They were randomized into 4 groups-150 patients ( age : 42.5 12.7 ) performed strengthening exercises ; 150 patients ( age : 41.3 11.5 ) performed flexibility exercises ; 150 patients ( age : 41.0 13.2 ) performed strengthening exercises and used abdominal bracing in daily activities/exercises ; and 150 patients ( age : 40.6 12.3 ) performed flexibility exercises and used abdominal bracing in daily activities/exercises .