Does Oxygen Delivery Predict Performance During An "All-Out" Critical Power Test?
Bibliographic record
Abstract
Critical power (CP) is the maximal power output where oxygen uptake and metabolic markers can be maintained for an extended period of time without drifting to maximal values. Classically, CP is identified from several repeats of constant load exercise to exhaustion across a range of exercise intensities, resulting in a hyperbolic function: Tlim = W'/(P-CP), where Tlim is the time to exhaustion, P is the power output, CP is the asymptote and W' is the curvature constant. Recently it has been demonstrated that power/force/torque stabilizes by the final 30 s of single "all out" cycling or knee extension exercise bouts maintained for ∼3-5 min and this is strongly correlated with the traditional CP test value. However, the O2 delivery (O2D) during all out CP tests remains uncharacterized and may provide insight into physiological mechanisms that determine performance in such a test. PURPOSE: To determine if O2D differences between healthy subjects predicts task performance during all out CP tests. METHODS: 7 healthy male subjects (24.85 ± 8.475 yrs) completed a maximal effort isometric handgrip exercise test. Exercise consisted of rhythmic isometric maximum voluntary forearm handgrip contractions (MVC's; kg. 1 s contraction: 2 s relaxation duty cycle) for 10 minutes in the supine position with the arm at heart level. Subjects were required to attempt an MVC on every contraction, with visual feedback on force output provided continuously on a computer screen. Constant verbal encouragement was provided, but subjects were not aware of elapsed time. CP was calculated as the average peak contraction force during the last 30 s of the all out exercise trials. Forearm blood flow (FBF) during exercise was calculated from brachial artery diameter (echo ultrasound) and mean blood velocity (Doppler ultrasound). Mean arterial pressure was measured with finger photoplethysmography. Arterial content (CaO2) & O2D was calculated based on arterial oxygen content ([haemoglobin] from venous blood sample and oxygen saturation from pulse oximetry and FBF). RESULTS: The mean CP estimate was 26.91 kg ± 4.9. FBF plateau during the CP timeframe at 507.09 ± 166.14 ml/min. Pearson Product Moment correlation between FBF and CP was r = 0.784 (P = 0.037). The mean O2D during the last 30 s of exercise was 101.24 ± 30.38 O2 ml/min (correlation of O2D & CP r = 0.78, P = 0.038). CaO2 was 20.34 ± 1.23 O2 ml/dL and was not correlated with CP (P = 2.05). O2D accounted for 61% of the variance in CP (r2 = 0.61) CONCLUSIONS: Skeletal muscle oxygen delivery is a strong predictor of critical power. This supports the contention that factors determining vasodilatory responsiveness and/or capacity are important determinants of CP.
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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 | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".