Inspiratory muscle training in patients with heart failure and inspiratory muscle weakness: a randomized trial.
OBJECTIVE
This study sought to evaluate the effects of inspiratory muscle training in inspiratory muscle strength, as well as in functional capacity, ventilatory responses to exercise, recovery oxygen uptake kinetics, and quality of life in patients with chronic heart failure (CHF) and inspiratory muscle weakness.


BACKGROUND
Patients with CHF may have reduced strength and endurance in inspiratory muscles, which may contribute to exercise intolerance and is associated with a poor prognosis.


METHODS
Thirty-two patients with CHF and weakness of inspiratory muscles (maximal inspiratory pressure [Pi(max)] <70% of predicted) were randomly assigned to a 12-week program of inspiratory muscle training (IMT, 16 patients) or to a placebo-inspiratory muscle training (P-IMT, 16 patients). The following measures were obtained before and after the program: Pi(max) at rest and 10 min after maximal exercise; peak oxygen uptake, circulatory power, ventilatory oscillations, and oxygen kinetics during early recovery (VO2/t-slope); 6-min walk test; and quality of life scores.


RESULTS
The IMT resulted in a 115% increment Pi(max), 17% increase in peak oxygen uptake, and 19% increase in the 6-min walk distance. Likewise, circulatory power increased and ventilatory oscillations were reduced. The VO2/t-slope was improved during the recovery period, and quality of life scores improved.


CONCLUSIONS
In patients with CHF and inspiratory muscle weakness, IMT results in marked improvement in inspiratory muscle strength, as well as improvement in functional capacity, ventilatory response to exercise, recovery oxygen uptake kinetics, and quality of life.
Dall'Ago
Pedro
P
Department of Physiological Sciences, Fundação Faculdade Federal de Ciências Médicas de Porto Alegre, Porto Alegre, Brazil.
Chiappa
Gaspar R S
GR
Guths
Henrique
H
Stein
Ricardo
R
Ribeiro
Jorge P
JP
D001945:Breathing Exercises; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006333:Heart Failure / Q000150:complications* / Q000503:physiopathology; D006801:Humans; D001239:Inhalation; D007320:Inspiratory Capacity; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000209:etiology / Q000503:physiopathology / Q000534:rehabilitation*; D010101:Oxygen Consumption; D011788:Quality of Life; D012132:Respiratory Muscles / Q000503:physiopathology*; D016138:Walking