Single and multiple factor predictors of low BMD
| Low BMD | ||
|---|---|---|
| Occurrence (%)/N | OR (95% CI) | |
| One-variable risk factor | ||
| Runner (vs non-runner) | 23.5 (12) | 5.2 (0.6 to 43.5) |
| <85% Expected weight† | 32.3 (10) | 5.6 (1.4 to 22.5)* |
| Low BMI <18.5 kg/m2 | 30.8 (4) | 2.3 (0.6 to 9.2) |
| BMI Z-score <−1.0 | 50.0 (6) | 7.0 (1.8 to 27.9)* |
| Stress fracture‡ | 37.5 (3) | 3.2 (0.6 to 15.8) |
| <1 serving calcium§ | 42.9 (3) | 3.9 (0.8 to 20.2) |
| Cumulative mileage (>30)¶ | 50.0 (5) | 6.4 (1.5 to 27.1)* |
| No ball sport history** | 28.6 (2) | 1.9 (0.3 to 10.8) |
| Two-variable risk factors | ||
| Stress fracture +<85% expected weight | 50.0 (3) | 5.6 (1.0 to 32.0) |
| Cumulative mileage (>30) +BMI Z-score <−1.0 | 60.0 (3) | 8.0 (1.2 to 53.8)* |
| Cumulative mileage (>30) +<85% expected weight | 62.5 (5) | 11.0 (2.2 to 55.4)* |
| <85% Expected weight +<1 serving of calcium | 75.0 (3) | 16.5 (1.6 to 175.0)* |
| Cumulative mileage (>30) + stress fracture | 75.0 (3) | 17.3 (1.6 to 185.6)* |
| Three-variable risk factors | ||
| Cumulative mileage (>30) +<85% expected weight + stress fracture | 75.0 (3) | 17.3 (1.6 to 185.6) |
| Runner +<85% expected weight +<1 serving of calcium | 75.0 (3) | 16.5 (1.6 to 175.0) |
Logistic regression analysis (OR (95% CI)); χ2 analysis (occurrence), *p< 0.05.
†Expected weight calculated using the Hamwi formula.
‡History of sustaining one or more stress fractures.
§Intake of less than one serving of a calcium-rich food per day.
¶Reported running an average of >30 miles per week over the past year.
**Athlete did not report history of participation in soccer or basketball prior to age 14.
BMI, body mass index; BMD, bone mineral density.