For most people, breathing happens automatically and receives little attention in exercise programs. Yet a growing body of research suggests that the muscles involved in breathing can be trained much like other skeletal muscles, a concept that has also entered broader scientific and public discussion through practices such as the Wim Hof Method. A new randomized controlled trial published in Scientific Reports indicates that breathing training, specifically inspiratory muscle training (IMT), may improve respiratory function and aerobic fitness in sedentary adolescent boys.
Researchers led by G. Li investigated the effects of a 12-week breathing training program based on inspiratory muscle training in 41 healthy but physically inactive male adolescents aged 16 to 18 years. Participants were randomly assigned to either a training group or a sham-training control group while continuing their regular school physical education classes.
How the Training Program Worked
The breathing training intervention focused on progressively strengthening the muscles responsible for inhalation using a pressure-threshold device. Participants completed three supervised sessions per week, with each session consisting of three sets of 30 resisted breaths. Training intensity gradually increased from 50% to 80% of maximal inspiratory pressure over the course of the study.The control group followed the same schedule but trained at a very low resistance level that was not expected to produce significant physiological adaptations.
Significant Improvements in Respiratory Function
Before and after the intervention, researchers measured several indicators of respiratory performance, including maximal inspiratory pressure, peak inspiratory flow, forced inspiratory volume, forced vital capacity and maximal expiratory pressure.
After 12 weeks, the breathing training group showed significantly greater improvements than the control group across nearly all respiratory measures. The largest gains were observed in inspiratory muscle strength and airflow-related variables, suggesting that the participants became more efficient at generating force during inhalation.
Better Endurance and Faster Recovery
The researchers also evaluated aerobic fitness using the Yo-Yo Intermittent Recovery Test Level 1. This assessment provided estimates of maximal oxygen uptake (VO₂max), total running distance and post-exercise heart-rate recovery. Participants in the inspiratory muscle training group achieved higher estimated VO₂max values, covered longer running distances and demonstrated faster heart-rate recovery one minute after exercise compared with the sham group.
Importantly, the study estimated rather than directly measured VO₂max, meaning the findings should be interpreted as indicators of improved aerobic performance rather than definitive proof of changes in maximal oxygen consumption.
Why Stronger Breathing Muscles May Matter
According to the authors, more efficient inspiratory muscles may reduce the energy cost of breathing during exercise. In theory, this could help delay respiratory fatigue and allow a greater proportion of blood flow and oxygen delivery to support the working muscles of the limbs. These findings support the broader concept that breathing training may enhance respiratory efficiency during exercise, potentially reducing the energy cost of ventilation and improving overall endurance performance in active and sedentary individuals.
Some researchers have proposed similar physiological mechanisms to explain certain adaptations reported in intensive breathing practices, including those popularized by the Wim Hof Method. While the present study does not investigate such practices, it supports the broader idea that respiratory muscles can adapt to training and may influence whole-body exercise performance.
A Practical Tool for Sedentary Adolescents
One of the most notable aspects of the intervention was its simplicity. Sessions lasted approximately 20 to 25 minutes, were performed only three times per week and required a portable respiratory training device. The researchers reported that the program was safe and well tolerated. by all participants. Because sedentary behaviour remains a growing concern among adolescents worldwide, the study suggests that breathing training could represent a simple, accessible complement to physical education programs for sedentary adolescents.
Read the full study here