Training Heart Failure Patients with Reduced Ejection Fraction Attenuates their Muscle Metaboreflex and Lowers Muscle Sympathetic Nerve Activity at Rest and During Mild Dynamic Exercise
Bibliographic record
Abstract
We have shown that muscle sympathetic nerve activity (MSNA) is elevated at rest in patients with heart failure due to reduced ejection fraction (HFrEF) and, in contrast to healthy subjects, increases during moderate dynamic 1‐leg exercise. We hypothesized that exercise training in HFrEF may reduce MSNA during both mild and moderate intensity 1‐leg dynamic exercise and static handgrip; attenuate the muscle metaboreflex; and improve skin blood flow. We studied 27 stable, medicated HFrEF patients (6 women; mean age 65 ± 2 SE [range 42 to 80] years; mean left ventricular ejection fraction 30 ± 1% [range 12–40]); of either ischemic (n=18) or non‐ischemic (n=9) etiology, both before and after 6 months of cardiac rehabilitation (aerobic exercise for 45 minutes, 5 times per week at 60–70 % of VO 2peak ); plus 18 healthy, age and sex‐matched, medication‐free volunteers (6 women; mean age 57 ± 2 [range 48 to 72]). Before and after training, we assessed VO 2peak (open‐circuit spirometry); the skin blood flow (SBF) response to reactive hyperemia (laser flowtometry); and fibular MSNA (microneurography) at rest (n=18), during 1‐leg cycling (2 min each unloaded and at 50% of VO 2peak , n=16) and, to assess the muscle metaboreflex, during post‐handgrip ischemia (PHGI) after 2 min of 30% static handgrip (HG). In HFrEF, pre‐training VO 2peak and skin vasodilatation were lower (P<0.001) and resting MSNA higher compared to controls (P=0.01). Exercise training improved VO 2peak by 3.0±1.0 ml·kg −1 ·min −1 (P<0.001) and increased the SBF vasdilatory response in HFrEF to a mean value similar to controls (P=0.78). Relative to pre‐training, resting MSNA decreased by 6.0±2.0 bursts/min (P=0.01, N=18) and 7.3±3.4 burst/100 heartbeats (P=0.04). During 1‐leg cycling, MSNA decreased in control (P=0.01) but increased in HFrEF (P<0.001). Exercise training attenuated MSNA burst frequency and incidence during unloaded (P=0.04) but not loaded cycling (P=0.34). The rise in MSNA burst frequency during HG in HFrEF was unaffected by training, but its elevation during PHGI was abolished (P<0.05). We conclude that the exaggerated metaboreflex of HFrEF is attenuated by exercise training. This may contribute to a lower MSNA during mild but not moderate intensity cycling. Support or Funding Information Supported by Heart and Stroke Foundation of Ontario and Canadian Institutes for Health Research This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
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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 | 0.000 |
| 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".