A Transfer Entropy Approach for the Assessment of the Impact of Inspiratory Muscle Training on the Cardiorespiratory Coupling of Amateur Cyclists

Abstract

The strength of cardiorespiratory interactions diminishes with age. Physical exercise can reduce the rate of this trend. Inspiratory muscle training (IMT) is a technique capable of improving cardiorespiratory interactions. This study evaluates the effect of IMT on cardiorespiratory coupling in amateur cyclists. Thirty male young healthy cyclists underwent a sham IMT of very low intensity (SHAM, n = 9), an IMT of moderate intensity at 60% of the maximal inspiratory pressure (MIP60, n = 10) and an IMT of high intensity at the critical inspiratory pressure (CIP, n = 11). Electrocardiogram, non-invasive arterial pressure, and thoracic respiratory movement (RM) were recorded before (PRE) and after (POST) training at rest in supine position (REST) and during active standing (STAND). The beat-to-beat series of heart period (HP) and systolic arterial pressure (SAP) were analyzed with the RM signal via a traditional non-causal approach, such as squared coherence function, and via a causal model-based transfer entropy (TE) approach. Cardiorespiratory coupling was quantified via the HP-RM squared coherence at the respiratory rate (K 2 HP−RM), the unconditioned TE from RM to HP (TE RM→HP) and the TE from RM to HP conditioned on SAP (TE RM→HP|SAP). In PRE condition we found that STAND led to a decrease of TE RM→HP|SAP. After SHAM and CIP training this tendency was confirmed, while MIP60 inverted it by empowering cardiorespiratory coupling. This behavior was observed in presence of unvaried SAP mean and with usual responses of the baroreflex control and HP mean to STAND. TE RM→HP and K 2 HP−RM were not able to detect the post-training increase of cardiorespiratory coupling strength during STAND, thus suggesting that conditioning out SAP is important for the assessment

Information Flow Between Heart Rhythm, Repolarization, and the Diastolic Interval Series for Healthy Individuals and LQTS1 Patients

“…Specific ion channels (especially several K channels and Na/K exchangers) are responsible for this process. Repolarization may be perturbed also in the presence of heart diseases, for example, hypertrophic cardiomyopathy, coronary artery disease, and others (Dispersion of Ventricular Repolarization in Hypertrophic Cardiomyopathy) (Zareba et al, 1994;Christiansen et al, 1996;Savelieva et al, 1999).…”

“…Several authors have studied information transfer related to heart rate variability (represented by time series of RR intervals) in different contexts ( Zheng et al, 2017 ; Javorka et al, 2018 ; de Abreu et al, 2020 ). Information flow between the QT and RR intervals was discussed by Porta et al (2017) , interval for a group of 15 healthy individuals as a function of the angle at which the tilt table is placed.…”

Optimizing phase variability threshold for automated synchrogram analysis of cardiorespiratory interactions in amateur cyclists

“…We tested the experimental hypotheses that the strength of cardiorespiratory phase synchronization could be affected by an orthostatic challenge and could be modulated by the intensity of IMT. In order to test these hypotheses, we considered 30 male recreational cyclists (age: 20-40 years) before (PRE) and after (POST) performing IMT [34][35][36]. All the experimental procedures were performed at the Cardiovascular Physical Therapy Laboratory, Department of Physical Therapy, UFSCar, São Carlos, Brazil.…”

“…The approach is based on the assessment of the strength of phase synchronization as a function of the threshold over the original pairs, on the computation of the 95th percentile of the phase synchronization strength as a function of the threshold over the surrogates and on the maximization of the distance between the two curves computed at the same value of the threshold. The approach was tested on a database of 30 male recreational cyclists before and after performing an 11-week inspiratory muscle training (IMT) [34][35][36]. Three different intensities of IMT were considered and cardiorespiratory control was perturbed through a postural manoeuvre.…”

Can respiratory muscle training change the blood pressure levels in hypertension? A systematic review with meta‐analysis

“…In relation to autonomic modulation, it is known that respiratory training promotes an increase in parasympathetic modulation and a reduction in sympathetic modulation, favoring a better hemodynamic function 13,14 . In addition, the increase in respiratory muscle strength favors an increase of cardiorespiratory coupling with possible effects on central respiratory network and its interactions with sympathetic drive and vagal activity, 15 which may be associated with reductions in blood pressure in patients with systemic arterial hypertension 11 . Moreover, this training modality may be an option to individuals that have some physical limitation or even for the more advanced age, which may present some limitation to the dynamic and conventional exercises 10,11,16 …”