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Inspiratory Muscle Training in Heart Failure as a Promising Tool in the Heart Failure Toolkit: From Physiology to Practice: History
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Contributor: Maria Isakoglou , Eleni A. Kortianou

Heart failure (HF) is a heterogeneous clinical syndrome with increasing prevalence among adults worldwide. It is characterized by complex central and peripheral alterations that contribute to exercise intolerance, fatigue, dyspnea, and reduced quality of life. Inspiratory muscle weakness (IMW) plays a key role in this vicious cycle by exacerbating symptoms and further limiting functional capacity. Inspiratory muscle training (IMT) has emerged as a potential adjuvant in comprehensive HF management and is a physiologically grounded and promising tool in the contemporary HF therapeutic toolkit. Its integration into multimodal rehabilitation programs may mitigate the cycle of dyspnea and deconditioning in patients with HF. On this basis, we provide an overview of the pathophysiological mechanisms underlying IMW and present the practical characteristics of IMT programs, synthesizing current evidence regarding its clinical efficacy and implementation challenges.

  • cardiac rehabilitation
  • exercise
  • heart failure
  • inspiratory muscle training
  • inspiratory muscle weakness
Heart failure (HF) is a heterogeneous syndrome in which the heart is unable to handle a human’s metabolic needs due to its structural and/or functional abnormalities. The prevalence is 1–2% in the Western world [1], and it is accelerating due to the demographic trend of an aging population and an increase in risk factors [2]. Patients with HF are classified according to the left ventricular ejection fraction (LVEF) into HF with preserved (HFpEF: LVEF ≥ 50%), mildly reduced (HFmrEF: 41% < LVEF ≤ 49%), and reduced (HFrEF: LVEF ≤ 40%) ejection fraction [2], and they face various symptoms regardless of the disease severity. The limited exercise capacity [3], dyspnea, and poor quality of life (QoL) [4] are the most common expressions of the disease. Moreover, muscle weakness in both peripheral [5] and inspiratory muscles [6] is present in patients with HF regardless of LVEF magnitude. Inspiratory muscle weakness (IMW) is diagnosed when maximal inspiratory pressure (MIP) is reduced by less than 70% of predicted values [7]. Additionally, patients with HF demonstrated significantly reduced endurance capacity compared to healthy control subjects, indicating impaired respiratory muscle endurance in this population [8].
The skeletal muscle hypothesis, originally proposed by Coats et al. [9], describes the vicious cycle that contributes to the progression of HF and the generation of its characteristic symptoms. It emphasizes that HF is not solely a consequence of central cardiac dysfunction but also involves important peripheral abnormalities, particularly affecting skeletal and respiratory muscles. Although left ventricular dysfunction is a defining feature of the disease, it initiates a cascade of systemic effects. This dysfunction promotes a catabolic state, leading to structural and metabolic abnormalities in skeletal and respiratory muscles. Muscle alterations during physical exertion heighten ergoreflex activity, which sends signals to the central nervous system and increases sympathetic nervous system activity [9].
The resulting peripheral vasoconstriction and increased left ventricular afterload further impair cardiac performance. Through this mechanism, the skeletal muscle hypothesis explains why patients with HF experience symptoms such as exercise intolerance, early fatigue, and dyspnea, often out of the degree of left ventricular dysfunction [10]. Furthermore, it also provides a physiological basis for the beneficial effects of exercise training, which can improve muscle function and symptoms. This is why exercise training is highly recommended in clinical guidelines as a non-pharmacological therapy [11]. Aerobic exercise (AE) is the most common exercise modality in HF rehabilitation programs due to multiple benefits on patients’ exercise capacity, cardiac function [12], functional capacity, and QoL [13]. Furthermore, inspiratory muscle training (IMT) is recommended as an adjuvant exercise in the most severe patients, enriching the conventional exercise programs [14].
To date, there is a variety in training loads and modalities implemented in patients with HF. Therefore, a comprehensive patient evaluation of respiratory muscle status is essential to enable clinicians to implement appropriately tailored IMT interventions.
In light of these considerations, this entry provides a comprehensive overview of inspiratory muscle pathophysiology in patients with HF and further delineates the various modalities of IMT, outlining their theoretical rationale and mechanistic underpinnings. Additionally, it synthesizes current evidence regarding the effects of IMT and gives practical considerations supporting the structured and individualized implementation of IMT in clinical practice.

