CORRESPONDENCE: LETTER TO THE EDITOR
Effects of Inspiratory Muscle Training in Patients With Chronic Heart Failure
Ioannis D. Laoutaris, PhD*,
Athanasios Dritsas, MD,
Stamatis Adamopoulos, PhD, MD,
Margaret D. Brown, PhD and
Dennis V. Cokkinos, MD
* Onassis Cardiac Surgery Center, Stress Testing and Cardiac Rehabilitation Laboratory, 356 Sygrou Avenue, 176 74, Athens, Greece (Email: ylaoutaris{at}yahoo.gr).
We read with interest the article by Chiappa et al. (1) reporting on the improvement in limb blood flow and attenuation of inspiratory muscle (IM) metaboreflex after inspiratory muscle training (IMT), explaining an IMT-induced increase in peak oxygen consumption (VO
2) and decrease in ventilatory equivalent (VE/VCO
2) in chronic heart failure patients with IM weakness but not severely impaired functional capacity (2). IMT was performed using a threshold trainer at low intensity (30% of IM strength [PImax]).
A change in peak VO
2 or VE/VCO
2 was not shown before using a similar IMT methodology (3,4) even in more advanced chronic heart failure with IM weakness (4). In contrast, peak VO
2 was increased after high-intensity endurance respiratory muscle training (5,6).
Although Dall'Ago et al. (2) reports that PImax is independent of functional status, a low PImax was previously associated with reduced exercise capacity (7). The authors further report (1) that 4-week IMT resulted in diaphragmatic hypertrophy and PImax increase by 72%. However, in all IMT studies (3–6), PImax increased by 25% to 28% within 8 to 12 weeks. Moreover, change in muscle morphology requires chronic training (8), while IMT using the threshold trainer did not change diaphragmatic contractility in normal subjects (9).
Thus, IM weakness might be overestimated in Ribeiro's studies (1,2), although patients might have ‘felt better’ during IMT and increased their physical activity in parallel, possibly contributing to the reported benefits.
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References
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1. Chiappa GR, Roseguini BT, Vieira PJC, et al. Inspiratory muscle training improves blood flow to resting and exercising limbs in patients with chronic heart failure J Am Coll Cardiol 2008;51:1663-1671.[Abstract/Free Full Text]2. Dall'Ago P, Chiappa GRS, Guths H, Stein R, Ribeiro JP. Inspiratory muscle training in patients with heart failure and inspiratory muscle weakness. A randomized trial. J Am Coll Cardiol 2006;47:757-763.[Abstract/Free Full Text] 3. Johnson PH, Cowley AJ, Kinnear WSM. A randomized controlled trial of inspiratory muscle training in stable chronic heart failure Eur Heart J 1998;19:1249-1253.[Abstract/Free Full Text] 4. Weiner P, Waizman J, Magadle R, Berar-Yanay N, Pelled B. The effect of specific inspiratory muscle training on the sensation of dyspnea and exercise tolerance in patients with congestive heart failure Clin Cardiol 1999;22:727-732.[Web of Science][Medline] 5. Mancini DM, Henson D, La Manca J, Donchez L, Levine S. Benefit of selective respiratory muscle training on exercise capacity in patients with chronic congestive heart failure Circulation 1995;91:320-329.[Abstract/Free Full Text] 6. Laoutaris I, Dritsas A, Brown, MD, Manginas A, Alivizatos PA, Cokkinos DV. Inspiratory muscle training using an incremental endurance test alleviates dyspnea and improves functional status in patients with chronic heart failure Eur J Cardiovasc Prev Rehabil 2004;11:489-496.[CrossRef][Web of Science][Medline] 7. Chua TP, Anker SD, Harrington D, Coats AJS. Inspiratory muscle strength is a determinant of maximum oxygen consumption in chronic heart failure Br Heart J 1995;74:381-385.[Abstract/Free Full Text] 8. Brunotte F, Thompson CH, Adamopoulos S, et al. Rat skeletal muscle metabolism in experimental heart failure: effects of physical training Acta Physiol Scand 1995;154:439-447.[Web of Science][Medline] 9. Hart N, Sylvester K, Ward S, Cramer D, Moxham J, Polkey M. Evaluation of an inspiratory muscle trainer in healthy humans Respir Med 2001;95:526-531.[CrossRef][Web of Science][Medline]
Related Article
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Reply
- Jorge P. Ribeiro, Gaspar R. Chiappa, and Ricardo Stein
J. Am. Coll. Cardiol. 2008 52: 1889.
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