Melbourne Heart recruit John Aloisi admits constant travel can really have a detrimental effect on a players game.

The former Sydney FC striker was speaking of the problem that the Australian national team currently has with its key senior players under injury clouds leading into the World Cup later this year.

Aloisi believes it becomes a lot harder to get your body right as you get older and travelling definitely makes things even tougher on top of the physicality of the game.

"It catches up with you, especially the travelling - that's what kills players," Aloisi said. "As you get older the body can't recover as you put it under pressure.

"People don't realise what effect travel has on you, especially in situations such as some qualifiers where you travel round the world, play, fly back and play again immediately for your club.

"Especially muscle injuries can be put down to the workload - getting two weeks off between seasons just doesn't give you time to recover, when other players are getting two months off."

Aloisi, who was a member of the Socceroos' 2006 squad that did so well in Germany, admits that that particular group of players were better off than this lot mainly due to the fact that the more important players were four years younger back then and at the peak of their powers.

"Players at the last World Cup were fresher and younger, and not only that but Guus Hiddink could maybe take a risk pushing one or two of the older players as he had some younger guys to come in," he said.

"This time around the older players are the key ones. I just don't know if you could put them through the same routine as 2006."