Table 2 Effects of caffeine on resistance exercise, jumping, and sprinting performance: results from the two-way, repeated-measures ANOVA
Variable | AA genotype (placebo) | AA genotype (caffeine) | AC/CC genotypes (placebo) | AC/CC genotypes (caffeine) | Main effect for genotype p-value | Main effect for caffeine p-value | Genotype × caffeine interaction effect p-value | Effect size for condition and its 95% CI |
|---|---|---|---|---|---|---|---|---|
Movement velocity and power in the bench press with different loads | ||||||||
 MP at 25% 1RM (W) | 1892 ± 299 | 2012 ± 325 | 2152 ± 501 | 2279 ± 517 | 0.139 | 0.001 | 0.918 | 0.29 (0.12, 0.46) |
 MV at 25% 1RM (m/s) | 1.41 ± 0.12 | 1.44 ± 0.14 | 1.46 ± 0.16 | 1.49 ± 0.15 | 0.411 | 0.035 | 0.566 | 0.20 (0.02, 0.39) |
 PP at 25% 1RM (W) | 3287 ± 374 | 3409 ± 384 | 3598 ± 688 | 3703 ± 804 | 0.215 | 0.033 | 0.868 | 0.20 (0.03, 0.37) |
 PV at 25% 1RM (m/s) | 2.21 ± 0.18 | 2.27 ± 0.18 | 2.31 ± 0.20 | 2.35 ± 0.17 | 0.244 | 0.008 | 0.806 | 0.26 (0.07, 0.46) |
 MP at 50% 1RM (W) | 1182 ± 145 | 1217 ± 154 | 1279 ± 214 | 1333 ± 249 | 0.196 | 0.008 | 0.545 | 0.22 (0.06, 0.39) |
 MV at 50% 1RM (m/s) | 0.94 ± 0.08 | 0.97 ± 0.08 | 0.96 ± 0.11 | 0.98 ± 0.10 | 0.711 | 0.019 | 0.955 | 0.21 (0.02, 0.42) |
 PP at 50% 1RM (W) | 1979 ± 201 | 2036 ± 220 | 2122 ± 394 | 2203 ± 406 | 0.228 | 0.090 | 0.753 | 0.21 (− 0.03, 0.46) |
 PV at 50% 1RM (m/s) | 1.41 ± 0.09 | 1.43 ± 0.09 | 1.44 ± 0.18 | 1.48 ± 0.16 | 0.468 | 0.031 | 0.489 | 0.23 (0.03, 0.45) |
 MP at 75% 1RM (W) | 789 ± 144 | 838 ± 151 | 849 ± 148 | 928 ± 198 | 0.281 | <  0.001 | 0.229 | 0.36 (0.19, 0.56) |
 MV at 75% 1RM (m/s) | 0.56 ± 0.07 | 0.60 ± 0.07 | 0.58 ± 0.10 | 0.63 ± 0.10 | 0.618 | <  0.001 | 0.514 | 0.48 (0.27, 0.72) |
 PP at 75% 1RM (W) | 1210 ± 238 | 1289 ± 233 | 1369 ± 207 | 1453 ± 293 | 0.128 | 0.007 | 0.940 | 0.31 (0.10, 0.54) |
 PV at 75% 1RM (m/s) | 0.80 ± 0.12 | 0.88 ± 0.09 | 0.86 ± 0.17 | 0.91 ± 0.17 | 0.433 | <  0.001 | 0.243 | 0.50 (0.26, 0.77) |
 MP at 90% 1RM (W) | 501 ± 128 | 582 ± 132 | 588 ± 109 | 675 ± 143 | 0.103 | <  0.001 | 0.850 | 0.61 (0.31, 0.93) |
 MV at 90% 1RM (m/s) | 0.33 ± 0.06 | 0.38 ± 0.07 | 0.38 ± 0.12 | 0.43 ± 0.09 | 0.182 | <  0.001 | 0.909 | 0.57 (0.28, 0.89) |
 PP at 90% 1RM (W) | 821 ± 225 | 970 ± 231 | 994 ± 301 | 1165 ± 308 | 0.099 | <  0.001 | 0.789 | 0.57 (0.25, 0.91) |
 PV at 90% 1RM (m/s) | 0.50 ± 0,09 | 0.59 ± 0.11 | 0.59 ± 0.18 | 0.67 ± 0.13 | 0.117 | <  0.001 | 0.966 | 0.59 (0.27, 0.95) |
Muscle endurance test | ||||||||
 Maximum repetitions at 85% 1RM | 6.8 ± 2.3 | 8.2 ± 2.2 | 7.8 ± 2.4 | 8.8 ± 2.2 | 0.397 | <  0.001 | 0.454 | 0.53 (0.27, 0.81) |
 MP matched for repetitions (W) | 376 ± 86 | 449 ± 96 | 476 ± 122 | 531 ± 159 | 0.074 | <  0.001 | 0.406 | 0.53 (0.31, 0.79) |
 MV matched for repetitions (m/s) | 0.25 ± 0.04 | 0.30 ± 0.04 | 0.30 ± 0.05 | 0.33 ± 0.04 | 0.034 | <  0.001 | 0.094 | 0.85 (0.50, 1.25) |
 PP matched for repetitions (W) | 607 ± 178 | 674 ± 187 | 741 ± 297 | 808 ± 300 | 0.201 | <  0.001 | 0.994 | 0.27 (0.14, 0.41) |
 PV matched for repetitions (m/s) | 0.38 ± 0.06 | 0.43 ± 0.05 | 0.44 ± 0.09 | 0.48 ± 0.08 | 0.108 | <  0.001 | 0.198 | 0.51 (0.28, 0.77) |
CMJ | ||||||||
 CMJ vertical jump height (cm) | 34.8 ± 6.2 | 35.6 ± 5.9 | 36.6 ± 5.2 | 37.6 ± 5.4 | 0.447 | 0.017 | 0.752 | 0.15 (0.03, 0.28) |
Wingate | ||||||||
 PP in the Wingate test (W) | 874 ± 208 | 943 ± 197 | 864 ± 273 | 954 ± 260 | 0.998 | <  0.001 | 0.542 | 0.33 (0.16, 0.52) |
 MP in the Wingate test (W) | 583 ± 77 | 614 ± 67 | 606 ± 120 | 646 ± 132 | 0.517 | <  0.001 | 0.583 | 0.35 (0.20, 0.52) |
 MinP in the Wingate test (Watts) | 338 ± 108 | 372 ± 79 | 350 ± 109 | 414 ± 114 | 0.505 | 0.011 | 0.396 | 0.44 (0.09, 0.81) |