Contractor Williams Tarr has started work on the 26,000 sq ft extension to Fit City in Irlam on behalf of Salford City Council, Salford Community Leisure and Sport England.
The £2.8m project is partly funded by a donation from the Hamilton Davies Trust. The scheme will provide a new sports hall, fitness suite, multi-purpose hall, squash court, changing rooms. There will also be a poolside café and new reception facilities.
The work also provides space for a future coaching classroom on the first floor. External works include an extension to the existing car park to provide 57 additional spaces and a drop-off lay-by and cycle racks for 20 cycles.
John Hughes, director of Williams Tarr, said: "Over the years we have undertaken numerous projects in the area and we currently have five acres of land available for development at Wharfside Avenue."
The work is scheduled for completion in June 2012.