Roller derby doesn't rate a mention in many child-rearing manuals, but young mothers in western Sydney are prominent among women flocking to the booming contact sport.
"I loved the physicality particularly after the pregnancy,'' said Peta Wilson, of Penrith. ''I love having a challenge at 33."
Ms Wilson (derby name Zoe Da Belle) a mother of two, joined derby when her first child was one, after seeing Drew Barrymore's feel-good film Whip It.
The Western Sydney Rollers, who began 3½ years ago with just a dozen members, this year boast four teams, of which the newest - The Zombees - made its debut last week.
A few hundred people come to watch at Penrith Valley Regional Sports Centre in Cambridge Park, but longer-established leagues attract bigger crowds.
The roller derby boom in the outer suburbs reflects a nationwide trend, with more than 80 leagues operating, of which 29 are in NSW.
Combining athletic competition, grand theatrics and a tough-girl philosophy, roller derby is run entirely by players.
Leonie Simpson (derby name Barge Simpson), 39, is the club's acting president and organises the ''fresh meat'' intake of recruits. She remembers when her fledgling team struggled to secure enough players for a game - now she is turning applicants away.
She attributes the sport's popularity in the west to its inclusiveness. The club's players include women of all shapes and sizes, ranging in age from 20 to 47.
"We're also more family oriented, it's a bit different out west - we know people are mums."
Caillie Bost, 37, ( ''Cail Storm'') is a nurse and mother of two young boys. She joined roller derby just over a year ago and juggles a hectic schedule that includes four to six hours of training a week.
"I need the balance to keep me sane, to keep me healthy as a mum," she said. "It's a great culture to be part of, it's family-friendly and people come from all walks of life."
The sport itself is far from friendly - Ms Bost was out of derby for two months after sustaining a knee ligament injury.
The roller derby revival began in 2001 in Austin, Texas and has spread across the world. Each team has five members who dress in eye-catching outfits and adopt derby alter egos for the bouts.
Two ''jammers'', or point scorers, distinguishable by the stars on their helmets, must overtake the opposing team's four blockers, who try to stop them using moves such as the ''booty block'', ''shoulder barge'' and ''can opener''.
Do you play Roller Derby now, or would you consider it? Comment below or join the conversation in the Essential Baby forum.