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February 20, 2026Frontiers in Network PhysiologyOpen Access

Inspiratory muscle training increases maximal inspiratory pressure ~26% and enhances cardiac vagal modulation vs placebo.

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Why the study?

Does a 4-week inspiratory muscle training program at moderate load improve inspiratory muscle strength, cardiac autonomic modulation, spontaneous baroreflex sensitivity, and respiratory pattern in healthy young men?

Comparison

IMT at 60% of MIP vs placebo at 10% of MIP

Design

Randomized controlled trial

Follow-up

4 weeks

Key result

Inspiratory muscle training increased maximal inspiratory pressure by 26% and enhanced cardiac vagal modulation in healthy young men without changing baroreflex sensitivity after 4 weeks.

Authors

TGThiago Rodrigues GonçalvesSFSelena Cristina Henriques FontesMCMichele Vaz Canena

Discussion

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Overview

IMT may improve inspiratory strength and vagal tone in healthy young men; extends RCT evidence for respiratory-driven autonomic effects without baroreflex change.

Key Points

  • The study aims to determine the effects of a 4-week inspiratory muscle training program on cardiorespiratory physiology.
  • 22 healthy young men were divided into an experimental group and a placebo group.
  • Participants underwent pulmonary function tests and cardiopulmonary assessments before and after the training.
  • Interventions included a moderate-load inspiratory muscle training program over 4 weeks.
  • Heart rate variability, blood pressure variability, and baroreflex sensitivity were measured during various tasks.
  • Inspiratory muscle strength increased by approximately 26%, with improved peak inspiratory flow.
  • Vagal indices of heart rate variability indicated enhanced parasympathetic modulation post-training.
  • Changes in the respiratory pattern included reduced Ti/Ttot ratio and increased expiratory time.
  • No significant changes in blood pressure variability or spontaneous baroreflex sensitivity were noted.

Study Design

Type

RCT (n=22)

Blinding

single-blind (participants)

Randomization

simple randomization

Multicenter

No

Structured PICO

Does a 4-week inspiratory muscle training program at moderate load improve inspiratory muscle strength, cardiac autonomic modulation, spontaneous baroreflex sensitivity, and respiratory pattern in healthy young men?

P
Population
22 healthy young men (mean age 27 ± 4 years, BMI 21.8 ± 3.4 kg/m2) without abnormal cardiac electrical function or pulmonary function.
I
Intervention
Inspiratory muscle training (IMT) using an inspiratory resistor portable device at a load of 60% of maximal inspiratory pressure (MIP), performing 30 breaths twice a day for 4 weeks (30 days).
C
Comparator
Placebo IMT using an inspiratory resistor portable device at a load of 10% of maximal inspiratory pressure (MIP), performing 30 breaths twice a day for 4 weeks (30 days).
O
Outcome
Changes in inspiratory muscle strength (MIP), cardiac autonomic modulation (heart rate variability), spontaneous baroreflex sensitivity (BRS), and respiratory pattern.surrogate

Main Result

Effect estimate: 26% increase in MIP in IMT group vs no change in placebo

Absolute Event Rate: 170.5% vs 136.1%

p-value: p=<0.001

A 4-week inspiratory muscle training program improves inspiratory muscle performance and vagally mediated heart rate variability in healthy young men, driven predominantly by respiratory mechanisms rather than baroreflex changes.

Limitations

  • Adherence to training protocol was self-reported with limited observation.
  • Spectral analysis used indirect rather than direct neural measures of autonomic modulation.
  • Central respiratory motor output was not directly measured, limiting mechanistic insight.
  • Unequal group sizes reduced statistical power.
  • No female participants included, limiting generalizability.
  • Smaller final sample size in the placebo group resulting from the exclusion of data due to signal loss and/or discontinuation during the 4-week protocol

Cite This Study

Gonçalves et al. (2026) conducted an RCT in Healthy young men aged approximately 26-28 years without cardiac or pulmonary dysfunction (n=22). Inspiratory muscle training (IMT) vs. Placebo training at 10% MIP was evaluated on Change in maximal inspiratory pressure (MIP) (26% increase in MIP in IMT group vs no change in placebo, p=<0.001). Inspiratory muscle training increased maximal inspiratory pressure by 26% and enhanced cardiac vagal modulation in healthy young men without changing baroreflex sensitivity after 4 weeks.

synapsesocial.com/papers/6997f984ad1d9b11b3452586https://doi.org/10.3389/fnetp.2026.1761610
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