Inspiratory muscle training improves blood flow to resting and exercising limbs in patients with chronic heart failure.
OBJECTIVE
We tested the hypothesis that inspiratory muscle loading could result in exaggerated peripheral vasoconstriction in resting and exercising limbs and that inspiratory muscle training (IMT) could attenuate this effect in patients with chronic heart failure (CHF) and inspiratory muscle weakness.


BACKGROUND
Inspiratory muscle training improves functional capacity of patients with CHF, but the mechanisms of this effect are unknown.


METHODS
Eighteen patients with CHF and inspiratory muscle weakness (maximal inspiratory pressure <70% of predicted) and 10 healthy volunteers participated in the study. Inspiratory muscle loading was induced by the addition of inspiratory resistance of 60% of maximal inspiratory pressure, while blood flow to the resting calf (CBF) and exercising forearm (FBF) were measured by venous occlusion plethysmography. For the patients with CHF, blood flow measurements as well as ultrasound determination of diaphragm thickness were made before and after a 4-week program of IMT.


RESULTS
With inspiratory muscle loading, CHF patients demonstrated a more marked reduction in resting CBF and showed an attenuated rise in exercising FBF when compared with control subjects. After 4 weeks of IMT, CHF patients presented hypertrophy of the diaphragm and improved resting CBF and exercise FBF with inspiratory muscle loading.


CONCLUSIONS
In patients with CHF and inspiratory muscle weakness, inspiratory muscle loading results in marked reduction of blood flow to resting and exercising limbs. Inspiratory muscle training improves limb blood flow under inspiratory loading in these patients.
Chiappa
Gaspar R
GR
Exercise Pathophysiology Research Laboratory, Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil.
Roseguini
Bruno T
BT
Vieira
Paulo J C
PJ
Alves
Cristiano N
CN
Tavares
Angela
A
Winkelmann
Eliane R
ER
Ferlin
Elton L
EL
Stein
Ricardo
R
Ribeiro
Jorge P
JP
D000328:Adult; D016022:Case-Control Studies; D002908:Chronic Disease; D015444:Exercise; D005080:Exercise Test; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006333:Heart Failure / Q000150:complications / Q000503:physiopathology*; D006439:Hemodynamics; D006801:Humans; D001239:Inhalation; D007866:Leg / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D010991:Plethysmography; D012132:Respiratory Muscles / Q000503:physiopathology*; D012146:Rest; D013318:Stroke Volume; D014661:Vasoconstriction; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology