Averaged Percentage Heart Rate (HR) Increase and Systolic and Diastolic Blood Pressures (BP) Versus Range of Serum Caffeine Levels
| Caffeine level (mg/L) | 0 | 0–0.5 | 0.5–1.0 |
| HR increase (%) | 17.6 ± 9.2 | 16.3 ± 8.9 | 11.0 ± 4.5 |
| Systolic BP (mm Hg) | −4.6 ± 19 | −3.7 ± 8.6 | −4.0 ± 8.9 |
| Diastolic BP (mm Hg) | −0.2 ± 11 | −4.3 ± 10 | −2.0 ± 4.5 |