Dr. Neeru Jayanthi and colleagues at Loyola University Health System near Chicago tracked 891 young athletes. Participants included 618 athletes who sought treatment for sports injuries and 273 uninjured athletes who came in for sports physicals.
Study participants included 124 tennis players, 74 of whom played tennis exclusively.
Among single-sport tennis players, the ones who suffered injuries spent 12.6 hours per week playing organized tennis and only 2.4 hours per week in free play and recreation.
However, by comparison, the uninjured tennis players spent only 9.7 hours per week playing organized sports, and 4.3 hours a week in free play and recreation, even while having a similar total number of weekly hours.
"The findings suggested more participation in a variety of unorganized sports and free play may be protective of injury, particularly among tennis players," Jayanthi said in a statement.
Jayanthi presented the findings at the Society for Tennis Medicine and Science and United States Tennis Association-Tennis Medicine and Injury Conference in Atlanta.