The fire, at Xercise4less on Sundorne Retail Park, was discovered on Tuesday afternoon and was quickly dealt with before fire service personnel arrived.
The changing rooms were reopened today and repairs to the damaged area are expected to be completed by Saturday.
A spokesperson for Xercise4less said "On Tuesday, there was a small small electrical fire isolated to the ladies changing room. The club completed a full and safe evacuation and the small fire was extinguished before the fire service attended. No other services in the club have been affected and the ladies changing room is now fully operational.
"There has been some minor cosmetic damage to the changing room which will be completed by Saturday."