*Article* **Impact of a Breathing Intervention on Engagement of Abdominal, Thoracic, and Subclavian Musculature during Exercise, a Randomized Trial**

**Petr Bahenský 1,\*, Václav Bunc 2, Renata Malátová 1, David Marko 1, Gregory J. Grosicki <sup>3</sup> and Jan Schuster <sup>1</sup>**


**Abstract:** Background: Breathing technique may influence endurance exercise performance by reducing overall breathing work and delaying respiratory muscle fatigue. We investigated whether a two-month yoga-based breathing intervention could affect breathing characteristics during exercise. Methods: Forty-six endurance runners (age = 16.6 ± 1.2 years) were randomized to either a breathing intervention or control group. The contribution of abdominal, thoracic, and subclavian musculature to respiration and ventilation parameters during three different intensities on a cycle ergometer was assessed pre- and post-intervention. Results: Post-intervention, abdominal, thoracic, and subclavian ventilatory contributions were altered at 2 W·kg−<sup>1</sup> (27:23:50 to 31:28:41), 3 W·kg−<sup>1</sup> (26:22:52 to 28:31:41), and 4 W·kg−<sup>1</sup> (24:24:52 to 27:30:43), whereas minimal changes were observed in the control group. More specifically, a significant (*p* < 0.05) increase in abdominal contribution was observed at rest and during low intensity work (i.e., 2 and 3 W·kg<sup>−</sup>1), and a decrease in respiratory rate and increase of tidal volume were observed in the experimental group. Conclusions: These data highlight an increased reliance on more efficient abdominal and thoracic musculature, and less recruitment of subclavian musculature, in young endurance athletes during exercise following a two-month yoga-based breathing intervention. More efficient ventilatory muscular recruitment may benefit endurance performance by reducing energy demand and thus optimize energy requirements for mechanical work.

**Keywords:** breathing pattern; breathing exercise; load; diaphragm; adolescents
