RPE (units) CON DEP-PLA DEP-CAF iEMG ( ) CON DEP-PLA DEP-CAF 47.266.8 45.569.0 39.361.9 52.0620.1 44.766.6 41.361.7 46.169.2 45.269.3 42.962.3 52.5612.6 51.7615.8 44.765.7 11.061.7 10.761.7 10.361.5 12.660.5 12.761.3 12.461.3 14.661.6 14.661.1 14.961.5 16.462.4 1761.7 17. 62 154620 149619 156619* 17162 16862 17462* 17562 17262 17861* 18062 17863 18262 3.260.3 3.460.2 3.360.3 4.160.3 4.160.2 4.160.4 4.260.3 4.260.2 4.260.5 4.260.3 4.360.2 4.260.5 101.7640.4 68.0615.8 111.4639.0* 35.7617.8 34.1610.6 56.8621.1* 28.5613.2 26.2611.6 37.967.8* 55.4644.3 60.9638.0 63.4625.1 143.8611.3 140.965.0 144.0615.3 182.2616.7 173.465.6 180.5619.8 186.8619.8 176.766.5 184.9621.8 190.1618.8* 179.5610.2 185.4622.0 245.5634.2* 209.0619.0 255.3650.5* 217.9622.3 207.5615.4 237.3631.3* 215.3627.8 202.9616.7 222.8625.5 245.6651.3 240.3642.4 248.8634.9 2-km 3-km

RPE (units) CON DEP-PLA DEP-CAF iEMG ( ) CON DEP-PLA DEP-CAF 47.266.8 45.569.0 39.361.9 52.0620.1 44.766.6 41.361.7 46.169.2 45.269.3 42.962.3 52.5612.6 51.7615.8 44.765.7 11.061.7 10.761.7 10.361.5 12.660.5 12.761.3 12.461.3 14.661.6 14.661.1 14.961.5 16.462.4 1761.7 17. 62 154620 149619 156619* 17162 16862 17462* 17562 17262 17861* 18062 17863 18262 3.260.3 3.460.2 3.360.3 4.160.3 4.160.2 4.160.4 4.260.3 4.260.2 4.260.5 4.260.3 4.360.2 4.260.5 101.7640.4 68.0615.8 111.4639.0* 35.7617.8 34.1610.6 56.8621.1* 28.5613.2 26.2611.6 37.967.8* 55.4644.3 60.9638.0 63.4625.1 143.8611.3 140.965.0 144.0615.3 182.2616.7 173.465.6 180.5619.8 186.8619.8 176.766.5 184.9621.8 190.1618.8* 179.5610.2 185.4622.0 245.5634.2* 209.0619.0 255.3650.5* 217.9622.3 207.5615.4 237.3631.3* 215.3627.8 202.9616.7 222.8625.5 245.6651.3 240.3642.4 248.8634.9 2-km 3-km 4-kmiEMG expressed as percentage of EMG value obtained during MVC. CON: control condition; DEP-PLA: low carbohydrate availability with placebo ingestion; DEP-CAF: low carbohydrate availability with caffeine ingestion.Price of 2-(3-Butyn-1-yloxy)acetic acid *Significantly higher than DEP-PLA (P,0.05). doi:10.1371/journal.pone.0072025.tmuscle glycogen depletion and/or a psychological strategy.1438382-15-0 supplier However, despite the subjects being aware that they were depleted, they were not able to identify which capsule (caffeine or placebo) had subsequently been ingested, and, even then, adopted a more aggressive pacing strategy in DEP-CAF than DEP-PLA. Both iEMG and RPE at the beginning of the DEPPLA trial were also similar to the DEP-CAF trial, even with a lower PO, suggesting that any effect of manipulation may have happened in the muscle. Furthermore, caffeine supplementation restored the PO in the first two kilometers and it was not associated with a reduced PO in the rest of the time trial.PMID:33742652 In contrast to the results of the present study, Hettinga et al. [24] reported that a higher PO in the first 2 km of a 4-km cycling TT results in an impairment of the PO in the second half of the trial. It should be noted however, that the pacing strategy during the first 2 km in the Hettinga study was dictated by the researchers, and the participants were “enforced” to perform a constant PO at 105 above the mean PO until the end of the second kilometer. This “enforced”, constant-paced exercise during the first 2 km may have induced a greater physiological strain than self-paced exercise, and provoked a reduction in PO during the second half of the trial [39,40]. Therefore, caffeine seems to attenuate the decrement in power output observed early in CON and DEP-PLA conditions, and preserves the ability to optimally perform the second half of the trial. Even though mean PO was higher in the first 2 km of DEPCAF compared with DEP-PLA, the RPE was not significantly different between the conditions, suggesting that participants were able to perform the first 2 km of a 4-km cycling TT with a higher PO/RPE ratio when caffeine was ingested. This is in accordance with previous results suggesting that, independent of the physiological or metabolic status, athletes normally adopt a pattern of increase in RPE proportional to the exercise distance completed [41?3]. For example, positive (e.g. nutritional supplementation) and negative (e.g. hypoxia) changes in the homeostatic status throughout the TT have been reported to provoke an increase or reduction in PO, respectively, in order to maintain the same RPE template during exercise trials [42?4]. Caffeine may influence RPE vi.