Comparative Effects of Four Brief Breathwork and Mindfulness Interventions on Anxiety and Psychological Flexibility: A 4-Arm RCT

This four-arm, single-blind randomized controlled trial examines the effects of four brief daily 5-minute practices over 28 days on psychological flexibility and physiological variables in Spanish-speaking adults. Participants will be randomly assigned to one of four groups: Box Breathing, Cyclic Sighing, Mindfulness focused on exhalation with the syllable "AH", or Conscious Cyclic Sighing. Outcomes include state and trait anxiety (STAI), positive and negative affect (PANAS), psychological flexibility (MPFI-24, Psy-Flex), and physiological variables (heart rate, respiratory rate, heart rate variability). Assessments are conducted at baseline, daily during the 28-day intervention, at post-intervention (day 31), and at 2-month follow-up.

NCT Number	NCT07621042
Lead Sponsor	Valencian International University (VIU)
Conditions	Anxiety, Psychological Flexibility, Stress
Enrollment	240 participants
Start Date	2027-01
Primary Completion	2027-03 (estimated)
Study Completion	2027-05 (estimated)
Updated on ClinicalTrials.gov	2026-06-04