Heart Rate (Beats per Minute) Obtained During Scans Using 4 Levels of Plasma Caffeine Concentration
| Plasma caffeine concentration (mg/L) | ||||
|---|---|---|---|---|
| PCC | ≤1 | 1 < x ≤ 3 | 3 < x ≤ 5 | >5 |
| Rest | ||||
| Women | 62.4 ± 10.8 (31) | 51.4 ± 7.3* (31) | 68.0 ± 14.3 (6) | 60.9 ± 10.6 (29) |
| Men | 60.2 ± 13.0 (38) | 53.8 ± 12.1 (12) | 55.7 ± 9.0† (14) | 60.1 ± 9.3 (14) |
| Stress | ||||
| Women | 92.5 ± 14.4 | 79.3 ± 23.6* | 91.5 ± 9.7 | 78.2 ± 15.2* |
| Men | 80.9 ± 19.7† | 73.3 ± 18.8 | 74.4 ± 15.8† | 70.6 ± 13.2 |
* Significant variations in the heart rate between the baseline scans (plasma caffeine concentration < 1 mg/L) and studies with increased plasma caffeine concentrations.
↵†Intersex differences in the heart rate observed for the respective plasma caffeine concentrations.
Numbers given in parentheses for the rest scans indicate the number of MPI sessions fulfilling the criteria. Differences were considered significant for P < 0.05.
PCC = plasma caffeine concentration.