Post-Exercise Controlled Breathing Enhances Cardiovascular Recovery and Autonomic Balance: A Randomised Crossover Study.

Background and

Objectives

Controlled breathing can influence autonomic regulation and haemodynamics; however, the role of its timing relative to exercise remains unclear. Materials and

Methods

Fourteen healthy, physically active men (mean age 21.8 ± 0.7 years; body mass index within the normal range) participated in this randomised crossover study. Each session consisted of five 5 min cycling bouts at 50% of heart-rate reserve, interspersed with 3 min passive recovery periods. The three conditions were: control (no structured breathing), 30 s hyperventilation (approximately 30 breaths·min-1) performed before each bout, and the same hyperventilation performed after each bout. Resting heart rate variability spectra (low-frequency [LF], high-frequency [HF]) were assessed pre- and post-session; arterial blood pressure was measured stage-wise; quadriceps muscle oxygen saturation (StO2) was monitored using near-infrared spectroscopy; and a discriminant co-integration index (Dsk) was calculated to integrate multisystem responses.

Results

Compared with baseline, LF power increased and HF power decreased after exercise in the control and post-exercise hyperventilation conditions (p < 0.05), whereas pre-exercise hyperventilation attenuated these shifts. Post-exercise hyperventilation blunted the rise in systolic blood pressure and reduced diastolic blood pressure compared with control (p < 0.05). Both breathing interventions accelerated StO2 recovery, with higher early recovery StO2 following pre-exercise hyperventilation and sustained advantages after post-exercise hyperventilation (moderate-to-extensive effects). Dsk values were consistently highest after exercise, indicating stronger and more coherent multisystem coupling.

Conclusions

In this acute crossover study of healthy young men, hyperventilation performed before or after exercise induced distinct short-term cardiovascular and muscular responses, reflecting respiratory-driven modulation of haemodynamic and autonomic processes. The timing of hyperventilation influenced these responses, suggesting that deliberate hyperventilation may acutely modify exercise-related regulatory mechanisms.