Deep Slow Breathing and Cardiovascular Changes After Moderate Intensity Training in Runners

Abstract

Background: Blood pressurAe and heart rate change after moderate intensity exercise, and controlled breathing may influence these cardiovascular responses. Evidence in recreational runners remains limited. 
Objective: To compare pre and post intervention changes in systolic blood pressure, diastolic blood pressure, and heart rate between runners receiving deep slow breathing and normal breathing. 
Methods: This nonrandomized quasi experimental two group pretest posttest study included 20 recreational runners, with 10 participants in each group. The reported deep slow breathing protocol used a 4 4 8 pattern for 5 minutes and was delivered across 8 sessions over 4 weeks. Within group changes were analyzed using paired tests and between group differences in change scores using independent tests, with nonparametric alternatives when assumptions were not met. 
Results: Systolic blood pressure decreased by 6.10±3.98 mmHg in the intervention group and 1.70±2.94 mmHg in controls, with a between group mean difference of −4.00 mmHg (95% CI, −7.69 to −1.11; p=0.012). Heart rate decreased by 9.30±7.13 and 3.10±4.31 beats/min, respectively, with a mean difference of −6.20 beats/min (95% CI, −11.74 to −0.66; p=0.030). The between group difference in diastolic blood pressure was not statistically significant (−2.40 mmHg; 95% CI, −5.62 to 0.82; p=0.135). 
Conclusion: Deep slow breathing was associated with greater reductions in systolic blood pressure and heart rate than normal breathing. Because allocation was nonrandomized and the source documents contain unresolved inconsistency regarding the exact measurement timeline, the findings should not be interpreted as definitive causal evidence or as a quantified measure of recovery kinetics.