ROBERT Harvey has got a lot to answer for. So does Michael Tuck. And Kevin Bartlett. Craig Bradley and Simon Madden too.

Together they have created problems for a lot of footballers. Not just by their undoubted skill and ability on the field but because of their amazing durability and longevity within their careers. They have blazed trails that every veteran footballer looks to for inspiration.

Harvey, in particular, as the contemporary peer, inspires every veteran footballer to find a way to last beyond accepted barriers. He has defied common logic to perform in an environment that so many players are unable to endure.

Harvey will turn 37 next month and is still going strong, prompting his captain, Nick Riewoldt, to declare that he should continue next year.

He racked up 30 possessions in a game for the 118th time last week; he is a freak and, as such, is an exception to the rule. We would all like to be like Rob, but the reality is we can't.

Life as a professional footballer beyond the age of 30 is like the twilight zone. Just when players think they have got a handle on the game, everything changes.

Of course, 30 is just a number but for those who get there with their professional careers intact, it means so much more than that.

Invariably those that achieve the "honour" of reaching this twilight zone are elite players, high performers within a tough business. They share experiences within the game that few players amass but they pay a price for that knowledge.

After enduring over 10 years and 200-plus games at the top level, even the luckiest player carries the scars from the wear and tear of the game's demands.

Not all of them are visible, but they are there all the same. The body changes and adapts to the demands placed on it. Injuries carried through previous seasons create imbalances that are difficult to rehabilitate.

Towards the end of a long and steady career, it is not illogical to expect that the slow and gradual climb that every player embarks upon from a first-year player is replicated on the way back down to retirement.

It simply does not happen. The gradual drop-off that every player hopes for is more like a cliff than a slippery slide and inevitably players just fall off it.

The game continues progressing at warp speed. It becomes quicker and more demanding every season and as the physical requirements "trend up", a mature footballer's physical capabilities "trend down". Ultimately, something has to give and it ain't the game that we play.

This concept is all very real for me because I spent the last four years of my career in this phase and I can see the challenges that players go through in a similar situation.

During the week, we learnt of a setback in Scott West's rehabilitation from his stress-related knee injury. He has been as durable in this game as any and he now faces a battle to be fit for the Bulldogs' finals tilt.

When I say fit I don't mean aerobically; that's a given. The fitness I speak of is reducing pain and rehabilitating his body to enable him to compete. We all know if he gets out there fit and sound, he performs, so the battle will be won and lost in the medical room.

Likewise, Nigel Lappin has been as reliable as any in his time at the Bears and the Lions. He has played with and through some debilitating injuries and has a well-known capacity to buffer pain.

His Achilles tendon injury has sidelined him since round four and, like West, he has been unable to get fit enough to return to the game.

During this season we have already seen a few drop off the cliff. David Neitz's body gave up on him, perhaps Matthew Carr's did the same at 29 and Fraser Gehrig is clinging to the edge with arthritic hands.

The challenges for "veterans" within the game are little different to any player, other than the fact that their time is running out. As a player's body ages they are in fact working from an increasingly compromised preparation to produce an output that is below their career best.

They can still contribute well to the team but the blue sky of their youth has gone and they become a known quantity; no longer potential but actual; no longer a rising star but a fading one. But still within all this reality, these players can and do have a great impact on the best performance of their teams.

Look at Richo play his best football at the age of 33, Aka turn matches for the Doggies at 31, Michael O'Loughlin at 31, Scott Burns, Adam Simpson, Dustin Fletcher, Andrew McLeod, Tyson Edwards etc.

All of these players are nearing the end of their careers (and the edge of that cliff) but while they are up and about, their contributions are immeasurable to their respective teams. Their leadership, experience and undoubted ability is a heady mix of attributes that every club needs and every coach wants.

The worst-case scenario is worth the risk when the upside is so good.

So when another certain 30-something player becomes available at the end of this year, would you want your club to take him? As he said in his interview during the week, why wouldn't they?

Ben Cousins has had the best part of two years out of the game but we know how physically fit he is. He can play the game and will star for at least a year or two; he might even do another Harvey and be a five-year prospect.

Then again, there is more than one cliff to consider on the Ben Cousins horizon and only one guy has the answers to that.