Objective: Evidence is accumulating, predominantly among clinical trials in adults, that yoga improves blood pressure (BP) control, with downregulation of the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS) projected as underlying mechanisms. This pilot study assessed whether Hatha yoga has the potential to reduce BP among youth and whether dampening of the SNS and/or HPA activity is a likely pathway of change.
Design: Thirty-one seventh graders were randomly assigned to a Hatha yoga program (HYP) or attention control (AC) music or art class. Baseline and 3-month evaluations included resting BP; overnight urine samples; and saliva collected at bedtime, upon awakening, and at 30 and 60 minutes after awakening for α-amylase and cortisol assays.
Results: Twenty-eight (14 in the HYP group and 14 in the AC group) students were assessed both before and after the intervention. BP changes from pre- to post-intervention were -3.0/-2.0 mmHg for the HYP group and -0.07/-0.79 mmHg for the AC group (p=0.30 and 0.57, respectively). Changes in systolic BP (SBP)/diastolic BP (DBP) for the prehypertensive (75th-94th percentiles for SBP) subgroup analyses were -10.75/-8.25 mmHg for the HYP group (n=4) versus 1.8/1.0 mmHg for the AC group (n=5) (p for SBP=0.02; p for DBP=0.09). Although no statistically significant group differences were observed with changes in SNS or HPA awakening curves (area under curve for α-amylase and cortisol, respectively), a small to moderate effect size was seen favoring a reduction of α-amylase activation for the HYP group (Cohen d=0.34; prehypertensive d=0.20).
Conclusions: A school-based Hatha yoga program demonstrated potential to decrease resting BP, particularly among prehypertensive youth. Reduced SNS drive may be an underlying neurohormonal pathway beneficially affected by the program. A large-scale efficacy/effectiveness randomized clinical trial is warranted.