Table 4.
Means ± standard deviations and RM-ANCOVA statistics (covariate: habitual caffeine consumption) for the different perceptual responses across the experimental trials of study 1 (2.5 mg*kg−1 caffeine). CAF: 2.5 mg*kg−1 caffeine, PLA: placebo, START: rating 1 min after start, PRE-EX: last rating during the trial, individual sampling time defined by the shortest individual trial, EX = rating at exhaustion.
| Study 1 (2.5 mg*kg−1) | Time point |
ANCOVA statistics |
|||||
|---|---|---|---|---|---|---|---|
| Condition | START | PRE-EX (iso-time) | EX | Effect of condition | Effect of time point | Effect of condition × time point | |
| Perceived fatigue (0–10) | CAF | 3.5 ± 1.8 | 8.3 ± 1.2 | 9.2 ± 1.0 | F(1,33) = 1.095, p = 0.303, ηp2 = 0.032 | F(1.4,46.7) = 95.183, p < 0.001, ηp2 = 0.743 | F(2,66) = 0.381, p = 0.685, ηp2 = 0.011 |
| PLA | 3.3 ± 1.7 | 7.9 ± 1.4 | 9.1 ± 1.0 | ||||
| Effort (6–20 BORG Scale) | CAF | 11.3 ± 2.3 | 17.5 ± 2.0 | 19.5 ± 1.1 | F(1,33) = 0.233, p = 0.632, ηp2 = 0.007 | F(1.6,52.6) = 100.468, p < 0.001, ηp2 = 0.753 | F(2,66) = 0.036, p = 0.965, η2p = 0.001 |
| PLA | 11.4 ± 2.1 | 17.4 ± 2.0 | 19.3 ± 1.2 | ||||
| Physical strain (6–20 BORG Scale) | CAF | 10.3 ± 2.1 | 16.7 ± 2.0 | 18.7 ± 1.2 | F(1,33) = 2.555, p = 0.120, ηp2 = 0.072 | F(1.7,54.8) = 122.539, p < 0.001, ηp2 = 0.788 | F(2,66) = 0517, p = 0.599, ηp2= 0.015 |
| PLA | 10.4 ± 2.1 | 16.5 ± 1.9 | 18.4 ± 1.0 | ||||
| Affective valence (+5 – −5) | CAF | 2.5 ± 1.2 | −1.2 ± 2.1 | −2.2 ± 2.1 | F(1,33) = 0.517, p = 0.477, ηp2 = 0.015 | F(1.5,48.4) = 64.945, p < 0.001, ηp2p2 = 0.663 | F(2,66) = 1.337, p = 0.270, ηp2= 0.039 |
| PLA | 2.4 ± 1.3 | −1.0 ± 2.1 | −2.0 ± 2.3 | ||||
| Arousal (1–6) | CAF | 3.7 ± 1.1 | 4.8 ± 1.0 | 4.9 ± 1.2 | F(1,33) = 1.953, p = 0.172, ηp2 = 0.056 | F(1.3,42.3) = 3.727, p = 0.029, ηp2 = 0.101 | F(2,66) = 0.390, p = 0.679, ηp2 = 0.012 |
| PLA | 3.9 ± 1.0 | 4.9 ± 1.2 | 4.9 ± 1.2 | ||||
| Dominance/control (0–10) | CAF | 7.2 ± 1.5 | 4.8 ± 2.1 | 3.7 ± 2.4 | F(1,33) = 0.044, p = 0.835, ηp2 = 0.001 | F(1.5,47.9) = 130.438, p < 0.001, ηp2 = 0.561 | F(2,66) = 0.020, p = 0.980, ηp2= 0.001 |
| PLA | 7.1 ± 1.4 | 4.7 ± 2.1 | 3.6 ± 2.1 | ||||
| Boredom (0–10) | CAF | 1.5 ± 1.7 | 0.9 ± 1.6 | 0.9 ± 1.7 | F(1,33) = 0.005, p = 0.941, ηp2 < 0.001 | F(1.5,51.0) = 3.505, p = 0.049, ηp2 = 0.096 | F(2,66) = 0.219 p = 0.804, ηp2 = 0.007 |
| PLA | 1.3 ± 1.7 | 1.2 ± 2.1 | 0.5 ± 1.0 | ||||
| Motivation (0–10) | CAF | 7.1 ± 1.8 | 4.4 ± 2.4 | 3.6 ± 2.6 | F(1,33) = 0.322, p = 0.574, ηp2 = 0.010 | F(1.5,49.5) = 28.184, p < 0.001, ηp2 = 0.461 | F(2,66) = 1.206, p = 0.306, ηp2= 0.035 |
| PLA | 7.2 ± 1.3 | 4.7 ± 2.2 | 4.1 ± 2.7 | ||||
| Attentional focus (0–100) | CAF | 56.6 ± 21.7 | 80.0 ± 16.4 | 90.0 ± 13.3 | F(1,33) = 0.327, p = 0.571, ηp2η = 0.010 | F(1.3,41.5) = 17.312, p < 0.001, ηp2 = 0.344 | F(1.6,53.0) = 1.359, p = 0.263, ηp2 = 0.040 |
| PLA | 56.9 ± 26.8 | 84.3 ± 14.2 | 94.0 ± 6.9 | ||||
| Decisional conflict (0–10) | CAF | 1.6 ± 1.5 | 7.2 ± 2.1 | 8.7 ± 1.4 | F(1,33) = 0.657, p = 0.423, ηp2 = 0.020 | F(1.5,50.4) = 151.328, p < 0.001, ηp2 = 0.821 | F(1.6,53.8) = 1.152, p = 0.315, ηp2 p2 = 0.034 |
| PLA | 1.4 ± 1.6 | 6.5 ± 2.5 | 8.8 ± 1.5 | ||||