Title

The impact of 6 months of exercise-based cardiac rehabilitation on sympathetic neural recruitment during apneic stress.

Document Type

Article

Publication Date

6-16-2021

Journal

American journal of physiology. Regulatory, integrative and comparative physiology

Volume

321

Issue

2

First Page

174

Last Page

185

URL with Digital Object Identifier

https://doi.org/10.1152/ajpregu.00080.2021

Abstract

The current study evaluated the hypothesis that 6 mo of exercise-based cardiac rehabilitation (CR) would improve sympathetic neural recruitment in patients with ischemic heart disease (IHD). Microneurography was used to evaluate action potential (AP) discharge patterns within bursts of muscle sympathetic nerve activity (MSNA), in 11 patients with IHD (1 female; 61 ± 9 yr) pre (pre-CR) and post (post-CR) 6 mo of aerobic and resistance training-based CR. Measures were made at baseline and during maximal voluntary end-inspiratory (EI-APN) and end-expiratory apneas (EE-APN). Data were analyzed during 1 min of baseline and the second half of apneas. At baseline, overall sympathetic activity was less post-CR (all P < 0.01). During EI-APN, AP recruitment was not observed pre-CR (all P > 0.05), but increases in both within-burst AP firing frequency (Δpre-CR: 2 ± 3 AP spikes/burst vs. Δpost-CR: 4 ± 3 AP spikes/burst; P = 0.02) and AP cluster recruitment (Δpre-CR: -1 ± 2 vs. Δpost-CR: 2 ± 2; P < 0.01) were observed in post-CR tests. In contrast, during EE-APN, AP firing frequency was not different post-CR compared with pre-CR tests (Δpre-CR: 269 ± 202 spikes/min vs. Δpost-CR: 232 ± 225 spikes/min; P = 0.54), and CR did not modify the recruitment of new AP clusters (Δpre-CR: -1 ± 3 vs. Δpost-CR: 0 ± 1; P = 0.39), or within-burst firing frequency (Δpre-CR: 3 ± 3 AP spikes/burst vs. Δpost-CR: 2 ± 2 AP spikes/burst; P = 0.21). These data indicate that CR improves some of the sympathetic nervous system dysregulation associated with cardiovascular disease, primarily via a reduction in resting sympathetic activation. However, the benefits of CR on sympathetic neural recruitment may depend upon the magnitude of initial impairment.

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Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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