Table 4.
Results of the regression model estimating pain score difference (N=1009)
| Conditional random effects | Variance (95% CI) |
| Participant (intercept) | 9.16 (8.28 to 10.13) |
| Residual | 26.83 |
| Conditional fixed effects | B coefficient (SE) | 95% CI | z-score |
| Intercept | 2.70*** (0.51) | 1.68 to 3.72 | 5.29 |
| Menstrual status | 1.47*** (0.09) | 1.28 to 1.66 | 15.43 |
| Previous-day pain | −0.86*** (0.01) | −0.87 to 0.85 | −143.43 |
| Body mass index (BMI) | 0.05* (0.01) | 0.01 to 0.10 | 2.86 |
| Mean weekly exercise frequency | −0.27** (0.08) | −0.44 to 0.10 | −3.12 |
| Previous-day exercise | 0.92** (0.18) | 0.56 to 1.27 | 5.08 |
| Some college education level | −0.84 (0.62) | −2.11 to 0.42 | −1.35 |
| College or higher education level | −2.07** (0.52) | −3.10 to 1.03 | −3.96 |
| Mean weekly exercise frequency×previous-day exercise | −0.14* (0.06) | −0.26 to 0.01 | −2.22 |
| Zero inflation terms | B coefficient | 95% CI | z-score |
| Intercept | −0.91*** (0.01) | −0.93 to 0.88 | −63.84 |
| Same-day exercise | 0.70*** (0.02) | 0.66 to 0.75 | 32.09 |
Previous day pain and BMI were sample mean centred. BMI and education level were kept as covariates in the model based on their significant associations with mean day-level pain scores (Pearson’s r=0.15 for BMI and Kruskal-Wallis χ2=18.061 for education level, p<0.001).
*P<0.05, **p<0.001, ***p<0.0001.