Mount Annan Leisure Centre manager Craig Lambeth said it wasn't so much a summer trend as a ``new start''.

``There is certainly an influx people get back into their routine after a fairly enjoyable Christmas period,'' he said.

He said memberships and inquiries at the Welling Drive centre which had about 2000 members were up about 15 per cent over the warmer months.

Plus Fitness managing director John Fuller said: ``I think people are more conscious of their body image (in summer)''.

``Fitness in Macarthur is alive and well.''

So well, in fact, that Plus Fitness which has about 3000 members recorded 160 new memberships at their Camden and Narellan gyms in the last two weeks of January.

In the first three days of February (Monday to Wednesday), 173 potential gym junkies had booked appointments.

``We've been so overwhelmed by the interest in the Macarthur area, that we've committed to building a brand new fitness and aquatic centre,'' Mr Fuller said.

``It's expected to be complete in June 2010.''