Caffeine effects on velocity selection and physiological responses during RPE production
Bibliographic record
Abstract
Caffeine (CAF) blunts estimated ratings of perceived exertion (RPE) but the effects on RPE production are unclear. This study examined effects of acute caffeine ingestion during treadmill exercise where participants exercised at prescribed RPE 4 and 7. Recreational runners (maximal oxygen consumption = 51.4 ± 9.8 mL·kg−1·min−1) (n = 16) completed a maximal treadmill test followed by trials where they selected treadmill velocity (VEL) (1% grade) to produce RPE 4 and RPE 7 (10 min each). RPE production trials followed CAF (6 mg·kg−1) or placebo (PLA) (counterbalanced) ingestion. Participants were blinded to treadmill VEL but the Omni RPE scale was in full view. Repeated-measures ANOVA showed a main effect (trial) for VEL (CAF ∼5 m·min−1 faster) for RPE 4 (p = 0.07) and RPE 7 (p = 0.03). Mean heart rate and oxygen consumption responses were consistently higher for CAF but failed to reach statistical significance. Individual responses to CAF were labeled positive using a criterion of 13.4 m·min−1 faster for CAF (vs. PLA). Ten of 32 trials (31%) were positive responses. In these, systematic increases were observed for heart rate (∼12 beats·min−1) and oxygen consumption (∼5.7 mL·kg−1·min−1). Blunted/stable respiratory exchange ratio values at higher VEL for positive responders suggest increased free fatty acid reliance during CAF. In conlusion, mean results show a mild effect of CAF during RPE production. However, individual responses more clearly indicate whether a true effect is possible. Trainers and individuals should consider individual responses to ensure effectively intensity regulation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".