Table 2.
Differences in placebo vs caffeine conditions for the performance outcomes.
| Exercise Test | Outcome | Caffeine Condition (mean ± SD) |
Placebo Condition (mean ± SD) |
d (95% CI) | Relative Effects (%) | p |
|---|---|---|---|---|---|---|
| Squat jump | Jump height (cm) | 31.9 ± 4.9 | 31.0 ± 5.5 | 0.18 (0.03, 0.32) | +2.9 | 0.039 * |
| Countermovement jump | Jump height (cm) | 36.4 ± 6.5 | 35.2 ± 6.5 | 0.18 (0.05, 0.32) | +3.3 | 0.011 * |
| Isokinetic knee extension at 60° s−1 | Peak torque (Nm) | 256.9 ± 44.5 | 240.3 ± 45.6 | 0.37 (0.15, 0.61) | +6.9 | 0.002 * |
| Average power (W) | 193.8 ± 36.9 | 182.3 ± 36.8 | 0.31 (0.13, 0.50) | +6.3 | 0.001 * | |
| Isokinetic knee flexion at 60° s−1 | Peak torque (Nm) | 147.1 ± 24.6 | 140.7 ± 28.7 | 0.24 (0.02, 0.46) | +4.6 | 0.034 * |
| Average power (W) | 118.7 ± 21.0 | 111.3 ± 25.9 | 0.32 (0.01, 0.59) | +6.7 | 0.015 * | |
| Isokinetic knee extension at 180° s−1 | Peak torque (Nm) | 180.2 ± 27.8 | 174.0 ± 31.9 | 0.21 (0.02, 0.40) | +3.5 | 0.031 * |
| Average power (W) | 353.4 ± 57.0 | 338.1 ± 66.6 | 0.25 (0.04, 0.46) | +4.5 | 0.025 * | |
| Isokinetic knee flexion at 180° s−1 | Peak torque (Nm) | 110.0 ± 18.1 | 106.8 ± 20.3 | 0.17 (−0.07, 0.40) | +3.0 | 0.168 |
| Average power (W) | 212.9 ± 38.0 | 205.8 ± 46.7 | 0.17 (−0.04, 0.38) | +3.5 | 0.115 | |
| Bench press at 50% 1RM | Barbell velocity (m·s−1) | 0.83 ± 0.08 | 0.80 ± 0.09 | 0.33 (0.06, 0.61) | +3.5 | 0.021 * |
| Bench press at 75% 1RM | Barbell velocity (m·s−1) | 0.57 ± 0.06 | 0.54 ± 0.07 | 0.42 (0.21, 0.64) | +5.4 | < 0.001 * |
| Bench press at 90% 1RM | Barbell velocity (m·s−1) | 0.39 ± 0.07 | 0.35 ± 0.07 | 0.59 (0.27, 0.89) | +12.0 | < 0.001 * |
| Rowing ergometer test | Peak power (W) | 725.4 ± 133.5 | 715.4 ± 106.4 | 0.08 (−0.27, 0.43) | +1.4 | 0.647 |
SD: standard deviation; d: effect size; CI: confidence interval; * denotes statistically significant differences.