Table 3.
Results of the multiple regression analysis showing the variance in muscle thickness/ratios explained by physical characteristics (gender, age, height, body mass, BMI) of the subjects. Only the significant predictors in the multivariate model are listed
| Dependent variable | Significant predictors | Final standardized beta coefficient (predictor) | Significance of predictor, P-value | Change in R2 for addition of predictor |
|---|---|---|---|---|
| TrA | ||||
| Resting thickness (cm) | Body mass | 0.636 | < 0.0001 | 0.41 |
| Thickness during hollowing (cm) | Body mass | 0.559 | < 0.0001 | 0.31 |
| Difference, rest to hollowing (cm) | BMI | −0.295 | 0.026 | 0.09 |
| TrA contraction ratio | BMI | −0.524 | < 0.0001 | 0.20 |
| Age | 0.251 | 0.047 | 0.06 | |
| TrA preferential activation ratio | BMI | −0.531 | < 0.0001 | 0.28 |
| OI | ||||
| Resting thickness (cm) | Body mass | 0.563 | < 0.0001 | 0.29 |
| Age | −0.264 | 0.020 | 0.07 | |
| Thickness during hollowing (cm) | Body mass | 0.563 | < 0.0001 | 0.32 |
| Difference, rest to hollowing (cm) | Gender | 0.422 | 0.001 | 0.18 |
| OI contraction ratio | Gender | 0.333 | 0.009 | 0.10 |
| Age | 0.299 | 0.018 | 0.09 | |
| OE | ||||
| Resting thickness (cm) | Body mass | 0.547 | < 0.0001 | 0.30 |
| Thickness during hollowing (cm) | Body mass | 0.553 | < 0.0001 | 0.31 |
| Difference, rest to hollowing (cm) | Gender | −0.314 | 0.017 | 0.10 |
| OE contraction ratio | − | − | − | − |
| OE + OI contraction ratio | − | − | − | − |
| Sum TrA + OI + OE | ||||
| Resting thickness (cm) | Body mass | 0.650 | < 0.0001 | 0.42 |
| Thickness during hollowing (cm) | Body mass | 0.663 | < 0.0001 | 0.44 |
TrA, transvs. abdominis; OI, internal oblique abdominis; OE, external oblique abdominis; OE + OI, OE and OI together (see text for details) ‘−’ indicates that none of the physical characteristics assessed was a significant predictor.