Comparison of participant characteristics between sport specialisation groups (n=946)
| Characteristic | Sport-specialised athletes (n=759) | Non-sport-specialised athletes (n=187) | P value | ||
| Freq. | (%) | Freq. | (%) | ||
| Gender (% male) | 304 | (40%) | 109 | (58%) | <0.001 |
| Age | 14.2 | ± 2.91 | 13.4 | ± 3.22 | 0.002 |
| Median income | 0.05 | ||||
| Lower-middle | 69 | (9%) | 12 | (6%) | |
| Upper-middle | 571 | (75%) | 136 | (73%) | |
| High | 119 | (16%) | 39 | (21%) | |
| White (n=916)* | 633 | (86%) | 161 | (88%) | 0.56 |
| Medical history | |||||
| Asthma | 141 | (19%) | 29 | (16%) | 0.33 |
| ADD/ADHD | 73 | (10%) | 18 | (10%) | 1.00 |
| Anorexia/bulimia | 3 | (0%) | 1 | (1%) | 0.79 |
| Anxiety | 51 | (7%) | 14 | (8%) | 0.71 |
| Depression | 22 | (3%) | 5 | (3%) | 0.87 |
| Diabetes | 3 | (0%) | 1 | (1%) | 0.79 |
| Migraine | 45 | (6%) | 12 | (6%) | 0.80 |
| Sport | |||||
| Contact sport | 588 | (78%) | 175 | (94%) | <0.001 |
| Limited-contact | 184 | (24%) | 73 | (39%) | <0.001 |
| Non-contact | 320 | (42%) | 70 | (37%) | 0.24 |
| Cigarette use (n=663)* | 1 | (0%) | 0 | (0%) | 0.36 |
| Alcohol use (n=662)* | 78 | (14%) | 18 | (16%) | 0.73 |
| Reported legal PES use | 117 | (15%) | 19 | (10%) | 0.09 |
| Consideration of banned PES use | 26 | (3%) | 2 | (1%) | 0.14 |
| Age started organised sports | 5 | (4-6) | 5 | (4-6) | 0.28 |
| Relative is a coach | 78 | (10%) | 35 | (19%) | <0.001 |
| Number of seasons with coach | 0 | (0–0) | 0 | (0–2) | <0.001 |
| Unrestricted internet access | 408 | (54%) | 76 | (41%) | 0.001 |
| Reason for playing sports | 0.001 | ||||
| To have fun | 391 | (52%) | 119 | (64%) | |
| Stay fit | 64 | (8%) | 19 | (10%) | |
| Make friends | 11 | (1%) | 1 | (1%) | |
| Win a championship | 69 | (9%) | 8 | (4%) | |
| Be part of a team | 111 | (15%) | 27 | (14%) | |
| To be strong | 18 | (2%) | 3 | (2%) | |
| To make parents happy | 2 | (0%) | 1 | (1%) | |
| Unspecified | 93 | (12%) | 9 | (5%) | |
| Use of weight training regimen | 341 | (45%) | 57 | (31%) | <0.001 |
| Belief that athletic ability is influenced by weight | 370 | (49%) | 83 | (44%) | 0.29 |
| History of intentional weight loss | 150 | (20%) | 35 | (19%) | 0.75 |
| History of intentional weight gain | 99 | (13%) | 19 | (10%) | 0.29 |
| Weeknight hours of sleep | 8 | ± 1.22 | 8.4 | ± 1.31 | 0.001 |
| Weekend hours of sleep | 9.1 | ± 1.29 | 9.3 | ± 1.29 | 0.23 |
*The number in parentheses represents the number of cases with available data for the given characteristic.
PES, performance-enhancing substances.