Percentage of time before and after theophylline administration spent in the different physical activity phases
| Physical activity | Before | After | p Value |
| Level 0 | 74.8 | 75.0 | 0.75 |
| Level 1 | 15.6 | 14.9 | 0.81 |
| Level 2 | 6.4 | 6.5 | 0.70 |
| Level 3 | 2.5 | 3.5 | 0.06 |
Data are expressed as means.