What is the sociologist's, anthropologist's and psychologist's explanation for why Elaine joined the soccer team?

Story:

Elaine Spira is a Grade 11 student in an Ottawa high school. She is an excellent student and has some good friends. Her mother is disabled, and she has a brother who is in grade 3. Her father works long hours, and the family has come to rely on her to look after her brother and do a number of household chores on a regular basis. Elaine felt that she needed to do some sort of extracurricular activity after school because she was having problems with academic and family stress. Her mother's brother has just moved back to the area and is living with the family. He has offered to take over some of Elaine's responsibilities in excnanqe for free rent. Elaine is not at all artistic, but has always been strong and well-coordinated. She decided to try out for the Junior Girl's soccer team, as she liked the sport. She just made the team and, although she is not a starter, she has had regular playing time. Her skills have improved as the season has progressed. Elaine's stress problems have been reduced with the regular exercise she is getting. She is considering trying out for one of the indoor teams (volleyball or basketball) next year.