One of the stereotypical images of grassroots sport is the sight of the slightly overweight trainer wearing the padded jacket, carrying the bucket and sponge.

Every team should have one and it seems that no matter what injury happens on the pitch, the sponge is the magical answer.

When people found out that I was a physio working in professional football, the first question guaranteed to be posed was about an ailment that the quizzer has.

But the second inevitable question would be about the magic sponge and what makes it so special.

Truth is there isn't really any magic to it. The cold water often does little other than, for a very limited period of time, reduce the blood supply to the injured area to prevent swelling.

It was probably invented to buy players a bit of time, a way to almost justify spending a few extra seconds on the ground to allow the pain to pass before they could get back on their feet and resume their game.

It's a tricky job as physio deciding whether or not to run on the pitch when you see a player down injured.

Some are just down to catch their breath and some players are there because they made such a meal of the fall or dive that they've got to justify their injury by getting some sort of treatment or risk a booking for play acting.

It's true that some players will take all the time can when the physio arrives on the pitch and will often whisper that they're okay, they just need a second or two to catch their breath.

The physio then whips out the magic sponge and the referee will look away.

After all, if the magic sponge has arrived then the player must surely have a problem?

But this can cause problems for players and physios.

I can recall arguing with many officials, including North-East-based and now Premier League referee Michael Oliver who began life as a fourth official.

Many times he tried to stop me running on the pitch to attend to a player who looked to be seriously injured.

He was just doing his job, but my argument was that referees weren't the ones who should be deciding how badly injured a player was and when I could run on the pitch with my magic sponge.

More often than not the physio gets his own way as the consequences of not getting on the pitch in time can be disastrous.

Imagine if the medical man at Tottenham that day hadn't been allowed to reach Fabrice Muamba for a few seconds longer, it would have been the difference between life and death for the Bolton player.

But physios can also get the decision wrong and I learned this the hard way a few times.

When attending to a player, he has to leave the pitch with you following on-field treatment.

That means he's missing for the next phase of play and if that's a centre-half you've just pulled from the pitch and your team is defending a corner, the manager isn't going to be too happy about it.

And it isn't always just for a rest or a breather that players go down.

I once ran on to the pitch at Wolves in a midweek Carling Cup game to help a player who needed the toilet, but couldn't wait the 20 minutes that was left until half-time.

Perhaps he'd had one too many isotonic drinks in the build up, so my medical bag and myself were used as a human shield to spare the player from having to leave the field to go to the toilet.

It was a good job that it was a Carling Cup game and one side of the stadium was completely closed!

Ice cold water and ice sprays in your medial bags should form part of your medical equipment in grassroots sport. The effect of both is very limited but its better to have a limited effect than nothing at all.