If you want to pit a Sydneysider against his fellow citizen, try uttering the words ''personal trainers in parks'' and watch the spittle fly.

In the increasingly blurred zone between public and private, nothing, it seems, divides the city like a lycra-clad Adonis with a stopwatch giving orders to grunting, paying customers in a communal park.

"Indulgent thing to do": Garry Egger on personal training. Credit:Darren Pateman

Fitness expert Garry Egger brought tensions to a head this week when he described personal training as a ''middle-class, indulgent thing to do''.

Egger, who wrote Australia's physical activity guidelines in 1999, urged councils to crack down on operators who ''interfere with other people's right to common recreational services''.