Aerobic gymnastics (formally Sport Aerobics) involves the performance of routines by individuals, pairs, trios or groups up to 6 people, emphasizing strength, flexibility, and aerobic fitness rather than acrobatic or balance skills. Routines are performed for all individuals on a 7x7m floor and also for 12–14 and 15-17 trios and mixed pairs. From 2009, all senior trios and mixed pairs were required to be on the larger floor (10x10m), all groups also perform on this floor. Routines generally last 60–90 seconds depending on age of participant and routine category.