Longitudinal and Immediate Effect of Kundalini Yoga on Salivary Levels of Cortisol and Activity of Alpha-Amylase and Its Effect on Perceived Stress

CONTEXT Stress is defined as an alteration of an organism's balance in response to a demand perceived from the environment. Diverse methods exist to evaluate physiological response. A noninvasive method is salivary measurement of cortisol and alpha-amylase. A growing body of evidence suggests that the regular practice of Yoga would be an effective treatment for stress. AIMS To determine the Kundalini Yoga (KY) effect, immediate and after 3 months of regular practice, on the perception of psychological stress and the salivary levels of cortisol and alpha-amylase activity. SETTINGS AND DESIGN To determine the psychological perceived stress, levels of cortisol and alpha-amylase activity in saliva, and compare between the participants to KY classes performed for 3 months and a group that does not practice any type of yoga. SUBJECTS AND METHODS The total sample consisted of 26 people between 18 and 45-year-old; 13 taking part in KY classes given at the Faculty of Dentistry, University of Chile and 13 controls. Salivary samples were collected, enzyme-linked immunosorbent assay was performed to quantify cortisol and kinetic reaction test was made to determine alpha-amylase activity. Perceived Stress Scale was applied at the beginning and at the end of the intervention. STATISTICAL ANALYSIS USED Statistical analysis was applied using Stata v11.1 software. Shapiro-Wilk test was used to determine data distribution. The paired analysis was fulfilled by t-test or Wilcoxon signed-rank test. T-test or Mann-Whitney's test was applied to compare longitudinal data. A statistical significance was considered when P < 0.05. RESULTS KY practice had an immediate effect on salivary cortisol. The activity of alpha-amylase did not show significant changes. A significant decrease of perceived stress in the study group was found. CONCLUSIONS KY practice shows an immediate effect on salivary cortisol levels and on perceived stress after 3 months of practice.