TABLE 5.
Mediation analysis for male bone outcomes.
| β | SE | P | |
|---|---|---|---|
| BSI (mg2/mm4) | |||
| Sport Group to VJ (a path) | 6.964 | 1.861 | <.001 |
| Direct Effects of VJ on BSI (b path) | 1.254 | 0.300 | <.001 |
| Total effect of Sport Group on BSI (c path) | 21.298 | 5.900 | <.001 |
| Direct Effect of Sport Group on BSI (c’ path) | 12.568 | 5.836 | 0.034 |
| Indirect Effects of Sport Group on BSI through VJ (ab)* | 8.733 | 3.257 | 41.0%* |
| Bias-corrected 95% CI from bootstrapping | 3.583 | 16.839 | . |
| SSIp (mm3) | |||
| Sport Group to VJ (a path) | 6.523 | 1.840 | <.001 |
| Direct Effects of VJ on SSIp (b path) | 11.540 | 3.654 | 0.002 |
| Total effect of Sport Group on SSIp (c path) | 136.021 | 69.214 | 0.052 |
| Direct Effect of Sport Group on SSIp (c’ path) | 60.752 | 70.377 | 0.390 |
| Indirect Effects of Sport Group on SSIp through VJ (ab)* | 75.269 | 34.079 | 55.3%* |
| Bias-corrected 95% CI from bootstrapping | 22.659 | 158.15 | . |
| Hip aBMD (g/cm2) | |||
| Sport Group to VJ (a path) | 6.628 | 1.877 | <.001 |
| Direct Effects of VJ on aBMD (b path) | 0.005 | 0.001 | <.001 |
| Total effect of Sport Group on aBMD (c path) | 0.137 | 0.027 | <.001 |
| Direct Effect of Sport Group on aBMD (c’ path) | 0.103 | 0.027 | <.001 |
| Indirect Effects of Sport Group on aBMD through VJ (ab)* | 0.034 | 0.015 | 24.7%* |
| Bias-corrected 95% CI from bootstrapping | 0.012 | 0.073 | . |
| FN Z (cm3) | |||
| Sport Group to VJ (a path) | 6.628 | 1.877 | <.001 |
| Direct Effects of VJ on BSI (b path) | 0.015 | 0.004 | <.001 |
| Total effect of Sport Group on FN Z (c path) | 0.290 | 0.084 | <.001 |
| Direct Effect of Sport Group on FN Z (c’ path) | 0.191 | 0.084 | 0.026 |
| Indirect Effects of Sport Group on FN Z through VJ (ab)* | 0.100 | 0.045 | 34.4%* |
| Bias-corrected 95% CI from bootstrapping | 0.036 | 0.221 | . |
| Hip CSA (cm2) | |||
| Sport Group to VJ (a path) | 6.628 | 1.877 | <.001 |
| Direct Effects of VJ on CSA (b path) | 0.026 | 0.007 | <.001 |
| Total effect of Sport Group on CSA (c path) | 0.552 | 0.132 | <.001 |
| Direct Effect of Sport Group on CSA (c’ path) | 0.380 | 0.132 | 0.005 |
| Indirect Effects of Sport Group on CSA through VJ (ab)* | 0.172 | 0.070 | 31.2%* |
| Bias-corrected 95% CI from bootstrapping | 0.061 | 0.360 | . |
*
indicates % of bone outcome mediated by muscle power.
Covariates included in analysis: weight, height, and PAQ-AD score.
BSI, bone strength index; SSIp, density weighted polar section modulus strength-strain index; aBMD, areal bone mineral density; CSA, cross sectional area; FN Z, femoral neck section modulus.