Inspiratory muscle training reduces sympathetic nervous activity and improves inspiratory muscle weakness and quality of life in patients with chronic heart failure: a clinical trial.
OBJECTIVE
To evaluate the effect of inspiratory muscle training (IMT) on cardiac autonomic modulation and on peripheral nerve sympathetic activity in patients with chronic heart failure (CHF).


METHODS
Functional capacity, low-frequency (LF) and high-frequency (HF) components of heart rate variability, muscle sympathetic nerve activity inferred by microneurography, and quality of life were determined in 27 patients with CHF who had been sequentially allocated to 1 of 2 groups: (1) control group (with no intervention) and (2) IMT group. Inspiratory muscle training consisted of respiratory exercises, with inspiratory threshold loading of seven 30-minute sessions per week for a period of 12 weeks, with a monthly increase of 30% in maximal inspiratory pressure (PI(max)) at rest. Multivariate analysis was applied to detect differences between baseline and followup period.


RESULTS
Inspiratory muscle training significantly increased PI(max) (59.2 ± 4.9 vs 87.5 ± 6.5 cmH(2)O, P = .001) and peak oxygen uptake (14.4 ± 0.7 vs 18.9 ± 0.8 mL·kg(-1)·min(-1), P = .002); decreased the peak ventilation (VE)/carbon dioxide production (VCO(2)) ratio (35.8 ± 0.8 vs 32.5 ± 0.4, P = .001) and the VE/VCO(2) slope (37.3 ± 1.1 vs 31.3 ± 1.1, P = .004); increased the HF component (49.3 ± 4.1 vs 58.4 ± 4.2 normalized units, P = .004) and decreased the LF component (50.7 ± 4.1 vs 41.6 ± 4.2 normalized units, P = .001) of heart rate variability; decreased muscle sympathetic nerve activity (37.1 ± 3 vs 29.5 ± 2.3 bursts per minute, P = .001); and improved quality of life. No significant changes were observed in the control group.


CONCLUSIONS
Home-based IMT represents an important strategy to improve cardiac and peripheral autonomic controls, functional capacity, and quality of life in patients with CHF.
Heart Institute, University of São Paulo Medical School, Brazil.
Priscila R
PR
Mello
Grazi M
GM
Guerra
Suellen
S
Borile
Maria U
MU
Rondon
Maria J
MJ
Alves
Carlos E
CE
Negrão
Pedro
P
Dal Lago
Cristiano
C
Mostarda
Maria C
MC
Irigoyen
Fernanda M
FM
Consolim-Colombo
D001341:Autonomic Nervous System; D005080:Exercise Test; D005081:Exercise Therapy; D005260:Female; D006333:Heart Failure / Q000523:psychology*; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000523:psychology*; D001239:Inhalation; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D018908:Muscle Weakness; D011788:Quality of Life / Q000523:psychology*; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires; D013564:Sympathetic Nervous System