This entry is adapted from the peer-reviewed paper 10.3390/encyclopedia6050111

References

  1. Correale, M.; Paolillo, S.; Mercurio, V.; Limongelli, G.; Barillà, F.; Ruocco, G.; Palazzuoli, A.; Scrutinio, D.; Lagioia, R.; Lombardi, C.; et al. Comorbidities in chronic heart failure: An update from Italian Society of Cardiology (SIC) Working Group on Heart Failure. Eur. J. Intern. Med. 2020, 71, 23–31.
  2. Khan, M.S.; Shahid, I.; Bennis, A.; Rakisheva, A.; Metra, M.; Butler, J. Global epidemiology of heart failure. Nat. Rev. Cardiol. 2024, 21, 717–734.
  3. Miura, Y.; Fukumoto, Y.; Miura, T.; Shimada, K.; Asakura, M.; Kadokami, T.; Ando, S.; Miyata, S.; Sakata, Y.; Daida, H.; et al. Impact of physical activity on cardiovascular events in patients with chronic heart failure. A multicenter prospective cohort study. Circ. J. 2013, 77, 2963–2972.
  4. Sacco, S.J.; Park, C.L.; Suresh, D.P.; Bliss, D. Living with heart failure: Psychosocial resources, meaning, gratitude and well-being. Heart Lung 2014, 43, 213–218.
  5. von Haehling, S.; Ebner, N.; Dos Santos, M.R.; Springer, J.; Anker, S.D. Muscle wasting and cachexia in heart failure: Mechanisms and therapies. Nat. Rev. Cardiol. 2017, 14, 323–341.
  6. Hamazaki, N.; Kamiya, K.; Matsuzawa, R.; Nozaki, K.; Ichikawa, T.; Tanaka, S.; Nakamura, T.; Yamashita, M.; Maekawa, E.; Noda, C.; et al. Prevalence and prognosis of respiratory muscle weakness in heart failure patients with preserved ejection fraction. Respir. Med. 2020, 161, 105834.
  7. American Thoracic Society; European Respiratory Society. ATS/ERS Statement on respiratory muscle testing. Am. J. Respir. Crit. Care Med. 2002, 166, 518–624.
  8. Chiappa, G.R.; Roseguini, B.T.; Vieira, P.J.; Alves, C.N.; Tavares, A.; Winkelmann, E.R.; Ferlin, E.L.; Stein, R.; Ribeiro, J.P. 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.
  9. Coats, A.J.; Clark, A.L.; Piepoli, M.; Volterrani, M.; Poole-Wilson, P.A. Symptoms and quality of life in heart failure: The muscle hypothesis. Br. Heart J. 1994, 72, S36–S39.
  10. Katayıfçı, N.; Boşnak Güçlü, M. Inspiratory muscle weakness further impairs exercise capacity and respiratory functions and increases dyspnea perception in patients with heart failure. Sci. Rep. 2025, 15, 32229.
  11. Ponikowski, P.; Voors, A.A.; Anker, S.D.; Bueno, H.; Cleland, J.G.F.; Coats, A.J.S.; Falk, V.; Gonza’lez-Juanatey, J.R.; Harjola, V.P.; Jankowska, E.A.; et al. 2016 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure: The Task Force for the diagnosis and treatment of acute and chronic heart failure of the European Society of Cardiology (ESC). Developed with the special contribution of the Heart Failure Association (HFA) of the ESC. Eur. J. Heart Fail. 2016, 18, 891–975.
  12. Callum, K.; Swinton, P.; Gorely, T.; Crabtree, D.; Leslie, S. Physiological and psychological outcomes of high intensity interval training in patients with heart failure compared to moderate continuous training and usual care: A systematic review with meta analysis. Heart Lung 2024, 64, 117–127.
  13. Yang, C.; Zhang, L.; Cheng, Y.; Zhang, M.; Zhao, Y.; Zhang, T.; Dong, J.; Xing, J.; Zhen, Y.; Wang, C. High intensity interval training vs. moderate intensity continuous training on aerobic capacity and functional capacity in patients with heart failure: A systematic review and meta-analysis. Front. Cardiovasc. Med. 2024, 11, 1302109.
  14. Pelliccia, A.; Sharma, S.; Gati, S.; Bäck, M.; Börjesson, M.; Caselli, S.; Collet, J.P.; Corrado, D.; Drezner, J.A.; Halle, M.; et al. 2020 ESC Guidelines on sports cardiology and exercise in patients with cardiovascular disease. Eur. Heart J. 2021, 42, 17–96.
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