Table 1.
Descriptive characteristics of the study population at baseline in each study phase, mean±SD or N (%)
| Characteristic | Historical (n=56) | Pilot (n=66) | Intervention (n=78) |
| Observations* | 102 | 166 | |
| Age (years) | 19.2±1.3 | 18.9±1.1 | 18.8±1.1 |
| Time at risk for BSI† (years) | 0.9±0.2 | 0.9±0.2 | 0.9±0.2 |
| Total follow-up time‡ (years) | 1.0±0.1 | 1.0±0.1 | 0.9±0.1 |
| School | |||
| Institution 1 | 36 (64.3%) | 31 (47.0%) | 34 (43.6%) |
| Institution 2 | 20 (35.7%) | 35 (53.0%) | 44 (56.4%) |
| Academic year | |||
| Freshman | 29 (51.8%) | 34 (51.5%) | 47 (60.3%) |
| Sophomore | 5 (8.9%) | 16 (24.2%) | 11 (14.1%) |
| Junior | 14 (25.0%) | 7 (10.6%) | 11 (14.1%) |
| Senior | 6 (10.7%) | 8 (12.1%) | 8 (10.3%) |
| Graduate | 2 (3.6%) | 1 (1.5%) | 1 (1.3%) |
| Race§ | |||
| White | - | 40 (60.6%) | 53 (68.0%) |
| Black | - | 5 (7.6%) | 5 (6.4%) |
| Asian | - | 2 (3.0%) | 2 (2.6%) |
| American Indian | - | 0 (0.0%) | 0 (0.0%) |
| More than one race | - | 5 (7.6%) | 2 (2.6%) |
| Unknown/not reported | - | 8 (12.1%) | 8 (10.3%) |
| Missing | 6 (9.1%) | 8 (10.3%) | |
| Total CRA Score¶ | 2.2±1.9 | 3.1±2.0 | 3.0±2.2 |
| Current miles (per week) | - | 46.2±17.2 | 41.1±15.4 |
| BMI (kg/m†) | 19.9±1.6 | 19.9±1.6 | 20.0±1.4 |
*Participants who had remaining athletic eligibility at the end of the historical or pilot phase were rolled over into the next phase of the study. No participants were enrolled in both the historical and intervention phases.
†Time at risk subtracts time off due to BSI recovery.
‡Total follow-up time does not subtract out the time due to BSI recovery.
§Data on race could not be determined from the historical phase.
¶CRA Score was measured differently in the historical phase and represents an approximation. We did not have dual energy X-ray absorptiometry scans to measure bone mineral density and low energy availability was approximated based on survey questions on nutrition.
BMI, body mass index; BSI, bone stress injury ; CRA, Cumulative Risk Assessment.