Characteristics of adolescent athletes in Spring 2020 and Spring 2021
| Variable | 2020 (n=13 002) | 2021 (n=4419) | P value |
| Sex (male) | 6117 (47.0%) | 2106 (47.9%) | 0.338 |
| Age (years)* | 16.3 (1.2) | 16.1 (1.3) | <0.001 |
| Grade (%) | <0.001 | ||
| 9th | 3089 (23.8) | 1209 (27.4) | |
| 10th | 3419 (26.3) | 1103 (25.0) | |
| 11th | 3743 (28.8) | 1161 (26.3) | |
| 12th | 2751 (21.2) | 946 (21.4) | |
| Region* (%) | <0.001 | ||
| Midwest | 9124 (70.2) | 2935 (66.4) | |
| Northeast | 279 (2.1) | 440 (10.0) | |
| Southeast | 946 (7.3) | 349 (7.9) | |
| Southwest | 146 (1.1) | 393 (8.9) | |
| West | 2507 (19.3) | 302 (6.8) | |
| School enrolment* | 864 (412–1515) | 793 (358–1382) | <0.001 |
| Funding—public (%) | 11 327 (87.3) | 3896 (88.2) | 0.152 |
| County poverty (%) | 11.6 (4.2) | 11.5 (4.8) | 0.019 |
| County under 18-year poverty (%) | 15.1 (6.5) | 14.9 (7.6) | 0.362 |
| County median house income* | 63 653 (14 318) | 66 101 (17 007) | <0.001 |
| Number of high school sports | 1.9 (0.8) | 1.9 (0.9) | 0.815 |
| Number of total sports* | 2.7 (1.1) | 2.2 (1.2) | <0.001 |
| Sport type* (%) | <0.001 | ||
| Individual | 2252 (17.3) | 922 (20.9) | |
| Team | 6257 (48.1) | 2578 (58.3) | |
| Both | 4493 (34.6) | 919 (20.8) |
Data presented as mean (SD) or n (%).
*Variables included as inverse propensity score weight in models comparing outcomes in the two groups.