically used in sport".

A bemused Larkins last night said: "That's four to six black cups of coffee – exactly what the AFL blokes are taking now."

One No-Doz tablet contains 100mg of caffeine and a cup of coffee about 80mg.

Larkins said under the original code, players taking up to four No-Doz at a time could have been punished as drug cheats.

"If the old system was in place, these blokes would get pinged because they would be over the limit," he said.

The controversial pills could yet be banned again.

The Australian Sports Anti-Doping Authority yesterday revealed caffeine remained on a WADA "monitoring program" designed to detect patterns of misuse.

In 1988, modern pentathlete Alex Watson was disqualified from the Seoul Olympic Games for using caffeine as a performance-enhancing drug.

Originally published as Caffeine pills face AFL ban