Children as young as two are hopping on BMX bikes, climbing rock walls and attempting skateboard manoeuvres in a quest for more adrenalin-pumping pastimes than kicking the footy or going for a swim.

Once the domain of pre-teens and adolescents, extreme sports report an influx of younger participants as the sports become safer and more widely available.

Young and the restless: Two-year-old BMX daredevils (from left) Jackson Fretwell, Isabella Booker, Georgia Murray and Lily-Rose Smith. Credit:Sahlan Hayes

''Extreme sport is seen by kids as cool and by parents as safe,'' Monash University sports lecturer Tom Heenan said. ''It's lost its fear factor.''

The Australian Sports Commission has nominated extreme sport as one of the six strong trends that will impact sport over the next 30 years. Skateboarding, roller sports and rock climbing, for example, will be showcased for the first time at this year's Youth Olympics in Nanjing.