Training heart failure patients with reduced ejection fraction attenuates muscle sympathetic nerve activation during mild dynamic exercise
Muscle sympathetic nerve activity (MSNA) decreases during low-intensity dynamic one-leg exercise in healthy subjects but increases in patients with heart failure with reduced ejection fraction (HFrEF). We hypothesized that increased peak oxygen uptake (V̇o ) after aerobic training would be accompani...
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| Published in: | American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2019-10, Vol.317 (4), p.R503-R512 |
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| Main Authors: | , , , , , , , , |
| Format: | Article |
| Language: | eng |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Muscle sympathetic nerve activity (MSNA) decreases during low-intensity dynamic one-leg exercise in healthy subjects but increases in patients with heart failure with reduced ejection fraction (HFrEF). We hypothesized that increased peak oxygen uptake (V̇o
) after aerobic training would be accompanied by less sympathoexcitation during both mild and moderate one-leg dynamic cycling, an attenuated muscle metaboreflex, and greater skin vasodilation. We studied 27 stable, treated HFrEF patients (6 women; mean age: 65 ± 2 SE yr; mean left ventricular ejection fraction: 30 ± 1%) and 18 healthy age-matched volunteers (6 women; mean age: 57 ± 2 yr). We assessed V̇o
(open-circuit spirometry) and the skin microcirculatory response to reactive hyperemia (laser flowmetry). Fibular MSNA (microneurography) was recorded before and during one-leg cycling (2 min unloaded and 2 min at 50% of V̇o
) and, to assess the muscle metaboreflex, during posthandgrip ischemia (PHGI). HFrEF patients were evaluated before and after 6 mo of exercise-based cardiac rehabilitation. Pretraining V̇o
and skin vasodilatation were lower (
< 0.001) and resting MSNA higher (
= 0.01) in HFrEF than control subjects. Training improved V̇o
(+3.0 ± 1.0 mL·kg
·min
;
< 0.001) and cutaneous vasodilation and diminished resting MSNA (-6.0 ± 2.0,
= 0.01) plus exercise MSNA during unloaded (-4.0 ± 2.5,
= 0.04) but not loaded cycling (-1.0 ± 4.0 bursts/min,
= 0.34) and MSNA during PHGI (
< 0.05). In HFrEF patients, exercise training lowers MSNA at rest, desensitizes the sympathoexcitatory metaboreflex, and diminishes MSNA elicited by mild but not moderate cycling. Training-induced downregulation of resting MSNA and attenuated reflex sympathetic excitation may improve exercise capacity and survival. |
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| ISSN: | 0363-6119 1522-1490 |