Left ventricular adaptations following short-term endurance training
Why this work is in the frame
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Bibliographic record
Abstract
This study examined the effects of short-term endurance training (ET) on the left ventricular (LV) adaptation and functional response to a series of exercise challenges with increasing intensity. Eight untrained men, with a mean age of 19.4 +/- 0.5 (SE) yr, were studied before and after 6 days of ET consisting of cycling 2 h/day at 65% peak aerobic power (VO2max). LV ejection fraction and LV volumes were assessed by radionuclide angiography at rest and during exercise at three uninterrupted successive work rates corresponding to 53, 68, and 83% of VO2max, each lasting 20 min. ET produced a calculated plasma volume expansion of 11.4 +/- 2.2% (P < 0.05). The increase in plasma volume was accompanied by an increase in VO2max from 45.9 +/- 1.9 to 49.0 +/- 1.0 ml x kg(-1) x min(-1) (P < 0.01) and a decrease in maximal heart rate (197 +/- 2.3 to 188 +/- 1.0 beats/min; P < 0.01). Resting LV function was not changed, although there was a trend for higher stroke volumes (SVs) and improvement in the rapid filling phase of diastole (P = 0.08). Training induced an increase in exercise SV by 10.4, 10.2, and 7% at 53, 68, and 83% VO2max, respectively (P < 0.01). These changes were secondary to increases in end-diastolic volume, which increased significantly at each exercise work rate following training (139 +/- 6 to 154 +/- 6 ml at 53% VO2max, and from 136 +/- 5 to 156 +/- 5 ml at 83% VO2max; P < 0.01). End-systolic volumes were unchanged after ET. A significant bradycardia was observed both at rest (decreasing 7%) and exercise (decreasing 10.4%). LV ejection fraction during exercise was increased slightly by training, reaching significance at the highest work rate, after 60 min of exercise. (P < 0.05). Cardiac output was higher following training at the highest workload (20.8 +/- 2.2 vs. 22.9 +/- 3.1 l/min; P < 0.01). These data indicate that short-term training elicits rapid adaptation to the LV functional response exercise, with increases in SV being secondary to a Frank-Starling effect with minor changes in contractile performance. This produced a volume-induced bradycardia and increase in LV filling, which may be of benefit during prolonged exercise.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| 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) | 0.000 | 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 it