Impaired left and right ventricular function following prolonged exercise in young athletes: influence of exercise intensity and responses to dobutamine stress
Bibliographic record
Abstract
We examined the effect of intensity during prolonged exercise (PE) on left (LV) and right ventricular (RV) function. Subjects included 18 individuals (mean +/- SE: age = 28.1 +/- 1.1 yr, maximal aerobic power = 55.1 +/- 1.6 ml . kg(-1) . min(-1)), who performed 150 min of exercise at 60 and 80% maximal aerobic power on two separate occasions. Transthoracic echocardiography assessed systolic and diastolic performance, and blood sampling assessed hydration status and noradrenaline levels before (pre), during (15 and 150 min), and 60 min following (post) PE. beta-Adrenergic sensitivity pre- and post-PE was assessed by dobutamine stress. High-intensity PE (15 vs. 150 min) induced reductions in LV ejection fraction (69.3 +/- 1.3 vs. 63.5 +/- 1.3%, P = 0.000), LV strain (-23.5 +/- 0.6 vs. -22.3 +/- 0.6%, P = 0.034), and RV strain (-26.3 +/- 0.6 vs. -23.0 +/- 0.6%, P < 0.01). Both exercise intensities induced diastolic reductions (pre vs. post) in the ratio of septal early wave of annular tissue velocities to late/atrial wave of annular tissue velocities (2.15 +/- 0.15 vs. 1.62 +/- 0.09; 2.21 +/- 0.15 vs. 1.48 +/- 0.10), ratio of lateral early wave of annular tissue velocities to late/atrial wave of annular tissue velocities (3.84 +/- 0.42 vs. 2.49 +/- 0.20; 3.56 +/- 0.32 vs. 2.08 +/- 0.18), ratio of early to late LV strain rate (2.42, +/- 0.16 vs. 1.97 +/- 0.13; 2.30 +/- 0.15 vs. 1.81 +/- 0.11), and ratio of early to late RV strain rate (2.03 +/- 0.17 vs. 1.51 +/- 0.09; 2.16 +/- 0.16 vs. 1.44 +/- 0.11) (P < 0.001). Evidence of beta-adrenergic sensitivity was supported by a decreased strain, strain rate, ejection fraction, and systolic pressure-volume ratio response to dobutamine (P < 0.05) with elevated noradrenaline (P < 0.01). PE-induced reductions in LV and RV systolic function were related to exercise intensity and beta-adrenergic desensitization. The clinical significance of exercise-induced cardiac fatigue warrants further research.
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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) | 0.001 | 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".